Rack and pinnion

[David Fisk]

Has anyone tried using nylon pinnion gears on their shopbot? I've heard it can reduce a lot of vibration.
What about split racks with spring loading on one rack? I've never seen these but I was told that it can take out backlash.

[David Fisk]

Does anyone know of any sources for nylon pinnion gears? And spring loaded racks?

[danhamm@abccom.bc.ca]

David,
I have had pinion gears made, for other pieces of equipment.. "lasers"... they make a metal spline
insert that fits inside of the nylon gear..
Know saying that,you realize that the steppers can create approx 60 to 80 lbs of force, you only have a couple of little teeth trying to hold it..

Personally I don't think thats the way to go to
get rid of the harmonics involved..my 2 bits...

[David Fisk]

I got this idea from a guy who has been tinkering with cnc's of his own design for the last ten years. Do you have any ideas for getting rid of some of the harmonics? Maybe I should ask some gear companies to see how much they can handle. I really am shooting in the dark since I don't know much about these things.

[danhamm@abccom.bc.ca]

You mention vibration and backlash, they are two
different events, I have vibration on my PR at certain times moreso when using a carving application.. Backlash I don't have any problem
with that I know of..
What is the particular thing in your operation
that is causing a problem? the sound or is there
a measurable discrepency in some way..

[David Fisk]

Well as I mentioned I really don't know much about these things, so I have a lot of quessing that I do. I'm cutting small parts and each has very short line segments going around complicated curves. It is these short segments I believe is causing me many headaches because of the vibration they cause at the low speeds that I've had to use. The bits that I've been atempting to us are 1/32" in diameter and so any slight problem seems amplified on the small bits. I'm just trying to do what I can to reduce any vibration ect. As far as backlash I have no test of any kind. I wish I had new of some way to test for vibration and backlash so I could once put these things out of my mind. There is also the possiblity that my spindles are not true enough. I don't know what should be acceptable and what is not. I have between .002-.006 inches of run out on my chucked in cutting tools. This seems like it would be way too much for such a small tool, but once again I don't know. I've spent a pile of money trying different laminate trimmers to see if I could find a difference. I even went so far as to install precision bearings in one trimmer and it didn't do anything. It apears as though I can have different amounts of run out depending on "how" I put my collet in. I talked to one machineist and he said that he has the same trouble turning break drums. I wonder if the air spindles have as much runout. I'm very reluctant to spend any more money to find out though. . . .

[Wdyasq@yahoo.com]

A 1/32" bit is .03125". .006 runout is ~20% of the bit diameter.

Question, Would you run a 1/2" bit in a chuck with 1/8" runout? The ratio is almost the same.

One might be able to fake backlash control with a lightly and properly 'sprung' elastic tie-down. I can elaborate if necessary. Be sure and think about the 'slack' in the "Z" axis too. With bits as small as you are running, everything is critical.

Ron Brown - wdyasq@yahoo.com (mailto:wdyasq@yahoo.com)

If Stupidity got us into this mess,
then why can't it get us out? - Will Rogers

[danhamm@abccom.bc.ca]

If you can beg or borrow a dial indicator you can
measure the flex in your chuck, although using
1/32 bits I can't see you putting much stress on
your tool, you are using a laminate tool for your work? cuold there be some flex in the mounting?just using your finger or a rubber as apull weight if you have a
fish weigher even better..

For peace of mind you can "probably" write a little program in notepad to give a good indication of backlash, example move your x axis
in .001 increments positive and then negative
then in .005 increments each time moving your y axis to create a "V" mark..you should be able to see a discrepency if there is one..then do it too
you y axis the same..

Now chuck runout in my way of thinking is when you put in a 1/4 in. bit and it cuts a groove thats larger by .010 0f a in.
Chuck flex is when you can see a mismatch on a
corner cut where they join of .005
this can also be mounting flex or tool flex but it
all results in a mismatch..
Stepper vibration especially on small segment cutting at slow speeds happens because you have both axis moving at alternating turns, like your turn my turn to make a corner, this sets up the
harmonic..
Some suggestions: try running a little faster,I know that this seems contrary..but: also try changing the ramping for cornering.
Try setting your work higher so that you zaxis is
not under as much stress and has more support..
Also maybe you have to give up a little bit on size and go to a 1/8 in bit to accomplish your cut outs..

[gfacer@istar.ca]

To add to Dan's Message,

If you can get a dial indicator (cheapo ones aren't more than $30), you can use it to measure the backlash. move the machine into the dial indicator (a little, enought for tension), and then set the dial to zero. Now, either a) move it back slowly in .001 increments, the number of moves before it starts ACTUALLY moving in .001 increments is your backlash. OR B) (and my prefered method, as I have just been doing this) Move the machine back in .100 movements, and the difference in the dial (say it moved .095) and the required .100 is your backlash.

