Plasma table cutting terrible

[workingonit]

Hey guys, we have a 2008 20' koike plasma table w hypertherm box on a watertable that we bought new and it has done well for us, but as of late the cut quality is jagged and 1/16-1/8 out on a 4x8 sheet length cut. I am thinking its the motors and/or gantry rails. Anyone come across this or know how to properly trouble shoot? I think it requires a rebuild, but to what extent?

[Batcat]

Check rack and pinion for wear.

[weldguy]

Sounds like it could be any number of things. I would give your entire drive system a good cleaning and during that process you may notice worn gears, gear lash, crap built up on the rails or rack, also the gantry may be slightly out of square from the table. I am sure you will find something and a good cleaning never hurts

[workingonit]

We have been troubleshooting/ cleaning unit. However most of our guys are production geared and thus dont know about proper trouble shooting. If a guy wanted to install new rails and motors. Where would you buy them from?

[adbuch]

I would contact their customer service department for information of replacement parts.
David

https://www.koike.com/customer-service

[robertspark]

If you power up the cnc machine (so the motors have holding torque) and grab the Z axis carriage and try to push it from side to side (left + right) does it move / wiggle

Move the gantry to the edge of the table .... say the front edge so you can get a good grasp on it

Now move the Z+ A axis carriage from one side of the machine to the other (left to right) along the X axis..... and try to move it at locations you stop at say every 4-8 inches..... does it move or have more waggle or play than at the ends of the machine..... if so.... the rack is probably worn...... if the play is consistent..... the pinion is probably worn.... but it could be a little greater in the middle (given this is the area that will get the most usage...)

Some racks are hardened.... meaning the pinions are designed to wear out first ..... i.e. an easy changeover (or at least quicker... than a rail [no realignment / squaring up])

Some racks are made from the same material as the pinion (C45??).... so they should both wear the same... however.... the pinion gears do more mileage than the rack so again the pinion is much more likely to wear out / down than the rack.

You could try adjusting the stepper or servo motors inwards / or the drive gear assembly to compensate for this wear and backlash.... that would be a regular (first port of call) maintenance exercise...

Now you have done the X axis (left to right).... move the X+Z axis carriage to the right or left and walk up the side of the machine grabbing the carriage firmly and trying to move it up and down the machine (long ways) .... again see how much play is in it.... do the same on the other side.... and make adjustments accordingly as detailed above.