Blown Driver??? (again)

[joe@hcitables.com]

One of my drivers will contol its motor properly at higher speeds but at slower (cutting) speeds, it cannot move the motor - it trys, makes straining noises, the control software shows the lost steps but NO movement.

After talking to support, I switched around the cables and motors to verify that it is the driver (not the cable or motor).

I'm ordering a new driver (I have an IMS board) but it seems strange that it would work at one speed but not another (at the slower speed it 'wants' to move and will move with human assistance).

This is the second time this has happened. The folks at SB have been great about isolating the problem and telling me how to fix it but I really do not want to keep buying drivers.

I'm careful about keeping the motors plugged when the control box is powered and keeping the box powered down when the SB is not in use.

Is there something else I should be doing to prevent the driver damage?

Thanks in advance

[ron brown]

Rick,

Intermittent problems are real teasers. Sometimes a freyed wire, a bad plug and even a bad motor can give intermittent problems. You may have several small things contributing to the one problem that shows.

I would check resistance in your cables, check plugs and do this while moving the cables too... try and find if you have a loose, broken or internally broken wire. Do the same with your motor. I have had similar problems and they are quite frustrating, not to mention maddening and expensive.

Ron

[elcruisr]

We found a problem with keeping good contact between the wago wire connectors and the wires. We pulled the wires out of the connectors, tinned the wires and reseated them. That solved an intermittent connection problem for us, don't know if that's part of your problem though.

Eric

[simon]

Hi
Last night I had just started to cut when the big axis went off the rails.
Turned out that X2 has failed, and the other one is torquing assymetrically.
I isolated the motor, and it works ok plugged in to other channels.
X2 channel makes the motor shudder and move very slowly without any strength. I can stop the shaft with finger and thumb.
As an emergency measure, until I can get a part shipped to New Zealand, I would like to connect X2 motor to the accessory channel.
Currently this is driving a Y2 motor. I remember when I got the bot I had to set the tiny switches to make A work as Y in reverse.
Can the same be done for X2? If so, can anyone tell me what are the settings of the switches for this? AND Does anyone know what is wrong with X2
I guess this means a new board or something expensive and time consuming.

[simon]

Hello all
I think Ive sorted out the switch thingy, but I am minus one axis. It works on the accessory axis, no. 1 was x.
However I suppose I will need another board if I want to run on 2 Y axes.
I guess you were all asleep in your hemisphere...do I have the most easterly shopbot in the world?

[gerald_d]

Simon, which SB do you have? Ours is an early PRT (Sept 2000) and it has plug-in driver chips - we don't have to change the whole board. You can follow some links in this thread. (http://www.talkshopbot.com/forum/messages/26/2931.html)

[scott_smith]

Simon
My Bot is a 2002 model PRT. The drivers are soldered in. I had the exact symptoms as your machine. I sent my control board to ShopBot for repair and they only replaced the 2 “voltage suppressors” on the X2 channel (the parts that have the arrow on the picture). The part number on the suppressor is 1.5KE51CA. If it happens to me again, the first thing I’d try is changing them out first.

3963

Scott

[simon]

Hi Gerald

I got it in 2003. It is a PRT 96, and it has V3.53 printed on the board. There are no speed jumpers.
It is one like yours, scott, and it has the voltage supressors arrowed in the picture.
I will use the aux to get over the current workload, and see if I can get some suppressors.
Once again, thanks for your kind response. This forum is great.

[simon]

Scott
Are voltage supressors the same as resistors?
Strange you had the same symptoms on the same channel.

[scott_smith]

No, not like resistors. More like a 50-volt zener diode. They protect the drivers and other circuitry from voltage spikes. Sometimes they lose their life saving others. Do a Google search for “1.5KE51CA”. That may clear things up a little. If your not comfortable changing parts on a board and troubleshooting a little by trial and error, send the board in for repair.

