Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: Jerry In Maine on June 03, 2013, 01:46:23 PM
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Just finished a new machine and configuring Mach3.
Under "set steps per unit" for my X and Y axis I get 1 inch of movement when I ask it to give me one inch so I have to assume that my steps per unit setting is correct, BUT manually driving either axis one inch (measured with my dial indicator) causes the display to read 10 inches
So my display reads actual measured movement * 10. G-code files are that ran just fine on my previous machine are thus one tenth the size I designed them to be.
Both the X and Y axis are belt drive via two pulleys. My Z runs on a lead screw and its display reads just fine.
Any help?
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Sounds like you may be missing steps when jogging. Try MDI'ing a slowish feed and see if that works correctly, something like G1X1F5. If that travels the correct distance then your Acceleration is likely too high.
Hood
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MDI'ing for one inch gives me one inch as best I can measure on the dial indicator and + 1.0006 on Mach3's screen.
Ill adjust my acceleration,, but its pretty conservative now. A manual move gives a slow ramp up and down rate.
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Try reducing the Velocity, that way you may get better accel.
Also you may be needing a wider pulse, so that may be worth a try.
What do you have the kernel set to? Best to just have it as high as you need and not over.
Hood
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Wider pulse seems to be helping...have to re-measure to be sure but movement seems more proportional now....
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still losing steps - badly. I've tried every combination of settings both in mach3 and the hobbycnc driver board.
Both of the belt driven axis - X and Y - have the issue. The lead screw driven Z seems fine. Even with 1/1 stepping set and very conservative velocity and acceleration settings.
Steppers are 300 oz/in units from hobbycnc so I believe they're of decent quality and have enough power. Driver board seems fine...wonder if I just hit on a motor, driver, gear ratio, etc, etc combo that just 'ain't going to work...
I'm stuck, and worse I've got a two week road trip starting this Wednesday and its going to nag me the entire time...(I'm kinda obsessive that way ;)
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Just poked at it again a bit more....could just be a coincidence but the onscreen scales still differ by x10 when i manually move the X and Y and the speed, accel, etc doesnt seem to matter, however i can still MDI for one inch and get exactly one inch. Using the same computer as I did on my previous all lead screw machine so I think it should be ok
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What is your setup?
In other words do your drives have microstepping? if yes what is it.
How exactly is your axis driven. You say belts so I assume you are meaning you are using a toothed belt fixed to the frame and the motor has a pulley so that you are basically using the belt and pulley wheel as a rack and pinion set up?
If so what is the pitch of the belt and how many teeth on the pulley?
Hood
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Try MDI a G0 and see if it still is OK, ie G0X1
Hood
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Yes, just did. Asking for one inch gets me one inch. I don't know how it would do if I actually ran a Goode file because my spindle hasn't arrived yet...but I can zero the scales, manually move either x or y maybe a foot or so and the actual distance moved will only be about 1/10th of what the onscreen scales show.
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So you can MDI a 1inch move and its ok but you cant jog without a problem?
Can you attach your xml and I will have a look at it.
Hood
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Trying but having trouble with the attachment....might show up twice...will wait a bit and try again.
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...
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Ok can you please answer the questions I asked above regarding the way your axis is set up, pitch etc.
Also what version of Mach3 are you using?
Reason I am asking is your steps per unit do not seem right, they are very course.
Hood
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I might have it right now...
Noticed that the onscreen scales were off from measured distances by. Factor of 10. In desperation I multiplied the steps per unit by 10 and the results were close.
If it is right now I can't figure way the "set steps per unit" (under SETTINGS) would give me coarse numbers, because as mentioned I could ak for one inch and get exactly that.
Let me do some more checks and if its still wrong ill get you that ino you asked for.
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Steps per inch were off by x10. Still can't figure how I was getting the right amount of movement under MDI unless I had some other setting right or wrong...both X and Y steps per inch are now at 1422, and to get that I looked up the math. In hindsight I should have done that first - lesson learned for the future. I did increase the step pulse.
Thanks for your patience and help.
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The xml you attached earlier had 34 for X and Y steps per unit so it must have been the wrong xml.
Hood
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Don't understand that either....they're at 1422 now.
Seems lots of stuff lately has been out of my range of comprehension.
Again, thanks. I like getting help from folks far off because they can't reach over and slap me for being ignorant. ;)
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As long as its working thats all that matters :)
Hood