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melticus
Membersorry guys. I’m changing job at the moment so have not had time to get back to my machine today. thanks for your replies. I am indeed using an external stepper motor driver to drive my axis. My 8ntension is to publish my machine design when I get it working.
What I mean by torque reduction is I observe that while it is stepping, it is easy to stop the x carriage with the slow g1 command. with the fast g0, the movement nearly takes my finger off. Not very scientific but that’s how I did it…
Memberthanks zootalaws. I like your process. I will try that. As an update, I did do a repeatability test with hand coded GCode. first I used a g0 based command
G0 x10.0 y10.0
g0 x10.0 y50.0
g0 x50.0 y50.0
g0 x50.0 y10.0
g0 x10.0 y10.0
g0 x0.0 y0.0I copy and pasted this 30 times in the file to repeat it over and over with my pencil jig
The machine repeated the pattern perfectly with no slips.
Then I did the same test except changed all to g1 with f40
This was slow. BUT. I was seeing slips in my x axis (gantry). I did notice the torque was much reduced at this slow rate. so I am suspecting my stepper controller.
By the way the machine is clean. I removed all dust and grit from the drive system.
I will try your test,do it, to see If I can get any more clues
Getting close to the truth I think! Thanks guys.
MemberCool,
I will try the repeating Gcode. I will write it myself. At least I know that is correct, eliminating an unknown. Good practical advice, thanks pca. Will let you know my results..
MatthewMemberThanks PCA but I dont think thats it. I dont have end stops. I just set the machine home in the middle of the bed so it never goes near the end stops.
Also this error happens while printing. the depth is 3 mm and I set the steps to 1mm so the system passes three times to get to the depth. this is always offset.
Still puzzled:-/
MemberThanks CMCGRATH5035. Here are my files:
CamGTextJpgsThe Cam.jpg shows the original file in CAM.js.
Then I have two examples of the affected prints.
There is an obvious X scaling issue. But you can see the italic type effect and the error between passes.
I checked again the tightness as you suggest. but it is solid and the pencil is wedged in very tight. I cant see the issue as a slip though. it is too repeated. consistantly.
MemberIts a belt Zootalaws.
I ran it extreamly slowly ( limited the feed to to about 10mm per min and limited the seek to 100mm per min) same result.
Another reason I think its not a slip because the “error” is exactly the same every time. A slip should show up as a step on one round.
I also made an Astrix with the Jog Buttons at full acceleration 50000mm/min and I get perfect repeatability with a 500mm Astrix still goes perfectly to the middle everytime. I thought this would prove no slippage? (BTW I am testing this by replacing the tool with a pencil attachment.)
With the current setting I have about .1mm accuracy (hope to improve it by adding micro stepping). Would this be a possibility? if my CAM is assuming microsteps then I will lose accuracy consistantly as the motors wont step? I am using CNC.js as my CAM program.
Wish I had a way to show you the images.
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