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Steps per in Motor tuning
« on: July 05, 2009, 09:03:20 PM »
I'm sorry if this has been covered before, I did do a search but what I found still made me question my setup.
I have 1/2-10 single start Lead Screws, STMD Drivers set to 1/10 micro-stepping and finally Tormach 280oz steppers 1.8.
If I figure this correctly my "steps per" should be:
tpi * 200 * micro-stepping = steps per
10 * 200 * 10 = 20000
Is 20,000 a little high?

thanks for the help.
Re: Steps per in Motor tuning
« Reply #1 on: July 05, 2009, 09:17:50 PM »
Your stepper has 200 step per revolution, multiply by 1/10 (1/10 micro stepping)= 2000 steps per revolution = .100in


your screw has 10 threads per inch, this mean that it need 10 revolution to obtain 1 inch.


So 2000 steps/revolution multiply by 10(screw pitch)  should equal 20000 steps to get one inch.

Hope this help, Jeff
Re: Steps per in Motor tuning
« Reply #2 on: July 05, 2009, 09:52:58 PM »
Thank you for confirming my math.
I have been testing my motors and drivers by just having them turning on the bench. I loaded up the scorpion G-code and it seems that the X-axis and Y-axis are turning but they will sometimes stop turning however I know they should be turning because I'm following the tool path on screen. When I hold the motor in my hand I can feel it vibrate like it wants to move. Now this only happens if I let the PC and drivers sit for about 1/2 and hour. If I restart the PC and power cycle the drivers the motors seem to turn properly.
I'm wondering if I have the "Step Pulse" & "Direction Pulse" set correctly. I have the SP set at 5 while the DP at default 0.
I forget where I read about setting the SP to 5 I think it was PmInmo site. Maybe I should set the DP to 5 as well? The motor does seem to stall when a direction change is sent...
My PC is a AMD 2000+ (1.6Ghz) with 1GB ram, the OS is stripped down to the bare bones. I have the Kernal Speed is the default 25K. How does increasing the Kernal Speed effect the performance of the motors?

Thanks again for the help.

Re: Steps per in Motor tuning
« Reply #3 on: July 05, 2009, 10:09:02 PM »
Check the feed for too much rpm, on mach3 screen, just lower the feed slider.

Hope this help, Jeff
Re: Steps per in Motor tuning
« Reply #4 on: July 06, 2009, 08:56:10 PM »
I do believe that has done the trick Jeff, thank you very much.
One more question, is the feed rate set in g-code or is it a value set and saved on the computer's profile?

Offline Chip

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Re: Steps per in Motor tuning
« Reply #5 on: July 06, 2009, 10:29:59 PM »
Hi, Drools

Your Max feed rate is set in Motor Tuning "Velocity" setting, It's used with G00 moves, The "F" value in your G code set's the feed-rate and remains constant for all other move's untill it's value is changed.

So it sounds as though your Velocity value need's to be reduced,  Use g00 moves to set it Up.

Also in Motor Tuning  "Acceleration",{Deceleration} play's a factor, Think of it as the speed your stepper's can start from a stopped condition and reach the max Velocity or decelerate from Max Vel., Without loosing step's.

In Config, General Configuration you can set a default F speed for Start up.

Chip
Re: Steps per in Motor tuning
« Reply #6 on: July 07, 2009, 09:34:27 AM »
I will have a look at that setting tonight.
In my motor tuning section I have the following:
Each Axis is the same.
Steps per: 20000
Velocity: 60
Acceleration : 1
SP: 5
DP: 5

thanks again for the help.