Axis Configuration Questions
28 Oct 2012 22:06 - 29 Oct 2012 00:26 #25942
by cotang
Axis Configuration Questions was created by cotang
Hi all,
First off my machine works great with linuxcnc. The only question I have is the axisi configuration page. Under the Pulley teeth(Motor:Leadscrew) values what do I put if I have a 10 tooth pulley attached to my motor and no lead screw? is it 10:1? How about the leadscrew pitch? These values would make sense if I have a lead screw attached but I don't.
Also when I'm testing an axis to travel in +1 Inch is would travel 1.25 instead of 1. So I know I have some sort of configuration setup wrong and not a black lash issue because when I stop the test, the (pen) would always head back to where it starts (+/- 2 thou).
I think my next step is to look at the Motor Step /Rev. My motors are 1.8 degree +/- 5 which means it could be either 190 or 210.
Any help would be great.
Thanks
First off my machine works great with linuxcnc. The only question I have is the axisi configuration page. Under the Pulley teeth(Motor:Leadscrew) values what do I put if I have a 10 tooth pulley attached to my motor and no lead screw? is it 10:1? How about the leadscrew pitch? These values would make sense if I have a lead screw attached but I don't.
Also when I'm testing an axis to travel in +1 Inch is would travel 1.25 instead of 1. So I know I have some sort of configuration setup wrong and not a black lash issue because when I stop the test, the (pen) would always head back to where it starts (+/- 2 thou).
I think my next step is to look at the Motor Step /Rev. My motors are 1.8 degree +/- 5 which means it could be either 190 or 210.
Any help would be great.
Thanks
Last edit: 29 Oct 2012 00:26 by cotang.
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28 Oct 2012 23:45 #25950
by BigJohnT
Replied by BigJohnT on topic Axis Configuration Questions
1.8 degree is 200 steps per rev.
Is this a belt driven machine?
How far does one rev of the stepper move the axis?
Is your drive using microstepping? if so how many microsteps?
John
Is this a belt driven machine?
How far does one rev of the stepper move the axis?
Is your drive using microstepping? if so how many microsteps?
John
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29 Oct 2012 00:18 - 29 Oct 2012 00:28 #25953
by cotang
Hi John, Thanks for the quick reply. The machine is belt driven for the X and Y axis. The Z is lead screw driven. The Microstepping is 1/16 with hardware switches set correctly. How would I go about to determine the distance for 1 rev? I guess I can mark the tooth and jog the machine 1 full rev...I measure approx 2 inch of distance travel per 1 rev.
Sorry, updated my original post. It goes 1.25" instead of 1 inch...
The 10 tooth pulley is a XL 0.2" pitch.
Replied by cotang on topic Axis Configuration Questions
1.8 degree is 200 steps per rev.
Is this a belt driven machine?
How far does one rev of the stepper move the axis?
Is your drive using microstepping? if so how many microsteps?
John
Hi John, Thanks for the quick reply. The machine is belt driven for the X and Y axis. The Z is lead screw driven. The Microstepping is 1/16 with hardware switches set correctly. How would I go about to determine the distance for 1 rev? I guess I can mark the tooth and jog the machine 1 full rev...I measure approx 2 inch of distance travel per 1 rev.
Sorry, updated my original post. It goes 1.25" instead of 1 inch...
The 10 tooth pulley is a XL 0.2" pitch.
Last edit: 29 Oct 2012 00:28 by cotang. Reason: More Information
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29 Oct 2012 01:31 #25961
by BigJohnT
Replied by BigJohnT on topic Axis Configuration Questions
Ok you have 200 steps per rev x16 microsteps = 3200 steps per rev. 1/2 rev = 1" so your scale needs to end up at 1600. So motor pulley/leadscrew pulley is 1:1 and leadscrew = 0.5. This will get you close, however the belt will be stretched a bit so the scale will not be the exact mathematical scale. You will have to measure a move and make small adjustment to your scale.
John
John
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29 Oct 2012 08:52 #25974
by cotang
Thanks John,
It seems to be close enough to diddy by trial and error. The only thing is that repeataility is in the +/- 5 thou which is good enough but as I increment by 1 inch, I'm not really getting the measure I want.
ie.
at 1 inch, I'm getting 0.97 repeatable to plus/minus 5 thou.
at 2 inch, I'm getting 2.00 repeatable to plus minus 5 thou. (This one is spot on)
at 3 inch I'm getting 3.01 repeatable to plus minus 5 thou.
at 4 inch I'm getting 4.04 repeatable to plus minus 5 thou.
at 5 inch I'm getting 5.06 repeatable to plus minus 5 thou.
Is this normal? or am I expecting way too much from a home built machine.....
