Belt drive gear boxes

[bleeth]

This is continued from here:

http://www.talkshopbot.com/forum/showthread.php?p=108544&posted=1#post108544


Sound great Gerry. Maybe we can negotiate some improved pricing too with a combined purchase! I emailed an enquiry for complete kit price and also asked if they had any shop drawings to adapt from.

Torchmate uses one on their lasers which is an open design not too suited for flying woodchips. You can't see much in the picture (attached) but it gives an idea.

I just did a little calc for design purposes based on precision machining of the mounting plate and no "idler arm" using Motiontek parts with a 20 tooth small pulley and 60 tooth large pully to utilize their pre made up 600mm 120 tooth belt the center distance of the two shafts comes out to 196.53mm. This gives a belt length of 600mm which is their larges stock length.
That's like 7" and seems large to me. Mike's list called for a 150 tooth belt and I went with what they had that was closest to that. That's obviously not a critical number and I'm not sure what the issue would be if a smaller belt was used to bring the center distance down. If their 360mm belt were used then the center spread is 76.415. Thats only about 10mm between pulleys and could be too close for comfort but if there are no other physical constraints then the result is about as small as a gear box you could go. For the 400mm belt the spread is 96.455 and that yields 30.6 in between pulleys

[danhamm]

Have you looked at the R&P design at this fella's site, I purchased 12 of his linear bearing slides to play with. good to deal with..

[gerryv]

Hi Dave, Yes, It should be cheaper for two or more sets because of the prep work and setup costs being spread. Maybe some other guys might be interested as well if they come across the thread.

I'll dig around my files on my home computer when I get back as I think I recall saving some images of these things. my gut feeling is that having them on an angled pivot and spring is to allow for self-adjustment for wear of the rack/pinion to eliminate increased backlash over time. Also perhaps to soften the blow, so to speak, in the event of crashing the hard stops.

As my original post stated, I'm also seriously considering a 5' wide new machine instead of going this route. Although Brady's comments were well received and give me more confidence in risking that kind of additional cost, I was surprised that there was only one response from an owner of one of these new units. Maybe everyone is richer than me and buying Alphas these days! Then again, maybe the economy is so worrisome that no one is buying :-(

Gerry

[gerryv]

Hi Dan,
Yes, I took a look following your recent post. Thanks. They could prove to be an option if I decide to widen my current table and gantry to 5'.

I've just finished grinding my rails using an old machinists trick so I'm hoping that I won't need to add new rails at least on the long X axis.

[bleeth]

Edited my last post below for a few calcs.
Dan-No I haven't seen that. It looks pretty interesting and the adaptation to a PRT looks almost no brainer. SB got away from the spring tensioner with the PRS due to the weight and force moments of the gantry. His Nema 34 set is a 2:1 reduction which would mean going back to the well for different motors than Mike suggests or getting different torque and speed results.

Something else I would like to incorporate in the new motor and pulley shaft design would be a keyway instead of just the flat grind. Could mean some post ourchase precision machining.

I'm out of town through Monday now but will see what develops here over the weekend!

[hh_woodworking]

Check here for belt reduction plates http://www.cvsupply.com/servlet/the-MechMate/Categories

[gc3]

Check here for belt reduction plates http://www.cvsupply.com/servlet/the-MechMate/Categories

ooohhhh no not another MM link :rolleyes:

[oddcoach]

Hi guys
I'm in for doing this too and i can make the plates and shafts needed.
i can put the key way in and press the bearings in. I will make some calls monday.
already have a design in my head.
John

[Gary Campbell]

Dave, John...
I have a VCPro file that I used to design a double reduction belt box. It fits the PRS bolt pattern and accepts the OEM OM motor. If you want to take a look, send ma an email.

[chunkstyle]

I would be interested in a 3/1 belt drive box as well. I just started drawing up the existing motor mount plates on my PRS to start prototyping a belt box design. I've read and re-read Mikes post over at MM on belt drives and I remember part of the discussion over how many teeth are engaged in the belt (belt wrap is what I think they were calling it) vs. distance between gears. More wrap being better. I'm wondering if that would be a limiting factor in the size of the box. Dunno.

[gerryv]

There are a number of them pictured in this long discussion. I got this from an unnamed 'botter but no, it wasn't Gene :-)
http://www.mechmate.com/forums/showthread.php?t=366

I think I recall reading somewhere on this forum that it would be a good idea to design them to use a larger pinion gear to improve messing with the rack - and maybe reduce backlash?

[gc3]

There are a number of them pictured in this long discussion. I got this from an unnamed 'botter but no, it wasn't Gene :-)
http://www.mechmate.com/forums/showthread.php?t=366

I think I recall reading somewhere on this forum that it would be a good idea to design them to use a larger pinion gear to improve messing with the rack - and maybe reduce backlash?

.5" wide rack 20 degree PA 30 tooth pinion...

if you do a imaginative google search you will find dxf files for a nema 34 motor mount/reduction bxs that will work with several different bot machines...

[wberminio]

Count me in also.

[Gary Campbell]

Guys...
I am attaching a layered DXF of the VCP file I was using for my belt box design. Note: This is not a completed project. It is simply layers of bolt patterns and shaft centers that may or may not be correct for your use.

This design was for 9:1 double reduction (3:1 twice) and was intended to have 2 layers of belts. The centers came off one of the websites that sell belts and pulleys and has an online calculator.

There is no additional info or support available. Confirm all dimensions.

[bleeth]

Well guys, looks like some great progress and info here. It's deep back into the daily grind tomorrow AM but hopefully in the afternoon I'll have a chance to collate some of the info posted here and sent in PM's. It looks like this one is turning into a group project and I think that's great.
To make sure all who want to help and/or benefit are on the same track I'd like to see if the following work as a few "standards". No rocket science here but just trying out baseline points to keep everyone on the same track:

1. Everyone plans on using NEMA 34 motors.
2. 3:1 is the common reduction size.
3. Some may be doing this on a PRT and some on a PRS which may mean a slightly different overall design but the motor mounting plate should be the same or adaptable to both.
4. Anyone who can't handle dxf I can do dxf to PDF conversion or Artcam Vectors but if anyone needs Vectric vectors we'll need another volunteer.
5. Design will include keyways for shafts which need to (obviously) match keyways in readily available gears or gears will also require machining.
6. All design and/or ideas here are open source. Parts manufacturing for others for a fee is fine. If/when it gets down to that let's remember that this is SB's site and be respectful. This is simply another "hot-rodding" scheme for older Bot's and nothing more.

All who want in send me an e-mail and/or PM with your e-mail address, phone, etc and I'll set up a database for off site info exchange. Lurkers welcome!

Dave

[wberminio]

Hey Dave
What's your email ?
You can count me in!

[br928]

Dave,

I would go with 3.6:1 ratio. That way all the unit value will stay the same as a 3.6 gearbox motor. Just use 72 and 20 tooth pulleys. That is 0.5 deg/step.

