PRT 4G board Experience

[zeykr]

A friend was considering the PRT 4G upgrade and knew I had ordered one so was asking how I liked it. I didn't have it then, but promised a response as soon as I recieved and installed it. Thought some of the rest of you might be interested also, so here is my response to him.

----------------------------------------------
Got 4G board in friday and installed friday night - would not work, but short version is they posted a bad version of Shopbot alpha software (3.4.28) and put a new one up on site saturday morning (3.4.29) that worked fine (thanks Frank). What a relief - thought I'd done something wrong ;-)

Machine sounds much smoother in operation with this new board - very much like Gary Beckwiths's we saw at Kansas camp.

It can definetly run faster, but found that my computer is not fast enough to keep up in 3d where computer is sending lots of data fast so I get communication errors if I try to move too fast in 3d. My shopbot computer is a 1.8ghz clone and it had problems communicating much at all. I hooked up to my dell laptop which is only a 1.4ghz and it works much better, but still can not keep up with 3d much above MS 3,3. Suspect it's something about the USB port that made the difference between clone pc and laptop. Clone may only be USB 1.0 or something.

So, I'm looking for a new computer to try on the shopbot, but results so far using the laptop are:

3D (the wheat model from James B in foam and rearing horse in oak toilet seat) I can run at 3,3 with no problem. Tried 5,5 in foam and got data errors.

2D table surfacing - I ran at MS 7 with a ramp speed of 12. It surfaced the table fine at 7ips. Had to modify the slow corner speed just slightly to smooth out the corners.

2D cutting - I ran one cutout job at MS 5, RS 12 with no problem

I've jogged at speed of 13 without a problem so far, but have mostly left it at 11 or 12. (kinda scary when it moves that fast!)

vr settings for 2d were: VR, .16, .2, .2, .2, .2, .2, .2, .2, .16, .2, 150, .08, 50

On 3d I had VR the same except slow corner speed was 40

So overall so far, very happy with the upgrade.

Thanks Shopbot! You've put new life in the PRT!

[dingenis]

thanks ken,
very helpfull inf
i ordered a g4 upgrade
wil post when i got it installed
dingenis

[randy]

Ken, interesting info.

If you are not sure whether you have USB 2.0, here is a link that might help you.

http://www.usbman.com/Guides/checking_for_usb_2.htm

It would be interesting to see if adding a USB 2.0 card to your PC improves performance (and a lot less expensive than another computer).

Randy

P.S. I smell a Christmas present to myself in the air.

[larry_r]

Ken thanks for the heads up on the G4 upgrade. I am curious as to whether you have a spindle or a router.

[zeykr]

Randy,
Thanks for the USB info, I'll check it out.

Larry, I have a 5hp spindle.

As a further update, shopbot thinks it's probably not my CPU speed that is causing the comm problem and is looking into it.

[joenagel]

I have also just upgraded to the new 4G board and am having massive comm errors while trying to use the Shopbot probe. I think I have ruled out the probe as the problem. I'm running one last test.

My computer was hooked up with a usb to serial adapter when I was running the old board, so I don't think It's the usb connection

I'm getting really good at emailing Frank.

[steve4460]

What version of software are you running?.
Version .29 had broblems there is an new on ready for download ver. .30 check it out

[joenagel]

I started with .28 and had the same issue as Ken.
Then went to .29 and now at .30.
From what the version release notes state .30 only fixes the m4/m5 commands from the keyboard.

[zeykr]

Sounds like Robert Ball had problems with .29 and comm errors on his Alpha also, so sounds like a comm problem may have been introduced with changes for 4g. Release notes for .30 don't say anything about fixes for comm erros.

I've been in contact with shopbot as well, so we know they're looking at it. Hopefully something will work itself out soon.

Edit: looks like Joe and I were typing at same time.

[rhfurniture]

What I would be really interested in is how much smoother the cut is if run at the SAME speed.
I am also considering this, but mainly for cut quality, not speed (not really an issue on my benchtop with 2hp router doing small stuff)

R.

[zeykr]

Ralph,
The 4G certianly sounds and looks much smoother, but I've not had time to do an actual comparison or test. I'll be out of town for a week so can't try it soon. Maybe someone getting a new 4G can make a before and after conversion test for comparison and share the results with us.

[lto]

Does anyone know whether the 4G will offer improvement in resolution, (or smoothness of cut), over the standard un-geared Alpha? Specifically at low cut speeds of approximately 2 IPS?