The dial indicator can also be used to measure the runout on the bit, although pretty difficult on that size. I believe air tools do have much tighter tolerances.

[gerald_d]

An extract from the current ShopBot specs:

Step Resolution: 0.002"
Repeatability: 0.005"
Positioning accuracy: +/- 0.005" to 0.015"

From this is deduced that the SB cannot be moved in .001" increments as mentioned above. Your screen may show it, but measuring anything better than 0.010" would seem to be a bonus after reading the supplier's specs.

[David Fisk]

I believe I've found the majority of my troubles. The wood that I used to build my table is very light. I started tapping on my shopbot x rail and noticed on the far rail there was much less vibration. I had replaced that side of the table due to breakage in my move to Florida with some Southern Yellow pine. When I tap on the edge closest to the metal rack it would bounce not unlike a "DIVING BOARD". So I will be either replaceing the bad side or glueing on some plywood and putting a extra 2x4 across the inside to make it more rigid. I sure wish I would have taken that machine shop class in High School! Thanks to all for the in-put. I really learn a lot from all the dialog on this forum. Thanks!

[David Fisk]

Does anyone know of any vibration reducing techniques they could shair? Would there be any value to wrapping the rails in felt? Or putting thin rubber or felt between the bolted steel parts? I have a bunch of felt and thought it might help, but I don't want to waist it. What about Using thick grease on the rack and pinnions?

[David Fisk]

What about something like undercoating spray for cars?

[Wdyasq@yahoo.com]

David,

Vibration control is an interesting science. Rubber mounts and 'vibration dampening compounds' only mask problems. To achieve true vibration control things like inertia and mass dampening need to be addressed.

High-wire walkers use a balancing pole, it doesn't make the wire any more stable. It changes the center of balance and makes it easier for the walker to control his body and therefore, the wire.

Improving rack to gear contact will help. Eliminating slack in bearings will help. Felt and undercoating will only make things seem to be quieter in my opinion.

Ron Brown - wdyasq@yahoo.com (mailto:wdyasq@yahoo.com)

If Stupidity got us into this mess,
then why can't it get us out? - Will Rogers

[David Fisk]

Ron,
Have you ever delt with lightening holes? I was told that by drilling a series of holes across a piece of metal that it will become more stiff then the original. I was thinking that perhaps I could add some metal with holes drilled in and bolt it to the x cross bracing and carriages etc. Or maybe I could even use wood. I don't know if the technique would work with wood or not.
I don't know how big the holes need to be or the spacing though, so it would be a real experiment.

[gerald_d]

David,

You are touching on very many subjects here and we could discuss these things for many hours and days, but I want to cut back on my posts to this board. Maybe just some pointers:

1. For static parts (table and x-rails) you can reduce vibration by increasing mass. The more stiffeners and less holes, the better.
2. Drilling holes in metal can never make it more stiff. (popular urban legend) If you remove material (reduce mass), you will always remove stiffness. (However, there is a very tiny chance that you will get less vibration because you have shifted the resonant frequency point, but extremely unlikely in a ShopBot)
3. For the moving parts, there needs to be a balance between mass and stiffness. Too much mass can overload the stepper motors when you try and accelerate the moving parts too fast. However, you seem to be doing tiny, low speed work on your ShopBot, and it would seem that you could add a lot of mass to the moving parts.
4. Putting rubber/felt in the joints will make the system "sloppy" and less accurate.
5. "Undercoating" for cars is intended more for noise and corrosion control - it will do nothing for vibration of a ShopBot.
6. Even if all vibration is totally eliminated, you still have a system driven by stepper motors and the step resolution is .002". The other specs are also re-printed above. Think carefully if you have purchased the right machine for the job. . . . . . . .

[Wdyasq@yahoo.com]

David,

Gerald touched a few of points of vibration control. And yes, I have drilled holes in material - for lightening, not for stiffness. There are some places one can remove material if stiffness is NOT the objective.

Mixing wood and metal in engineering is interesting. In fact any time materials of different strengths are mixed it is difficult to get both to work properly and together. Even the best of engineers have problems whit mixing high/low strength material in the same unit. Bonding, glue shear and fastener shear are just three of the problem needing to be addressed.

Enforcing what Gerald said about the mass/stiffness, I might try adding a chunk of weight firmly tied to the router. You might need to address the ramp settings.

Gerald is right on the many hours and days of discussions we could have. The solutions might not be as practical once we sober up.

