Rods "Spaceship" Scratch built Plasma Cutter build

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19 Feb 2017 05:39 #88234 by Joco
You shouldn't need to pull again.

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19 Feb 2017 06:37 #88236 by rodw

You shouldn't need to pull again.


Thanks James, I think I had a network timeout the first time round when I first tried. Now I just have to work out what it all means!

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19 Feb 2017 11:23 #88245 by racedirector
Rod

I have a spreadsheet which calculates step-per-mm (or steps-per_in), if you give me the relative info I can calc it for you. If you want, I need driver micro steps, motor revs per step (usually 200), rack module number, gear ratio if any (1:1, 2:1 etc) and pinion teeth.

Cheers
Bruce

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19 Feb 2017 11:51 #88247 by rodw

Rod

I have a spreadsheet which calculates step-per-mm (or steps-per_in), if you give me the relative info I can calc it for you. If you want, I need driver micro steps, motor revs per step (usually 200), rack module number, gear ratio if any (1:1, 2:1 etc) and pinion teeth.

Cheers
Bruce


Bruce thanks, It would be great if you could check my maths.
23 tooth pinion, 1.25 module (supposedly)
5:1 gear reduction (90:18)
4000 microsteps (becasue Mesa lets me do it)
200 ppr (1.8deg) steppers
So I made that to be 221.432988602 pulses per revolution. I'd have to check, but I think I had to drop that to about 210 to get it calibrated.

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19 Feb 2017 11:52 - 19 Feb 2017 11:52 #88248 by rodw
Sorry, thats 20x microsteps for 4000 ppr.
Last edit: 19 Feb 2017 11:52 by rodw.

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19 Feb 2017 11:55 #88249 by racedirector
Here ya go



That is a lot of microsteps, what drivers are you using?
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19 Feb 2017 11:57 #88250 by racedirector
With a zillion decimal points:

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19 Feb 2017 12:24 - 19 Feb 2017 12:24 #88253 by rodw
Bruce, thanks, I just checked my hal. I am running 261 mm per rev and the measured rack distance per rev on the pinion is about 5mm over what it should be (should be 23 * 1.5 * pi) so go figure....

The outer diameter of the pinion is exactly 1.3" so I'm wondering if it isn't an imperial pitch but it did not match up with a gear calculator.

Yes, when I first started, I pushed the Mesa card as fast as I could and then increased the microstepping up to 25x before I got following errors then backed off a bit. I then reduced the step timing from 2500 to 1500 but never tried to see if I could go further. Any way they are not missing a beat at 18 metres per minute.

I'm using Longs motor DM542a steppers. There are a lot of other 542's out there but from what I've seen, these are a better class of controller.
Last edit: 19 Feb 2017 12:24 by rodw.

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19 Feb 2017 12:27 #88255 by racedirector
Rod, send me your email address - brucen at bsww dot com dot au, and I'll send you the excel file so you can play with everything yourself :)

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19 Feb 2017 21:28 #88303 by rodw

Rod, send me your email address - brucen at bsww dot com dot au, and I'll send you the excel file so you can play with everything yourself :)


Email sent. Thanks Bruce.

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