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Author Topic: How many times have you read this  (Read 1525 times)

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Offline Jim P

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How many times have you read this
« on: March 03, 2013, 03:12:21 AM »
New to cnc and nothing works and i need motor tuning help!! Once, twice maybe 3 times.  :D

I have been cruising around with my demo Mach3 on my homemade unit for about 4 months now. writting simple g code and basically cutting air. I got my license copy about 2 weeks ago I guess about the same time I decided to replace the single start Acme screws with 5 start. I also replaced my home made anti-backlash nuts with some real ones from an on-line linear motion place.

With the single start screws I was running 8th steps. Everything always worked. OK, it worked as it was instructed to and the instructions may not have always been valid. I replaced the screws because the single start max velocity that worked reasonably well was 18.I was setting things on fire it was so slow I finally got around to installing the 5 start screws tonight. Set the Steps per to 3200 and here is where it gets interesting. I unmounted my steppers because everything was just buzzing and making noise. I wanted to make sure I didn't change anything on the install that caused this.

 ( working with inches). I could not figure out what the acceleration and velocity. I finally got the y Axis moitor to smooth out around a velocity around 750 and acceleration maxed. I think it was around. 652 . The x Axis will not run on this setting. I have to bump the velocity up to about 1000.  I tried full steps and could not find a reasonable velocity that ran smoothly. I changed nothing else. Now first off do these numbers sound in the ballpark or am I way off. If someone could hold my hand and give me a Velocity and acceleration that has been pr oven to work I will try that.  should I just stay at 1/8 steps or go to full.
Thanks everyone.
JimP

Offline Tweakie.CNC

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Re: How many times have you read this
« Reply #1 on: March 03, 2013, 07:55:16 AM »
Hi Jim,

Welcome to the forum.

In my opinion Velocity and Acceleration are best found by 'trial and error' for each axis in turn – starting very low then working your way up until steppers stall then reducing the settings by at least 30% to achieve reliable performance.

I recommend you use your 1/8 micro-stepping rather than whole steps though.

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.

Offline Jim P

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Re: How many times have you read this
« Reply #2 on: March 03, 2013, 08:50:45 AM »
Thanks Tweakie