Replied by cotang on topic Axis Configuration Questions
Ok you have 200 steps per rev x16 microsteps = 3200 steps per rev. 1/2 rev = 1" so your scale needs to end up at 1600. So motor pulley/leadscrew pulley is 1:1 and leadscrew = 0.5. This will get you close, however the belt will be stretched a bit so the scale will not be the exact mathematical scale. You will have to measure a move and make small adjustment to your scale.
John
Thanks John,
It seems to be close enough to diddy by trial and error. The only thing is that repeataility is in the +/- 5 thou which is good enough but as I increment by 1 inch, I'm not really getting the measure I want.
ie.
at 1 inch, I'm getting 0.97 repeatable to plus/minus 5 thou.
at 2 inch, I'm getting 2.00 repeatable to plus minus 5 thou. (This one is spot on)
at 3 inch I'm getting 3.01 repeatable to plus minus 5 thou.
at 4 inch I'm getting 4.04 repeatable to plus minus 5 thou.
at 5 inch I'm getting 5.06 repeatable to plus minus 5 thou.
Is this normal? or am I expecting way too much from a home built machine.....
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29 Oct 2012 10:01 #25978
by Rick G
Replied by Rick G on topic Axis Configuration Questions
You might want to check for backlash / binding / loose pulley, etc. first.
To check a movement in the positive direction I first go negative, then positive, set my dial indicator at 0, then make a positive move and measure the result, then the same move negative and see it the dial indicator goes back to 0.
so
G1 X-1
G1 X0 ;SET DIAL INDICATOR
G1 X1 ; READ DIAL INDICATOR
G1 X0 ; READ DIAL INDICATOR
Repeat several times.
Then make a bunch of longer moves at different rates and see if at the end the machine returns to the start location to check for missed steps.
Rick G
To check a movement in the positive direction I first go negative, then positive, set my dial indicator at 0, then make a positive move and measure the result, then the same move negative and see it the dial indicator goes back to 0.
so
G1 X-1
G1 X0 ;SET DIAL INDICATOR
G1 X1 ; READ DIAL INDICATOR
G1 X0 ; READ DIAL INDICATOR
Repeat several times.
Then make a bunch of longer moves at different rates and see if at the end the machine returns to the start location to check for missed steps.
Rick G
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29 Oct 2012 19:05 #25993
by BigJohnT
Replied by BigJohnT on topic Axis Configuration Questions
That all depends on the type of belt you used. XL belts are not terribly accurate but fine for most things. You can develop a position compensation table once you get the scale as close as possible.
linuxcnc.org/docs/html/config/ini_config...d_sub_axis_section_a
John
linuxcnc.org/docs/html/config/ini_config...d_sub_axis_section_a
John
The following user(s) said Thank You: cotang
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29 Oct 2012 22:12 #26000
by cotang
Thanks John, you've been a great help. Aside from all this, what type of belt would you recommend and also what type of motor controller work great with linuxcnc without the hassle?
Replied by cotang on topic Axis Configuration Questions
That all depends on the type of belt you used. XL belts are not terribly accurate but fine for most things. You can develop a position compensation table once you get the scale as close as possible.
linuxcnc.org/docs/html/config/ini_config...d_sub_axis_section_a
John
Thanks John, you've been a great help. Aside from all this, what type of belt would you recommend and also what type of motor controller work great with linuxcnc without the hassle?
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30 Oct 2012 02:15 #26005
by BigJohnT
Replied by BigJohnT on topic Axis Configuration Questions
All the CNC machines I've seen (not a whole lot but a few) have the round tooth type of belt.
For steppers you can't beat Mesa 5i25 7i76 combo and gecko G203v or G251 depending on the power you need.
John
For steppers you can't beat Mesa 5i25 7i76 combo and gecko G203v or G251 depending on the power you need.
John
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30 Oct 2012 06:02 #26030
by cotang
I just purchased a dial indicator, how to I determine if I can a missing step issue or a backlash issue? Is there different test to determine which?
Replied by cotang on topic Axis Configuration Questions
You might want to check for backlash / binding / loose pulley, etc. first.
To check a movement in the positive direction I first go negative, then positive, set my dial indicator at 0, then make a positive move and measure the result, then the same move negative and see it the dial indicator goes back to 0.
so
G1 X-1
G1 X0 ;SET DIAL INDICATOR
G1 X1 ; READ DIAL INDICATOR
G1 X0 ; READ DIAL INDICATOR
Repeat several times.
Then make a bunch of longer moves at different rates and see if at the end the machine returns to the start location to check for missed steps.
Rick G
I just purchased a dial indicator, how to I determine if I can a missing step issue or a backlash issue? Is there different test to determine which?
Please Log in or Create an account to join the conversation.
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