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Motor tuning calculations
« on: March 29, 2009, 10:46:26 AM »
Hello to all this is the setup,

Units = Inches
Stepper motor - 200 step / rev
Driver - 1/2 step -
Lead Screw - 10 tpi

When I setup in motor tunning I am using this calculation ...

200 x 2 x 10 = 4000 steps per inch (motor does not run correct) ... but this does not work ... 2000 steps per inch does the job, but this does not make sense to me from what I have read.

I started with 400 steps per inch ... but this was not correct either, the motor does run smoothly ... only gives me about 1/4 of an inch.

Could someone help show me where I messed up the calcualtion.

Thank you.
Re: Motor tuning calculations
« Reply #1 on: March 29, 2009, 10:54:51 AM »
Sounds to me like you're not really running 1/2 steps.  If you set it to 200, and tell it to move 1", does the motor turn exactly one turn, or half a turn?  I"m guessing you'll find it moves a full turn.

Regards,
Ray L.
Regards,
Ray L.

Offline bowber

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Re: Motor tuning calculations
« Reply #2 on: March 29, 2009, 11:42:59 AM »
Make sure your acceleration is very low to start with, this will stop you losing steps and giving you a false reading.
With half step and a 10 tpi lead screw you should have 4000 units per inch (unit) so as Ray said it looks like your not running half step.
Also check your lead screw, if it's a 5 tpi twin start it'll look like a 10 tpi. To check this turn the screw 1 turn by hand and measure the movement.
Sorry if this is all obvious to you but I thought it's worth mentioning.

Steve
Re: Motor tuning calculations
« Reply #3 on: March 29, 2009, 12:04:52 PM »
Strangeness indeed ...

I did a power down power up reset ... set the acceleration from 10 to 4 and X axis to 4000 steps ... looks like it is working, now that I am at least in the ball park I can fine tune ... thought maybe my grade 1 math was forgotten LOL. 

Gcode ?

G0 X1.0
G0 X0.0

Would this move the table 1 inch and then move it back to the beginning?

Offline Hood

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Re: Motor tuning calculations
« Reply #4 on: March 29, 2009, 01:37:57 PM »
Gcode ?

G0 X1.0
G0 X0.0

Would this move the table 1 inch and then move it back to the beginning?


Yes as long as you zeroed the X axis before you started.
 G0 is a rapid move so will go at the full speed that your velocity is set at in the motor tuning. G1X1F10  will do the same thing but at a feedrate of 10 inch per minute.

Hood
Re: Motor tuning calculations
« Reply #5 on: March 29, 2009, 01:53:41 PM »
Great, thank you all for the help.
Re: Motor tuning calculations
« Reply #6 on: April 24, 2009, 08:38:44 AM »
Hello, I am having the same problem where Mach3 is doubling the step on the X / Y drives/motor ... the Z drive/motor works just great.  I had been using it for a few weeks now and back to the same flakey problem.

If I drop 4000 steps to 2000 it works just fine.

This all happenend when I went to adjust the max feed rate down on the X/Y drives.  I only touched the feed rate.   I have tried reinstalling Mach still the same put a created a new profile still the same.  I placed the Z drive in place of the X drive still the same, tried to rule out the drive to make sure it is running in half step.  Using the latest stable Mach version.

Another thing that I have noticed is the Max Feed Rate always defaults to 6 on the main control screen when Mach is restarted ... I change this and it still goes back to 6 why is this when it should remember what I have set it for?

Best I can tell is Mach / Windows problem does anyone have any suggestions?

Attached is the xml file maybe I am blind.
« Last Edit: April 24, 2009, 08:42:38 AM by nickle989 »

Offline Hood

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Re: Motor tuning calculations
« Reply #7 on: April 24, 2009, 09:28:36 AM »
What does the Drive Test look like?
The feedrate resetting to 6 is normal, if you want to have a differennt feedrate set at startup the put F**** (**** being the speed you require) in the initialisation string on General cofig page

Hood
Re: Motor tuning calculations
« Reply #8 on: April 24, 2009, 09:55:12 AM »
The drive test look normal.  On the init string G80 G61 F4  ... does it need to be sepperated by commas or spaces  .. ie.  G80,G61,F4 ?

The feed rate resetting at least gives an explantion of that, Thank you.

I am reformated the controler machine right now ... I am hoping it is a windows xp problem ... trying windows 2000.

P4 - 1.2 Gig
1 Gig of ram
Radeon card

I have contacted the manufacture of the controller and drives .. SOC-Machines ... they have been running Mach for a few years.

Offline Hood

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Re: Motor tuning calculations
« Reply #9 on: April 24, 2009, 10:17:06 AM »
On the init string G80 G61 F4  ... does it need to be sepperated by commas or spaces  .. ie.  G80,G61,F4 ?

Shouldnt matter whether you have it all with no spaces, have spaces or have commas.

Hood