[gerryv]

My 2006 PRT Alpha, while relatively new to me, is turning out to be a very good machine. That said, it has direct drive steppers which limit it's resolution. whether or not I choose to go ahead with a new 5' wide PRS and sell the PRT, I think this upgrade could turn it into a heck of a machine. For this reason, I'd like to go ahead and commit. Although I have more time on my hands than the fellas that have to make their living on their 'bots, I'm also likely the least experienced in this group in terms of Shopbots specifically. How can I support moving this forward in addition to being prepared to buy a well thought out set of reducers?

[Dusty Knobel]

I have a PRT and am interested in your project. There is an interesting design sold for joe's hybrid cnc (http://www.cncrouterparts.com/product_info.php?cPath=24&products_id=65 ). This may be one you've already researched.

Dusty Knobel
Olympia, WA

furnituremaker hostedby live.com

[bleeth]

Good thought Stan. Worth considering assuming parts availability. Motiontek doesn't have 72 tooth pulleys but MSC may.
It's also not that tough to apply the math for correct Unit Values as long as the input numbers are correct. I believe the formula has been posted on this forum previously.
Gerry: Got the time to do some research?
Erminio: Left click on my name at the top of the post and you will have an e-mail option.
Regarding belt wrap: The closer together the pulleys are the more belt is in contact with teeth.
I'm thinking the gear box should be enclosed at least on all but the bottom. Any other thoughts on this?
I have seen that Dusty. It is done for smaller motors and shaft sizes.

[richards]

The higher the ratio, the larger the pulley.

Remember that the Y-axis pulley will extend below the spur gear.

A 60-tooth pulley is 3.8" in diameter (60 X 0.200 / 3.1416). A 72-tooth pulley is 4.58" in diameter. A typical spur gear is only 1.25" in diameter. On my PRT-Alpha, the pulley extended below the rail. That caused a reduction in the usable gantry clearance by more than 1-inch.

[gc3]

here is a source for 4.8/1 boxes

[chunkstyle]

Mike,

For those of us using a PRS standard with the newer control boxes and O.M. controllers, would the pk299 still be candidate for upgrading the motors?

[gerryv]

Dave,

Yes, for sure I'll make time available. I fully agree with you that this should be approached as a "hot-rodding" exercise, especially for older machines.

I'll also kick in a few hundred right away as I'm sure there's going to be some upfront costs that whoever is building them will need to bear. I'll contact you off-line in that regard. It could be considered as a downpayment towards my set if things proceed; otherwise an investment in learning.

In my case at least, I'd vote for them being built on a good milling machine by a skilled machinist to make sure they are precisely centered, sized, etc. I recall Mike addressed this as a potential issue after building his first set. I'm guessing that the fellows interested in doing this, like me, don't have something like a 7.2:1 alpha at their disposal to maximize precision, which is why we're doing it (chuckle).

I'm assuming steel might be the best choice but perhaps one of the very hard, machinable plastics like Delrin would work well also. I'm also guessing that some of the fellows who use their machines a lot would want good quality, replaceable bearings as well but I stand to be corrected in that regard. As I recall, decent bearings are not expensive but precise seating is important.

I also like the idea of going with the 3.6:1 so hope that would allow us to address the overhang issue Mike brings up.

[bleeth]

For those with a PRS but older 4G type control box the size of the gearbox is not an issue. It affects the PRT more.
I think the plate should be 1/4" aluminum at a minimum and actually lean towards steel with sides and top welded on. The back can be screwed to studs and for a PRS the front and back can have elongated holes to hard mount like the existing motor mounting plate and have tabs to mount with torsion springs like the PRT. This does mean 2 different designs. I haven't come up with a "one size fits all" concept yet. Anyone else?

Anyone into the math to work out the operational differences between the 3:1 and 3.6:1 based on Mike's suggested motors?

Gerry: You have mail.

Tim: I have no idea about the new control boxes. I expect it is doable but someone with more knowledge than I have would need to answer that one.

[gerryv]

Probably a naive question to the group but can one not just go with their existing 1:1 steppers and existing drivers and still get pretty significant improvement, especially in resolution? Mine are Vexta ASM911AA's. I imagine it would get pretty pricey having to replace those and possibly their drivers, especially being alphas. Just brainstorming.

[gerryv]

That's a real good point Mike. I just measured mine and there is 2.5" to work with from the bottom of the grey Y strut up to the rack, assuming full meshing of the teeth. anything more will hang down and reduce clearance under the gantry. I wonder if there is a creative way around this, assuming it's important to some?


The higher the ratio, the larger the pulley.

Remember that the Y-axis pulley will extend below the spur gear.

A 60-tooth pulley is 3.8" in diameter (60 X 0.200 / 3.1416). A 72-tooth pulley is 4.58" in diameter. A typical spur gear is only 1.25" in diameter. On my PRT-Alpha, the pulley extended below the rail. That caused a reduction in the usable gantry clearance by more than 1-inch.

[bleeth]

Gerry:
As I recall Mike did do a 3:1 gearbox on his older Alpha. I'm a little hazy on it but I believe it depended on wether you had 4 or 6 wires coming from the motors whether you could wire them half-coil or not. The primary baseline for most of us is in the case that we have older geared standard motors and a Gecko control box. The ideal change would be tapered hob geared motors but they are not available in weight that is needed. Therefore the belt drive / heavy 1:1 standard motors combo serves 3 purposes. High torque, increased cutting speed and high resolution. At this time we have much lower torque and speed, but the resolution on the standard is actually better than the the first Alphas. They had torque and speed.
If you cannot wire your Alpha motors half coil then the gearbox will slow you down but you would get better resolution. You probably won't lose much, if any, cutting speed due to the speed restrictions inherent in the design of the PRT Gantry. That is why I changed my gantry last year to the PRS style and redid the x rails to hardened steel on aluminum bar stock and extrusion. I guess I have close to a few thousand in it. If I could afford it I would just buy a new Alpha upgrade from SB.
All SB motors under discussion were customized by Oriental for SB. On the geared motors it was the use of a tapered hob gear reducing the backlash that you get on a straight gear motor. However, even those will develop backlash eventually. I have some of that now. The gearbox will not.

[gc3]

here is another dxf file for boxes...and a video of test run

http://www.youtube.com/watch?v=eKl5K0-1z5g

[br928]

After Mike's post and looking at my PRT, a 72 tooth pulley will extend below the gantry and reduce the clearance. However, the way I mounted my spindle the collet nut is below the gantery by about an inch also when the Z is completly retracted. At least in my case I can stay with the larger pulley. No reason the X axis can't be 3.6:1. The larger pulley there is no problem.

[bleeth]

I located the "how to" determine Unit Values and will make it available with the rest of the info I am collating. The difference between 3.6:1 and 3:1 is pretty small performance wise but obviously should make the SB unit values work as long as you also use a 25 tooth pinion. No guarantee you won't have to tweak them a bit.
Quite a few people have used 1/2" aluminum plate for their boxes and some have reported no issue with having them open sided. With shop employees around I'll definitely close mine off.
I also found Mike's report on his original 3:1 gearbox for his 1:1 Alpha. I didn't see anything about the actual changes to operating speeds but he did make clear that resolution was much improved and made it "the cnc I wanted in the first place". There was input from Ted in changing the motors stepping rate from 1000 to 500. This is done in the drivers.
From what I picked up the motor should definitely have some adjustability for mounting and tightening the belt or alternately a roller bearing pushing against the outside of the belt to hold tension. An advantage of using 1 or two opposing rollers is using a longer belt and having more of the belt engaging the smaller pulley.
One way or the other since there is an adjustability factor in there the parts can be cut on your own machine that way.
Heavy Acrylic was used by some but I personally won't. After all, the motors do get warm and even heavy aluminum isn't that tough to machine on the bot.
On the PRS you have all the room in the world for either gearing. To me the next issue is definitely seeing if pulleys can be located with factory keyways. If anyone does end up with flattened shaft and allen screws plan on making sure you seat them with loctite or you will regret it and use 2 for each pulley and/or gear.