We cut some parts in 1 ½” HDPE. The job requires the use of a 3/8” diameter tool, so we cut in 3 passes followed by a cleanup pass at .7 IPS. If improved resolution would allow the cleanup to run at 2-4IPS this would greatly reduce the file cycle time.

Thanks for your input

[Brady Watson]

Yes. It increases resolution 2.5 times.

[zeykr]

Brady,
I think LTO is asking about putting the 4G on his alpha.

[Brady Watson]

Ahhh...yes I missed the Alpha part...In that case no...

[lto]

I had gathered that the 4G is not an option for the Alpha. My thought was just that in some cases such as ours, were we to add another Bot, we may be better served with a 4G than an Alpha.

Cutting mostly HDPE, it is almost hard to imagine cutting at the speeds some cabinet makers do with the Alpha.

[joecmay]

found com errors can be caused by heat at the gecko drives. we set up a test system on the bench with 4 motors before going live in production area. the test program would run about 10-12 mins. then the comerrors would hit. we put a muffin fan aimed at the gecko drives then ran the test program for 2 hrs. with no problems. we are running in production now. just in from shopbot. it seems if there is voltage drop on the 5 volt line the com errors start also. 4.8 volts seems to be the level where problems start.

[matt_r]

I'll throw my 2 cents in here too. Should have read this thread before pulling my hair out last night. I was toiling witht the .28 software - and it was killing me. No internet access at the shop, so I went home, got online, found v.30 and downloaded it. Installed it this morning, and it ran fine. Cut 4 VCW files - taking about 10-15 min each. The smoothness and speed is awesome. The control software still seemed a little glitchy.

My wife got a call from Shopbot while I was at the shop. She said that they are recalling the 4g boards. I need to call them today and get the lowdown.

-Matt

[steve_staley]

To anyone who has not gotten a call from Shopbot about the 4g boards yet, they are sending out replacement boards due to what joe alluded to. Comm issues with the blue earth board not recieving enough voltage to connect, in some cases not at all, in others, pullimg volts from a back door usually (in my case) long enough to run a file, not long enough to finish it. Machine lost steps, lost x location then continued on. Hope this helps!

[joenagel]

Did they give you any idea when they would ship? I forgot to ask when they called me. I need to know if I should reinstall my old board. If they are shipping soon I'll just wait for it to show up.

Joe

[steve_staley]

Sorry, same w/ me. Called twice today, still waiting for a reply, guess they're a bit swamped, or tired of angry callers. Hope to get either a board or a call tomorrow Steve

[Brady Watson]

Yo Stevie! Nice to see you posting!

-B

[scottj]

Hi All,
Thanks for your patience on this issue. We are shipping the new boards out as quick as we can build them and they are going out in the order that they were originally sent out. We have already started to ship these so you should be getting the new board soon.

Scott, ShopBot Tools

[ted]

Just to add a bit to Scott's remark. Yes, we found an incorrect connection on the V4g boards that causes the micro-controller to see a lower voltage than it should. (I won't say who's mistake it was, but I wouldn't worry about him being fired.)

Anyway, as Scott indicated, we've tried to let the 27 people who got the first boards know as soon as we figured it out. It was a bit confusing, because many of the boards seem to work OK. And some people, including my wife Sallye, have been using them productively for weeks.

We have some replacement boards in stock, and plenty of parts on hand. So we are hoping that with a little feverish overtime work we will have corrected boards on the way to all shortly. (Our target is to have half of them out by tomorrow.)

We regret the inconvenience to ShopBotters and look forward to getting everyone going with their upgrades. The V4g's are really a nice improvement to PRT performance.

Ted Hall, ShopBot Tools

[joenagel]

Ted,

We are all in the manufacturing business in one form or another, that's why we have your machines. These things happen to the best of businesses. I'm just glad you found the problem and responded so quickly

Joe

[jay_p]

So, all you 4g'ers. Have you received your new boards yet, and you happy with the upgrade? I am considering making the leap soon.

Thanks

Jay

[jay_p]

One more question. Is everyone using USB connections now, or the high speed serial connection? What is a high speed serial card anyway?

Thanks again

Jay

[zeykr]

Jay, New board has fixed my communication errors and is running well. I am very happy with upgrade - I don't run a whole lot faster than I did (yet anyway), but do have my jog set to 8ips and it sure looks and sounds smoother when running.

I am using usb now, but have a Quatech high speed serial in shopbot computer that I will try out when I get a chance.