Scott

[mikejohn]

OK folks
I have the same problem.
Half way through a file a horrible sound and the x car jumped the rails.
After dropping the motors I found the number 1X motor (the one on the 'far side' of the table) was happy to run in jog speed, didn't want to move in move speed. 2X motor was ok.
Swapped the 1X and 2X cables and the first motor now works OK, second motor not wanting to run in Move.
So I know the problem is the driver.
Two questions (or maybe more!)
Any ideas why a driver should blow mid file? I was by the stop switch and hit it immediately the horrible noise started.
How do I use the 'spare" A axis driver.
Is it a case of re-configuring this driver to make it think its 1X, or can I simply unplug it from A and plug it into 1X?
Or do I need to unsolder and resolder?
If its a reconfigure job, how do I do it?
Thanks as usual
.....................Mike

[mikejohn]

since posting the above, I think Ive found the answer to how to use the A channel in other posts.
But I would still like to know why it blew.
Is it possible the noise I heard was something else, and when I hit the emergency switch this is when the driver blew?
Like others before me, I dont want to keep replacing drivers
Incidentally, the machine has done a maximum of 5 hours, probably less (maybe I will start keeping a log of operating hours).
I wonder if I get a replacement part under warantee?
Im going back to the workshop now to try and get things moving.
.............Mike

[gerald_d]

Mike, you have a later version of the control board than mine, so I can't really help you move channels.

The major consensus on cause of blown drivers is bad connections in the circuit between the driver and the motor. (Overloads are rarely an issue). Check that your cables/connectors are secure from being tripped over......

Apparently there is also a "voltage surge protector" (or something like that) that blows on your style of board - it is not always the driver.

[fleinbach]

Mike

I'm not sure if this will help since it sounds like a hardware problem. But there is a possibility the software glitched. I would trying deleting the ShopBot.ini file then restart the software. It will create a new one

[gerald_d]

Mike, I made the last post before reading the rest of the thread, and see now that I didn't add anything that hasn't been said before. Sorry that I can't be of any more help other than to send you a card.....Thou shalt not operate thy ShopBotte on Friday the 13th.

[mikejohn]

It is Friday the 13th without a doubt.
This is a detailed version of events.
First of all I always remove the power plug from its socket before touching any part of the ShopBot.
I have never noticed any cable being kicked or pulled, in fact the cables are all out of the way of feet.
Yesterday I prepared a piece of timber for cutting today, It was 8mm to thick, so I did a CR to remove this material.
I then had to stop for the day, leaving evrything in place.
Today I decided I would aircut the file before trying the real thing.
The file ran well at first, cutting two 35mm holes into the wood, first a 10mm hole (12mm bit) then the offset 35mm hole, with 4 repetitions at 8mm depth each time. (As I was cutting air, this isnt really important) Then the file went on to cut a 1450mm groove from 0 along the X axis.
Towards the end of this 'cut' I heard the bad news and immediately hit the emergency stop button (I was stood right beside it).
I then found that the x carriage would move OK in Jog Mode, but made a nasty noise in Move mode.
I stopped, and discovered the x carriage had jumped the track with the left hand sets of wheels.
I switched off and unplugged the ShopBot.
I then dropped the motors and lifted the X carriage back onto the rails.
I found that it was not too difficult to turn the X2 motor by hand, but that the X1 motor did not want to turn at all.
I refitted the motors and tried to move them. The X1 motor was very unhappy.
I again switched off and unplugged everything, and dropped the motors.
Then, as mentioned above, I discovered the X1 motor would work in Jog but not in Move, and when I swapped the X1cables to the X2 position (and vice versa) it worked fine ,and X2 now didn't work.
I then came home to post the first of these messages and search for help on the forum.
I came up with two posiblities. Reconfigure A as X1, or replace the X1 chip with the A chip.
Not quite working out how you set the switches to tell the X1 motor to move in the opposite direction to X2, I decided to investigate swapping the chips.

3964
I removed the chip from the position on the right, and replaced it with the one from the position on the left.
I found that the left most pin on the bottom row of the right (X1) chip had broken off. I had to remove it from the socket before I inserted the old A chip. All of the 5 chips had a red spot in the top right hand corner and I ensured I kept them in this orientation.
I carefully pushed the A chip into the X1 socket and switched on.
Previously, when switching on the lights I have indicated in red in this picture came on for a couple of seconds, then went off. The light indicated with the green spot stays on.
3965
On this occasion the only light to come on was the furthest right, the X1 position, apart from the green power light, and it didnt go off.
After a number of seconds, maybe 10 or 15, I switched off and disconnected the power.
I then found the chip was hot

