PlasmaCam Speed Override / Jog Wheel 'Freaking Out'

[mflux_gamblej]

I have a new to me plasmacam 4x4 dhc(1). I find that sometimes the machine wont power on right where when you power it on, the power light comes on, but the other lights dont blink, and the waiting light doesnt pulse prior to initializing. You cannot initialize the machine in this state.

I pressed the stop button a lot and messed with the encoder wheel that is used for speed override and jogging, then the machine will boot up OK.

I found during a cut last night that the speed override encoder wheel is freaking out. The machine slowed to a crawl and finally a stop during a rapid move. I thought that was odd, so then I saw in design edge that the rapid rate slider was set at zero, sure enough when I moved that bar with the mouse, it slowly crept back down. Then after that during the cut the feed rate swung wildly creeping up to 1000ipm, so I constantly overrode that with the mouse slider in design edge. Needless to say this is pretty bad.

Has anyone had to replace that jog wheel before on their control box? Is there a way to software lock it out so override is not possible during the cut? I tried the 'reset' button next to the wheel but that got turned off instantly as the wheel reading drifts around.

I might try to just disconnect that wheel entirely by cracking open the control and just disconnecting it entirely as I dont think i need it anyhow.

I'm new around here of course as my table is new to me (properly changed ownership via plasmacam form..) Hopefully someone has seen this before and dealt with the issue.

Thanks in advance for your experience.

[mflux_gamblej]

I took apart the control box, found that there was a lot of dust / plasma torching oxide particles inside. I cleaned up the PCB with isopropyl alcohol, blew it all out with air.

While I was in there I added in parallel to the STOP button (which is a normally open momentary switch) two leads to go out to a micro switch on a pop-away torch holder so that the machine can stop when the torch crashes. That was easy, it is all on crimp connectors. I drilled a hole in the side near the connector that goes up the tube to the motors and my stop sw wires go thru that hole and the wires go up the tube now also and down to the gantry/head. I dont have my pop away torch holder yet, it is ordered though.

I started the box back up after re-assembly and did not have the initialization problem at this moment. Under diagnostics in design edge you can see the state of the jog wheel A on, B on, A and B on, or A and B off. Those are the typical states for a quadrature encoder. I did not notice those changing on their own. I didnt cut anything else yet, but from now on I will be going to diagnostics, and making sure I see the stat A and B off prior to starting any cutting. I'll post here if my issue is fixed. You cannot see the part number of the encoder without desoldering it from the control pcb. I am avoiding doing that for now to see if that dust build up in the box was maybe causing some shorts from via to via on the pcb.

[djreiswig]

Sounds like it just needed a good cleaning.

[adbuch]

This is a typical problem on older or well used machines. Plasma dust can accumulate inside the controller and cause the problems you have described. I would encourage you to join the Plasmacam Owner's Community Forum - lots of very helpful and knowledgeable folks there to help you out.
David

https://owners-community.com/index.php

Plasmacam Owner's Community Forum.jpg

[mflux_gamblej]

I will be on the owners community soon, I submitted my xfer of ownership to plasmacam and confirmed on the phone that they're still doing those xfers. I just didnt receive my new login and so on yet from them. Its been about 2 days since I sent it in.

I also wondered, did I move the jog wheel during power on the time that this 'freak out' happened? I've had many experiences with joysticks / computer mouse, etc that if you are moving it during power on then it might drift the whole time. I dont know why that happens but it was another thought on what might have happened.

Still have not run another tool path yet, so dont know if the symptoms are gone yet.

[rdj357]

Blow it out with air, with the machine off, work the knob back and forth quickly like you're starting a boy scout campfire.

They use a cheap ass encoder and it can be erratic if it gets just a little contamination in it.