How straight can you cut 18 gauge w/ a plasma?

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I am going to be doing some body work on an old truck that I have.  Hopefully buying a plasma cutter soon and curious about how straight of a line you can cut with one.  Do the cutting guides help (chariots) or are they just gimmicks?Or just lay down some angle iron to use as a guide - similar to what I do when I am cutting w/ my circular saw?I'm sure the tool is only as good as the person using it, but more curious about ways to get a straight line.
Reply:If its on flat material, I'll use angle iron as a guide. If its a curved surface, flattened copper pipe works well. It can be bent to follow the contour of the piece being cut."I need this parade like I need a hole in the head"~John F.Kennedy
Reply:Unless you're making lots of curves, you will find that the 4.5" angle grinder will rival the plasma cutter in speed and makes perfectly straight cuts in the hands of a skilled grinder operator.  If not so skilled, you can always leave a little extra metal and use your flap disc to get it just right.
Reply:Originally Posted by 76GMC1500Unless you're making lots of curves, you will find that the 4.5" angle grinder will rival the plasma cutter in speed and makes perfectly straight cuts in the hands of a skilled grinder operator.  If not so skilled, you can always leave a little extra metal and use your flap disc to get it just right.
Reply:yeah right on the cutting wheel.   Make a groove in it first,  and pull it toward you as you cut.  once youve got a groove it will sit in that groove a lot better.IF it Catches...Let it Burn
Reply:If you use a grinder/cutoff wheel, becarefull of kickback.    Better yet, leave the guard on the grinder.I performed the below operation while cutting out some rust on my Ranger's cab.http://img.photobucket.com/albums/v6.../cutfinger.jpg"I need this parade like I need a hole in the head"~John F.Kennedy
Reply:Originally Posted by CrackerIf you use a grinder/cutoff wheel, becarefull of kickback.    Better yet, leave the guard on the grinder.I performed the below operation while cutting out some rust on my Ranger's cab.http://img.photobucket.com/albums/v6.../cutfinger.jpg
Reply:FYI, I use white 1/8" tub surround hardboard for a template material if I need to cut curves.  It's cheap, cuts easily with a saber/band saw, and can be easily laid out on using a Sharpie.  Acetone cleans off layout errors without messing the paint.- "If ya can't be handsome, ya may as well be handy!"   HTP Invertig 201Lincoln Power Mig 255CLincoln SP125+Thermal Dynamics Cutmaster 38
Reply:Originally Posted by GarauldFYI, I use white 1/8" tub surround hardboard for a template material if I need to cut curves.  It's cheap, cuts easily with a saber/band saw, and can be easily laid out on using a Sharpie.  Acetone cleans off layout errors without messing the paint.
Reply:Originally Posted by AZkick-n40I am going to be doing some body work on an old truck that I have.  Hopefully buying a plasma cutter soon and curious about how straight of a line you can cut with one.  Do the cutting guides help (chariots) or are they just gimmicks?Or just lay down some angle iron to use as a guide - similar to what I do when I am cutting w/ my circular saw?I'm sure the tool is only as good as the person using it, but more curious about ways to get a straight line.
Reply:Originally Posted by wroughtn_harvThink of using a plasma or cutting torch like riding a bicycle.By that I mean be looking ahead instead of worrying about where you're at.Another trick I've learned for straight cuts on flat metal is to pull it straight towards you if possible.I do a lot of stuff free hand or just following a sharpie mark.Have you ever watched a sign painter work a lettering brush?They're doing the same thing you're doing with your plasma torch.  It's about dropping into a zone and letting it happen.Dropping into a zone is where you go when you're in a reactive mode instead of a controlling one.  Athletes do it all the time.  The only difference between a weldor and an athelete is the alimony payments.
Reply:Originally Posted by tucsonbrokerWhat is tub surround hardboard?  Is that masonite or an acrylic?  Is it available at home depot?
Reply:My hands are far from steady so I have recently taken up a new technique in which I hold the torch against the fence/templet with both hands and then keep my arms locked and use leaning back with my body which results in the best cuts I've ever done. Obviously only good for relatively short cuts (Less then 18inches). Make sure you have a stable stance... and don't fall over backwards!
Reply:I've had good luck cutting flat straight cuts using a 72" metal ruler I got from either Lowes of Home Depot.  It's steel and springy enough to be able to clamped down on a curved surface.  My cutter came with a "chair" attachment for the torch.  It's mostly worthless.  Instead I use a drag cap that covers the tip of the torch.  It's probably 5/16 tall and slides right along the 3/16 metal ruler.  Using a piece of angle iron isn't as good since it bumps higher up on the torch.  This makes the cut wobble if you ever tilt the torch.  The metal ruler bumps the torch down at the tip and any tilt doesn't have much effect on the cut.I agree with wroughtn_harv, pulling the torch is much better.  Whenver I try to push the torch it seems to slip-stick-slip and makes a poor cut.Ancient threadLast edited by AndyA; 11-25-2009 at 09:58 PM.Reason: I kant spelDynasty200DX w/coolmate1MM210MM VintageESAB miniarc161ltsLincoln AC225Victor O/A, Smith AW1ACutmaster 81IR 2475N7.5FPRage3Jancy USA1019" SBAEAD-200LE
Reply:One of the technology advantages for cutting straight lines with plasma is with system designs that do not "stick" to the plate while cutting. When plasma cutting with non shielded torches operating at or above about 35 amps....and you are dragging the nozzle (also known as tip)....it is common to feel this sticking phenomenon.....it is actually caused by the nozzle welding itself to the plate.Torches with shield technology can be dragged along a template without sticking....and also some plasma systems that are not shielded (the Powermax30 by Hypertherm as an example) have been designed to eliminate sticktion (that's what engineers call the sticking) by using some advanced physics that keeps the nozzle closer to the electrical potential of the plate being cut. You will notice a much smoother cut with torches that don't stick....as well as longer nozzle life.Jim Colt
Reply:jimcolt, the sticking I was talking about is simply friction.  When you're pushing the torch, some of that force is pushing down into the workpiece.  When you're pulling the torch, some of the force is pulling up away from the workpiece.  So if you ever hit a little rough spot (mill scale, rust, bump, whatever) the pushing will tend to get hung, while the pulling will tend to move right over the rough spot.  I use a grounded drag cap when doing this.  I've done what you're talking about with no cap, just the exposed tip.  Basically welding the tip to the work piece.Dynasty200DX w/coolmate1MM210MM VintageESAB miniarc161ltsLincoln AC225Victor O/A, Smith AW1ACutmaster 81IR 2475N7.5FPRage3Jancy USA1019" SBAEAD-200LE
Reply:Originally Posted by 76GMC1500Unless you're making lots of curves, you will find that the 4.5" angle grinder will rival the plasma cutter in speed and makes perfectly straight cuts in the hands of a skilled grinder operator.  If not so skilled, you can always leave a little extra metal and use your flap disc to get it just right.
Reply:should be able to cut UBER straight with or without a guide.. with a guide, guarunteed.unless you've got a steady hand.[url=]
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