[matt_r]

I've been having issues with my upgrade, kept quiet here for a while, but now I'm looking for some insight. I got my first upgrade board, and it worked fine (once I got the right control box software loaded). As people had issues with the first boards, Shopbot sent out the second round of boards. I got mine about 2 weeks ago. I installed it, and sent the first one back to Shopbot, along with my PRT board(rebate). The second board started failing. Losing position in x, sometimes coming to a dead stop in X, but still functioning in Y and Z. After pulling drivers on and off and switching them around, I determined I had a bad Gecko driver. Shopbot sent me out a new one. I installed it, and still had problems with failure in X. So, this week, SB sent me out a new board (board #3), drivers and all. I installed it, and it immediately failed in x. So, I lifted a driver off board #2, and replaced the 'bad' one on board #3. X starts working just fine from that point. Then Y starts to fail. I do the same thing, swap out drivers. It seems to work fine, but then I'm running my test program (little 2 min program), and it starts to lose position in Y. Not drastically, but by like 0.100.

We're scratching our heads here. I've been checking my cable connections. My control box is 2 1/2 years old. I turned up the voltage on the power supply to 54 volts as I was advised to do in the upgrade sheet.

I'm not bashing on SB or support here, I'm just wondering if any of you have any ideas that I might try to diagnose the problem.

Thanks,

Matt

[patricktoomey]

Matt,

I would try a new power supply/controller case. If the failure rates were that high on the controller boards or drivers, there should be tons of people screaming. So it would seem like there is something else going on. Perhaps cables? I think an intermittent spike from the power supply or a bad cable could be blowing other stuff up. Also, bad Geckos are few and far between which would also likely indicate something else really bad is going on and killing them.

[daryl_alberson]

Matt, I seem to be having a very similar problem with my 4g upgrade. My control board works fine for a while, then all of my drivers randomly begin flashing. This happens very sporadically and I can't seem to narrow it down to anything specific. Please post if you do happen to find a solution. Thanks.

[Brady Watson]

Pat,
Geckos die more often than you hear about. I've had 2 DOA & 2 more that just gave up the ghost for no apparent reason.

For those having problems, I would turn DOWN the PS voltage to 48v in case your particular PS is 'clipping' at the higher voltage. Secondly, I would be absolutely sure that A) there is a current set resisitor plugged into the last 2 ports of the Gecko as well as B) be 100% sure that the Gecko is squarely seated in the connectors on the board. Some of the Geckos that I have purchased had poor quality connectors on them that cause intermittent disconnects, and the same thing could be happening on your board.

HTH,
-B

[zeykr]

I had problems on my second 4g board with one X motor dropping out after a long day of cutting. (was always the top gecko no matter which x motor it was plugged into). Messed with wiring, connectors and quite a bit of trouble shooting before eventually adding CPU heat sinks to each gecko and putting a couple stronger fans in the cabinent as well as moving the control box up where it could get more cool air flow. That's been several weeks now, and have not lost a motor yet since. Not sure it's cured, but hoping so. If it does prove to be a heat problem, I'm a little worried about what will happen when warm weather returns.

[richards]

Current Limiting Resistors: Here's the formula from the Gecko manual to determine the correct current limiting resistor:

The G202 will accommodate motor winding currents from 1 to 7A and 0.3 to 2A. Use the following equation to calculate the value, (in kilo-ohms) of the current set resistor:
R (in kilo-ohms) = 47 * I / (7 – I) or for the low current range, R = 47 * I / (2 – I)

Use the closest 5% resistor from Radio Shack.

Heat can be a problem with any stepper driver. I use a 1-inch thick aluminum plate as a heat sink for my Geckos. (I know that that size of heat sink is overkill, but room temperature is always better than using stepper drivers as a furnace.)

Reliability and Connectors: As far as reliability goes, I would suspect the connector before the stepper driver. One manufacturer of the slip-on connector, who formerly supplied parts used by Gecko, shipped faulty connectors. As far as I have read on the Gecko forum, the drives that used those connectors were recalled; however, the problem was that the spring-clips only worked the first time the connected was used. After that, the clips were deformed resulting in loose/no connections to the posts on the stepper driver. The vertical mounting of the Gecko on the G4 board may put more force on that connector than the more conventional mounting method.

The older model G201 stepper drivers used different components that were very unforgiving, but the G202/G212 models have taken all the nonsense that I've thrown at them for more than a year without any failure.

Voltage: I've run my test bench at 70-VDC for more than a year without any problem. I use a 50 volt toroid transformer and a PMDX-8020 power supply board (that rectifies and smooths the power - Remember, you multiply the transformer's voltage by 1.4 to get the rectified/smoothed voltage), but any transformer with the correct voltabe/current ratings should work just fine.