I removed the chip, so the board was as in the pictures, missing two chips, and switched on again.
This time the Y and Z lights came on and stayed on, but the chips didnt get hot.
I then tried moving these axis (using k and the arrow keys). Y made no sound at all, z made a sound as though it were trying to do something.
I switched off, took the pictures, came home and wrote this.
I will send this whole message to support, they should just about be having their breakfast.
I fear that it is a major board problem.
But I can't as yet see if I have contributed to it by swapping the chips. I don't think I did anything physically wrong. I didn't force anything. I lifted the chips out vertically, and replacement required little or no force.
Pins were straight after removal. Apart from the pin opposite the one that had broken. This was slightly bent. When I touched it it fell off.
I guess this is more for information than anything else. Probably nly support can help.
Like all these things, it really came at a bad time, just when I had impressed somebody with the ShopBot, and they were eager for samples!!
........Mike

[gerald_d]

Mike, maybe the only constructive thing that you might be able to do while you wait for the Durhammers to finish their cornflakes, is to find local stockists of the dubious chips and the 1.5KE51CA suppressors mentioned above. I do agree that it sounds like more than just those chips being the issue, but you have to do something.

Oh, also rush off your street address, name and contact number, to ShopBot so that they have an address to deliver your spares to. They still have all day to get UPS on their way - with luck (and cooperation) you can have spares by Monday.

PS. I have a feeling that the chips you swopped were not the driver chips - drivers push lots of power and should have a healthy heatsink??

[mikejohn]

Gerald
Firstly, because the problem I mentioned in me email has got worse, my next week is lost anyway, so getting the problem solved is a little less urgent. The opportunity I mentioned above is probably lost.
Here is a picture of what I assume to be the driver set up, there are 5 identical ones.

3966
There appears to be 3 chips in each of the 5 set ups. The two ringed in red are identical, so I asumed as people speak of the driver chip, then there would only be 5.
The largest chip is the one ringed in yellow, which I assumed to be the driver chip.

3967
This shows a close up of that chip, with the broken pin.
The number on the chip is PIC16C711-04/P
then 0352S7P.
This is the same number on the chips I exchanged.

As you say, the problem seems deeper. I have re-asesed the time the machine has actually run, and feel it is even less than 3 and a half hours.
When things go wrong, the first person I look to for blame is myself. I have read all the warnings and have been very certain to make sure the machine is disconnected when not in operation.
One small thing that might be relevant, or maybe a red herring. Immediately after the problem, when checking to see if the motors would run when dropped, I couldn't get the Computer to connect to the control box.
After a number of times of trying, the computer would lock up whilst trying to connect.I couldnt even get it to 'not connect' and give me the list of alternatives.
After a number of attempts, it re-connected OK.
So I am at a loss.
Hopefully support will supply an answer.
..........Mike

[gerald_d]

That PIC16C711 makes it a "microcontroller" - it is not a driver?

[fleinbach]

Mike

Did you try deleting the ini file? If it gets corrupted it will cause problems initializing the software.

Also pertaining to the chip there is a possibility that its is still okay with a broken pin. Depending on what the chip does most times not all pins are used. I have had many chips with broken pens that work just fine in the past.

[dvanr]

Mike,

Don't bother tracking down a local source of PIC chips (MicroChip) , they are programmable and Shopbot will have to program them first.

[mikejohn]

Simply swapping the chips, if they were not faulty in the first place shouldnt have caused a problem.
So, what does a driver look like?
How many drivers are there on a board?
..........Mike

[gerald_d]

Mike, as Dick pointed out, you swopped pre-programmed chips. If they carry identical programs that should be fine. Even if they carry different programs, they shouldn't fry themselves. Were those legs broken off, or melted off - does the chip smell burnt?

[mikejohn]

The legs were broken
There is no smell of burning at all
So what does a driver look like?
Im reluctant to try anything more without feedback from ShopBot support.
But I still feel that the root cause isn't clear.
Apart from being a terrible engineer, I'm also hopeless at electronics!
.............Mike

[cnc_works]

For what it is worth, one of my X drivers blew as well. In swapping drivers, I could not get the spare driver to work either. Upon close inspection I found one of the legs of the spare driver chip bent over and not plugged in. Straightened it up, plugged it in and it worked. Lucky me!

