Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: Geoff 330 on March 08, 2018, 07:28:33 AM
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Obviously new to this but I have been trying to understand it all. I am at the got road runner to load and cycle though the program stage but the machine appears to be adding steps for all three axis. I did use the calibration and it is moving the proper distance through that, but it does not fix the problem. It just keeps working diagonally up to the corner, way off the piece.
It's been a long process to get this up and running. I bought an eBay CNC machine that ended up having a bad breakout board. I put a new board in and wired it (after lots of videos) and it seems to do everything it should but when I actually run it, it trails off. I have most likely done something I shouldn't have but can't figure it out. As my father would say "I don't even know, what I don't know".
Any help would be greatly appreciated.
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After watching programs run it appears that it is not completing steps. Several times the motors are not moving when they should be. When the next line of code starts it is not in the right position for that line. Not sure how to fix that.
Any help would be appreciated.
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If the DROs are moving and the motors are not moving but making a grinding kind of noise then you are loosing steps. Try reducing the velocity and the acceleration on the motor tuning page by 50% and try again.
Mike
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Thanks for the response. The motors are not grinding and jog just fine. I just slowed the acceleration and velocity down with no change in the problem. It seems to not move in the negative direction while running gcode. I end up with my z axis all the way up and the xy diagonally off the work piece.
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Hi,
are you using a parallel port? Is it possible that your BoB is expecting 5V but your PC is producing 3.3V.
It does happen and some BoBs dont respond properly.
Craig
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Adding to what Joes is saying, if the direction change is seen by the driver every time it goes high, you would end up with what you describe.
The other possibility is that you have the step and direction set to active high when they are expecting active low. Thiscan be changed andtried on the ports and pins page.
Mike
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Finally got a chance to try some things with no change in problem. The motors won't move if I uncheck the active lows in the ports and pins. The set up I followed was for my Bob. It is a cheapo sainsmart 5 axis. Joe's, how would I determine what my volts are? My parralel port card is new and I specifically checked to see if it was 5V when I bought it but did not test it. There is a 5v indicator light on the breakout board that is lit but seems dim.
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Connect a multimeter between an axis Direction Pin and GND. When jogging that axis in one direction you should get approx. 5Volts and in the other direction approx. 0Volts.
Tweakie.
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Yep, 3.3 volts. The Bob has a USB input for power and is hooked up but does not seem to be doing anything. Any suggestions. At this point I don't know where to go. Another new parralel card? Diagnostic for the usb? Separate power source to a better Breakout board? I'm open. Just want to get this working.
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Hi,
if your stepper drivers handle 3.3V input you'd be fine. Your description rather sounds like the drivers
are not reliably operating with 3.3V inputs however. One possibility is to change the drivers, another is to
change the BoB to one that produces 5V outputs and yet another alternative is to use an amplifier between
your BoB and the drivers. One hex buffer IC would do step and direction for a three axis machine.
Hows you electronic skills?
Craig
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I am not at building circuit boards. I am completely new to CNC.
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Hi,
OK then you are going to have to replace probably the BoB to make it work.
Do you have manufacturers documentation for both the BoB you already have and your stepper drivers?
I'm hoping there might be a simple solution.
If your budget is tight then you may have to consider making an amplifier solution....one IC...$4.00 or so
and 2 sq inch of vero board...not that hard.
Craig
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Thanks, I'll do some research and see what I think will work best
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The simplest solution may be to just obtain a new PCI parallel port card that outputs 5Volt TTL signals. This thread may help https://www.machsupport.com/forum/index.php/topic,34848.0.html
Tweakie.