Matt, if you need to borrow a few G202s until you get things worked out on your G4, give me a call or stop by.

[robert_cheal]

My 4G board arrived yesterday. Before I proceed I am wondering if anyone has a basic check list for "Dummies" of addtional things to consider with a 6 year old control box, power supply etc. I know the fan is making noises when it first starts up and I would like to have a reasonable piece of mind that I did what was needed the first time. I would gladly add on what is needed if I knew what it was.

Thanks, Robert

[rhfurniture]

Oh ****, just ordered my G4, and REALLY do not want reliability issues.
Do the Gecko's in the G4 (at 48v) run seriously hotter than the old allegro's?
I ask because my control box is mounted upside down (ie board at top) on the ceiling. This is great for dust issues but i suspect not so hot on the heat dissipation. Maybe I had better put it upright against the wall, ie conventionally.

R.

[richards]

Ralph,
Let me assure you that the Gecko G202 is not the problem. Those drives are sold by the thousands every month. When lightly loaded (and 2-amps is lightly loaded), they hardly even get warm. The Gecko documentation clearly states that at 6-amps and above, that they must be used with adequate heat sinks. (The older model G201 drives are a different story.)

For six months, I had four drives bolted directly onto particle board with no heat problems. Those four drives were running 3-amp motors at 70-v. In that situation, the drives easily passed the finger test - meaning that I could hold the back-side of my fingers to the case indefinitely without discomfort. However, when I switched to 6-amp motors, I also added a 1-inch aluminum bar heat sink to the assembly.

If anyone is worried about heat, the drives can easily be bolted to a strip of aluminum as they were designed to be mounted.

Please don't take this wrong, but if I owned a G4 upgrade, the very first thing that I would do would be to mount those drivers solidly to a panel. Although standing the drivers on end and mounting them by their electrical connectors is novel, it's just not the way that they were designed to be mounted. The mounting holes on the G202's case are not there for decoration.

As I'm so fond of pointing out, I've been designing, programming and installing process control computers for more than thirty years. During that time, the number-one service call issue has been faulty electrical connections. The number-two service call issue has been electrical noise. If I were not a Mormon, I would bet that the real problem is being caused by either intermittent connections or electrical noise.

[rhfurniture]

Thanks Mike,
Looking at the shopbot website prt4g upgrade page, I can see that to mount them upside down would be foolish - a minor earthquake, low flying jet, or seriously heavy lorry could ease them out of socket. If I bolted an ally bar accross the top of them (I assume the yellow dots in the picture are threaded holes), then devised a way of applying light pressure in the direction of the board, then this might be OK. Would it be a bad idea to epoxy some fastening points onto the board itself? ( I am not a lecky geek), or even drill through it?

R.

[rhfurniture]

PS: Can anyone fill me in by what is meant by a high speed serial card in the context of the 4G. I assume the standard serial port on the back of my motherboard is not fast enough.
A min spec number would be useful,

R.

[benchmark]

Hi Ralph,

I am about to go 4G, I have been looking at this USB card

http://www.savastore.com/productinfo/product.aspx?catalog_name=Savastore&product_id=102 80080&pid=44&rstrat=0

This is the fastest USB I have found 480Mbps ...perhaps the Techies can through some light on the subject..


Paul

[rhfurniture]

Hi paul,
My existing serial cable is well buried in the building, so if I can get a serial card for 20 quid or so then I don't have to re-thread, and it is easier if I have to back-track.
Also I like as little software running as possible, so would rather not have to load up the usb driver.
Also I HATE un-necessary limitations (see above) even if I don't go near them.
AFAIK, usb is either v1 or v2, and I cannot find anything on the website or the installation instructions that says V2, so any old usb card/port should do it. But I should check with shopbot first...

[rhfurniture]

Would this work?
http://www.dabs.com/productview.aspx?Quicklinx=3ZRS&CategorySelectedId =11139&NavigationKey=11139,4294959977,4294957104 (http://www.dabs.com/productview.aspx?Quicklinx=3ZRS&CategorySelectedId =11139&NavigationKey=11139%2C4294959977%2C42949571 04)

[dirk]

