Cutting Accurately with Plasma Cutter

admin

I've been practicing with my plasma cutter but not having the greatest luck. I can get a clean cut, but accuracy is a problem. I believe my problem lies within the measuring. I'm mostly working with square tube, and it's furniturey stuff. Mostly welding 45 and 90 degree corners. I'm cutting a wedge out of the square tube and bending it so that there isn't an open end anywhere. When I make my cut, I usually have about an 1/8th of an inch to fill in. Working with 14ga material, it's difficult to build up the metal without blowing through. I end up having to build the metal up and grind it down a lot. Is that just normal or is there something I can do to improve? Plasma cutter - Hypertherm Powermax 30Air Supply - Quincy 11 CFM at 90 PSIWelder - Lincoln HD180 set at D for heat and 4-5 for wire speed
Reply:Any reason you're notching the tube for miters and not cutting 45s on a saw?? If the gap is even all the way down the weld seam I'd say you're probably not getting a tight enough radius when bending the remaining wall to produce your 90° corner after notching.
Reply:Picts would help. I'm betting since it sounds like you cut out a wedge and then bend the rest, that the  kerf is too wide. When you go to bend the remaining tab of material causes the two pieces to want to be a given width apart. It's not going to be easy to cut things to bend like that to zero without using a torch. You have to cut pretty much to zero just under the wall of the side you will bend. That way when the wall pivots it does so at that point. If you have an 1/8" wide kerf from the cutter at the back of that wall, the side will bend wide and leave you with a gap. If you heat the tab, you can pound the tube back to flat by forcing the tab material back in line with the corner..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:Here is the way I do miter cuts on rectangular tube. I find that spending a few minutes producing a jig or cutting guide helps you produce excellent results with a hand plasma (at least one that is designed for drag cutting (all Hypertherm's)). In these pics is a Powermax45, the Powermax30 does a better job with its extended nozzle. I actually had a big job a few years ago that required a lot of 45 degree cutoffs on a variety of different rectangular tube sizes. I have a horizontal band saw that I always used in these applications, however after building a few guides like the one pictured....I found that it was much faster than using the band saw. The more I used the jig, the better the cut quality got. A few seconds with a flap disc made for really nice, ready to weld miter joints.  Jim Colt   HyperthermLast edited by jimcolt; 12-09-2015 at 08:01 AM.
Reply:Cutting with a plasma cutter is like cutting with a saw. If you want a piece of wood 12" long you cut it so you leave the line. If you cut it on the line it will be to short, because the saw blade is a 1/16" or more wide. The plasma kerf is also 1/16" or so wide, so if your cutting on the line you are cutting out more metal then needed.www.georgesplasmacuttershop.comPlasma Cutter and Welder Sales and Repairs--Ebay storeTec.Mo. Dealer Consumables for the PT and IPT torch's
Reply:Originally Posted by jimcoltHere is the way I do miter cuts on rectangular tube. I find that spending a few minutes producing a jig or cutting guide helps you produce excellent results with a hand plasma (at least one that is designed for drag cutting (all Hypertherm's)). In these pics is a Powermax45, the Powermax30 does a better job with its extended nozzle. I actually had a big job a few years ago that required a lot of 45 degree cutoffs on a variety of different rectangular tube sizes. I have a horizontal band saw that I always used in these applications, however after building a few guides like the one pictured....I found that it was much faster than using the band saw. The more I used the jig, the better the cut quality got. A few seconds with a flap disc made for really nice, ready to weld miter joints.  Jim Colt   Hypertherm