[richards]

Tim,

My personal preference would be to order the PRS-Standard without motors (if possible) and then to add some PK296-F4.5A or PK299-F4.5A motors driven by Geckodrive G203v or G201x stepper drivers. The PK296-F4.5A puts out 440 oz*in holding torque when wired parallel. The PK299-F4.5A puts out 880 oz*in when wired parallel. With a 3:1 belt-drive, the smaller PK296-F4.5A would have 82 in*lbs of torque - or exactly what is published for the PRS-Alpha motors. It would also have basically the same resolution. The PRS-Alpha has 1,000 steps per revolution and the G203v has 2,000 steps per revolution. The Alpha has a 7.2:1 gearbox. The PK296-F4.5A could be fitted with a 3.6:1 belt-drive - meaning that the resolution would be the same.

The PK299 motors are larger and heavier, but they have 2X the holding torque - which probably would not be needed for most applications.

I've driven both the 296 motor and the 299 motor at over 100,000 pulses per second, which is probably 3x faster than the Shopbot controller can send pulses. Both motors had no trouble handling those high speeds (3,000 RPM); however, practical speeds for a stepper motor driving a belt-drive transmission on a CNC router are more like 500 RPM, which is about 16,666 steps per second - well within the capability of the current Shopbot controllers.

I have absolutely nothing against the RBK motors and controller, but I like simplicity. I have used many different 'packaged' solutions from Oriental Motor for over twenty years. All of them worked very well, but I've never found any of their 'packaged' motors/drivers that outperformed a well-matched PK29x motor and the proper Geckodrive stepper driver. My theory is that if things are kept simple, then normal replacement will be inexpensive and easy.

Not everyone likes to play with electronics. Not everyone likes to build their own belt-drive transmissions. Not everyone is comfortable with buying a partial machine and then adding electronics to it. For those who get nervous about 'tinkering', Shopbot has an excellent solution at a realistic price; but for those who want an Alpha class machine at a Standard price, the PK296 or PK299 motor is a realistic alternative.

[fozzyber]

I like this idea, I just bought a PRT standard and it has the PK299-01AA direct drive motors, the system does what I need it to do, but it does feel abit under powered, and the finish cut could be much better.
I know I need to upgrade to G4 controller, but this belt drive system would improve the system resolution, while retaining my motors.
Where do we go from here?

[bleeth]

Jerry:
I am working on a gearbox design for my PRS Style frame and others arre working on a design for a PRT. So far no-one has come up with pulleys and shafts that are readily available with keyways already machined.
Stay tuned for further developments. Some of us work for a living too!

[br928]

I think it will be easier to mill flats on the 1/2" shafts. I have not seen off the shelf XL pulleys with keyways.

[gerryv]

I've not yet come up with any keyed ones yet either. It kind of surprises me that they're not seeming to be readily available. I did find this info for those that are not fans of flats and set screws. I know nothing of the product but maybe someone else does?

SDP/SI say this about their timing and similar pulleys:Shaftloc® is a simple two-piece keyless fastener for mounting mechanical components onto a shaft within seconds. Due to its asymmetric thread geometry, a large radial clamping force is produced when the nut is tightened. These precision fasteners are vibration resistant and offer infinite radial and axial adjustments and are suitable for high-speed applications.

[gerryv]

Oops, I clicked too soon a posted. I meant to add that I think MISUMI USA may have them but I've not managed to figure out their catalogue structure yet. Anyone else know about them?

[bleeth]

I concur that milling flat and using set screws is an easier way to go, The Oriental Motors also come standard with 2 flats. I just see too much chance of failure with those (having already dealt with it). I figure if it has to be custom machined the couple of hundred bucks it may take is still not much for the added value and protection. Blow out one piece of heavy acrylic and you will wish you had spent this.
This blog post from Misumi seems to confirm it:

http://www.misumiusa.com/blog.aspx

Their catalog may call for a call to their distributor!:
I called and got part numbers for the pulleys:
20tooth: ATP20XL050-B-NUF ($19.70 ea)
72 tooth ATP72XL050-B-NUF ($44.90 ea)

These are aluminum clear anodized with hub.

On page 1107 of their Metric 2010 catalog.
Belts are on page 1177 of the same catalog
Shafts are on page 201 of the inch 2009 catalog

This looks like our deal Gerry!!

[br928]

Good find with this supplier.

Any advantage of the aluminum over the carbon steel material for the pulleys? Seems like you could get the set screws tighter with steel material without fear of stripping the threads.

Dave, Did you get a copy of their catalogs? I didn't see where you could download them in pdf format.

[bleeth]

Stan: I had the Customer service rep help me find the catalog pages through their on line PDF viewer:

http://us.misumi-ec.com/pdf/fa/PDFViewer.html?catalog=Metric&page=88

Seemed quicker than ordering catalogs. If yo9u want to order full catalogs here is the page to do that:

http://us.misumi-ec.com/contents/catalog/

I would probably order hard copies if I were into a lot of development projects but for "green" sake since this is a limited project the pertinant pages downloaded is fine for me.

Discussion of aluminum vs steel is a good one but the pulleys I have seen in XL are aluminum. with the keyway and loctitie I don't foresee an issue. I built too many aluminum fish boats for Alaskan waters not to respect the material. Note on the shafts page the steel are chrome plated. That kind of takes the issue of dissimilar materials coming in contact out of the picture too.

Their front page has a link to a message regarding possible slowdowns due to the earthquake. As long as it is not too severe I can deal with it.

BTW: Wish I had realized you were in Baton Rouge when I was up there last year doing the Marriott-would have been nice to meet in person.

[Brady Watson]

If you get the steel pulleys you can tack weld or braze them in place - this avoids all kinds of problems screwing around with set screws etc. I had to do this on my mill. It doesn't take much to tack a pulley to a shaft & it isn't like you are going to be removing them on any frequent basis. If you do have to remove a pulley, a couple zings with a grinder and it's off again...

-B

[ironsides]

Mike, look for a PM in your Forum profile.

George Kelly

[danhamm]

I think you can get the gearing with keyed shafts from these folks..

[fozzyber]

Please, I don't want to stir the $*|t but it seems that finding keyed pulleys is very difficult....
It seems to me if a keyed shaft was really needed, would it not be easier to find? I'm not trying to start a war, I'm the new guy, and know the least, I'm just trying to bring up a different point of view....
If it needs keys it needs keys....
but if the torque is that bad, Why cant you just drill it and roll pin it?