Paul
I haven't tried that particular card. I have tried about 15 others. Ones I thought would work didn't. If I were you give it a try as long as you can return it. Let us know how it worked out.
I stopped by John Forney's a couple of weeks ago and he was loosing some steps on his G4 board. His problem turned out to be not having the pot for low speed resanance adjusted. I've found that turning the pot full counter clockwise seems to be the right adjustment for the standard shopbot motors. If you look at the opposite end of the connectors on the Gecko drive there is a small hole with a white screw inside, that is the pot to adjust low speed resanance. Here's a link to the manual for the 202s and it would be good to read it over if you have ar plan to buy a G4.
http://www.geckodrive.com/photos/G202_MANUAL.pdf

Dirk

[dirk]

Another note on USB verses using a PCI card. Up to this point I've found the Quatech DSC100 to be the best card and most reliable. The Shopbot software is being optimised for a USB connection and very well could offer comparible performance in the future. There are issues with how an individual computer deals with USB. For instance the computer might be assigning that port as a slower keyboard port. This is just one example as there are others. Ted has been working on diagnosis software so if this type of problem exist it can be rectified.
Dirk

[dirk]

More to add:
I personally don't believe there to be a problem as far as the way the Geckos are mounted on the G4 board. The new black connectors are very tight and actually are difficult to remove. I think if there are connection issues it's in the Wago Connector. It's something you can't see, and if you have a problem with a particular motor I would completely remove all connectors and reseat the Wago connectors.
Dirk

[rhfurniture]

Dirk,
Peronally I've never had a problem with the Wago's - I keep them well taped up. Are the gecko's in the G4 held in by screws or is it a push connector? I am thinking of my upside down board and gravity.

R.

[dirk]

The Geckos are pushed in from the side. The box would have to be laying on it's side for gravity to be a factor. The Wagos can loose connection and it may just be intermittent. Very hard to trace if their's a problem. Overall I think they are reliable, but some of the previous post suggest that may be a possible cause.
Dirk

[rhfurniture]

Dirk,
>The box would have to be laying on it's side for gravity to be a factor.
That is what I mean - the box is lying on it's side, with the board (in horizontal plane) attached to the ceiling of the box.

R.

[daryl_alberson]

I'm not sure if the problem is solved, but I turned the voltage back to 44V and everything seems ok so far. I had problems with all drivers flashing at both 48V and 53V.

Daryl

[ted]

A little info that may be helpful for some:

ON HEAT. As the Geckos hardly even get warm being driven as we are driving them, it seems very unlikely that heat is an issue. It is possible that we have suggested setting the voltages higher on the power supply than we should have. As the power supply heats up and is near it max voltage it may be becoming unstable. The units we tested here with the 4g boards all had new power supplies and these may have been less vulnerable to such a problem. I'm aware that we tried several things with Matt's 4g's but I don't know if we explored possible issues with the 48v supply. It is certainly the case that we are drawing more power from them with the 4g's than previously. I'm thinking that for the few boards showing this problem, we should replace the power supply (leaving it at 48), and perhaps also try setting the current slightly lower at the Geckos.

GECKO RELIABILITY. The robustness of the GECKOs seems pretty good so far. We have managed to blow a few out, but this has typically been the result of a short in the motor wiring. In a box of 100 Geckos, we typically have only one or two that fail during our burn-in tests. We do run all the 4g boards for about an hour burn-in and accuracy test. We've had very few reports of blown Geckos in the field so far. [We don't yet know if Matt's Geckos are now bad, which would suggest a motor wiring problem, or whether it is a board/power-supply issue.]

USB ADAPTERS. The PRT/PRSalpha boards and the PRT/PRSstandard-4g boards communicate with the Control Box at 480,6000 Baud. This speed is not supported by a standard PC serial port. There are both PCI cards for desktops and PCMCIA cards for laptops that provide higher serial speeds. As Dirk mentions above, we have had good experience with the Quatech cards. Hooking up to the alpha or 4g with one of these HS serial cards is thus an option. (Typically ~$50 for a PCI card and about ~$125 for a PCMCIA card.)

But let me put in a word for USB, which I believe is the best way to go. I would first admit that getting USB robustly and standardly implemented on PCs has not gone as fast as I might have liked. But increasingly the USB hubs on PCs are put on an efficient bus and provide the through-put that they should be capable of. Further, hanging a USB device on an -outboard- hub that is a known USB 2.0 hub will often guarantee more efficient communication if you are having a problem because it forces the all devices on that line to be processed by the 2.0 controller.

There are two primary reasons for sticking with USB. The first is speed. We will probably keep increasing the speed of communication with the controller (only natural in the push for higher and higher resolution). The second is noise resistance. The electronics of the USB line are inherently more noise resistant than a serial cable. More importantly, USB internally checks and corrects data transmission on the USB line and does this at a very high speed. This basically guarantees noise free data arriving at the control board except in extreme conditions.