Donn

[mikejohn]

I'm sorry to ask the same question for a third time but...........what does the driver chip look like.
Gerald says "drivers push lots of power and should have a healthy heatsink"
I don't appear to have anything chip-like with a healthy heat sink.
...........Mike

[dmdraper]

I know it sounds weird, but do as Frank suggested. Uninstall and reinstalled the ShopBot software, incuding the .ini file (be sure to record your settings first). I had a problem with the Z motor not driving and even went so far as to send my controller into ShopBot only to find out nothing was wrong with it. IMO, the software (v3.4.1) can become corrupt and will cause one axis (only) to malfunction. This may not fix your problem, but it's a quick fix to try to eliminate one potential cause.

In fairness to ShopBot, I only notified them yesterday of my findings when I reinstalled the software and the problem corrected itself. I don't know that they have a chance to evaluate it.

Dave D.

[mikejohn]

David
I was running in DOS 2.39
What I never mentioned above is mine is the very last of the PRT96's
still don't know what a driver looks like
........Mike

[mikejohn]

I will try re-installing.
Would this account for all the symptoms shown in my big post above?
..........Mike

[bleeth]

Mike: We had a couple Power blinks around here yesterday and at the time my bot computer was on and so was the controller. SB3.4 was not on and neither was my monitor. When I turned the monitor on my video driver had defaulted to a windows generic. I had to restart the computer again to get the driver to reload. Then, when sb3 was opened, the panels were in the wrong location on the screen and it couldn't find the controller. It took two more restarts till things were back to normal. And all of this was just one week after I reformatted the hard disk and therefore it's like a new installation. I don't even care what causes such problems as it is beyond my technical expertise, but I do know that before I mess around with any hardware I always try turning things off and rebooting a few times before getting out the wrenches. Good luck with your repair.

Dave

[gerald_d]

Mike, I know what a driver looks like on my version of the board (have changed 3 or 4), but it looks like it is an absolute secret what they look like in the later PRT's. I'm wondering too, is there anyone who has actually blown/changed/seen a driver on the 2002 to 2004 PRT's?

[mikejohn]

Dave
The problem for me was it happened mid-file, and the programme seemed to work in everyway bar the move on one motor.
Doing what I thought was the right thing, I posted a message, emailed support (no response yet) then trawled through the Forum and thought I had discovered the answer to my problem.
But either I have had a chain reaction on the board, one thing causing another to fail, or maybe there is a software problem.
I will check the software posibility tommorow.
Certainly I had to turn off and reboot a number of times before I could restart, but without a positive change to the problem.
I guess if I was in the States I would have overnighted the board to ShopBot, but from here its not that easy (or inexpensive).
I do wonder if a brand new (less than 3 and 1/2 hours work) ShopBot, which was working well, should be expected to pack up mid-file, particularly when air-cutting.
..............Mike

[scott_smith]

Mike, Someone needs to answer your question:

The two “3955” chips are the drivers. The ones you have in red in your pictures.
This is from Allegro’s web page: “The 3955 is designed for driving one winding of a bipolar stepper motor in a microstepping mode.” (That’s why there are two per channel).
They are soldered into the board and have no heat sinks on our style of control board.
Scott

[bleeth]

Mike: My answer to that question is "Not bloody likely!" I would have been on the phone at 9:01 AM Durham time (They start work late there). It does sound suspiciously like something let loose that shouldn't have and I guess it's part of the "either it breaks right away or runs darned near forever" syndrome that is part of our electro/mechanical society.

I wonder how many bots there are running in western Europe. Maybe they need a local support branch or at least an "authorized service tech"

Dave

[mikejohn]

Dave
Although I am unhappy about what has happened, I look at things like this in this manner.
The ShopBot was working, and working well, I love it. So until it went wrong nobody could have known about any fault.Like you say "I guess it's part of the "either it breaks right away or runs darned near forever" syndrome that is part of our electro/mechanical society.
I emailed support early, giving all the information you have seen here.
It is the response from ShopBot that will determine my "not bloody likely" reaction.
As I said earlier, I have learned to first assess my actions when things go wrong. In this case, up to swapping the chips, I can not see how I could have possibly contributed to the problem. Even the chip swapping was no physical problem. My confusion about what the chips do comes from reading earlier threads about this problem. Here they talk about simply unplugging and swapping.
The only things that can be unplugged were the chips I swapped.
Its lunch time in Durham now. Maybe I will get an answer after lunch.
Your question about the number of 'Bots in Europe, even outside America is an interesting one. I am due to host the first Eurobot event in September, and I don't have this information.
............Mike

[gerald_d]

Mike, don't hold your breath for a prompt reply to an e-mail. If you want them to despatch something this week, you had better call them.