Ron Brown - wdyasq@yahoo.com (mailto:wdyasq@yahoo.com)

If Stupidity got us into this mess,
then why can't it get us out? - Will Rogers

[David Fisk]

Thanks again for the input. It seemed kind of obserd to me that by removing material it would stiffen. But it was a machinist who told me so I just wanted to bounce the idea off on the board.
I think I can make the Shopbot do what I would like considering what others have done with it.
From a laymans standpoint I'm trying to improve what I can without getting too complicated. I've been banging on the rails with my hand, clamping MDF on and the rattling/vibration seems to dampen significantly. If anyone knew of a simple way to measure the vibration I could at least be a little more scientific about my analysis/experimentation.
So far the best improvement I've seen was from glueing MDF to the 2x10's far more then adding the 2x4 making it a sort of I beam. I hope that the information can save others a lot of trouble. This forum is great for that.

[gerald_d]

David, banging on the rails is a perfect way of assessing the stiffness by judging the natural frequency. You want your table to "hum" after a smack - if it just "shudders" (shimmies like a bad steering wheel), then it needs stiffening up.

Don't forget the diagonal braces to the legs, 4 in y-direction and 4 in x-direction. Fill in corners with gussets wherever possible.

[Wdyasq@yahoo.com]

David,

The MDF changed the resonant frequency just as Gerald mentioned in one of his points. If you are trying to make an "I" beam, plywood would be a better choice for the web than MDF or solid wood - I hate to get into too many engineering principles on this forum. BUT, as was stated, you are changing both mass and structure. The resonance WILL change.

Frequency analysis and vibration dampening is a complete branch of engineering. It would require sensitive data acquisition equipment and technical design time to scientifically 'engineer' a solution. The evaluation would be expensive.

Ron Brown - wdyasq@yahoo.com (mailto:wdyasq@yahoo.com)

If Stupidity got us into this mess,
then why can't it get us out? - Will Rogers

[David Fisk]

Gerald, thanks for the "hum" tip. I replaced the legs some time ago with reinforced concrete block. Which made a big differance. It seems like I am chasing a moving object. First it was the legs that were big vibration contributors then it moved to the wood sides. Now after reinforcing the wood parts the metal rails them-selves are doing the shutter. I think having a bunch more of those aluminum brackets would help a lot. The rattle is more evident near them then near the x strut cross braces.

Ron, thanks for the plywood tip. I had a bunch of MDF laying around that didn't work well with my vacuum clamping system so thats what I used. It was just glued to the inside and outside edge of the wood holding the x rails. I said I beam, but it was really a sideway "T" that was formed when I first attached a 2x4 to the inside of the 2x10. I think what I would like to do is get a metal I beam that would fit inside the utility strut to try and stiffen things up a bit. I'm guessing this would add sufficient weight at the same time, and maybe I could use some bolts to push the y carriage up to straighten it.

[Mayo]

David, if you're primarily experiencing the rattling when cutting or making very small movements, you might want to check your settings on the 4th parameter of the VT command. (the setting for ramp threshold angle)

Not sure if your manual is the same but it's described on page 80 in mine.

If your machine is trying to rapidly change speeds of the motors all at the same time, it may be a source of rattling because of ramp settings.

Also the 8th parameter of the VU command relates to the cutting of circles using ramp speeds. My manual states that circles with a diameter of .2" or less will be cut at ramp speed. You may or may not want to change the default .2" size circles and see if that changes anything.

Also, I had been advised to make ramp speeds about 60% of the move speeds. This helped make things less jerky over all.

[jim_melton]

My PRT96 that I got last Feb. was ordered with the steel table from SB. Other than the fact that the WHOLE table seems to lurch a bit when making sudden direction changes, I really don't have any of the problems that I see in these threads. I have noticed that the new tables from SB come with additional angled braces that mine didn't come with. And that would probably solve the lurch problem. As far as vibration goes, mine does have a rattling sound every now and then. I have tried finding the source, but am beginning to think that it might be the motor springs singing on the bolts. I haven't found anything loose that would cause it. I only notice my rattle when I'm doing an air cut. It doesn't affect the accuracy or function of my SB. Is it just me though, or does it seem that alot of the problems are on tools with WOOD tables?

As a side note:

My full time job is as a QA Inspector at a major aircraft turbine engine overhaul facility. A lot of you might be surprised as to what simple things such as coatings can do do dampen vibration. We have a 3.0" drive gear that would fail BIG & BAD if it wern't for a .030" thick plasma coating on each side. We also have gears that were failing in flight until they put a simple retaining ring out by the teeth. The ONLY purpose of the ring is to dampen vibration.

If you are having problems with the machine due to your vibration, then you need to fix it. If it's just bugs you to hear it, turn the router on or turn up the radio. :o)

[sheldon@dingwallguitars.com]

Jim,

That rattling sounds like it might be the rack vibrating against the strut or Y-rail between mounting points.