Yes, it is the case that it is sometimes difficult to get the USB drivers correctly installed on PCs. But as things get more and more standardized, this becomes less of a problem. For example, on a new XP PC that is on the internet, after the ShopBot USB is first plugged in, Windows automatically goes to the internet and finds and installs the correct drivers in just a few seconds.

That said, USB adapters (and their drivers) are not all created alike. There is an old standby chip that is used by several different companies (Prolific chip) such as ATEN, Dynex, and IO Gear. It is surprisingly efficient and in most PC setups allows communication at speeds that support fast, high-res, stepping on ShopBots. This is the adapter that we currently ship with tools. The chip made by SiLabs, also supports very efficient communication and we are considering putting it right on future boards. There are other chips such as the one made by FTDI (found in Sealevel adapters and others) that despite impressive specs, performs poorly. The chips are capable of high speeds, but only when communicating in huge chunks of data. Because of the constant interaction between the PC and the control box, our communications packets are relatively small and don't work well with FTDI.

We are experimenting with a system to help test out the performance of the communication systems on individual computers. The current beta software ships with a program called "SpeedTest" in the "c:\Program Files\ShopBot\Diagnostics" folder. This program can be used to test the efficiancy of communications in a ShopBot realistic way (and to evaluate USB adapters). It is best used with a loopback connection made between pin 2&3 on the USB serial connector. That is, the control board is not connected during this test. As we get a little more data on this test, we will be able to use it to determine if a particular PC/USB is working in the right ballpark to support full speed on a ShopBot. I'll have more to say about this one as time goes by.

[ricks]

I have a question about installing my 4G board.
Measuring the voltage output of the power supply, the instructions (as I read them) have the WAGO connector attached, the Geckos are on the board, but the motor cables are not attached. I expect my meter probes go into the two square holes in front of the wires on the WAGO.
My question is, is it OK to power up without the motors connected?

Thanks,
Rick Samish

[Brady Watson]

Rick,
Yes. You want to measure voltage between the 2 prong Wago connector that originally connected to the middle of the PRT control board.

Alternatively, if you have the room, you can measure directly off of the screw terminals on the PS itself.

-B

[ricks]

Thanks Brady,
My last question, above, is most important to me.

Can I power up the board without the motors connected to it?

Another question I have is, does it make any difference in the amount of communication errors there might be when connecting the serial/USB converter, either with a long USB cable or a long serial cable? About 15 feet of cable.

Rick

[Brady Watson]

Yes. You can power up the board without the motors connected without worry. Be sure to power off the board/Geckos before connecting or disconnecting the motors from the board.

Yes...I have run into frequent communication problems & disconnects when using a USB cord longer than 12 feet. Shorten it up to decrease the chances of communication errors.

-B

[ricks]

Thanks again Brady,

A great help.
Rick

[mariss]

A couple of notes on the G202s:

1) The drive is rated at 80VDC, designed for 100VDC and comes apart at 114VDC to 116VDC. Every drive is tested at 7A and 100VDC while running the test-stand motor at 6,000 RPM. The MOSFETs used are rated at 33A continuous and we use only International Rectifier Inc devices.

2) The G202 has short-circuit protection. If the drive sees something really bad (like a motor short) it shuts down in 3 microseconds. The biggest drawback is there is no indicator to show it has entered protective shutdown. Recycling the power supply or momentarily reseting the drive clears the protection latch. If the problem persists then it just shuts down again.

3) The LED is a power indicator. No LED lit means no power on the drive. The brightness varies with how busy the drive is. It is busiest at low speeds or while stopped, it is least busy at high speeds.

Mariss

4)

[rhfurniture]

Well I have to say, the 4g board has gone into my machine without a problem. After tying to get a high speed serial card to work, I gave up and settled with the USB setup supplied, and it all works just fine. I havn't bother'd with upping the supply voltage from 44v (I didn't have a voltmeter...), as I'm unlike to ever want to go much faster than 5ips jog/3ips move. The movements are much quieter, and the resulting cut is definitely much better as a result of the reduced vibration. Higher jog speed is definitely very nice, especially for those with big machines (mine is only 32" sq).
My question is that I am considering upping my machine to 2 by X steppers, 2 x Y steppers plus Z. I assume I will have to buy another Gecko, but what do I need to change on the board - is this possible?

R.

[Brady Watson]

RH,
You cannot run 5 drivers with a single 4G board...You'll need either the development board or 2 4G boards in tandem to accomodate the extra driver. You probably want to call SB & verify this, as they may have added a way to add another driver to the 4G that I am not aware of.