[grant]

Mike, we are real short on people here today so we've had a tough time keeping up with everybody. It sounds like your X driver is definitely dead and unfortunately I think the chip swap you made may have taken the rest of the board out by allowing the damage caused by the short to spread. We are trying to send you a replacement board, but we have no record of a phone number for you on file and can't make an international shipment without one. If you call or email us in the next hour we can send your board out today. If you have a problem like this in the future please call us as soon as you can. I know international phone charges can be high but when we get busy we are all on the phone pretty much solid and emails have to wait. I sincerely apologize for the inconvenience, now that we are aware of your problem we are doing everything we can to get you the parts you need.

Regards,

Grant Bailey
ShopBot Tools Inc.
1-888-680-4466
grant@shopbottools.com (mailto:grant@shopbottools.com)

[benchmark]

Mike

Phone calls to Shopbot via Telediscount only cost 2p per minute, just dial 0844 462 90 90. Calls to mobiles in the USA are the same number and cost.

All the best for the new board


Paul

[grant]

Gerald Dorrington was nice enough to pass along Mike's number, it made in on the DHL shipment by the skin of it's teeth. Mike, you should see it next week and please call us before you hook it up.

Regards,

Grant Bailey
ShopBot Tools Inc.
1-888-680-4466
grant@shopbottools.com (mailto:grant@shopbottools.com)

[dvanr]

In the mean time Mike, Take another photo of your board and control box from a little further back.
Maybe we can tell what version of box you have and where the driver is in the box ... ( Do you see a little man in a tweed jacket and black cap sitting somewhere on the right ? or is that left?)

[mikejohn]

Gentlemen all
It has been said many times before on this Forum, but it is worth saying again. ShopBot support are the best there is.
Unfortunately time differences meant that Grant was handling my problem after I had left the computer for the day, but I found 5 emails this morning, including the details of the shipment.
Although the initial problem does seem like a failure on the board, I probably did not help matters by swapping the chips.
I feel my experience makes this warning a sensible precaution. Be absolutely certain that any remedy you attempt, using information gleaned from this forum, applies to the equipment you are using! Be aware that quite a number of different set-ups have been used, even with similar sounding models,like PRT.
If someone is writing prior to any changes there will, of course, be no warning that a later model should be treated differently. Hind sight is a wonderful thing. My impatience to get working again as quickly as possible was, in retrospect wrong. I should add that throughout this forum advice is given to check with support. Unfortunately I depended on an out of date thread, and acted unwisely.
No company can know a component will fail after only 3 and 1/2 hours. They really have to be congratulated on there response.
I was so disappointed yesterday because I really love my ShopBot, it excedes my expectations by a long way.

Gerald, thanks for passing on the phone number, I owe you, again!

Thanks to all of you, and I will re-install the software.
................Mike

[gerald_d]

Good Morning Mike,

It's a pity you missed the middle paragraph of my 6.25am post yesterday. That's all the information needed by DHL, UPS etc. Grant has used your address on file, which is probably different to where you are now. You might have a new problem to get things to the right address, and I might have made it worse by helping Grant to rush it off.

You are getting a new board this time, but what are you going to do next time? Maybe at your leisure start to develop your drill of how to change a channel over to the spare Aux.