[bleeth]

Dan:

The overall geometry of the timing belt pulleys is different from the spur gears at Rush although they may customize them. eg: a 20 tooth spur gear has a diameter of only 11mm while the timing pulley is much larger as well as a very different tooth design.

Jerry: Many of these are operating with no keyway. I just want to improve it. New bots are keyed now. It just makes sense to eliminate possible issue areas to me.

Thats too easy Brady!!;)

[ken_rychlik]

Dave, the alpha ASM 98aa t7.2 or t3.6 motors are keyed. The alpha asm 911aa direct drive has flats on the shaft just like the old std motors.

I don't have any idea about the new std motors they are using now.

I think all of the motors that you are trying to improve will have flats on the shaft. From that point on with the design, I agree that keys are great.

Make sure you find belts that don't streach. A friend of mine has an ezrouter with belts and I think his belt boxes have a lot of play in them. You can grab his powered up gantry and move it 1/8 inch very easy. Just be carefull that you don't introduce play into the system.

Good luck

[bleeth]

Yeah Ken: OM confirmed the PK299's and Pk296's's come with flats and we'd have to order many to get them customized by them with a different shaft.
The belts I have specified in my list are Kevlar reinforced.

For me at this point it's a matter of having a chat with my machinist regarding putting a key in the motor shaft and getting the design from my head to Cad.

I heard back from a machine shop I have worked with in the past. The job of putting a keyway into the motor shaft without dissembling the motor is doable by him. The "bad" news is he quoted $80/motor for 3 motors. Now that I know it can be done I'll look a little further for competitive quotes but I am moving ahead on final design based on keyways and a 3.6/1 gear ratio. It is now a question from me if anyone out there who is interested and wishes to proceed is also doing this for a PRS type frame. For all, if you have reached conclusions on basic components let me know and I will shoot for some cost savings.
Left to determine is the bearing to use and the final shaft design.

[fozzyber]

Will the pinions need to be keyed as well? ( I assume so, weakest link and all) what is the availability of keyed pinions?

[bleeth]

Easy-SB has them as well as many suppliers. Keyed spur gears are common.

[Brady Watson]

If you get 30T pinions, then availability is excellent - directly from ShopBot.

A length of shaft in a non-spinnig lathe, and a sharp tool will make short work of manually scraping in (poor man's broach) a keyway into the shaft, if you really want one...You can easily scrape off about .001-.002" per pass by just running the carriage back and forth with a sharp parting tool or similar. Same is true for a pinion gear itself if you want to put a keyway into it & nobody's got one.

If you were feeling particularly crafty, you could mount a lathe tool holder to the bot and do it via CNC with the shaft held down in v-blocks. You'd be shaving off metal until you got to the desired depth on the keyway.

As I said before...you really don't need a keyway (it's nice, but not necessary) - to mount any of these components to a shaft. I would weld the pinion to the shaft and then adjust it as needed in & out. Same with the pulley. Tack 'em on - see what works. You'll probably replace pinions once every 1 or 1.5 years if you actually use the tool enough, and breaking a couple of tacks on a shaft is easier than monkeying around for 6-months trying to find off the shelf parts with keys etc that match.

Also...don't rule out the power of a good shaft clamp coupler or pulley with clamp built in. Most can be machined for adjusting to shaft size and they hold like no tomorrow.

-B

[br928]

Dave,

Steel pulleys are available from MiSUMi. Just use a "M" prefix in place of the "A" in the parts you listed earlier.

[bleeth]

Stan: Stuff rusts here as fast as it does in La!! I don't mind the aluminum there since at this point I've decided to use aluminum plate for the box. I don't know what you drive but in today's world the timing pulleys on your car could well be aluminum.

[fozzyber]

I think Stan was thinking about the threads on the set screws striping in Al.
v/s steel.
But if you are using keys, it does not matter as much.....
IF I wanted to use ground flats on shafts I would feel better with steel pullys, but with key ways Al should be fine....

[gerryv]

I'm guessing that one could choose either alum. or steel if the items are dimensionally equal. It seems all of the drawings and such would be identical. The fly in the ointment might be that the supplier would insist on either or but, from my years as an industrial supplier, we typically allowed mixed part numbers as long as the volume numbers were there - assuming that we were talking about non-custom, stocked items. That was a long time ago though, maybe things have changed so I guess we'd need to ask and maybe even push back a little if no - a sale is a sale in this economy.

[gc3]

I'm sure Mr Richards and others will remember these...

[bleeth]

Nice research Gene!

Regarding keyways: For those who have standards and are planning on using 20 and 72 tooth pulleys for a 3.6:1 the standard pinion is a 25 tooth with an OD of +/- 1.375. The 30 tooth is larger. Using the 30 would change your unit value requirement. They carry 25 tooth with keyway but Diane says they are listed as a 12 bore. I'll request from tech a true measurement. If it is 12 to make it easy to source pinions I would just have that end of the shaft turned down to 12 from the 1/2" needed for the pulleys or get the pulley in 12mm .

[br928]

I have had black oxide steel pulleys on my CNC plasma cutter for several years. No sign of rust yet. It sits next to a roll up door close to my ShopBot. We do have high humidity here. Now the ground rails on the Bot is a different story. I have to keep them clean and occasionally coated with T-9 to keep the rust at bay.

Bottom line. Simple solution (most cost effective) is to tack weld the pulley to the shaft as Brady suggest using steel. The steel does cost a few dollars more. If using keyways either material will work. The aluminum does look a lot sexier though. They even offer nickel plating if you really want it to shine!

[fozzyber]

http://www.talkshopbot.com/forum/attachment.php?attachmentid=11888&d=1301531650

is it me or do the side plates look really thick? like 1/2"

also what is the dia of the 72 tooth pulley?

[fozzyber]

also instead of bolting up 2 plates with stand offs has any one thought of using 2"x6" .25" wall thickness aluminum tubing as the carrier for the gears and motors?

[bleeth]

Hey Stan:
Chrome pulleys, polished plates, and racing flames!!

Yeah Jerry, those plates are 1/2" aluminum just like my spindle motor mount. No chance of movement or deflection and if you want to put covers over it easy to drill and tap the edges. Look at the side view and you will see the motor is "let in" a bit. The Misumi 72 Pulley OD is 115.92mm (4.56").
Are you thinking to use the tubing with holes as needed and the pulleys in the middle? seems to me 1/4" aluminum is too thin. There are times you may wish to tap it. not much thread in the wall and 1/4" is pretty flexible under stress.

[fozzyber]

Are you thinking to use the tubing with holes as needed and the pulleys in the middle? seems to me 1/4" aluminum is too thin. There are times you may wish to tap it. not much thread in the wall and 1/4" is pretty flexible under stress.

Yes, use tubing with the pulleys in the middle, I was thinking the box, would have less deflection and movement, than bolting it together. Just an idea....

[br928]

[QUOTE=bleeth;109033]Hey Stan:
Chrome pulleys, polished plates, and racing flames!!
QUOTE]

Now that gives new meaning to "hot rodding" your ShopBot!

[bleeth]

Now if I can just figure out how to mount the 6-pack carbs and blower!

[br928]

Dave,

I don't know about the carbs but if you hook a electric motor or a PTO off your tractor to the blower, you can use it a vacuum source for the table. Just a thought!