-B

[waynelocke]

Brady,
The 4g boards come with 4 drives and a fifth can be added and is labeled, I think, Accessory A on the board.
Wayne

[rhfurniture]

Brady,
There is a set of connections on the board for slotting a 5th Gecko into, I didn't know if it was connected up or there was the pin selections available, or what they may be. If only 4, what do them that want a second Z/Indexer do?

Ralph.

[richards]

As long as your power supply can handle the extra motor, slaving an axis is not a big deal - even if you want to add more motors than the control can normally handle. You can slave any axis (use two motors) by adding some very simple circuitry external to the controller board. Basically, all that you need to do, is to grab the step and direction signals that go to the primary stepper driver, and feed those signals through a buffer chip (TTL logic with at least 15ma current per output) to an external G202. Usually Radio Shack carries little proto boards and chips. The parts will set you back about $5.00. (Of course, you'll also need to add another G202 stepper driver and another stepper motor.)

Since a slaved motor is usually the mirror image of the primary motor, you will either have to invert the direction signal going to the slaved motor or swap motor leads (read the G202 instruction sheet).

[Brady Watson]

RH,
If there is a 5th slot for a Gecko, then you're good to go. Save the trip to Radio Shack. Do NOT buy a G212. You want the G202 ONLY. When you get it, open it up & pull off one of the known good Geckos and open it up. Set the jumpers to be the same on the new one as the old one is. Replace cover & put it back in.

Since you are using the same PS as your PRT had, you will be fine with the extra motor. As Mike points out, you'll want to swap the black & green wires on ONE end (usually the motor end) to reverse direction. You will also want to set the 5th driver to operate on the SAME channel as the axis it will be doubling up on in SB3. If it is the Y axis, you will have 2 motors on channel 2 (as well as channel 1, if you have 2 X motors). There may or may not be a dip switch on the 4G board to assign the new Gecko to a particular channel. Check with SB to be sure.

-B

[richards]

Brady,
The G212 is perfectly usable for some applications. If anyone happens to have one, they can easily turn the G212 into a G202 by removing the pulse multiplier board and inserting a HCPL2531 Optocoupler (available from Digi-Key for $1.30). The conversion takes about 2 minutes. Of course, it makes no sense to buy a G212 just to convert it into a G202, but if only a G212 is available from some local supplier, it is just a G202 in disguise.

The more important point, to me, is that I'm beginning to get the impression that the hobbiest attitude of making do with whatever is available, that has been part of 'botters culture, is beginning to be looked down upon. The Shopbot is a wonderful machine, but it's not a rocket and it doesn't take a rocket scientist to make it work. Adding a second motor to any axis on a PRT class machine that has been upgraded with a G4 kit, would require, at the most, a motor, a G202 stepper driver, a motor mounting bracket, a spur gear, a rack, a spring assembly, and a $5.00 kludge from Radio Shack. The whole conversion, less the cost of the motor mount bracket and a length of gear rack should cost less than $400.

Ted and his crew have already done all of the hard work by writing the SB3 code and building the controller electronics. Adding a couple of 7404 type chips to buffer the step and direction signals is something that anyone who has ever tinkered with logic gates can do. (Be sure to use the version that can sink/source 15ma per output).

[Brady Watson]

Mike,
The G212 is NOT suitable for CNC duty...that pesky multiplier board drops small movements and was a source of real confusion for a while there when a few of us were testing the early 4G setups. What burns me up is the fact that Gecko doesn't advertise this little glitch openly. I've got 5 212s that I have converted to 202s with a replacement opto. Thanks for bringing this to light, Mike...other tinkerers need to know this fact!!!

I hope you didn't think I was saying that people shouldn't tinker with the Bot...oh contraire! Come to my shop...you will find no less than 3 SB science projects in various states of mad science!

-B

[richards]

Brady,
I'm way off topic for this thread, but I totally agree with you. The G212 (or G210 or G340) or any Gecko stepper driver that uses a step multiplier board is NOT suitable for CNC duty. I've converted all my G212s to G202s and my G340s to G320s to eliminate the pulse multiplier board.

As you know, one big advantage of the Geckos with pulse multiplier board was that you could set a jumper on the driver to select between sink mode or source mode. The Geckos without a pulse multiplier board require the step and direction signals to sink at least 15ma. Since the Shopbot controller (to my best recollection) sourced those signals, the Geckos with a pulse multiplier board looked like a simple way to use existing controllers with Gecko drivers. But, you, Ted and Dirk discovered that even when the pulse multiplier was set at 1:1, the multiplier circuitry modified the timing of the step and direction signals - making the G212/G210/G340 unsuitable for use in applications with multiple axes.

