Messages

11

General Mach Discussion / Re: Progressive Move Error with X and Y

« on: August 27, 2008, 08:09:37 PM »

Hood,

I have not bypassed the breakout board yet.  I will be trying that soon but will finish some more testing before going to that step.  I'm still not sure I understand how to hook up the 5v supply.  Based on some previous posts it sounds like I need to hook the negative side of my 5v source to one of the pins at or above pin 18 and the positive side to the gecko drive's common pole.  I'm hoping I can use 1 5v supply for all three drives but still not sure about that either.

Sage,

The CNC4PC board uses pins 1 through 9, 14, 16, and 17 as output.  I had originally connected the drives as follows:

X-Driver Step   -   2
X-Driver Dir                   -   3
Y-Driver Step   -   4
Y-Driver Dir                   -   5
Z-Driver Step   -   6
Z-Driver Dir                   -   7

When I disconnected the Z-Driver and connected X and Y (modifying the motor config accordingly) as follows:

X-Driver Step   -   2
X-Driver Dir                   -   3
Y-Driver Step   -   8
Y-Driver Dir                   -   9

I ran the full gear crossing program 3 separate times and it was spot on.  Not even a thousandth off when done each time.

I then connected Z (modifying the motor config accordingly) backup as follows:

Z-Driver Step   -   2
Z-Driver Dir                   -   4

Unfortunately I walked away during the 9 minute program and the Z drive crept down into my work piece and ruined my Starrett edge/center finder.  It was at this point that I realized I definitely had a problem with noise or interference. 

I now need to repeat my tests and start checking other pins on the breakout board to see if I can possibly find another configuration that will work.

Ultimately, I am going to bypass the board.

I think you are referring to my point that I could run just the X stepper alone and it would do all moves without error.  I could then run just the Y stepper alone and here again it would do all moves without error.  It was only when I did combined X/Y moves together that I would begin to notice the errors.

What confuses me is the fact that Mach is 2.5D.   The Z axis doesn't move while the X or Y axis moves so I'm not totally sure I understand where the noise/interference is coming from?!  But I agree that it appears to be the breakout board or parallel cable.

I may not get all the tests done tonight but I will post my findings when I'm done.

I can't thank everyone enough for keeping with this thread and helping me along.  It was been very frustrating at times.

Best Regards.

Carl

12

General Mach Discussion / Re: Progressive Move Error with X and Y

« on: August 26, 2008, 09:47:49 PM »

I'm not sure this is even worth posting as it may just add more confusion to the equation but here goes. 

I moved the y output on the breakout board to another set of outputs for the step and dir pulses and ran a perfect test three separate times.  I did not have the z drive hooked up.

I then hooked up the z output to the original location of the y outputs on the breakout board and noticed that the Z drive had a progressive error.  However, the y and x axis were still corrrect which seemed odd to me based on previous testing.   I then moved the z ouput to some odd ports on the board but it would not run the stepper properly.  According to CNC4PC, it should work on the ports I'm using.

This appears to be where the problem is occuring.  When I did the original testing on the x and y axis, I did not have the z axis compeleted yet so did not realize there was a problem until after cutting my first gear crossing which included the z axis.

More testing tomorrow if I have time.

Best Regards.

Carl

13

General Mach Discussion / Re: Progressive Move Error with X and Y

« on: August 25, 2008, 09:51:14 PM »

Sage,

Yes, I was definitely confused but your suggestion was a good one.  I ran the program with just the X-Axis connected (the y and z were disconnected at the breakout board.  I ran 6 tests and the X axis was very close with the respective runs showing 2, 2, 3, 3, 3, 3 on the dial indicator after each run.  So the X-Axis was repeatable.

When I did the same test for the Y-Axis, it was a little off but not by much showing 0, 1, 1, 2, 3.5, 4 on the dial indicator after each run. 

Looks like I will need to start hunting down interference problems.  Not sure how to do that so any suggestions would be greatly appreciated.

Thanks again for your help.

Best Regards.

Carl

14

General Mach Discussion / Re: Progressive Move Error with X and Y

« on: August 24, 2008, 06:07:58 PM »

Chip,

The attached spreadsheet has some details on the tests using your config files.  The MachCarl_Test_1.xml clearly performs the best.  When I set it to Exact Stop, it performed even better.  It looks like I need to stay around 10 IPM as anything higher starts to exaggerate the errors.  If I can get consistent runs with this configuration, it will be acceptable for what I'm doing right now which is only cosmetic for the gear crossings.  I cut the gear teeth by hand using a Carroll Dividing head.