[mikejohn]

Gerald
Its OK, I will be at the address Grant used next week. Thanks again for your help.
Maybe, In all seriouseness, we could start new threads for tuition in 'hands on' maintenance where there is certainty of the steps to take. In fact also warning when not to take these steps.
Sometimes I know there are things Im quite capable of, if only I fully understood the steps to take. I can do a lot of car repairs, but only because I am repeating what I have seen others do before me.
What stopped me flicking the aux dip switches was that I thought as the x motors go in different directions, how would it know which was which? If any one can answer this, I would be interested.
Certainly I will go back and do all the 'loose wire' checks advised above, and make sure no wire can be accidently pulled.
I was going to add this to the 'getting started' thread, maybe calling it 'Getting re-started'

I imagine many 'newbees' like myself are so entranced with what the 'bot can do that they are more interested in making it produce things than doing all the 'extra' good stuff advised here. I am still earthing (grounding) through the V-wheels. An earth lead in series from the Z carriage, through Y and X to the table and then earth is going in immediately.
I will also be going back over all the old threads that are relevent to possible problems. Maybe its up to me to make sure the ShopBot can perform well mechanically, not only via use of software planning.
.........Mike

[bleeth]

Mike: I'm pleased, but not surprised, that SB has responded so positively. I have also found all of them and especially Grant to be good people.
Yesterday aft when I got home the hard-drive on my 3 weeks out of warrenty HP went out. This follows on a reformatting of the SB computer last week which followed a power spike in my office blowing the power supply in that computer as well as taking out my new router and dsl modem, adding machine, and credit card reader, but strangely not effecting the surge suppressors at all! That computer had an extended service plan on it that had run out literally days before.
If I know DHL you should have your new board Monday. I had a shipment show up from Venice to Seattle a couple of years ago in 24 Hours.
On the subject of checking out for loose wires: It's a real good idea to periodically go over the bolts for tightness too, and when you are done make sure to verify the axis locations.
Any conclusion on the exact camp locale yet?

Dave

[gerald_d]

Mike, do you really have DIP switches? (There was a time that they were dispensed with) The different direction issue of the x-motors is most easily sorted out. (when we got our 2000PRT, all the motors were going in the wrong direction!):

Each motor has two coils inside of it, connected by 4 wires from the driver to the motor. If you change the polarity on any one coil then the motor changes direction. Therefore, if you must change the direction, find a pair of wires that drive one coil and swop those wires around. This swop is done at the plug-in connector of the motor cable. Look carefully at the sequence of colours of the 4 wires at the connectors - you will see that one x-motor-cable has a pair of wire colours reversed at one end.

Bottom line; the control board doesn't make one motor motor run opposite to the other - that is done with the motor cables. If you do have DIP switches, the direction is not an issue.

[mikejohn]

Gerald
Why are these things so obvious once you know how!
In my long explanation I said "Towards the end of this 'cut' I heard the bad news and immediately hit the emergency stop button .
Would a ShopBot moving at 50mm (2") per second, air cutting, (no opposing force) have enough momentum to move a sufficient distance after hitting the emergency button to induce sufficient current to blow a driver?

To Dave and all the many others who are interested in attending EuroBot 2005. The event will be held in mid-Dorset close to the town of Blandford Forum. With the numbers of possible attendees growing daily, expect a lot if the event to be in a seperate meeting place,close to, but apart from my workshop. (Close to a bar though, with specially warmed English beer)

...........Mike

[gerald_d]

Mike, when you heard the "bad news" that driver was already blown, so it couldn't have been the over-run that did it.

Blandford Forum (http://www.imagesofdorset.org.uk/Dorset/019/intro.htm) <---- Nice little town for two Bastards


Alas EuroBot 2005 (http://www.eurobot.org/eng/index.php) has been taken

[phil_o]

Are the driver problems associated to the new alpha Shopbots as well as the PRT's? The Alpha's have a new control box. Are the circuit boards and drivers better as well?

[gerald_d]

In the Alpha's the drivers are in modules supplied by the stepper motor manufacturer. They are separate from the control board.

[mikejohn]

BotSpot Europe 2005?

[gerald_d]

Geckodrive have launched a new model driver this week. This is the test they go through:

"All drives have had the 4 motor outputs shorted to ground 2 times
each at 7A and 80VDC. The motor outputs have also been shorted A to
B, C to D, A to D and B to C 2 times each at 7A and 80VDC. This is
16 hard short-circuits while operating at max limits for each drive.

All drives have had all 4 motor outputs disconnected 8 times at 7A
and 80VDC (this ruined four 25A SPST contactor type relays due to
contact arc erosion)."