The same general condition exists with the non-sychronized feed-back loops on the Oriental Motor Alpha steppers and stepper drivers. On a single motor move, the non-sychronized feed-back works great, but on a multi-motor move, the non-sychronized feed-back can and does cause problems. The work-around, of course is to NOT push the alpha past its limits.

There are a lot of little 'things' that we all learn to work-around. It's just part of life. In fact, right now in Utah, we're still in a too-long cold spell where day-time temperatures stay below freezing. Most of us have learned to slow down and live with the ice instead of holding tire manufacturers to their advertising claims. I think that the same thought process should be used with Oriental Motors and Gecko stepper drivers. I know for a fact that the CNC community is a small (but important) market for Gecko stepper drivers. Most of the drivers are sold to manufacturers of other types of process control machines. I would assume that the same thing holds true at Oriental Motor. Just because a particular product doesn't work well with a CNC machine doesn't necessarily mean that the product is defective; it just means that it was intended to be used to do other things.

As far as your tinkering goes, you've given us a lot of very valuable suggestions. I'm using two Fein vacuums, after reading about it in one of your posts. I'm also using your combined vacuum plenum/spoil board. (And frankly, I'm amazed that there is still so much discussion about using a separate vacuum plenum and spoil board, when your method works so well.) I'm also using gear boxes on my Alpha in large part because of what you and Dirk and a lot of others posted or emailed to me. (My old mind is fading fast, so I don't remember the exact chronology of who did what first, but the end result is that a lot of us have decided that a geared motor gives better/smoother cuts than a direct-drive motor.)

It's that concept of sharing of ideas, of learning from each other, or goading each other on, that makes this forum so valuable and the Shopbot such a valuable machine. There are a few other forums sponsored by CNC 'companies' that have become stagnant. One in particular, here in the USA, looked like it might become a popular site where ideas would be shared, but there are very few new posts on that site. (I was squelched by their moderator for suggesting that there were other ways to solve a problem than to wait for a 'company solution'. It's been months, but that 'company solution' still isn't available. I still check their site, but I no longer have any interest in buying their product.)

The Shopbot community is different and I think that we all have a right to be justifiably proud to be members of this community. It's because of people like Ted and his crew that are willing to innovate; people like you and other regular posters who try to help those of us who are still new to CNC; people like Dirk who have spent a great deal of time, effort and money to give new life to older machines; and, people like Gerald D., Mike John, and others who have given great support over a long period of time, and have now moved on, that makes a sophisticated machine like a Shopbot usable by the average joe.

[Brady Watson]

Nice post, Mike. I agree with you 100% (and understand every reference)...and I am reminded why I bought a ShopBot in the 1st place ~ The USERS!!! It wasn't so much the fact that there were others near me that possesed a machine, but to use the classic analogy of the average ShopBotter being a cross between McGyver & Fred Sanford...I admittedly liked that part the best...because having known nothing about CNC starting out, the 'come in the water's fine' mantra was believable...and true!

There were (and are) SO MANY innovations that have come out of THIS COMMUNITY compared to others out there. I was and still am amazed at how this community's creativity has brought forth so many solutions to so many impossibly expensive or difficult problems as a group. THIS is THE website that other brand CNC router owners read intently!!! There is only ONE ShopBot board!

One thing I like about you Mike is that you have a high regard for excellence & that comes through in your posts, and is appreciated. Your technical & electronics savvy is a real asset to ALL of us on here, so thanks for sharing YOUR tricks with us!!!

Now if I had just a little more heat...a little more money and a LOT more time I could finish all of the SB-powered science projects in various states of development...


-B

[rhfurniture]

I have just dug out a spare leg from a pre G4 batch, identical to that which I am currently machining. It is a single cut on 30mm elm, and used the same tooling and hold-down technique that I had last week. Obviously there may be differences in cutter sharpness and wood grain, but the cuts appear of identical smoothness - the only difference being that pre-g4 was cut at 15mm/sec and post G4 at 20mm/sec. So I would modify my above post to say that there was a slight improvement in cut quality (my machine is pretty firm anyway) I will bring my camera into work tommorow.

R.

[rhfurniture]

Not that you can tell much. The G4 cut actually feels smoother (and that is not just wishful thinking) so for me G4 does win with a significantly better cut.

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