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Astronowanabe
09-25-2011, 10:23 PM
Just a question from the "shop made tools" thread page 144 (that's gross)
using strong magnets to stick cutting guides to work.

The question is does the strong magnetic field interact with plasma and make a cut go where it would not have gone without the magnetic field?

wierdscience
09-26-2011, 12:19 AM
Dunno about the magnets,but my Thermodyne plasma cutter manual specifically recommends against using metallic straight edges and guides. Claims it causes premature wear of the nozzle and electrode.I switched to edges made from 1/4" Masonite and the consumable life tripled.Guess the mfg knows what they are talking about after all:)

camdigger
09-26-2011, 03:42 AM
Dunno about the magnets,but my Thermodyne plasma cutter manual specifically recommends against using metallic straight edges and guides. Claims it causes premature wear of the nozzle and electrode.I switched to edges made from 1/4" Masonite and the consumable life tripled.Guess the mfg knows what they are talking about after all:)
I have an older Hypertherm 380. The metal tip on that is electrically live - ie not a drag tip. Newer machines apparently do not have live tips?

Evan
09-26-2011, 04:28 AM
The question is does the strong magnetic field interact with plasma and make a cut go where it would not have gone without the magnetic field?

I am sure it will. It sure does affect Mig welding.

PTSideshow
09-26-2011, 05:58 AM
According to Jim Colt of Hyperthrem, it doesn't effect the the air plasma output.
There are some grades of steel plate that are highly magnetic. In industrial uses we occasionally run into plasma cutting issues (cut edge angularity, short consumable life) when this type of plate is handled with powerful lifting magnets...then put on a plasma cnc machine for cutting. I have seen areas on these plates where....if you dropped a 3/4" wrench on the magnetized area...you would literally have to pry the wrench off the plate!

Cutting near magnets will not generally have any affect on an air plasma cut.

Jim Colt Hypertherm

But even the drive magnets I use from hard drives don't effect it.
http://i35.photobucket.com/albums/d200/ptsideshow/Tools/WElding%20equipment/DSCF0009.jpg
http://i35.photobucket.com/albums/d200/ptsideshow/Tools/WElding%20equipment/DSCF0008-1.jpg
http://i35.photobucket.com/albums/d200/ptsideshow/Tools/WElding%20equipment/DSCF0013-1.jpg

I have since switched to a thicker ply wood "", as the magnets did pull the screws out after a number of cuts.

winchman
09-26-2011, 06:18 AM
I hope the cut in the last picture isn't typical of the results you get with your plasma cutter.

http://i35.photobucket.com/albums/d200/ptsideshow/Tools/WElding%20equipment/DSCF0013-1.jpg

That's really nasty looking.

madmec
09-26-2011, 06:41 AM
I have an older Hypertherm 380. The metal tip on that is electrically live - ie not a drag tip. Newer machines apparently do not have live tips?

The tip (at least the part you see during operation) aint live on any plasma cutter. It is a Nozzle to focus the arc burning between a tungsten electrode inside the nozzle and the workpiece to concentrate the energy for instantly melting the Material. It needs to be isolated from the Workpiece, otherwise the arc would burn between the Electrode and the Nozzle, overheating the nozzle.

Greets from germany

Thomas