What a test! Do not try this at home!


Link (http://www.cnczone.com/modules.php?name=News&file=showarticle&threadid=10 752)
Geckodrive (http://www.geckodrive.com)

[Brady Watson]

Sweet! It's about time! I think that they originally had a 'Vampire Drive' kit of sorts that was an add on for the 201 & 210s. I may try these out on my Bridgeport with the stock N42s...in serial it will be running on the ragged edge (6.8A) and it's nice to see that there is some protection built in. The only other decent & reasonably priced stepper driver out there for the BP's big motors is the Larken Cobra16 (http://www.larkencnc.com/motion/steppers.htm) (I only see the Cobra10 now...2 months ago they had an 8 & 16...hmmm) which will handle a whopping 16A...they are rebuildable but cost $200 each.

Tired of waiting for Rutex to get their butts in gear with the 2000 series servo drives...so the servos will go in storage and I'll roll with the steppers for now...

-Brady

[mikejohn]

How sweet the sound of a working ShopBot after so long laying idle

OK, I know ShopBot asked me to call them before I reconnected, but they weren't at work as it was Memorial day

I have however encountered a problem for which I can think of two possible reasons, but need reassurance.
I was cutting out the panels for my dust proof, positive air pressure control box and computer cabinet out of 16mm MDF.
The first side cut out OK, but when part way through the second side I noticed when the 12mm two flute bit plunged into the material it hopped back up about 4mm. I re-zeroed Z and started again, but what I hadn't noticed was that Y was off now by about 5mm.
I suspect either the bit isnt sharp or I should have ramped in, not plunged staraight down.
Any thoughts please?

................Mike

[richards]

Mike,

It's good to see that you're operational again. I was beginning to wonder...

As far as the Z-Axis lifting goes, it shouldn't happen unless the code to perform that move is part of the sbp file. Unfortunately, it looks like you might have an electrical noise problem. 'Jittery' signals feeding the stepper motors can cause the type of problem that you've described. If the steppers are commanded to 'move' by extranious jitters, they try to comply; but, since the signals are erratic, they endup losing position. Because you have the problem on both the Z-axis and the Y-axis, I would suspect electrical noise.

On the other hand, in my experience, a dull cutter simply bogs down the machine. At times I've lost position on my alpha due to a dull cutter or by trying to make a really heavy cut, but the Z-axis has never 'lifted' on me - if my failing memory can be trusted.

[gerald_d]

4 points: Earthing, earthing, earthing and keep your router cable at least a 1/2" away from the motor cables over 90% of its length. (1" away is 4 times better than 1/2" away).

How's Roger's health?

[bleeth]

Mike: I think if your steppers lost position by a dull bit you should have heard some real complaining coming from the bit. If the y lost position because the bit bound odds are it would have gone out of square and hopped off the rail as well.
Check for shorts and ground issues and hopefully the circuits your router and controller are on are dedicated.

Dave

[mikejohn]

As I was cutting my high-tec control box cum computer consul, I was using a temporary set up which may well have power wire routed closer to control cables than in the original set up. The router cable is completely seperated from the motor cables, taking a route above the table.
The power to the control box may be touching the motor cables though.
............Mike

[beacon14]

Some bits do not cut the center out as they are plunging - they are only designed to cut sideways. If you use one of these bits and try to do a vertical plunge it can cause a loss of Z positioning, either due to lost steps or forcing the bit deeper into the collet.

[mikejohn]

Checked this morning and the power sockets (surge protector) was touching the motor cables.
Moved everything out of the way.
I had changed the file to ramp in over 75mm (8mm depth). Everything went fine. Then I cut a rectangle using the keyboard commands, typed -3 instead of -.3 (mm) and bounced the z axis off the table.
I must assume this is common. If the bit wont cut in,and the z axis can not go lower, it must lift the y carriage, then presumably the weight of the y carriage pushes the z carriage upwards. Any chance of this 3mm movement causing drivers to blow?
..............Mike

[gerald_d]

Mike, I think that you can relax about keyboard errors, jumping cars, etc. causing drivers to blow. From what I've heard (read), the drivers can sustain a short duration overload to the extent that the stepper motors skip steps. We have probably pushed the car off the rails about 20 times and blown drivers 4 times, but the events were not simultaneous. Our drivers blew at switch-on of the system, or during a jog - not during a load or overload while skipping steps against a stop or clamp.

