TrackerCNC Pro-Table 5x10 - Location Shift Mid-Cut

[JPopp_81]

Hi, We are working on a TrackerCNC Pro-Table, 5x10, with a Hypertherm 105 plasma cutter.
We have been running all good for over a year now, but have recently started having a "shift" in the location of the cuts vs their intended locations. We cut a lot of larger patterns with multiple middle cutouts. Lately, it has been losing, or gaining, position on what appears to be the Y axis in between cuts, throwing the interior pattern out of alignment and often the overall size as well.

We cannot figure out what is causing this. We cut 6 of these last week, consecutively, 3 per sheet, 1/4" aluminum sheet, no problems, cut perfectly. Now, this "shift" occurred right after the 1st pattern cut. And while we've had it happen before, it seemed to be an anomaly, as the problem would go away after closing and restarting our command & cut program. This time, the problem did not go away after a program restart or a full PC reboot. Instead, it made a shift mid-cut, rather than between a cut completion and cut start.

Any help or guidance towards a solution would be greatly appreciated.....

[adbuch]

I would recommend checking all of your drive pulleys, belts, gears, etc. to make sure they are in good condition with no slop. Also you can physically grab your gantry and see if you can move it back and forth with power applied to the motors (checking for slop). You could also have some mechanical slippage from something like a loose setscrew on one of your pulleys. Also make sure your torch mount is secure to your Z bracket.

David

[weldguy]

I would say this is not a computer or electronic related but rather mechanical. I suggest drawing a 50x120 rectangle and do a dry run (plasma off) and watch and listen carefully as it moves around the entire table. See if you notice it hickup, bind, or make any strange noises. This may help you locate the mechanical issue which is likely debree on the rails or gear rack, or a gantry not perfectly square to the long side if the table. Let us know what you find.

[adbuch]

Weldguy offers some great suggestions for additional tests you can do.
David

[JPopp_81]

Thanks! I read about some of these tests earlier & tried moving the gantry while motors were engaged. I could force it to move, but it took a bit of pressure & made grinding noises in the process. Same for the torch carriage moving along the gantry. I can technically move both, but not sure how hard a push it should take, or should it not move without extreme force....?

[adbuch]

Thanks! I read about some of these tests earlier & tried moving the gantry while motors were engaged. I could force it to move, but it took a bit of pressure & made grinding noises in the process. Same for the torch carriage moving along the gantry. I can technically move both, but not sure how hard a push it should take, or should it not move without extreme force....?

It would be more of a back and forth wiggling motion to check to see if you feel any slop or free play.
David

[weldguy]

Thanks! I read about some of these tests earlier & tried moving the gantry while motors were engaged. I could force it to move, but it took a bit of pressure & made grinding noises in the process. Same for the torch carriage moving along the gantry. I can technically move both, but not sure how hard a push it should take, or should it not move without extreme force....?

The test your speaking of may help you to find a rough spot on the short axis but the long axis you will never be able to keep the gantry square since both sides are independent. Also not a good idea to move the gantry with the motors plugged in, they will generate electricity like an alternator and although I am sure your controller has protection to a point its still not a good idea. Better to do the 60x120 dry run and watch for a hang up and then inspect that area. Also not sure if you regularly clean your v rails/bearing but a scotchbrite pad and compressed air will clean those up like new. Problem is the bearing pack down the plasma dust on your v rails and then things start to run tighter.

[adbuch]

I was suggesting that he try to move the gantry with the machine under power. My guess is a mechanical issue with gears, belts, pulleys, etc. A manual inspection of each separate component would be in order here.

David

[JPopp_81]

Thanks again! Today, I will run some dry-cut tests and do an in-depth inspection and cleaning of gears and rails. However, I might have to wait until lunchtime or after hours to hear anything from the tests. The table is in our fabrication shop, and it's fairly loud with saws, grinders, air tools, etc....

[weldguy]

Looking forward to hearing what you find.

[SegoMan DeSigns]

Check the electrical connections by giving each wire going into a connector a slight tug to make sure they were crimped properly, My TorchMate would intermittently do the same thing and the wire would actually pull out of the connector.

[adbuch]

Check the electrical connections by giving each wire going into a connector a slight tug to make sure they were crimped properly, My TorchMate would intermittently do the same thing and the wire would actually pull out of the connector.

Great suggestion Steve!

David

[JPopp_81]

Well...spent all day yesterday cleaning all tracks, rails, wheels, gears, etc, etc....
Ran several rectangular test cuts in a grid pattern, no issues, no jogs, no audible causes for concern.
The motors did sound a little strained when we ran a circular pattern dry run, but we seldom cut circles and we weren't sure if that's how they sound cutting a larger circle....
Turned on torch and cut same grid patterned rectangular cuts, no issues, no jogs. Today, I set up and starting cutting my large patterns. I cut 3 on a 4x10 sheet without issue, start to finish. I thought we were good to go....
Not the case... load 2nd sheet, start cutting, jogs slightly 2 times on pattern 2 of 3, then jogs another 2-3 times on pattern 3. It's moving up the table in small increments for about a total of 5/8" shift from its original start Y position, in about 100" +/- total movement distance.

Looks like tomorrow/Monday we'll be rechecking all of our electrical connections... not sure what else to do...

[adbuch]

For tables with servo motors, I would recommend testing the encoders. If you have stepper motor, they are probably running open loop. It is possible that you have a stepper motor that is missing some step. Does your table use a single or dual motor drive for the gantry?

David

[JPopp_81]

Good question... I'm pretty sure they're servo motors...

[adbuch]

Good question... I'm pretty sure they're servo motors...

[JPopp_81]

Ok...ok... not servos... I'm learning...lol