That's where most of my rattle comes from.

[sheldon@dingwallguitars.com]

David, I just read an earlier post regarding runout. It can be a pain, but where runnout is critical, you should dial in your collet by putting a mark on the arbor above the collet nut so that you can see it. Then install your collet with a length of drill rod or centerless ground shafting. Rotate the shaft by hand and check the runnout with a dial indicator. Loosen the collet nut and rotate the collet 1/4 turn, tighten and repeat untill you find the consistantly truest position. Mark the collet to line up with the mark on the arbor. Then always install the collet in the same position. It's best to be measuring the runnout at about where you expect your cutting edge to be.

Also, I found that at lower speeds, the steps are more noticeable and you can see it jump from step to step. I bought a new controller and the new higher res gear box steppers from Shopbot, but kept the smaller 20 tooth gears for a step resolution of about .001. It makes a big difference.

Gerald, would there be any way to hydraulically damp the steps?

This may be a really stupid idea, but if you are only going to be running a very low speeds, and keep your jog speeds low, you might try adding a sandbag to your Y car to add some inertia and damp the steps. There might be a sweet spot between too much and loosing steps and where you are now.

[gerald_d]

Hydraulic damping could be an option and it might be worthwhile to clamp in some old dampers from a motorcycle scrambler front fork (long stroke). . . . .

[David Fisk]

Thanks again for all the insites. I found another contributor to my vibration. My power supply is a switching type and I have the proper capacitor installed, but I thought I'd try a test. Since I don't own an O'scope to look at the pulses, I connected two car batteries in series and ran some air cuts. The results were much smoother then with my power supply. I think I might just hook up a battery charger and use batteries for a while until I can find a good linear power supply. Anyone know of a quality low cost linear power supply?

Gerald I'm not familiar with these dampers where would you clamp them?

[gerald_d]

David, sorry, but I'm cowardly going to sneak away here. My paying job is getting too far behind.

[Wdyasq@yahoo.com]

David,

Power supplies ARE available and can also be built rather inexpensively. You could find a local "Electrical Guru" to help with the design and building. Remember - ELECTRICITY CAN KILL YOU.

Many companies sell new surplus or used power supplies. ShopBot will probably supply you with a new one or advise what voltage and amperage is necessary. It is possible only a LARGE capacitor is needed to smooth your power problems.

Ron Brown - wdyasq@yahoo.com (mailto:wdyasq@yahoo.com)

If Stupidity got us into this mess,
then why can't it get us out? - Will Rogers

[flyboy]

Well, if you really want to mease vbration you need some equipment. I do vibration analisys on some tools here at intel and also for my airplane's propelors. The equipment here uses very acurate accelerometers and basically a recording occiliscope. If you have an occiliscope and play around with electronics you could make a simple one with a pen laser, mirror and a photosensor. And occiliscope. It's an idea. Or look and see how kids are making those sysmometers (don't have time to look up that spelling) earthquake thing you know. They use a soup can and string and measure sonic booms from the space shuttle. It should work for our shakebots too

[tucker-52@charter.net]

OK, I'm gonna stick my neck out here, knowing that it could well be chopped off, especially since I don't even have a SB yet. I'm still a wannabe, but I find the SB forum rather fascinating.
Talkin' about hum and vibration....you're gonna get that from just about ANY power tool, and a CNC is just that...a fancy power tool. Right?
OK, assuming (and we all know what "assume" stands for) that your tables, be them steel OR wood, are set up on a hard concrete floor....
think about that...there's nowhere for the vibration to be transferred to and absorbed by.
What would happen if you placed a piece of hard rubber, say 1" thick and 2 ft. sq. under each table leg? Remove the levelers from the leg bottoms for maximum contact and level the table with shims under the rubber. Fasten to the concrete floor with TapCon screws to prevent lateral movement. Well?
Ok, it's just a friendly idea from a future newbee. I know I gotta loooong way to go, so be kind.

[gerald_d]

Hi Mark, your neck is safe here! Welcome


Compared to high-end (mega$) CNC machines the SB can be called noisy. Higher frequency noise can be dampened with rubber on the floor. Our SB is steel table and free-standing on the floor - no lateral movement. The noise is not so bad that we have been tempted to slip rubber under the feet. (if we do get inclined that way one day, the rubber would be a lot smaller than 2 ft. sq. - maybe only 2"x2"x1/2"-it does not have to be bigger than the contact plate)

For wooden tables, I don't think that rubber would make any difference to noise.

My impression is that most SB'ers who talk about noise and vibration, do so because they don't get super-smooth cut edges. This slight roughness is then attributed to noise & vibration, which is only partly true.