[bleeth]

To all:

It's time to get moving. Below (or above depending on your viewing preferences) I posted a couple questions to assemble information for possible "group" purchasing. For the motors, if you need them, and the pulleys and bearings and also shafts I need to know who is in for what parts.

For me I am going with the PK299's and aluminum pulley's and I will make the motor mount adjustable so no idler is necessary. I am having all parts with ANSI keyways and will use 1/2" aluminum for the plates. I will use 3.6/1 (72 tooth and 20 tooth pulleys and reinforced belt)

E-mail or PM to me with your info.

Thanks;

Dave

[gc3]

another set of 3:1 gear boxes...

the design and supplier source is out there for all...

[gerryv]

Neat; I've been wondering whether the Z could be done with a belt as well. Thanks much Gene!

[gc3]

Neat; I've been wondering whether the Z could be done with a belt as well. Thanks much Gene!

parts for xy along with z bx view

[bleeth]

Those who let me know they wanted to be kept up on all developments and/or want to participate in possible group purchasing and I had e-mail addresses for have been sent a link to an online google doc spreadsheet that you can fill out.
If you did not receive the notice and would like to be added to the list then send me your e-mail address.

Gene: Keep going guy-you are making my design work easier by the day!

[gc3]

here are keyed shafts you are looking for.

[bleeth]

SB stock of the 25 tooth pinion with keyway is a 12mm bore. So your shaft, pulley's, and bearings for this part of the box can be sized for that from the getgo and then when you need pinions just order them there or you can have a 1/2" shaft turned down at the pinion end to accomodate that and use 1/2" bore parts for the rest.

The PK299's and PK296's both have 1/2" shafts so the easiest thing there is to use a 1/2" bore small pulley (20 tooth).

I have been offered a unit value formula that is reportedly dead on (and this source I believe totally) for any combo of parts. So for those who, for example, find the size of the 72 tooth pulley to large and therefore would rather use the 60 and have a 3:1 the only thing is to make sure the values are carried over when SB control software is upgraded.

[gerryv]

Is anyone else hoping to do their Z as well this way?

[Brady Watson]

Dave,
You can also just do it all with 1/2" shaft/bore components & use a 1/2" bore pinion. It takes very little work to mark 2 spots 90 deg off from each other and either shallow drill or buzz away an area with a Dremel & 1/8" end mill to create a flat suitable for seating a grub screw reliably.

1/2" bore pinions are WAY cheaper than 12mm ones with keyways.

The belt will snap before the grub screws fail, if properly seated in a pocket or flat.

-B

[bleeth]

My price comparison spreadsheet is still a work in progress. Some items I'd rather spend the money once on and have peace of mind. Your input is always welcome.
Now get back to work on the shop!!!!
I'm waiting for your "My new shop" thread. Hopefully I won't turn :confused: in the face waiting!!

Gerry: Leaving the z alone for now. Might change my mind for 3-d resolution later.

[gerryv]

Hi John & Others,

Just wondering if you're still thinking of building a set or for others? Is your machine a 1:1 PRT?

Mine is a 2006 vintage 1:1 alpha and I'm not quite sure which parts to order so if anyone else has a similar machine I'd be happy to hear about which parts you're ordering. I'm assuming/guessing I'd be using my existing motors. I'll plead the "geezer" excuse for being slow on the uptake here. :o

Also, anyone else thinking of doing their Z at the same time to improve 3D output?

[bleeth]

Gerry:
I am working on two gearboxes. First is the 3.6/1 and I may do a 3/1 if I decide the size of the large pulley is a pain. For each size it takes 2 different box designs for me: 1 for the x motors and a different plate geometry for the y. My designs are based on a PRS Frame and Misumi pulleys and belts and SB supplied pinion gears.

John told me he is working on boxes for the PRT frame. If I were you I wouldn't change motors either. Your plan on adding gearboxes is the way to go for you as the 1:1 Alpha motors have plenty of torque, it is just the resolution issue that the gearboxes will fix.

I'm not planning on changing my z motor at this time but you never know.

The purchase parts list can be pretty much the same for each.

At the moment I have the elevation of the x motor box done and am working on the section (side view).

Haven't decided whether I am going to cut my own plates or ask John to. Theoretically the bot should do it fine as is as long as I am gentle on the cutting. There is something comforting about having them cut on a mill though.

[gerryv]

Thanks much Dave, I'll keep an eye on things and just give me a kick in the behind if needed. I'm not in the same boat as some in terms of finding time on on hand or "gittin' 'r done" on the other hand as I'm just poking along in retirement ;)

[bleeth]

X motor box design is pretty much done. I have the pinion gears coming in to verify my "projected" sizing as there is no cad available. Two items left to engineer for it are the bearing and shaft. Leaning to a press fit bearing. If I use a flanged bearing it will move the pulley out from the plate and since there is "just enough" room to get the entire small pulley on the motor shaft without cutting a pocket in the plate that means less machining although it has to be more accurate.
The Y motor is more of a challange as the space on the z plate where the motor is mounted is only just as wide as the motor. Both the 60 and 72 tooth gears need more space. For the 72 tooth the center of the shaft needs to move a full inch. I will probably get out my handy dandy steel stretcher!

[bleeth]

Final parts selection for major components and shaft design is done. I will use the same design for the Y and just bolt a steel plate extension onto the z plate with a steel butt block to accomodate the wider width required. There is plenty of room to do the z and I am thinking of doing it at the same time just to keep things equal and make sure I have plenty of torque in it for the spindle with drill as well as resolution improvement.
The folks at Misumi have been very helpful but I did need to verify their info when it got down to the nitty gritty. The usual bit of ADDS from the service agent I was dealing with!
Upon final selection of nut and bolt sizes to hold it all together I will be ready to send plate design to toolpathing. The inside plate will take a flip operation but the outside one can all be milled from one side.
Modification of the design to accommodate it to a PRT with swivel and retaining toggle should be pretty straightforward.
FYI: Oriental is including shipping at no cost right now and first time orders at Misumi get a 30% discount.

[Brady Watson]

You're not done this YET ???!!! :D

-B

[bleeth]

How's the new shop comin Brady?

[Brady Watson]

Waiting on the 'lectric company...Meanwhile spending 40hrs a month commuting...

-B

[bleeth]

34's been my norm for years now-it does get old.

[bleeth]

The complete engineering and parts list is now complete for gearboxes based on PK299-4.5A motors and 3.6-1 gearing in a case constructed of 1/2" aluminum plate. It took longer than some may have expected as I did not want to shoot off partial parts orders and end up with extra shipping costs or do any of it in a "down and dirty" method. This design is to very exacting standards and includes keyways and keys for pulleys and spur gear, 2 hefty bearings press-fit into the plates, a precision stepped rotary shaft and 25 tooth pinion.
Standard SB unit values will work. Your 4 g board will need some minor modifications:
1. you may have to change your power supply
2. you may need to change your capacitor
3. You will have to change the resistors.

The above will depend on precisely what drives you have as well as the power supply and capacitors. For me, since my board was built by Dirk, the power supply and capacitors are sufficient. None of the three items are difficult to change or expensive.

