The Stovebolt Site Forums The Shop Area Paint and Body Shop Tools for making nice straight cuts on sheetmetal

What do you use? Simple sheers? Nibbler? Other?

Basic stuff that I haven't mastered.

Thanks,
Keith

The order I would place things is;

A sheet metal sheer is going to give the straightest, cleanest edge.
A nibbler (at least the ones I've used) cut tiny round bites out of the metal so you can go in any direction (round corners, etc.)
A nibbler is as straight as you make it go and leaves a somewhat serrated edge.
A plasma arc cutter can cut in any direction and is as straight as you can make it. You can use a straight edge of some sort to help the cut be straight. The edge is burned but can be pretty nice.
A cutting torch will leave a burned edge and will take some practice to leave nice edges.

Plasma arc (to me) seems my choice for space and versatility.

What about a "whizzer"? (die grinder with a cutting blade)

zip wheels on a die grinder will usually warp a sheet if yer making much of a cut - I love my new 'air scissors', did a number on the roof of a 52 sedan [sorry Joker ] in minutes to supply a patch for the nose of daBus

Bill

Anything like a die grinder or dotco that uses abrasion for cutting is apt to warp a flat panel due to the heat generated. An exception to that would be if the cut line is fairly short or if you take your time & do the cut in segments so the metal doesn't get too hot.

OK - thanks for the clarification.

I've always heard this was the "gold standard" for cutting sheet metal.

Beverly Shear

After using it a few times, I would agree with them. It's a real time and effort saver.

It's a nice piece of equipment but it won't work if you're cutting out rust & fitting a patch panel on a cab corner.

If you only need afew things cut straight take them to a hvac shop and have them cut them on their sheer.

A shear first but a nibbler works well with a straight edge
Dan

lately Ive been using an air powered sheet metal shear and 3" high speed air powered cutter. Both of which I got from Harbor Freight and have been very happy with them. So far I haven't experienced any warping of the metal from using the high speed cutter but the longest cut ive done so far was no longer than 12-16in.

http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=90114
http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=36568

A cute little trick that I have used when I didn't have access to a shear is to get two pcs. of bar-stock, like .250" x 2.000" or .375" x 2.500", size is not that all important, just as long as they are longer than your pc. of sheetmetal and that they are at least .250" to 1.000" thick. (cold-roll bar stock is better because it has a nice sharp edges on it).
If the length of the sheetmetal part is important you can scribe you a line on it where you want the final cut to be, this helps to setup the sheetmetal part to be cut. Then cut your sheetmetal with a grinder, bandsaw or a nibbler as straight as you can but about 1/32" to 1/8" or so, longer than needed. Then sandwitch your sheetmetal between the two bar-stock pcs. and c-clamp all 3 pcs. together at the ends of your sheetmetal so that your sheetmetal just sticks out from between the edges of the bar-stock about 1/32" or 1/16", or clamp so that the edge of the bar-stock is right on your scribed line. Clamp on the back side of the bar-stock so you have access to the trimming edged and the c-clamps are not in your way. The two pcs. of bar stock must be exactly on top of one another with no offset or step between them. Then use a small hand grinder like one of those 3" right angle die grinder with a FINE grit dics and grind your sheetmetal down to the edge of the bar-stock. The bar-stock also acts like a heatsink and you will not get any warpage. Sometimes I put some 'layout blueing' on the edges of the bar stock and that lets me know when to stop the grinding. You don't want to grind the bar-stock, just grind the sheetmetal down to the bar-stock all the down the length of your sheetmetal.
Then remove the c-clamps and dress the edge of your sheetmetal with a hand file just enough to remove the grinding burr.

This is not as hard as maybe I have made it out to sound.
But a person can get good enough at doing this that is is hard to tell the part was not cut on a shear.

Yes, it does involve some time to do this but it does make a nice straight clean edge. I have two pcs. of .500" x 2.000" cold roll bar-stock 36" long just for doing this at home.

I have worked for a sheetmetal company for 30 years and would often have to do this if we had a part that already had forms or bends in it and it would not fit under the shear machine hold-downs.

jig saw works good

Thanks for the detailed reply ED-I could see where that would work well under the right circumstances

Fire-That would be nice to work with-My father had one when we were kids..It had that hold down feature which would be a great benefit...My father gave it to my brother :o(

Have a great holiday everyboby...looks like nice weather

Keith

I have used a cutoff wheel in a 4" angle grinder with great results.
Ed

Martinsr's post "Example of excellent patch panel trimming tool"
#124331 - 01-30-2007 10:13 PM in paint & body

This

I sure like the air shears for cutting sheets ... just gotta find a creative use for the leavings

Bill

that's a nice cut...

the leavings?: how about Chritmas tree ornaments?
Paint em silver or gold ...maybe with some fake snow

Keith