Missing steps or something else?
- truehybridx
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28 Nov 2014 03:11 - 28 Nov 2014 03:17 #53497
by truehybridx
Missing steps or something else? was created by truehybridx
I'm wondering if anyone has come across this before.
In axis the drawing looks right, and when I run it through my laser cutter it comes out right too. But when I run my design on my probotix setup it messes up in a few spots, the same spots, every time...
A few are highlighted in the photo:
1. The "W" gets shifted over when the cutter goes around for the second pass (using a serif font in cambam seems to make it double pass each line to get it done)
2. The "S" tale gets misaligned.
3. The "O" doesn't finish in the same spot.
The "I" "L" and "N" all come out fine, and this mess up is repeatable..
Has anyone encountered such a thing?
Using CamBam 0.9.8 and LinuxCNC 2.5
Until the forums cooperate without throwing errors every 10 seconds heres the picture on imgur lol
imgur.com/YcEOAOf
In axis the drawing looks right, and when I run it through my laser cutter it comes out right too. But when I run my design on my probotix setup it messes up in a few spots, the same spots, every time...
A few are highlighted in the photo:
1. The "W" gets shifted over when the cutter goes around for the second pass (using a serif font in cambam seems to make it double pass each line to get it done)
2. The "S" tale gets misaligned.
3. The "O" doesn't finish in the same spot.
The "I" "L" and "N" all come out fine, and this mess up is repeatable..
Has anyone encountered such a thing?
Using CamBam 0.9.8 and LinuxCNC 2.5
Until the forums cooperate without throwing errors every 10 seconds heres the picture on imgur lol
imgur.com/YcEOAOf
Last edit: 28 Nov 2014 03:17 by truehybridx.
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28 Nov 2014 08:54 #53504
by andypugh
Replied by andypugh on topic Missing steps or something else?
It looks like mechanical backlash.
If you grab the spindle (with it turned off) can you shake it around significantly?
If you grab the spindle (with it turned off) can you shake it around significantly?
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- truehybridx
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28 Nov 2014 09:03 #53506
by truehybridx
Replied by truehybridx on topic Missing steps or something else?
the spindle has some flex but its pretty tight... well as best as it can be with the construction of the frame.
Another thing I just tried today was replaying the job but setting the feed override to about 60%. That almost fixed the "W" but it gave the "O" an even bigger tale :/
Could it be a mathematical problem? like the steps and velocities aren't quite right?
Another thing I just tried today was replaying the job but setting the feed override to about 60%. That almost fixed the "W" but it gave the "O" an even bigger tale :/
Could it be a mathematical problem? like the steps and velocities aren't quite right?
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28 Nov 2014 09:09 #53507
by andypugh
I wouldn't call it "mathematical" but you could try setting max velocity and max accel 10x slower and making step and space times 10x bigger.
If that works, then work on what the numbers really need to be.
(Rather than waste more wood, I would do the experiment version 1" up and 1" right of the previous on the same bit of wood by touching-off somewhere else)
Replied by andypugh on topic Missing steps or something else?
Could it be a mathematical problem? like the steps and velocities aren't quite right?
I wouldn't call it "mathematical" but you could try setting max velocity and max accel 10x slower and making step and space times 10x bigger.
If that works, then work on what the numbers really need to be.
(Rather than waste more wood, I would do the experiment version 1" up and 1" right of the previous on the same bit of wood by touching-off somewhere else)
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28 Nov 2014 17:17 #53511
by Rick G
Replied by Rick G on topic Missing steps or something else?
As Andy said reduce your velocity and acceleration and perhaps try taking lighter cuts.
Set X and Y at a known location, after running a part does the machine return to the exact same position? That will show if you are losing steps.
Rick G
Set X and Y at a known location, after running a part does the machine return to the exact same position? That will show if you are losing steps.
Rick G
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30 Nov 2014 02:33 - 30 Nov 2014 05:06 #53536
by truehybridx
Replied by truehybridx on topic Missing steps or something else?
I have not done the 10x thing to the velocities and steps yet. I do have tests that show there are hiccups in the cut when I'm doing diagonal moves (both axises moving) ((which oddly enough with the "W" balance out letting the position remain correct 0_0))
It really looks like the Y axis is taking off first when I would think both should move at the same exact time.
(my moves were: X0, Y0; X4, Y4; X0, Y0)
I have two pictures that show the actual cuts, then i drew in blue ink what it looks like to me.
imgur.com/YdEUmDs
imgur.com/l3zYKC3
It really looks like the Y axis is taking off first when I would think both should move at the same exact time.
(my moves were: X0, Y0; X4, Y4; X0, Y0)
I have two pictures that show the actual cuts, then i drew in blue ink what it looks like to me.
imgur.com/YdEUmDs
imgur.com/l3zYKC3
Last edit: 30 Nov 2014 05:06 by truehybridx.
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30 Nov 2014 16:36 #53541
by Rick G
Again reduce acceleration and velocity and see if problem still occurs, try a lighter cut or even mount a pen in the spindle and try the same move.
Rick G
Replied by Rick G on topic Missing steps or something else?
That might also indicate a too small a power supply problem.there are hiccups in the cut when I'm doing diagonal moves (both axises moving)
Again reduce acceleration and velocity and see if problem still occurs, try a lighter cut or even mount a pen in the spindle and try the same move.
Rick G
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01 Dec 2014 02:03 - 01 Dec 2014 02:08 #53546
by truehybridx
Replied by truehybridx on topic Missing steps or something else?
Reduced the velocity and acceleration and still has the little hiccups. They appear to be in the same place for that particular move.
For example going from 0,0 to 4,4 the hiccup happens about 1.5,1.5.
going from 4,4 to 0,0 the hiccup happens about 4,4.
Same thing when doing a different diagonal (say 4,0 to 0,4)
This is with the tool in the air not making any cut, I can see the tiny hiccup as it moves and feel it if I hold my hand on the tool as it moves.
The power supply is a 40v part of this kit www.probotix.com/3_axis_stepper_motor_dr...er_motor_driver_kit/
For example going from 0,0 to 4,4 the hiccup happens about 1.5,1.5.
going from 4,4 to 0,0 the hiccup happens about 4,4.
Same thing when doing a different diagonal (say 4,0 to 0,4)
This is with the tool in the air not making any cut, I can see the tiny hiccup as it moves and feel it if I hold my hand on the tool as it moves.
The power supply is a 40v part of this kit www.probotix.com/3_axis_stepper_motor_dr...er_motor_driver_kit/
Last edit: 01 Dec 2014 02:08 by truehybridx.
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01 Dec 2014 20:11 #53577
by Rick G
Replied by Rick G on topic Missing steps or something else?
If you go to x0y0 and mark that spot then make a bunch of diagonal moves then return to x0y0 is the machine in the correct spot or has it drifted?
Rick G
Rick G
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04 Dec 2014 09:07 #53670
by truehybridx
Replied by truehybridx on topic Missing steps or something else?
It mostly comes back to the same position. There was maybe one or two times when it wasn't exactly at the same place.
I figure the random jerks end up canceling each other out.
I would attempt to video it moving like this but I'm not sure how visible it would be on camera
I figure the random jerks end up canceling each other out.
I would attempt to video it moving like this but I'm not sure how visible it would be on camera
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