I am poised to place the order for the parts for the first sets.

If you are ready, willing, and able, I will produce full gearbox sets ready to go. If you have a PRS the "extension plate" for the Y will be included. If you have a PRT the gearbox plates will be designed for pivoting and tensioning as your current motors do. There will be introductory pricing as long as your order comes fairly quickly.

The overall size of the box is 5 1/2" x 10 1/2. The pinion gear is approx 3 1/8 from one end and centered so you can get an idea of how it will mount on your machine.

For total pricing and any questions please e-mail me.
DaveR (at) professionalmillwork (dot) com

[Brady Watson]

Pics baby...I wanna see pics! :D

-B

[bleeth]

You'll have to wait a little while longer Brady: I'm giving folks who want in a few days to get back to me so the first parts order covers everyone. They'll save some bucks that way!!

[bleeth]

Well, as mentioned in another thread I was waiting on a few fence sitters to get it together and also to get through a project that we were in the middle of to finish. Fence sitters fell off and project about wrapped up.
Just placed order for all the appropriate parts from Misumi and Oriental.
I think Misumi is a great source. I got everything except the pinions (SB), motors, plates, and nuts and bolts from them at a very fair price. They are doing the custom shafts for me including keyways and all for $14.30 each less the discount. I'd love to see their automation equipment.
Scheduled to ship next Friday.
For the aluminum instead of trying to get "plate" I can get a piece of 1/2" x 6" x 12' flatbar from my local supplier, cut my parts a little overlength on a friends bandsaw, set up a flip ops jig and cut them to size on the flip cuts.

[gundog]

I am not as tech savy as most of you. I have a PRS standard machine built in 08. What if anything would this do for me?

Thanks Mike

[bleeth]

Mike:
That means basically your machine is similar to mine. I expect increased speed in cutting and jogging as well as additional torque to enable the addition of a "piggy back" drilling spindle.
Are your drivers Gecko's?

Motors came in and other parts should be shipping today.

[gundog]

Mike:

Are your drivers Gecko's?



I don't know how do I find out.

[knight_toolworks]

Mike:
That means basically your machine is similar to mine. I expect increased speed in cutting and jogging as well as additional torque to enable the addition of a "piggy back" drilling spindle.
Are your drivers Gecko's?

Motors came in and other parts should be shipping today.

I did not follow everything but I take it these are less then whats on the prtalpha's?

[bleeth]

Mike:
Open up your control box. You should be able to tell by just looking at them. If they look similar to this:

http://www.geckodrive.com/product_thumb.php?img=images/G202 Website Picture.gif&w=90&h=80 (http://www.geckodrive.com/g202-p-48.html)

Then they are Geckos.

Steve: It depends. The first PRT Alpha's have a straight drive and resolution was less than many expected. Mike Richards built his gearboxes years ago specifically for his PRT Alpha. Much cleaner cuts was the result. If you have geared Alpha motors then this would not be an appreciable improvement.

[bleeth]

A little more on drivers.
I have a custom control box built with Gecko 202's set up to run SB Oriental Motors standard series . To run the PK 299's I am changing to I need to change the resister. On stock Gecko's (202 or 203's) this is really easy. If you have a 4G board from Shopbot then the Geckos may have a date code written in the little yellow box that starts with "SB". In that case the resister is hardwired on the board and will require changing there which is a little tougher, but not much. Marcus at Gecko is very helpful. You also may need to upgrade the power supply and/or the bridge rectifier and/or the capacitors.
Fortunately the electronic experts out there can give specific answers as long as the specific information needed is given.
The power supply is the big dougnut looking unit and the rectifier is the box wired to it that is around 1 1/2" square.
I have not done any research into possible modifications needed to the control box resistors or any other changes for other SB drivers.

This is a capacitor:

http://RSK.imageg.net/graphics/product_images/pRS1C-2266190t98.jpg (http://www.talkshopbot.com/product/index.jsp?productId=2103624)

This is what resistors look like:

http://RSK.imageg.net/graphics/product_images/pRS1C-2160256t98.jpg

And this is a bridge rectifier:

http://RSK.imageg.net/graphics/product_images/pRS1C-2160493t98.jpg

And just not to leave anything out this is a power supply (transformer):

http://www.parts-express.com/images/item_standard/122-640_s.jpg (http://www.parts-express.com/product/ProductImageZoom.cfm?partnumber=122-640&productimage=122-640_L.jpg)

None of these parts really cost much at all even if you do have to change them all.

[gundog]

My control board says PRT V 4.17 part 001740 and they look a little different than your picture I will take a picture and post it.

If this upgrade would give me smoother cuts I would be interested I am not that worried about increased speed. I cut UHMW & HDPE plastic and some of the cuts could be better. I currently make a 4" roller out of 1.25" UHMW that I have to cut oversize and turn on a lathe because the surface finish is unacceptable it would save me some time if I did not have to finish on a lathe I make 100 of these every 4-5 weeks.
Mike

[gundog]

Here is a picture of my control board.

[Brady Watson]

Here is a picture of my control board.

Mike,
It looks like you already have the latest version of 4G controls. Your machine should be equipped with 3.6:1 motors. The 3:1 belt reduction is really intended for machines with 1:1 drive motors. If you added 3:1 reduction to your 3.6:1 gearbox motors, you'd have a total reduction of 10.8:1 - which will seriously limit your top speed, at the expense of a minor "practical" improvement in edge quality.

The difference in step resolution between a 7.2:1 Alpha and your 3.6:1 Gecko box is about 25% - 1833 vs 2482 UV on XY. It's not a huge difference, but enough to add some improvement on edge quality.

Question: Are you finding that your edge quality is the same as when you 1st started cutting with the tool - or has it degraded over time?

Pinion gears don't last forever (especially if you don't lube your racks) and they directly affect your cut quality and amount of 'chatter'.

-B

[bleeth]

Brady:
You are certainly correct that the belt gear box is not made to be added to a geared motor, but rather to a 1:1, BUT, the idea for a standard is to replace the 3.6:1 motors with 1:1 motors and add the gear box. The result is not only increased speed in jogging but torque as well allowing faster cutting speeds.
For example, the current (latest) PRS Standard is not reccomended to add a drill as the motors don't have enough torque to handle the mass load.
For old Alphas with the 1:1 motors then it is to add the gearbox to the existing motor. Result: Better resolution.
The nice thing about doing it to a PRS standard is the construction of the gantry allows the higher cutting speed without sacrificing quality.
So what it would do for Mike is increase speed and torque but he would have to replace the motors as well. Although I haven't checked a newer 4G specifically, he would also probably have to change the resistors, and possibly the other items I mentioned below.
All need to remember that I still maintain in total agreement with Brady that this improvement is NOT the equivilant of an Alpha.
Remember what brought me to this:
1. Started with a PRT purchased slightly before the first Alpha's came out.
2. Added Gecko control box about 2 years later and incresed jog speed from 4 to 10ips but only increased cutting a little due to the limitations of the gantry.
3. Rebuilt the gantry about a year ago and decreased jogging to 8 ips but increased cutting from 1.75 to 3 ips.

All the above numbers are based on using 5mm to 3/8" bits in plywood/particle board and doing all required to maintain accurate sized parts that require no edgesanding before banding.

