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Speed and noise problem
« on: February 20, 2010, 04:34:09 PM »
Hi there,

I have made a 3 axis cnc machine (60x60x30) with 3 stepper motors. Firt everythnig was ok. At the first tryings the speed was very good. But after making motor tuning the machie starts to perform really really slow and noisy. When using manuel not bad (but again too slow), but when working with g codes the motors sound like screaming and they move too slow like nearly shacking. I couldn't solve the problem.

my motor tuning setup is "step:113.3786847, velocity:703.8, acceleration:254.6775" and the feed rate is normal.i tried different values but didn't worth much.

Could you please hepl me to solve the problem?

Offline Hood

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Re: Speed and noise problem
« Reply #1 on: February 20, 2010, 04:48:03 PM »
What kind of drives and what micro stepping do you have the drives set to?
Is there any reduction between motors and leadscrews?
What is the pitch of the leadscrews?

Hood
Re: Speed and noise problem
« Reply #2 on: February 20, 2010, 05:07:06 PM »
I use this driver circuit.
http://cgi.ebay.com/NEW-4-Axis-CNC-Stepper-Motor-Driver-12-36V-3-5A-TB6560_W0QQitemZ170446592459QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item27af6899cb

The screws are directly mounted to the motors with couplings, there are no other gear between. The pitch of the screaws is 5/3 mm and the motors are 200 steps, I use full step. For calculating the  values I used "set steps per unit" function under settings alt6.

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Re: Speed and noise problem
« Reply #3 on: February 20, 2010, 05:37:15 PM »
I would think using 8 microsteps would likely be much better than using full step.
Not sure what you are meaning by "The pitch of the screaws is 5/3 mm" could you explain that further?

Hood
Re: Speed and noise problem
« Reply #4 on: February 20, 2010, 05:41:53 PM »
I meant the screaw moves 5/3 millimetres per circle or I can say the dimension between two teeth of screaw is that.

Actually I tried different step options but didn't worth.

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Re: Speed and noise problem
« Reply #5 on: February 20, 2010, 05:48:08 PM »
So you are saying the pitch of the screws are 1.6666666666666666...... mm ? That just doesnt sound right.
Are they metric screws?
Do you have a link to the screws?
Are you set up in Metric or Imperial units?
Hood
Re: Speed and noise problem
« Reply #6 on: February 20, 2010, 05:53:46 PM »
ah yes I mean pitch. I use metric units. I set Mach3 metric. I measured it with a metric ruler. I'am not know much about these mechanical stuff. They are basic screaws, thinner of the one in the photo.
http://images.gittigidiyor.com/1935/aliminyum-govdeli-profesyonel-cnc__19356818_0.jpg

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Re: Speed and noise problem
« Reply #7 on: February 20, 2010, 06:04:31 PM »
Still sounds a very strange number for the pitch if they are metric screws, do you have a link to them from the place you purchased them?

Ok assuming they are 1.666666666666....mm pitch I would suggest you use 1/8 stepping so that would mean to turn your motor 1 revolution you would need 1,600 steps, one rev of the motor would move 1.6666666mm so for 1mm you would need 1600/ 1.66666666 = 960 steps per mm
Your Velocity looks slow but keep it that for now but your acceleration is likely way to high so set it down to about 50 for now and see how you get on.
Hood
Re: Speed and noise problem
« Reply #8 on: February 20, 2010, 06:29:23 PM »
Unfortunatelly I don't have a link or document about the screaws, I bought them from a little shop. But maybe I measured them wrong if it's not possible to have that pitch.

Here the time is to late for that noise I will try it in the morning for the first
Re: Speed and noise problem
« Reply #9 on: February 21, 2010, 09:24:47 AM »
I set the circuit for 1/8 microstepping as you said. And re-set the steps per unit again by using "set steps per unit" wizard. Now the sound problem is like solved and also the speed problem. But now the machine draws too little than the original dimensions when using g codes.