New Mill Build...Can I use LinuxCNC?

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18 Oct 2020 20:33 #186506 by rodw
Oh and the acceleration settings are the biggest culprit to lost steps.

and try typing

sudo apt-get install geany

Its the best text editor I've found and it should appear in your menus...

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18 Oct 2020 20:41 - 18 Oct 2020 20:42 #186509 by PCW
In general, I would use something like 5000,5000,20000,20000 for default timing
numbers. Unless you get a warning from LinuxCNC that the step timing is limiting
your maximum velocity, these numbers will have no effect on your maximum speeds.

You may be able to reach higher speeds by

1. Lowering your acceleration (currently you have 30 IPS/S accel
this means you get to full speed (1 IPS) in 33 ms, that may be asking too
much of your step motors/mechanics)

2. Raising the u step ratio on your drives. This has the effect of reducing vibration
and resonances which tend to cause stalling
Last edit: 18 Oct 2020 20:42 by PCW.
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18 Oct 2020 20:53 #186511 by rodw
This diagram from Lam shows how Microstepping works to smooth out motion (800 steps/rev on left, 25600 steps/rev on right)
Attachments:

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18 Oct 2020 22:35 #186525 by Mayberry Customs
Ok I will continue to experiment...I am starting to see that the big NEMA 34’s and 5mm pitch ball screws might not be the best combination...one lingering question I have and something I couldn’t find a definitive answer for is the current setting on the drivers...if a spec sheet like the one I posted says 1.4A per phase, do I set the drivers for that rating or since it’s a 4 phase motor do I multiply that 1.4A by 4 and set the drivers at 5.6A.

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19 Oct 2020 00:21 #186531 by Mayberry Customs
Ok after researching other NEMA 34 steppers available, it’s obvious it’s closer to 6A... This is most likely my main problem. Thanks

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19 Oct 2020 00:31 #186533 by tommylight

Mayberry Customs wrote: ...if a spec sheet like the one I posted says 1.4A per phase, do I set the drivers for that rating or since it’s a 4 phase motor do I multiply that 1.4A by 4 and set the drivers at 5.6A.

If a spec sheet says 1.4A you set the drives to 1.4A.
If they are 1.4A and Nema 34, do not expect much speed from them.

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19 Oct 2020 00:48 #186535 by Mayberry Customs
Ok thanks for the clarification. Andy
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19 Oct 2020 01:52 #186539 by Mayberry Customs
If I need to change these motors out, are there any NEMA 34’s that someone can specifically recommend? Or what to look for in general for something that is higher speed...The drives are rated up to 7.8A. I am seeing now across the internet that this is a common problem with these longs motor kits...I guess this is why I got a “great deal” on the motor and driver package lol

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19 Oct 2020 02:56 #186545 by rodw
You could try the moon ML34HD0L4700
www.moonsindustries.com/p/nema-34-standa...0-000004611110010545

They are not overly powerful (3.8 Nm) but are 7 amp and they go like the clappers!

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19 Oct 2020 06:09 #186561 by Mayberry Customs
Great, thanks for the suggestion!...I have been experimenting the last few hours and got it moving and sounding to please me for now...I did some manual test cuts to get a feel for speed and I feel ok about the max speed now...i tried numerous driver timing settings and landed on 5500 5500 500 500...it was just random settings From a driver on the Linux cnc list...I also settled on x32 microstepping (the highest setting) because it just seemed the smoothest. 20 for acceleration. I worked through several kinks with the home and limit switches, which are working correctly now. Next I guess I need to measure for accuracy and backlash.

Another issue I have is when I try to use gmoccapy the bottom part of the window is just cut off and when I maximize it it doesn’t fix the issue. No other window does this so it’s not a screen resolution problem I don’t think. Any help with that would be great.

I still have some questions on the spindle control for another day and I’m sure I will have more questions in the coming days and weeks. Thank you all for your help, it is greatly appreciated! Andy

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