The decrease in jog speed in step 3 above is due to the torque restraints of the standard motors, which are the same now as they were when I bought them. I anticipate being able to increase my jog to around 12ips (or maybe more if I'm lucky) and cutting to around 6-8ips with the new rig. My current resolution is just fine and in fact always has been. It has always been about cutting more parts faster and adding an additional tool to the gantry.
An item to remember: If one adds the dollars and time spent in design, engineering, and reconstruction of my machine over the years, including what I am doing now and the next step of a drill or second smaller spindle hung off my current spindle I may not be that far ahead of having sold my machine and simply buying a newer Alpha. Doing it a bit at a time and the knowledge gained along the way has been and remains fun as heck and rewarding as well.

[gundog]

I don't care about speed I am not running my machine to max now I would like to improve cut quality what would be my best move to do that? Most of my cuts are 2 IPS or slower. Sorry if this is getting off subject.

Mike

[bleeth]

Mike:
I sent you a PM.

Dave

[gundog]

All my racks and pinions are adjusted this is the same results I got cutting these from day 1 I have tried different speeds and feeds. The cutters I use are special designed for soft plastic from Onsrud. I have given up on getting a smooth finish and just cut them oversize and turn them to final size. Some of my other cuts are also not as nice as they could be would upgrading to alpha motors make a difference?

Mike

[richards]

I never had a lot of success cutting plastic. Using a cutter specifically designed for plastic at the manufacturer suggested feed and speed gave me the best results, but they were still far from ideal, i.e., lots and lots of handwork.

I got basically the same rough (chatter) marks on my PRT-Alpha with non-geared motors, my PRT-Alpha upgraded with a 3:1 belt-drive and my PRT-Alpha that had been upgraded to the 7.2:1 geared Alpha motors when cutting plastic.

There is also a lot of misunderstanding about stepper motors, particularly the PK299-F4.5 with belt-drive vs the Alpha 7.2 geared motor. The PK299 motor is larger and has more holding torque (880 oz*in when wired parallel). With a 3.6:1 belt-drive, that will give you 3,168 oz*in holding torque, or about 200 lb*in. The Oriental Alpha motor is limited to about 80 lb*in.

The PK299-F4.5 will easily spin at 1,000 RPM when powered by a 45 VDC power supply. Using a 30-tooth pinion gear, that means that the axis is traveling at 21 ips. (Oriental Motor recommends a maximum gearbox RPM that would give 20-IPS for the Alpha.) Running the motor at 1,000 RPM requires 33,333 pulses per second. I use Mach 3 on my test bench which allows me to run at 45,000 pulses per second without doing anything special. I BELIEVE that the Shopbot controller can handle 30,000 pulses per second, but I have not tried it.

Resolution for a PK299-F4.5 geared 3.6:1 is exactly the same as the Alpha geared 7.2:1. The Geckodrive G203v requires 2,000 pulses per revolution. The Alpha requires 1,000 pulses, so the Alpha moves an axis 2X farther per step, which also means that its 7.2:1 gearbox gives the same distance per step as a Gecko drive driven 3.6:1 gearbox.

You lose the Alpha MODE capability of the Alpha motors; however, with 2.5X more torque, you shouldn't need the Alpha mode if you use similar speeds and feeds.

The PRS-Standard is a fine machine and so is the PRS-Alpha. Both will give amazing results if you, the operator, do your part. If you have a Geckodrive equipped PRS-Standard, you can add belt-drive, new motors, and a 45VDC to 50VDC power supply to give you a machine that will give the PRS-Alpha a run for the money.

NOTE: At 50VDC, the PK299-F4.5 motors can run HOT, too hot to touch, so be careful. Those motors are rated at 80-Centigrade, so they can handle the heat, but your skin will blister if you touch a hot motor.

[bleeth]

Mike:

Every time you post I learn something!!
Theoretically the comparison between the added gearbox and the built in Alpha one should be valid but couldn't backlash come into play? Although the Tapered hob gears cut way down on backlash from straight gears over time they still will develop increased backlash. I spoke to Oriental Tech about this as I had always been under the impression that on the TH Gears they either self adjusted as the gears got worn or could be manually "tightened". They said no and when backlash becomes an issue then the fix is to replace the motors.

On another note the parts from Misumi shipped Friday. Although the 30 percent first order discount is given unless you open a credit account directly with them it comes in the form of a credit to use on another order and is usable for 1 year after issuance. Frankly I think I am way ahead anyway just by having the custom shafts done by them at way less then anyone could machine them for and I expect to be ordering more from them soon as their catolg has lots of linear actuator components as well and I'm starting to think about building a flatbed laser. Lots lighter frame and motors needed for that!!

[richards]

Dave,

Yes, mechanical gearboxes can have backlash, but so can belt-drives. It is impossible to have infinite tension on a belt-drive, so a belt that is too loose can also cause backlash. Most belt-drive designs have tensioning slots cut into the motor mount to allow you to adjust the belt's tension.

Also, the Oriental Motors with the TH gearbox are MUCH more compact than the PK299-F4.5 motors with a belt-drive transmission.

On my PRT-Alpha, the belt-drive extended below the Y-axis sufficiently to affect the height of material that I could cut; but, because the thickest material that I cut was less than 2" thick, that was not a problem.

Sometimes it's best to make a chart that lists the positives and negatives for each type of transmission. That way, there will be no surprises.

[roney c]

Hi all, it's been quite a while since I last posted anything on the SB forum. I used to use my Bot quite extensively for my custom work (I'll try later to post some pics). But in the last 2 yrs. , my vision took a turn for the worst and 7 eye surgeries later I'm left with aprox. 1/3 of my vision left *(not complaining mind you). Additionally i might add that this past Wed the ladder I was up about 10' on slipped out from under me, OUCH! The good news is that *this past Dec. I was able to sell *my 9000 sqft bldg, and auctioned off 25 yrs of tools BUT NOT MY BOT. And thank God, because, as it turns out I can see the computer screen from about 4" away w/my left eye and distance ok w/rt eye haha! So I've just relocated my Bot in a business incubator in NYC, (where I moved to recently from the PA countryside to live full time with my wife -even longer story). That reason plus the fact that NYC is an easier place for a vision impaired person to get around in. Anyway, in addition to doing CNC work for the young adults who call this place (3rdWard) their "craft business home" , I'll bring in outside CNC work, plus I'll be teaching basic, mid-level and advanced CNC routing classes! *
* * *All this having been said, I have spent many enjoyable hours with my iPhone 3-4" from my left eye reading these threads and this one in particular, with rapt interest. You fellow botters who post on here are all so brilliant and creative that I'm concerned my problem with my Bot will be overlooked as too simple, but it's not so simple to me. Here's my dilemma: '98-00 *PRT96, PC-3.25, (held into the alum C-channel w/2 large hose clamps) PK299-01AA 1:1 w/IMS drivers. - It runs very rough (vibrates the frame) and causes a lot of artifact in the product, (didn't always though).*
* * I wanted to upgrade to either the $1400 gecko board or the G4 board because I wanted better resolution and better cut/run speed, as the fastest I can jog is 4ips and cut @ 2-3 ips. However after a lengthy talk w/Frank @ SB, he basically told me that these upgrades won't be of much help. Being impaired as I am I'm just GLAD that I have a place to go to possibly make some bit of a living, but, I only have so much $$$ to spend to improve my Bots' performance. What does the Bot hive suggest?
* * If you've not fallen asleep reading this tome Bless you * *,-)

[roney c]

Edit: Bot is younger than I thought prob 2001-2002 as it has
an angled steel rail and precision V Wheels---

[jerry_stanek]

I would start with new bearings in the router. I don't have the PRT i do have an older PR that I upgraded to the 4g board and it did make a big difference. For I am not limited to the 2000 lines of code before you have the wait to load the next 2000 lines that alone speeds up the cut. Also my values went way up so my cuts look better.