Rubber under the table will do nothing for vibration of the moving parts or for smoothness of cuts. It may only (in some cases) reduce the nuisance to the ears.

[tucker-52@charter.net]

Thank you, Gerald, for not cutting my head off. I appreciate it.
I've been reading this forum to great length in all catagories because I'm going to be making a major investment (major for me!) soon in a new SB and I of course want every advantage starting out that I can get. Knowledge is power!(And profit!)
Rethinking the problems with noise and vibration, I have to wonder if the main problem stems from under-powered routers. My GUESS is that a lot of folks have opted to use whatever routers they had on hand or went for the 3 1/4 hp machines, and set their speed too fast and plunge depths too deep in order to crank out production as fast as possible. It's only natural to assume that if your router is straining and maxed out to cut your material, that it is going to cause vibration and a lot of noise, not to mention that your cuts will not be as smooth as they could be.

THAT'S why I'm leaning towards a 5hp Colombo spindle, single phase. Yeah, it's $3,750 compared to $350.00 for a Porter Cable or whatever, but it has a lot more torque and is much quieter.

Thanks again, Gerald, and any more input from you or anyone else is very welcome. You guys are why I'm going ShopBot!

Mark Tucker >tucker-52@charter.net (mailto:tucker-52@charter.net)

[bruce_clark]

Mr. Tucker,

I don't think that 95% of the people who use routers come even close to using the full 3.25Hp (or what ever HP their routers are). When you start breaking bits or your cutting bits tend to "bog" your router down, then you might want to look into a bigger motor, but 99.9% this condition can be adverted by changing your cutting strategy, not by purchasing a larger router motor.

Second, on the noise issue, I think that most people fail to take into account the actual noise of the cutting bit/work. Many times for me, this is actually louder (or as loud--depending on which router I am using) than the motor's noise. So, you may buy a whisper quite router to find that your shop is just as noisy. There are real and justifiable reasons for a Columbo/Perske motor, but I don't think it should be soley based on noise factors.

Just my personal two cents. I would get the Shopbot up and running and then find out if you really need the Columbo spindle.

Bruce Clark

[tucker-52@charter.net]

Thank you Bruce. Point taken. I may suffer from the "Tim Allen Syndrome"...if you know what I mean.

There are a couple of real reasons the Columbo looks attractive to me. The first is that a large part of my business will come (I hope) from smaller sign shops that do not have a CNC router. I'll be cutting a variety of materials but namely aluminum sheet, up to 1/4" thick, of various grades (read: hardness). There's not a whole lot on this forum that addresses that, so I'm thinking "better safe than sorry". Someone wrote about cutting 1/4" alum. and said that it took them 24 passes, I think, but they didn't specify
the router they were using or even if they were misting, to the best of my memory.

The second reason is that I'll be setting up shop in my Mom's basement (hey, it's free rent) and noise is an issue. The folks at ShopBot have assured me that the Columbo is many times quiter than a 3.25 PC, so that is shaping my decision as well. Then I read what you've had to say and I think, hmmmmmmm, don't you work for ShopBot too?

Any more input on this from you and anyone else will be greatly appreciated!

Mark Tucker

[ron_cleaver]

Mark,

What about insulating the ceiling of the basement to hold down the noise? There are many approaches to this, like regular fiberglass insulation, several layers of rigid insulation, or ceiling tile that has insulation attached to it.

[bob buttons]

mark it cost nothing to try the porter cable router. insulation is cheap! even going crazy with 10 layers is cheaper than one columbo. i have mine in my basement and it is loud but controllable. i have an isolation room that the bot is in packed with tons of insulation. it does the job fairly well. if you are cutting aluminum the noise of a bit hitting/cutting that will be loud period. so even if your router made zero noise the cutting noise will be there. plus any kind of dust collection system will add to the problem. my dust collector is almost as loud as my pc router no lie! by the way dont build a room for the bot til the bot is built! shopbots are not quiet in general just jogging around the table with the router off makes noise. it is a $6k machine expect noise for that price! lead screws with servo motors would help the noise but who wants to pay for them? good luck and have fun.

[carol]

If I may chime in here, gentlemen.... I cut 1/4" aluminum with a Porter Cable 7518 set at 16K-17K RPM with a 1/4" 2 flute end mill in .030 depth passes, lubricating every third pass with aluminum cutting fluid with an artist's brush on the surface to begin and then in the cut until finished. I get a good cut.
Now if I could just figure out to apply the cutting fluid automatically......

As to noise. It is marginally higher than with wood but not so much as to make an issue out of it. In a confined area like a basement, I'd want lots of insulation to absorb sound to protect me, let alone the folks up stairs. And yes, you would still wear the best sound muffs you can buy. Nobody's doing ear transplants yet.

