I've been playing around with my new plasma cutter and the first thing that I've learned is that I will not be cutting freehand, at least not any time soon. So I made a circle cutting guide that works really nicely and I was thinking about a straight cut guide, when it occurred to me: instead of moving the torch over the stationary material, how about moving the material under a stationary torch? It would work like a table saw. In fact, how about adapting an old table saw to a plasma cutter?
You could "rip" with it, or use the miter guage. Cutting to a line with a miter guage would be a lot faster than clamping a straight edge with the right offset. Cutting to a pattern would probably be easier with 2 hands guiding the pattern against the torch. Hey - you could have a #5 lens fastened in front of the torch for helmet/goggles free cutting.
It could have a water pan for "swarf" collection & fume extraction would be a lot easier with a fixed torch. If the fume extractor worked really well, you could use it inside! Foot pedal arc control. The torch would have to be easily removed for off-table use.
Limitations: really big pieces of material (4 x 8 sheets or 20' lengths).
But I'm a newbie at this plasma cutting thing and sometimes I get carried away solving problems that don't really exist. What do you guys think?
Lots of people told Henry Ford he was an idiot.
I can see where long cuts and big cuts would take special prep, but the idea sounds very logical and sensible. Just about all you would have to do is set up a fence. They sell the little single roller ball bearing things that you could make a planar surface with. ( I can't recall their actual name right now.) That would allow you to do bigger things without having to have a carriage and more support. It would also allow you to keep it very clean, as the slag wouldn't even get to the roller balls.
Keep us posted.
Most good things start with ideas we get while not trying to get them. Or at that 2 AM piss stop.
Great idea, Bob! Button rollers on, say, 12" centers, 6'x6' table, torch center mounted or better yet adjustable along one axis, 90 deg. out from rip fence. Catch can/pan water filled under torch, exhaust pulling out right around pan on bottom, just over torch on top. Provided the torch was solidly attached and you can maintain a good ground, I'd say you have a good idea in the making. You might even consider utilizing a belt on the rip fence, with rollers on each end, to prevent binding or dragging.
Best of luck, Jim
The only downside I see to it is the space that it consumes. But, if you have plenty of space, and do enough of that sort of work to justify it, then go for it.
You might also consider making up a straight guide that clamps to an existing workbench. Put it on when you need it, put it away when you don't. Let us know what the outcome is.
When you take up that much space with the rig (and effort building it) you may as well go all out and build a CNC plasma table given the relatively low cost to do so these days.
but its a lot easier moving the torch (it only weighs a few ounces). once you get into larger pieces a CNC setup would be preferred. i'd rather not be trying to manhandle a 4x8 sheet of anything, etc.
A plasma tourch will cut off your finger as easily as a table saw or band saw. I would put some kind of guard arount the torch head above and below the stock.
LOL, Doesn't grab your glove and suck your arm into the arbor either. Hey, they should advertise that! "PlasmaBurn 2000, Economical cauterizing feature saves on trips to the hospital."
Bob Engelhardt wrote:
Doesn't sound that stupid at all! Not to say that I love the idea. Depending of the size you intend to cut. Only problem needing some more care is moving the work around. Have you seen the tables of CNC nibblers? They use brushes (plastics, cheap!) and it is very easy to move heavy sheet metal around.
Great idea except that it seems like a radial arm saw approach would be better. Just replace the saw/motor with the torch and replace the table with a water tray.
That would allow you to keep the torch at a constant height above the work piece and it's also a lot easier to move the torch than a heavy piece of material.
Eventually you could even add a drive motor, something as simple as the motor from an electric drill to drive the movement of the torch for nice, uniform cuts.
Best Regards, Keith Marshall firstname.lastname@example.org
"I'm not grown up enough to be so old!"
CNC is not in my future - the $800 I spent on the plasma cutter was at the budget limit.
I don't generally cut large stuff, so if & when I do, a special set up is acceptable. I'd like the everyday small stuff to be convenient. Taking the cutter outside & dragging out a cutting table is the major inconvenience that I'd like to change. But having it inside really depends upon good fume extraction, which is much easier with a fixed-torch cutter. I plan on some experiments with fume extraction.
Today I cut a 9" square out of a circular piece of 3/16" mild steel. This is typical of my cutting jobs, so a table-saw sized set up would be appropriate. Another typical job is cutting pieces out of PC cases, also small enough.
I found that microwave oven magnets will hold down a cutting guide, so that's a problem solved (having to clamp down the guide). The work itself still needs to be clamped & avoiding that would be convenient.
For now I'm going to build a quick-and-dirty cutting table (bed frame angle) and get some more experience with my cutter. I'm kinda' keen on this idea, so there's a good chance that I'll build it, someday. If & when I do, I'll be sure to show it off here.
You may find that those powerful magnets bend the plasma and kink your lines
"Andrew Mawson" wrote
I was wondering about that. I know in welding, magnetic fields play havoc with the arc.
Andrew Mawson wrote:
I haven't noticed that yet, but it seems plausible. I tried magnets once as a work holder for stick welding and that arc was definitely affected. With plasma cutting, the speed of the air flow would diminish the effect. I should try some experiments, unless somebody else can speak from experience.
Bob Engelhardt wrote:
I just clamp on straightedges and move the torch. Today I had to make a 3-sided piece from angle iron. It had 2 corners which needed to be radiused. I used Mike Graham's method and made up a little jig from 1/4" plywood. Worked fine. Does it look laser cut? No. Can anyone tell after it's been welded? No.
Grant Erwin wrote:
Magnets are nice: they don't need access to both sides like a clamp does, and the straightedge position is more easily adjusted with them. For the same reasons, magnets are nice for holding the work to the table. This is for thin, flat (sheet) work. Doesn't work so well for angle iron, etc.
You should see what a magnet does to DC TIG.
I have no doubts that magnets near a plasma stream will bend it from its normal course. This is how they move the arc in a tv tube as well.
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Bob Engelhardt wrote:
Regarding fumes: The object (I presume) is to keep from breathing them, and I would guess the cutting table is below 'nose' level. May I suggest you first determine if the fumes are heavier (or lighter) than air. Why?
I was once in a 'nasty' environment where a lot of effort was made to exhaust fumes from a molding process. The mold press sat on the workshop floor and you could easily see the fumes falling almost straight down. Yet all the exhaust effort was being made to remove the fumes at ceiling level (approx 12 to 14 feet). Needless to say, the press attendants were always in a continuous flow of the fumes.
The 'engineering' was already done, the building was built specifically for the purpose, and......
I have no idea if fumes created from cutting are heavier than air, but intuition tells me they probably are. If so, a ground level exhaust system might be something to investigate....
Good luck, Ace