Sage,

I swapped the Z driver cable with the X driver cable and it would not run.  I went into the config and swapped the ports for Z and X also.  I may need to put in a different resistor for the driver since my Z axis uses a Nema 24 and my X and Y use Nema 34s.  I moved the Z driver cable to the Y stepper and it moved in one direction but not the other.   Other than the resistor, I can't think of any other changes I would need to make.  Not sure what this means but it wasn't what I expected.

Best Regards.

Carl

15

General Mach Discussion / Re: Progressive Move Error with X and Y

« on: August 22, 2008, 08:29:32 PM »

Probably a silly question but can I use the same 5v source for all 3 drivers?  Also, can I use just 1 of the the 0v pins, such as 18, for all three drives or should I use separate 0v pins for each driver?

Best Regards.

Carl

16

General Mach Discussion / Re: Progressive Move Error with X and Y

« on: August 20, 2008, 08:42:12 PM »

Jimpinder,

Thanks for the help with the direct wiring.  For the 0v return port, would this just be pin 1 on the parallel cable?

Best Regards.

Carl

17

General Mach Discussion / Re: Progressive Move Error with X and Y

« on: August 19, 2008, 09:32:56 PM »

Chip,

Thanks again for the help.  Here are the results from running this multiple times:

File 1:
1. Showed the best results but still some minor drift.
2. Noticed that the breakout board LEDs were dim on the step pins.  The dir pins were bright.

File 2:
1. Drifted more than File 1.
2. Noticed that the breakout board LEDs were very bright on the step pins.  The dir pins were bright.

My Original File:
1. About the same as File 2 above but drift was in different direction.
2. The LEDs were dim on the step pins.  The dir pins were bright.

I've been at this for hours but I will try to do some more quantitative tests tomorrow.  I hope I can go with File 1 and start making some chips.

By the way, I engraved my daughters name on a calculator she bought for school and it turned out nice.  I don't have the correct bits or speeds, but an old dremel bit did OK for a quick an dirty setup.

Best Regards.

Carl

18

General Mach Discussion / Re: Progressive Move Error with X and Y

« on: August 18, 2008, 08:48:07 PM »

Tweakie.CNC,

Thanks for the suggestions.  I had no idea what a schmitt was until I started researching it from your post.  Seems like an excellent idea to ensure a clean signal.

I got my breakout box made for the parallel cable but I guess I don't understand how the signal works when going direct from the PC to the driver as it didn't move the steppers.  I tried providing 5v to the driver common and then having the step/dir pins go direct to the driver also but nothing.  Will need to research more how it works when wiring direct.

I really can't say if I'm gaining or loosing steps.  When I run the program to cross out the gear spokes, it will perfectly machine the pocket in each quadrant which takes 13 passes to cut through.  But when it does the simplest of all the operations, which is to move from the current quadrant to the next quadrant, it gets the error.  Very puzzleing to me.

Back to reading and asking questions on how to wire direct.

Best Regards.

Carl

19

General Mach Discussion / Re: Progressive Move Error with X and Y

« on: August 04, 2008, 08:45:07 PM »

Well, it's back to the drawing board.  No luck when I ran the more complex gear crossing program.  Time to get a scope on the inputs and wire direct to the drivers.

Best Regards.

Carl

20

General Mach Discussion / Re: Progressive Move Error with X and Y

« on: August 02, 2008, 04:28:02 PM »

Well, I'm not ready to declare victory yet but today's work seemed promising.  Running my control program, I finally got good results.  Will try and run the gear crossing program later which should be the final test if things are working correctly.  Here's what I did to get to this point:

1. Replaced the dell latitude 8100 laptop with an older HP D530 desktop workstation I bought from geeks.com.
2. Set Motion Mode to Exact Stop as recommended by the team here.
3. Set Sherline 1/2 Pulse Mode as recommended by the team here.
4. Significantly reduced Acceleration in motor tuning.  The ramp up/down is currently over 2 seconds.

I'm in the middle of building a breakout box for the parallel port which is a real PITA so I will resume this effort if things don't go well with the next test.

Thanks again to everyone that has helped me through this project.  It has been greatly appreciated.  Great support team!!

Best Regards.

Carl