[bruce_clark]

Mark,

Couple of things you might need to consider. Most spindles like the Columbo are 220V 3Phase. I doubt that your Mom's basement has this type of power. Now, you might be able to get a phase converter or inverter, but you are still talking a LOT of amperage for this service.

Second, I have had VERY good luck with a Bosch 1617EVS. It is very quiet when run in the lower speeds, which you would want to do when cutting Al.

Third, if you will be cutting metal, you REALLY need some type of lubrication. I recommend a spray misting unit. So, you will also need to take in to consideration the noise of an air compressor--probably running the entire time of the cut. I use a spray mister when I cut plastic and it works great at preventing remelting.

As for cutting Al, you will need to take a fair number of passes because the Shopbot is not the most rigid of machines. Over doing it can set up serious vibrations which can an the very least knock your machine out of alignment and very worse bend/break things. So, a larger Hp spindle will not help much in this regard--except to add more mass to the gantry.

Finally, for clarification to all, I do not work for Shopbot. I HAVE done some programming work for them in the past, but otherwise I am just a regular Shopbotter and a thorn is ol' Ted's side since I keep asking him to add this and that to the Shopbot controls.

Bruce Clark

[tucker-52@charter.net]

To Ron C., Bob, Carol and Bruce...,

Alright, I read you all loud and clear..."Don't buy the big expensive spindle to start out with!"
You all are right, I can always upgrade later if I find that I "just gotta have one!"

Yes, insulation is cheap. If it comes to that, I'll do it, but after further consultation with my Mom, she says that if I'm down there making noise that it will sound like music to her ears if I'm making money too! (Bless her 80 yr. old heart!)

Carol, ShopBot does sell an automatic misting system for $550.00. Kinda makes a squirt bottle full of WD-40 look attractive, huh? By the way, what kind of router are you using for 1/4" alum?

Bruce, ShopBot does offer a single phase Columbo splidle, but it's about $500.00 more than a 3 phase. Just wanted to point that out. Dosen't matter, you guys have talked some sense into me. The Bosch sounds good. So does the Mikita. But I think Tim Allen would be disappointed! Arrrgh!

Ya'll have a nice weekend, and enjoy the play-offs!

Mark Tucker

[carol]

The router is a Porter Cable 7518, variable speed set at 16,000 RPM. Speed recommendation came from Onrud engineers. They have aluminum cutting bits, but regular 1/4" 2 flute end mills I get at a local machine shop supply house are more economical and the quality of cut is pretty good.

Move speed on XY is 0.25. Depth was going wacky after 4 pieces, making it necessary to re-zero the Z axis. Still experimenting with Z move speed.

Regarding that, I have gotten into the habit of jogging the Z to zero and then moving z to depth.

As to the Bosch 1617EVS. It is a very sweet machine and certainly can handle 0.030 depth cuts! It is a quiet machine, but once the cutter hits the material, discussion about noise can quickly become academic.

Have an adventurous spirit when you get your machine. Plan to practice. If you had all the answers before you began, what would be fun about that?

[carol]

Your comment about misters, (Carol, ShopBot does sell an automatic misting system for $550.00. Kinda makes a squirt bottle full of WD-40 look attractive,huh?) is interesting.

I went to the website and looked for it and couldn't find any thing. Where is ShopBot selling the automatic misting system? Pictures? Features?

[tucker-52@charter.net]

Carol, it's not advertised on the site. I had to inquire. Contact> Dianne@shopbottools.com (mailto:Dianne@shopbottools.com). She's a salesperson, and seems to know what she's talking about. Even women are into this. But be careful,.... she is a salesperson. Any good salesperson might sell you anything you want, regardless if you need it or not. That's their job, but if you're cutting a lot of non-ferrous metals, as I may be (hopefully) and need to be doing something else while the machine is working, this may well be the only way to go. She seems like a really nice person.

You're right. What fun would it be if I already had all the answers? WHO DOES? Damn the torpedeos
anyway. Let's learn and have some fun!!! Mark

P.S. The Porter Cable varible speed still looks good to me and I do not discount it as yet at all. Decisions, decisions.

[R Bouchard]

I bought the Columbo, and found a couple of things.

First you have to let the Colombo warm up for some time before you can cut with it. The bearings are so tight and acurate that they have tolerences at warm temps. this takes time. If you are not running steady, this is inconvenient.

The cooling system on the Columbo has to be the electric fan. I had one with a fan on the spindle, and it was far too noisy. It costs more for this type of cooling fan, so cost it in if you are getting the Columbo because it is quieter.

The Porter Cable routers are pretty good. they are cheap, fairly acurate and not that loud.

