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Re: Progressive Move Error with X and Y
« Reply #70 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

Offline Tweakie.CNC

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Re: Progressive Move Error with X and Y
« Reply #71 on: August 19, 2008, 01:55:50 AM »
Just a 'by the way' thing but if we profile cut a shape the number of +X steps equals the number of -X steps and the number of  +Y steps equals the number of -Y steps (this applies to any object where the toolpath starts and finishes in the same place). If steps are,say, gained at random then a 'gained step' when traveling in the +X direction automatically becomes a 'lost step' when traveling in the -X direction (and the same will apply to the Y axis) then gained steps may well cancel each other out exactly and no error will be observed. The same argument will not apply to lost steps, which are created somewhat differently.
All though it is a (very) long shot it is possible this could be cause of your problems.
« Last Edit: August 22, 2008, 02:45:23 AM by Tweakie.CNC »
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.

Offline Chip

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Re: Progressive Move Error with X and Y
« Reply #72 on: August 19, 2008, 03:28:14 AM »
Hi, Carl

Try these 2 XML's, I changed the Low-Actives around some, Don't change the Ports & Pins, Low-Actives.

If an Axis runs backwards, Use, Home & Limits, "Reversed" to change it's direction.

Chip
Re: Progressive Move Error with X and Y
« Reply #73 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
« Last Edit: August 19, 2008, 09:37:42 PM by cmnewcomer »

Offline jimpinder

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Re: Progressive Move Error with X and Y
« Reply #74 on: August 20, 2008, 04:40:52 AM »
Carl - sorry but Ive been away and lost the drift of this post.

It seems that you are trying to wire your computer direct to your stepper drivers. You say it will not work.

The 25 pin port for the printer provides the 17 data pins and the 7 signal return pins (essentially the 0v of the computer). No +5v signal is provided.

The leads from your port must be three to each driver card - step, dir, and a signal return (0v) for reference, otherwise your driver card cannot sense the voltage on the step/dir pins.

For some driver cards that is sufficient - they require step/dir and 0v.

Some, like my Gecko's require step/dir and a +5v  reference.

For this you need a seperate +5 volt supply (seperate from the motor power suppy that is (not derived from it)) I used a small telephone charger unit with a 5v regulator.

The signal return wire from the computer goes to the 0v of the 5 volt supply, and the +5 volts wire goes to the driver card.

See the attached diagram




Not me driving the engine - I'm better looking.
Re: Progressive Move Error with X and Y
« Reply #75 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

Offline Hood

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Re: Progressive Move Error with X and Y
« Reply #76 on: August 21, 2008, 07:39:22 AM »
no, pin 1 to 9 and 14. 16, 17 are  outputs, pins 10 to 13 and 15 are Inputs, pins 18 to 25 are 0v

Hood
Re: Progressive Move Error with X and Y
« Reply #77 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

Offline Chip

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Re: Progressive Move Error with X and Y
« Reply #78 on: August 22, 2008, 09:01:52 PM »
Hi, Carl

Pin's 18 to 25, Should be ganged together, If your going direct to the Printer Port you need to check them though as some don't connect/use, All of them.

Chip

Offline Sage

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Re: Progressive Move Error with X and Y
« Reply #79 on: August 23, 2008, 09:55:24 PM »
Next time you're testing, humor me with a simple test. Try a combination of X and Z moves or Y and Z moves. Maybe just swap Z for either X or Y in your standard test,  and see what happens to the X or Y accuracy. Let me know what happens.

Thanks
Sage