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Not getting microsteps
« on: June 28, 2014, 03:32:04 AM »
I have a problem with getting microstepping to work in mach3 (or maybe I just not understand it right)

I built a PRO cncrouterparts machine and is almost complete, I try to adjust the steps/per in mach3 so the machine will cut the size it should be.

I use DQ860MA drivers that can be set for many microsteps, after reading a bit about, that one does not need a lot of microsteps I set them to 16 (32.000) just to start somewhere.

I used this document http://www.machsupport.com/forum/index.php/topic,16315.0.html#new and wrote steps/rev = 16. stepper/teeth = 20. lead screw teeth = 64. multiplier = 3.2 and the result is 2048 steps/per. But if I write this in mach3 the machine moves only about half of what it should be, so I played around a bit with steps/per and found out that if I set it to 128 steps/per the machine was just on 1mm = 1 step in the DRO. But how can that be? Do I not get microsteps.

I tried to put the drives for 8 (16.000) microsteps and if I calculate this out I should put 1024 steps/per in mach3 but again it does not fit, I had to write 64 steps/per before it was right

So what am I doing wrong???

(sorry if my english is a little hard to read, I'm Danish so English is not my first language. I use the metric scale so my Units is set to mm.)

Offline ger21

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Re: Not getting microsteps
« Reply #1 on: June 28, 2014, 09:50:51 AM »
What is the pitch of your leadscrew?
Gerry

2010 Screenset
http://www.thecncwoodworker.com/2010.html

JointCAM Dovetail and Box Joint software
http://www.g-forcecnc.com/jointcam.html
Re: Not getting microsteps
« Reply #2 on: June 28, 2014, 12:14:13 PM »
I have no leadscrew, it means I have at my z axis. But first and foremost it is my x and y axis I'm trying to do.

It is R&P setup with a 3.2:1 belt drive reduction from CNCrouterparts http://www.cncrouterparts.com/pro-rack-and-pinion-drive-nema-34-p-226.html

Offline ger21

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Re: Not getting microsteps
« Reply #3 on: June 28, 2014, 12:25:18 PM »
With 1/16 microsteps, you have 200 * 16 * 3.2/3.14159 = 3259.4932 steps/inch, or 128.3265 steps/mm (3259.4932/25.4).

For 1/8 microstepping it would be 128.3265/2, or 64.1632.

The pinion gear circumference is pi inches (3.14159)
Gerry

2010 Screenset
http://www.thecncwoodworker.com/2010.html

JointCAM Dovetail and Box Joint software
http://www.g-forcecnc.com/jointcam.html
Re: Not getting microsteps
« Reply #4 on: June 28, 2014, 12:40:39 PM »
So many times thanks ger21 I knew I did not understand it correctly. It is much clear now.

so can you also help me figure out my z axis? it is a 5mm pitch rolled ballscrew, directly connected to my motor also with 1/8 microstepping.
http://www.cncrouterparts.com/ballscrew-z-axis-p-238.html

Offline ger21

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Re: Not getting microsteps
« Reply #5 on: June 28, 2014, 01:35:59 PM »
200*8/5
Gerry

2010 Screenset
http://www.thecncwoodworker.com/2010.html

JointCAM Dovetail and Box Joint software
http://www.g-forcecnc.com/jointcam.html
Re: Not getting microsteps
« Reply #6 on: June 28, 2014, 01:57:51 PM »
Thanks :-)