RB

[tucker-52@charter.net]

Thanks, RB. Why can't a cooling system on a Columbo be an automatic misting system? Just curious. Dosen't matter.You sound like that if you had it to do all over again, you might have gone with a 110v standard router too. Am I wrong?

All things considered, ya'll, I will say that I again appreciate the input from everyone. Now that it's reached this point, I think I'll just order a Porter Cable variable speed. Most of the rest of my tools are PC's, and at least they will be color coordinated. That's important too!!!!

Mark Tucker

[scott]

Mark:
I believe RB is a little confused. The Columbo spindle is fan cooled. It draws air from the top with an electric fan (similar to a computer fan).
The automatic misting is used to cool the cutter,not the spindle bearings. I have been looking into using a air cooler in our setup. This is a dry cooling system. Advantages are that you can use it to cool the cutter when cutting materials that can be ruined by liquids. They sell for around 20$200.00. Of course you do need a good air compresor also. I"ll post about it after I try it.

[bill.young]

Carol,

Would some kind of gravity feed drip system work for your cutting fluid? Maybe with a reservoir on the Y car to hold the fluid and a piece of small copper tubing to dispense the fluid near the end of the bit. Kind of like an IV.


You could use a valve in the copper tubing to regulate the flow, or maybe get fancy and use a solenoid valve that was controlled by one of the output switches.

Just a thought,
Bill

[gerald_d]

Kerosene is a very good cutting lubricant for aluminium.

[R Bouchard]

I am not confused at all. I am talking about the fan that cools the motor. On mine it was a fan attached to the top of the spindle, on the top of the motor, or router. the faster the router goes, the faster the fan turns, and the louder it gets. The upgrade is when you have an electric fan that is at one speed. This meant more expenses for me.

This has no bearing on the router bit temperature. I bought a really great misting system. It was called the Fogbuster. I highly recommend it. It kept the bit cool, and made very little mess.

And the above also has no bearing on the bearings that have to warm up. The router has a start-up routine that takes 5 minutes or so before you can cut with it. The bigger spindles are built to run all day, not turn on and off.

[carol]

RB - how about more info on the Fogbuster? Who sells it? How much? Web site? Pictures? You, know. The usual stuff inquiring minds want to know!

BTW, I was thinking about a drip system or a dragging wick. One problem is the 'draft' the router kicks up around the bit. I want to keep the cutting fluid in (or at least 'near') the cut.

I am using a water soluable aluminum cutting fluid. Cleans up easy.

Hmmmm..a solenoid valve on an output switch???? Anybody ever done this?

And, Diane at Shopbot, kick in some info here about the misting system you are offering.

[David Fisk]

Mark, You might want to consider getting the single speed Porter Cable and purchase a separate speed controller. This way you will have infinate adjustment on your speed. The variable speed model only has a few preset speeds. And they might not be suitable for metal.

[David Fisk]

I have been considering getting some utili track from Bishop Wise Carver Inc. and mounting it to my rails. Then removing the wheel bars and using four of their carriages as a replacement for my shopbots Y axis wheels and holddowns. I was thinking of replacing the round conduit with a piece of angle iron. BWC has polymer wheels for light to medium duty applications. There lightest carriage will handle about 20 pounds of force. I'm quessing that putting 4 of them on there will allow me to use it on my shopbot which has less then 60 lbs of cutting force. I'm going to be talking to one of there engineers on monday. This setup that I'm looking at will cost aproximatly $800.00 and is suppose have the same life span as their steel wheels. The polymer wheels are suppose to make for extremely quiet operation. I've been having trouble with my shopbot binding on the utility strut and I can't seem to get it staight and useable to its entire length. I thought this might help with the binding trouble. Any suggestion/input on these are welcome. There website is www.bwc.com

[garbob]

Try this site for air cooling - they are saying a reduction of 100 degree F. from compressed air temperature. No coolents or mess, about $200 US.

http://www.arizonavortex.com/cooltool.htm

[R Bouchard]

It has been a while. I would just search for Fogbuster on google...

It really works though.

RB

[sheldon@dingwallguitars.com]

I have a mister with a magnetic base. I don't use it much as after 10 minutes or so, the whole shop is in a fog. I'm not running it that hard, is there something I'm missing?


Scott, I'd be interested in your experience with the air cooler. We have problems with routing round overs on figured maple as any feed rate that is slow enough to minimize tear out causes end grain sections of the figure heat up and burn.

[tucker-52@charter.net]

To Gerald D. Kerosene may well be a good lubricant for cutting aluminum, but it is also quite flammable. Also, for folks that don't know, WD-40 is kerosene based. Careful!