[bleeth]

Beyond that I would also get a more robust clamp system set up for the router. Not sure why Frank doesn't think the 4g would help. Due to the frame construction you probably won't pick up much cutting speed but you will pick up Jog speed and resolution.
Triple check all your alignments for square and level and mechanical connections for tightness. If your computer is that old you will need one with more RAM if you change to the 4G as well as a USB hub and high speed convertor. This change will also allow you to update your control software and the newer version is smoother than the old.
And of course check those pinions!

[roney c]

Jerry, what do you mean by "bearings in the router" ? The PC 3.25 router is brand new.*
* * Dave, what about my frame (all steel tubing and heavy "C" channel const. with square corner angle rails) are you suggesting, is keeping my speed down? *My computer was "state of the art" 6 yrs *ago, I know I know six years is Moore's law X 4.*
* * My steppers are PK299-01AA
Would this be the best possible upgrade:
A - 3 new pk299-F4.5A (for X and Y)*
what about Z axis?*
B - G4 upgrade, plus High speed converter (what is that for and where do I buy one for $$?)
C - New 1/2" pinion (how many teeth)?
D - new 1/2" racks (are these sold in longer than 6' lengths)?
E - New or refurb Dell dual core USB 2/3
D - Vee Rollers maybe hardened Vee rails
* * What are the obvious and not so obvious flaws in my *current plan?
Thanks!

[bleeth]

Assuming that all is tight, square, and true, the part of your frame that keeps your speed down when cutting is the Y Gantry, not the main bed. It just has trouble handleing the torque put on it by the cutting bit. The PRT bolted together frame style gantry was redesigned to the PRS style for this reason. When I put the 4-G box on my PRT jog went way up but cutting speed didn't increase that much as the gantry just couldn't handle a lot more.
Odds are your racks are fine. I don't see much point in 1:1 new motors unless your's have an issue. Note that previously in this thread the whole package that included the F-4.5's was to be done with gearboxes. My purpose was to get the torque necessary to increase cutting speed on my new PRS style gantry beyond standard speeds as well as get smooth resolution over lower torque geared standard motors.
Here is a link to Orientals comparisons of what you have and the F4.5's:
http://catalog.orientalmotor.com/compare/all-categories/pk-series-stepping-motors?plpver=11&categid=100&prodid=3001048&itemids=12144+12150&origin=keyword&pcat=mypage


Brady has posted quite a bit about playing with pinion gear tooth ratio's.

The high speed converter is to get from the serial port that limits com speed and is how the 4-g gets its info to USB and the hub seems to keep the signal clean as well. They are pretty cheap. As I recall I got one part from Tiger and another from Amazon. After install my com speed went way up and loss steps caused by this went away. It wasn't an issue until I upgraded SB software to a newer version that allowed much larger and faster transfers. Previous to that I used a high speed serial port for quite a while.
I also recommend for any new standard computer to follow the Black Viper route for cleaning out the garbage, particularly Dell's.

Bear in mind that my machine has a 5HP Columbo that has a lot more power and weight then the PC router.

You said "It runs very rough (vibrates the frame) and causes a lot of artifact in the product, (didn't always though)."
The question I have is when did that change?
If this is new after the move then I will stand for now on needing to verify squareness, tightness and levelness before committing to major changes on the existing gantry. I'd also take a close look at the pinions and make sure they are tight as well as not worn. They are cheap to replace and if it has run quite a while since the last change (machine time, not calender) you should pay attention to all the posts by people who were getting rough results and did fix it with replacing pinions they "thought" were fine.

[roney c]

Thanks Dave and Jerry,
I'm going in tomorrow and put her all back together as she was before thus move, and just do just what you guys advise. Square, square, square. Check and replace pinions if necessary (most likely). Locate and install a new PC router holder on her (any suggestions here)? I do notice through feeling that the Vee rails have some burrs through wear and am wondering if purchasing new 90 degree Vee rails and (4) matching 90 degree Vee rollers for my axis aprox $300 from http://www.imsrv.com/ and bolt them onto my current X rails.

[bleeth]

Sounds like you're just dyin to buy something!!
You can clean up your rails with a file. The thing I like least about what you wrote about your rig is the hose clamps holding the router. SB has a much more sturdy clamp for a PC and as long as you are staying with a router I would get it.

[roney c]

Dave, your first comment about wanting to buy something made me laugh so hard my cracked ribs hurt. Actually I want to sped the least amount that's necessary to put Bot back into like new working condition....so file it is first, then new pinions since they've never been replaced. So as far as the new control software from SB goes, can I use it with my PRT and what are the computer requirement? ...

[bleeth]

The newer software requires at the least a 4-G board or Alpha control box. The older boards will not run with the newest software. If you go to the control software downloads spot on the SB main site there is a link to the newest software you can run. 3.4.27PRT

http://www.shopbottools.com/mSupport/controlsoftware.htm

Always good to laugh!

[roney c]

Thanks Dave. Today I got the X&Y rails filed lightly and the carriages reinstalled and rolling smoothly, although the y carriage rails are bowed out aprox .01, causing a tad bit of tightness at the extreme ends, but today I will apply a bar clamp across the 20" span (after loosening the rail bolts in the center of the offending rail). We want a tight fit w/o any impinging of the carriage movement, correct? Should I be able to keep the horizontal Vee rollers on the Y car from spinning (by holding tightly) while pushing samesaid Y car slowly? Looking for a sense of fit.
Got three new 20 tooth 20 pinions and the PC holder ordered as well, thanks Shopbot Dianne.

[bleeth]

The test for wheeel is with the motors unplugged roll the carriage back and forth and make sure all are turning. The wheels that aim sideways act as the holdown and if they are seated right hard handpressure is enough and then tighten them. That design is one of the weakponts. some guys in the past made different modifications to eliminate them.
How come you didn't get a new z pinion?

[roney c]

My Z pinion looks great compared to the others, they were inexpensive enough to buy so I would have had no reason to not buy one for the Z if it needed one It's probably in good cop diction because i didn't do much 3D work? Well see maybe I'll combine it with another SB order. So Dave what's going on with the belt drive units that were being talked about made earlier in this thread? I've not seen pics and noone is posting comments?

[bleeth]

Almost the same time as I got all the parts together I bought a set of Alpha Drivers at a price I couldn't refuse. So now I'm putting together a control box for them and will go to the Alpha motors instead. Hoping to have it running by February at the latest.