My Newb Plasma Table Attempted Build
- dvn4life1972
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12 Jun 2020 21:19 #171320
by dvn4life1972
I have 2 Y axis motors. Wouldn't that cause an issue with the opposite Y motor not being in on the swap?
Replied by dvn4life1972 on topic My Newb Plasma Table Attempted Build
Can you try swapping just the X,Y step connections?
( this does require homing to be disabled! )
I have 2 Y axis motors. Wouldn't that cause an issue with the opposite Y motor not being in on the swap?
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12 Jun 2020 21:31 - 12 Jun 2020 21:31 #171323
by PCW
Replied by PCW on topic My Newb Plasma Table Attempted Build
Ahh didn't notice know this, so no dont do that!
Is the position error cumulative?
That is is you draw a circle with a felt tip pen, do multiple runs shift in position?
Is the position error cumulative?
That is is you draw a circle with a felt tip pen, do multiple runs shift in position?
Last edit: 12 Jun 2020 21:31 by PCW.
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- dvn4life1972
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12 Jun 2020 21:38 #171325
by dvn4life1972
I haven't tried multiple circles or squares, but I had attempted to cut some parts and they seem to show that it favors one side and does not accumulate.
Replied by dvn4life1972 on topic My Newb Plasma Table Attempted Build
Ahh didn't notice know this, so no dont do that!
Is the position error cumulative?
That is is you draw a circle with a felt tip pen, do multiple runs shift in position?
I haven't tried multiple circles or squares, but I had attempted to cut some parts and they seem to show that it favors one side and does not accumulate.
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12 Jun 2020 23:21 #171341
by phillc54
Replied by phillc54 on topic My Newb Plasma Table Attempted Build
The more I look at it the more it appears to be something mechanical or lost steps.
If you look at the square you cut here
It is interesting that you show the leadin at the top, squares from the wizard have the leadin at the bottom unless angled, did you angle it 180?
If we follow the cut the way it is shown, the cut starts at the top centre then goes to the top right corner, the bottom right corner, the bottom left corner, the top left corner then ends at the top centre.
So the move from the bottom left to the top right is coming up short. That was why I originally asked bout backlash.
If your pic is correct then there is an issue with the Y axis moving in the positive direction or there is backlash. You preview is fine so it has nothing to do with the wizards. I think the reason you don't notice it with Toms square is because it starts and ends at a corner.
If you look at the square you cut here
It is interesting that you show the leadin at the top, squares from the wizard have the leadin at the bottom unless angled, did you angle it 180?
If we follow the cut the way it is shown, the cut starts at the top centre then goes to the top right corner, the bottom right corner, the bottom left corner, the top left corner then ends at the top centre.
So the move from the bottom left to the top right is coming up short. That was why I originally asked bout backlash.
If your pic is correct then there is an issue with the Y axis moving in the positive direction or there is backlash. You preview is fine so it has nothing to do with the wizards. I think the reason you don't notice it with Toms square is because it starts and ends at a corner.
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12 Jun 2020 23:31 #171343
by rodw
Replied by rodw on topic My Newb Plasma Table Attempted Build
I also think its in your environment somewhere. Otherwise there would be a lot of other complaints. Bear in mind that motion is part of the linuxcnc core so its nothing to do with plasmac.
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12 Jun 2020 23:42 #171344
by dvn4life1972
Replied by dvn4life1972 on topic My Newb Plasma Table Attempted Build
The lead in is actually at the bottom like you say it should be Phil. The table is oriented with the zero away from me, right by the garage door...so when I grab it off of the table I'm on the far end from zero looking at the part upside down. I just mark it how I'm looking at it.
I finally got the belts properly tightened a couple of days ago, I had originally secured the ends the wrong way and they were giving some. Aside from being tight I don't know how to get rid of backlash, isn't that a matter of teeth engagement inherent in the pulley and belt type?
I periodically feel the motors after they've been on a while on hold and today they definitely seemed quite a bit more hot. I'm thinking about just replacing them along with the drivers, just a thought at this point.
I finally got the belts properly tightened a couple of days ago, I had originally secured the ends the wrong way and they were giving some. Aside from being tight I don't know how to get rid of backlash, isn't that a matter of teeth engagement inherent in the pulley and belt type?
I periodically feel the motors after they've been on a while on hold and today they definitely seemed quite a bit more hot. I'm thinking about just replacing them along with the drivers, just a thought at this point.
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12 Jun 2020 23:59 #171346
by phillc54
Replied by phillc54 on topic My Newb Plasma Table Attempted Build
OK, that makes sense.
If it is backlash it should be able to be measured. If you use MDI you could G0X0Y0 then make a pencil mark, then make a pencil mark exactly 2" away along the Y axis, then do G0X0Y2 and it should move precisely 2" on the second then G0X0Y0 and it should end exactly where it started. Do this a several times and make sure you end each move exactly on the marks. You could also check the X axis the same to be sure.
If it is backlash it should be able to be measured. If you use MDI you could G0X0Y0 then make a pencil mark, then make a pencil mark exactly 2" away along the Y axis, then do G0X0Y2 and it should move precisely 2" on the second then G0X0Y0 and it should end exactly where it started. Do this a several times and make sure you end each move exactly on the marks. You could also check the X axis the same to be sure.
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- machinedude
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13 Jun 2020 00:10 #171347
by machinedude
Replied by machinedude on topic My Newb Plasma Table Attempted Build
i think the series of timing belts you are using have about .001 to .0015 in backlash, the GT series is about as good as they get. now using a long belt as a drive would probably need some kind of tension system to maintain everything with the full range of movement.
do you have any kind of cooling for your drives? if they get to warm they will loose steps.
do you have any kind of cooling for your drives? if they get to warm they will loose steps.
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13 Jun 2020 00:51 #171348
by dvn4life1972
I'm only measuring about .002" off average on both Y axis sides and on the X axis. They haven't been calibrated in a few years but they're Starretts so they should be pretty much accurate. I'm sure there's some margin for making the pencil marks, but regardless it's respectable IMO.
Maybe it's a motor?
Replied by dvn4life1972 on topic My Newb Plasma Table Attempted Build
OK, that makes sense.
If it is backlash it should be able to be measured. If you use MDI you could G0X0Y0 then make a pencil mark, then make a pencil mark exactly 2" away along the Y axis, then do G0X0Y2 and it should move precisely 2" on the second then G0X0Y0 and it should end exactly where it started. Do this a several times and make sure you end each move exactly on the marks. You could also check the X axis the same to be sure.
I'm only measuring about .002" off average on both Y axis sides and on the X axis. They haven't been calibrated in a few years but they're Starretts so they should be pretty much accurate. I'm sure there's some margin for making the pencil marks, but regardless it's respectable IMO.
Maybe it's a motor?
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13 Jun 2020 01:02 #171350
by phillc54
Replied by phillc54 on topic My Newb Plasma Table Attempted Build
Well 0.002 is a lot more accurate than you will get with a plasma axe.
Kinda what you would call frustrating...
You have already swapped drivers around and the issue stayed on the Y axis.
It may be a Y motor and that may also be contributing to that ripple Tom mentioned.
What make of drivers do you have?
Kinda what you would call frustrating...
You have already swapped drivers around and the issue stayed on the Y axis.
It may be a Y motor and that may also be contributing to that ripple Tom mentioned.
What make of drivers do you have?
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