View Full Version : cutting 3/4 to 2 inch bolt holes with plasma
It's a dry heat
06-25-2008, 11:22 PM
What to use for a jig for large bolt holes. Half inch thick metal. 3/4 to 2 inch holes. Haven't got my Powermax 30 yet. ordered monday 06/23/08, shipped yesterday 24th, UPS ground. Do I go to Lowe's (one mile away) and buy large washers, build from Plywood. Its for changing 3 point hitch points for Land Pride Quick hitch cat 1.
To get it out of the way. I know it doesn't do 1/2 inch.
Don't really want to weld my pins in for the top link, I need 14 1/2 inches separation from top to bottom links. This will be my last tractor tool to fix(mod). This one is a 7 ft. tool bar 400 lbs.
got my introduction to work from my software Web site, click on it to see something boring.
06-26-2008, 12:30 AM
I use plywood a lot for jigs like that. You have to get the torch, so you can determine how big the hole needs to be cut in the wood. The cut arc will always be at least 1/4-1/2" away from the wood, so if you zip[ along, it won't even scorch it. If you do scorch it, just cut some more jigs!. If the hole isn't critical (squeeze hold only, not shear loads) you might be able to freehand the cut using only a line drawn to follow...I've done some on trailer rails that way, and they were good to go.:)
06-26-2008, 09:52 AM
Howcome you bought a Powermax 30? It'll sever .5" according to the specs, but I'll bet you could cut the holes faster with an O/A torch!
06-26-2008, 10:01 AM
For my O/A, I use pieces of pipe or tubing cut to about 1/8" longer than the length of the tip. Then, if necessary I'll weld a little tab to it to clamp to. If you have multiple holes to cut, you can cut a bunch of them and gang them together, too.
06-26-2008, 11:51 AM
When cutting holes, in heavy plate it's good to drill a starter hole, to prevent blowback. Nice intro, Vern!
06-26-2008, 12:10 PM
When cutting holes, in heavy plate it's good to drill a starter hole, to prevent blowback.
blowback not withstanding, the P-Max won't pierce 1/2" plate so a starter hole is de rigueur.
06-26-2008, 04:06 PM
I cut them with a hole saw and battery drill, wouldn't cut thousands that way but for a few the cost/time cant be beat. We also do use a plasma on occasion, have patterns out of wood.
06-26-2008, 04:10 PM
You can do up to about 1 1/2 and the bat drill is too fast or too heavily loaded, those 1 1/8 in 3/8 were not a problem. My best time was 35 seconds with a but with about a dozen cuts under its belt. You couldn't keep it up in production and you couldn't average it but for the DIY crowd a couple could be doable in a few minutes.
As rocky said to prevent blow back and possible shorten the life of you consumables drill or torch a starting hole somewhere in the center. If you like you can roll the plazma torch into plate and this will help wash some of the metal away from the torch. If you have a Hypertherm with a drag tip then make your jig hole 3/8" larger than said hole and you'll be pretty close.
If you like you can roll the plazma torch into plate
This works with an O/A torch too. I have pierced 1" plate by starting at an angle and gradually rolling upright. You need to get it hot all the way through first tho---
It's a dry heat
06-26-2008, 10:58 PM
hankj, Just trying to cut costs in the hobbie shop. So Plasma seemed to be my first choice. I've got three bottles of gas in the shop now. c25 90 for 110v meg on cart , c25 200 for 220v shop welder, and tri gas 90.
Rocky D, good idea with pilot Help on consumables.
Sbarry To me a hole saw cuts one hole then dull. bad luck for me. Do you still have that little lincoln in the shopping cart?
TEK, I've got to learn the plasma roll!!!
FWI, I thought the tip from a new H30 can be drug on the work surface. Thats what HT shows on there site. It does not come with training wheels. or special tips, that I know of. https://www.hypertherm.com/Xnet/video/video.jsp?video=/PMX30_Operation_Video.flv
Pumpkinhead, go back into your pumplin.
06-27-2008, 09:13 AM
As mentioned before, I'd probably use the torch. But I do use holesaws quite a bit too. And properly cared for, they do last quite awhile. Cary uses them for everything, I think. (He probably has one welded up to use as a coffee cup. :D :p) Anyway, they do quite well, and make nice clean holes. Still, I think I'd use the torch with some sort of jig.
06-27-2008, 03:13 PM
With saws there needs to be some light lube and enough pressure and not overspeed them, you get the feel after a while and you need good saws but they last a long time. I like Rapid Tap or Tap Magic. A few drops every 1/8 of material, I dont flood it.
06-27-2008, 03:24 PM
I am certainly not negating a plasma or a torch, a decent shop should have both. I can get by without a lot of big machine tools, rarely need a lathe or mill and I got friends or sources for the occasional job but a couple welding machines, a torch, grinder, chop saw and plenty of hand tools do the majority of the work. As many complicated tools as there are the majority of the worlds work is done with simple hand tools, as far as technology has come there is still a use for a hammer and the farther I get down the line the more simple solutions I seem to find. I buy modern tools constantly, many perform the same old functions except more efficiently but I am on the constant lookout for simpler and "right now" ideas. Some are hard to beat, they still haven't come up with much improvement to the common Channelok or Vise Grips and I would be lost without adjustable wrenches.