[mikejohn]

Gerald
Two weeks ago I thought blown drivers was something that happened to other people on the Forum. Now I see them around every corner


As a general remark, I am finding that it is necessary to really think through what is going to happen when cutting. I had a piece I was cutting, wierd shape, well clamped down except that the last cut was done being held by one clamp only (with the expected twist in the material). ShopBot operating is a lot easier simulating in this Forum than it is in real life (but I am learning
)
...............Mike

[gerald_d]

Mike, if you don't want to think, you could get a 500 HP vacuum table and burn half the fuel on the planet!


It would be interesting to get a show of hands from the readers of this thread.......tell us how many drivers you have blown. Known score so far:

Gerald_D 4
Mike John 1 (maybe more while fault-finding)

[beacon14]

David B 1 with my old PR machine, 0 with the new Alpha (so far)

[Brady Watson]

David,
Very good point about center-cutting bits. If it doesn't center-cut, then you will knock the Z out of position because the bit will build up material on the end of it....shrouding the cutting point. Then the car will lift off of the track and/or you will lose Z position because the stepper will stall from the force put on it.

-Brady

[gerald_d]

We also need to hear from those that have blown nil drivers....

[mikejohn]

Wether or not having the surge protector touching the motor cables caused a problem I don't know (although in future no power lead will go anywhere close to a motor cable) but using a flat ended, two flute 12mm bit which doesnt want to plunge certainly upsets the Z.
Ramping in 75mm (3") to a depth of 8mm(1/3") eliminated the problem.
...........Mike

[gerald_d]

Mike, under these conditions, would you want to have "hold-down" rollers? Or would you prefer the forgiving nature of your y-car?

Anyway, back to the topic of this thread: blown drivers.... I am busy tinkering with a second (back-up) control system completely separate from the ShopBot controller. We have to have a back-up plan that we can fault-find and repair ourselves - the delays and costs involved by working across the ocean are just too great.

[jay]

Two year old machine, PRT, probably averages 24 to 30 cutting hours per week, NO BLOWN DRIVERS.


Yes the Y car has jumped the railes a few times man I hate it when you rack the Y car. Have had something leaning against the table that has stalled and lost steps in X as well. The machine is really good at cutting clamps too. I love plastic clamps. Isn't learning the do's and don'ts fun? All in all I have found Shopbot to be very forgiving and certainly robust for the variety of material we cut.

I am very very pleased with my Bot!

[evan]

Nil blown drivers on my PRT, nil blown drivers on my PRTALPHA Upgrade.

[bleeth]

I refuse to answer on the grounds that I don't go looking for jinxes!!

[mikejohn]

Do you look for Huckleberry Hounds?

[Mayo]

I have an older PRT 96 but I have had the control board replaced by Shopbot once due to a lightning strike. This newer board uses the IM481H driver, and it didn't come with an accessory driver even though the connection for one is there.

I may have a blown X2 driver. What might have caused this, is the X carriage ran over the motor cable! Twice!! I didn't notice this because the Bot was working fine for a few days after this happened. So I'm not sure that is the reason for the problem. And on inspecting the insulation of the wiring, the wires inside the gray sheath were not cut - just mashed. Just to make sure, I cut off this section of cable and reconnected the wago connector.

I determined the motor is fine by connecting the cable to the X1 connection at the control box. I then connected the repaired cable back to the X2 connection and the motor grinds and sounds horrible. This would indicate a bad driver?

What I have done now is, I removed the driver and installed it in the accessory channel on the controller board. I did this thinking maybe some other part in the X2 circuitry blew and the driver might still be OK. The drivers can only be removed by first removing the entire circuit board from the control box, so that you can get to the heat sink screws.

Now, I forgot if the cable from the blue earth board plugs into the upper or lower group of pins, and what position the red stripe is in?

And what position for the red stripe on the serial cable where it plugs into the control board (not the back of the control box).

3968

As you can see, the board is marked Ver 2.07 and I am using the windows software so I will change the the software so that the X2 motor is now located at the accessory channel (Using V I command)