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CNC plasma project



Gadget
05-30-2008, 07:29 PM
I finally got around to testing the CNC table with the plasma cutter. I did several trace tests with a magic marker and all were good with no lost steps. I hooked the plasma up and started cutting a part I need for the torch mount. The slotted arch was cut perfectly and then the unit stopped tracking (the CNC not the plasma). I wound up with a couple of chips on the controller board blowing out. I don't know if it was due to the plasma or if they just decided to go at that time. I prefer to think the latter.
The chips blew in such a way that the board is also damaged so I ordered a complely new controller. I guess I will have some spare parts.
Just to be on the safe side, I will put the controller assembly inside a metal container next time. If it blows again, I will have to rethink plasma cutting with this setup. The plasma cutter performed flawlessly though so there is some positive from the experience.

Gadget

JonB1974
05-31-2008, 03:58 PM
Dang, sorry to here this Gadget. Could be the latter, all boards can blow their chips now and then. But if it was a ESD problem build a gound/voltage isolation for the boards. I do it outta habit using a plastic project box like Xylotex use in their units. Oh by the way check out this guys setup.....I like it for a 4X4 table all his stuff looks isolated too.
http://i36.photobucket.com/albums/e12/DromSeciba/DCP03082.jpg
http://i36.photobucket.com/albums/e12/DromSeciba/DCP03077.jpg
http://i36.photobucket.com/albums/e12/DromSeciba/DCP03063.jpg
http://i36.photobucket.com/albums/e12/DromSeciba/DCP03095.jpg
Keep on tinkering ....... :D

Gadget
05-31-2008, 04:33 PM
Jon,
Could you clarify your ground/voltage isolation methods. I am not clear what you mean by this. I was thinking I should make a kind of faraday shield around the controller unit. This unit performed flawlessly when using a router or dremmel but burned out after a few minutes of plasma cutting. I hope it was just coincidence or possibly a cold solder joint that overheated.
Gadget

JonB1974
05-31-2008, 07:22 PM
"faraday".......Haven't heard his name in awhile....hehe. Ok Gadget, by isolation we're talking about completely,totally, and with out a doubt isolating the controller/drive circuts from the plasma/workpiece circuit. This should be addressed in such places as placing the controller in a insulating case and on a seperate circut from the plasma. The torch head holder should have a insulation piece seperating it from the torch and workpiece. The workpiece and it's ground should be isolated from the machine as much as possible. You can make insulators for the work table with nylon spacers on the strip attachments and so on......pretty much depends on how the machine is setup. You get the just of it. I personally try to keep my controllers out of the work area as much as possible. Hope this helps...... :D

Gadget
06-01-2008, 06:41 AM
Thanks Jon,
Looks like mine is pretty well isolated then. The primary frame is made of wood and the controller box is mounted on the wood frame at the rear of the unit. The wood frame is mounted on a metal frame which holds either the router table or the metal mounting for plasma cutting. The torch head mount is metal but it bolts to a wooden z slide so that is also insulated. The controller box is on a 110 circuit and the plasma on a 220 circuit.[attachment=0:1wu0u0ro]front.jpg[/attachment:1wu0u0ro]

JonB1974
06-01-2008, 09:04 AM
Ok Gadget, another way to check prior to power up is to use a multimeter in diode check mode to see if the work piece is isolated. I think it was just a board failure myself but better safe than sorry......remember to post video of the success when the new stuff shows up.... :D