[David Fisk]

FYI I spoke with the BWC engineer and he ran some quick rough calculations on the y axis. He recommended using the UTCAN2 carriage on number two rail. This is in the Acetal Polymer wheel Utili-Trac line they sell. The rail runs aprox. $66.57 per meter and the carriages are $94.07 each. The prices are less then there website. They charge less if you call for some reason. It would require four cariages and two rails. Each carriage has three wheels two for the load and one as a hold down. So it would be about $640 to upgrade the shopbots y carriage in this way. I guess it would be a little more if you used some angle iron to replace the wheel bars. They also sell a extruded aluminum that could be used to replace the utility strut completely. It is about $1.37 per inch with a $2.10/piece cut charge. That would require some special nuts for mounting anything.

[Wdyasq@yahoo.com]

David,

It appears you might be starting to chase your own tail. Once you upgrade the "Y" carriage, you will start thinking about the "X". That may leave the "Z" to upgrade. Then, what about those older stepper motors? How about a new control box? Do we now need a Steel Table?

My ShopBot was one of the old cable-driven units. It has the original old small Uni-Strut "Y" carriage. When I overload it-"It shivers and shakes like a mouse on the Ark." - to quote Baxter Black, so I don't do that. There are a few minor things I would change if I were to keep the original structure and starting fresh. I know the screen-door rollers have cost me enough by binding that I could have bought BWC wheels with the money I would have saved in material and router bits. It still always did the job it was designed to do-well, eventually with the cable-drive and encoders.

There are certain things I just cannot accurately do. I understand that. I try to avoid those situations.

If I get some jobs that demand a 'better/faster' tool, it will be time to take a long look at the problem. What can't be done is force a tool never designed to do jobs it wasn't designed to do. The UPS man can't bring me a bunch of boxes and have me make a tool as rigid as a Bridgeport Mill. Well, at least for $6K.

Ron Brown - wdyasq@yahoo.com (mailto:wdyasq@yahoo.com)

If Stupidity got us into this mess,
then why can't it get us out? - Will Rogers

[David Fisk]

Ron, don't be so pessimistic I was just providing some information to others who might want to improve their machines. I'm not doing anything different then others are doing. Maybe I don't have the mechanical skills to get my machine to work as well as others. I think that these carriages would help to eliminate some of the guess work. Upgrading our machines and helping each other is what this forum is about. I would still recommend others to buy a ShopBot. Upgradind to a PRT is very expensive and yes its probably worth it. But some of us can't afford the new Shopbot or its upgrade so we are left to figure things out for ourselves, and with the help of fellow shopbotters. But it seems to me for 650 dollors these new carriages and rails would go a long way to improve things. That is a far cry from the price of a bridge port. Because of the large expanse of the y carriage it is obvious that stiffening it would dramatically decrease the vibration in the machine. My x rails work very well now that I have stiffened my table with MDF. I can't do anything simple like that on the y rails thus the investigation into alternatives.

[djhazeleger@mindspring.com]

David,
I am assuming you have a PR model,I would work towards strengthening the y carriage. Do you have the larger 2" strut or is it the same strut as the x axis. If you have the smaller strut a simple change of a few parts and your set.
you might try placing a piece of angle iron over the strut (top and side boxing the strut) and have the wheel run on the corner of the angle. Since the strut is a u channel you can get flex there. a piece of cold drawn 1/4 x 1 1/2" flat bar capping the top of the rail also might work and have an excellent path for the wheels to ride on. If you can weld tacking a brace in a few places would also go along way.

[David Fisk]

Thank you Dirk for all the practical tips. I have the 2" on the Y. I took the wheels and hold downs off my y carriage and found that one corner was not flat. The funny thing is when its loose it lays flat and when you tighten it the corner goes up. I guess stress affects more then just us Shopbotters.
I guess my bot needs a psychiatrist, Ted can you help out with this
? This has been causing a lot of binding/missed steps. I put some washers under it while tigtening it to keep it flat. The carriage looks rather odd now, but it is running without binding. I don't have access to a welder so I'm stuck with nuts and bolts. Dirk, do you think adding bolts across the rail above the hold downs would be of benefit for stiffening? Or what about brazing I have a brazing torch. Maybe I won't need those niffty BWC rails and carriages after all

[djhazeleger@mindspring.com]

David
I would say no to brazing. I think you would apply to much heat and take a chance of warping. If you do weld be sure everything is perfect.I don't think the bolts would help much,if their is flex it will be in the middle of the bridge.
For my application I have not welded or stiffened My y axis. Any vibration problems I have enountered were the resanance of the steppers. A lot of this was resolved by replacing with a 24 volt supply. My next mod will be to upgrade to microstepping. I feel the y carriage could use some beefing up, and some of the suggestions I gave were options I was contemplating.
Dirk