The Stovebolt Site Forums The Shop Area The Tool Chest Cutting holes in sheet metal?

Anyone know of a cheap tool or a way to cut 4" round holes in 1/16" sheet metal?
I only need to cut 4 holes for tail/brake lights, and I will never use it again.
Maybe metal jig saw blades? Harbor F. did not show anything like this: A tool that bolts through the sheet metal and use an impact wrench to press out the hole? I need 4" diameter holes to fit my lights. Thanks.

I have never used one, but I would try this type of 4" hole cutter.

That looks like a nice and economical option.

A jigsaw with fine tooth metal blade and a half round file for cleanup will also work.

Grigg

Thanks guys for the advice. I have a set of hole saws for wood. But did not know if there were some 4" for metal.

I'd recommend using a drill press with a 4" hole saw. A hand drill might wrap you up. I drill in 22 gauge with a 3 5/8" hole saw, with a 1/2" drill. And if it catches up on one side, better hang on.

John

I agree with John, pretty much have to use a drill press. Additionally you may destroy the sheet metal if the hole saw hangs up.

I'd use a jigsaw as Grigg suggested, or an air drill with a cut-off wheel.

If you are trying to mount 4" Trucklite type lights, they take a 4 1/2" hole. Although a drill press would be the safer way of doing it, wusually don't have to option us putting it in a drill press. We use a Lenox bimetal. They can be bought on eBay for $16 including shipping. Item No. 230631333187. You will also need a mandrel. It takes a good 1/2" drill... The slower the speed the better. And it is just like drilling a any big hole in metal. I kind of tease the throttle towards the end because they can grab when you break through.

Mine are not Trucklite brand. I will have to check again, they may be 4 1/2" holes.
Thanks to all for the great info. I will check the e-bay number.

If it were me and I needed a couple of 4" holes in a sheet metal
panel, I just punch a hole thru big enough to start my aircraft
snips and cut it out the them.

Denny G

These blades are designed to be used in an air powered jigsaw:

http://www.northerntool.com/shop/tools/product_200337844_200337844

Since the saw costs over $100.00, for a one-time job I'd suggest doing a little adapting so they'll fit in an electric variable-speed jigsaw. With a little creative grinding, they should fit a regular saber saw. Use the 32 TPI blade for the smoothest cut.
Jerry

Agree with DG.

Agree with Crenwelge. I cut 4" holes in my VW tunnel with a variable speed hand drill and a 4" hole saw. It is about 1/16" thick, and I had no problem. Just go slow with steady light pressure.

I would have to drill a bunch of 1/2, or larger, holes around the scribed 4" diameter, on my drill press (if the sheet size fits in the throat), then "connect" the holes with a jig saw or snips.

Cutting holes in Sheet Metal?
http://www.pbase.com/dennygraham/sheet_metal
Decided to do a demo while my coffee was brewin'.
This was a five minute job from getting the tools
out to finished hole.
Back in the house, coffee's still percolatin'.

DG

Denny, I was thinking about your earlier comment that you'd just snip the hole out with your shears. I wondered if you'd give it a try and post pictures as you're known to do. I see now that you don't disappoint!

I too thought about that but remember that the OP claims the sheet metal is 1/16" which is about 16 gauge. Last week I was doing some straight cuts in 16 ga with some nice aviation snips and it's real work. I have not tried cutting a 4" circle in 16 ga sheet but I think it'd be quite difficult. Much more difficult than thin more or less flexible sheet metal like you showed.

In the end though there are several good ways to accomplish the task, the best method will suit the individual's ability, tool box, and budget.

Grigg

Yeah, my metal looks thicker than that. It's actually the rear panel across the back of a factory built bed. It has some small holes, about 2 or 3 inch already in it.
Guess I will have to go with one of the hole saws or jigsaw blade.
Thanks to all.

Yeah your right Grigg, looking back to the original post he did
seem very specific about the thickness. I see that he
was mounting tail lights in 'sheet metal' and so I automatically
think body panel, 18 or 20ga., which is well within the
capability of a good pair of Wiss snips that aren't dull or
sprung. 1/16" can be done but that's pushing it and you would
have to relieve the center before you could trim the hole to
the line.
If it was indeed 1/16" thick I probably would also
just punch it out with a hole saw.
DG

If you're going to enlarge existing holes the hole saw will not work unless you put something in the hole to guide and steady the pilot.

Jig saw and file are probably better suited if you have existing holes to enlarge.

Grigg

Have you thought of an electrical panel hole punch? These are used to enlarge a conduit hole in breaker boxes. I've never used one, but watched it done. They are hand tightened. Try Greenlee, or other sites, Hazard Fraught may also have that style.
Tom

A 4 or 4.5" "knockout punch" is unlikely to fit the budget, they're expensive used and extremely expensive new.
http://www.ebay.com/itm/Greenlee-Kn...MM-4-1-2-500-4654-500-5644-/151250032858

http://www.amazon.com/Greenlee-742BB-Standard-Knockout-2-Inch/dp/B0020448TI

I'll say, hate to think about how much I've sunk into Greenlee
punches over the years. Good thing I was able to do it before
I retired:
http://www.pbase.com/dennygraham/image/154795849
But I gotta admit, they did pay for themselves in time saved
and appearance of the end product.

DG

Being an electrician, I'll tell you that a greenlee knockout is by far the cleanest. It can dimple the sheet metal though. As far as 1/16" it might be asking alot of a KO set.

Your next option is a good old fashion hole saw and some cutting oil. Which is what I recommend. Keep a file handy to remove rough edges.

If you can find a carbide tooth hole saw that looks something like this. http://www.grainger.com/product/WESTWARD-Hole-Saw-6EXP3?s_pp=false It would be ideal. They make super clean cuts. Unfortunately the bigger they are, the more expesive they are.

So, the good old fashion hole saw is probably the best. You can get them anywhere, and they're cheap. So if you burn one up, no biggee.

I've used them on 1/4 plate for adding strength to a mezinine. Whe had to run 4" cunduit into the bottom of switch gear. USE LOTS OF CUTTING OIL AND TAKE YOUR TIME!

While all of these high priced cutters will work, there is no reason to spend that kind of bucks to cut a hole for light. I have been replacing the back end of trailers that backed into a dock too hard for 50 years. A bimetal hole saw will do the job for the 4 1/2" holes required for 4" sealed lights. For drilling holes in heat treated truck frames, I have been using a Jancy Sluggers for 30 years. I think I have worn out 3 of the Jancys. Jancy was recently bought by Fein, which is a German company. I haven't bought any since the buyout. I don't know if they are still made in Iowa or if they are now made in Germany. Fein is the very top of the line in Germany.

For enlarging an existing hole to a larger, here's a tech thread to do so...


http://www.jalopyjournal.com/forum/showthread.php?t=854599

Thanks guys, lots of good info. to choose from.

Crenwege, you were right. They are 4 1/2" diameter holes. I purchased some jig saw blades for metal today. Will soon know how they work.

I use a Lenox 4" bi-metal hole saw from Home Depot to cut holes in my truck beds for gooseneck hitches. It was around $30 for the hole saw and the mandrel. just take it slow and easy, and gently rock it in a circular motion to cut.

Here's another sneaky trick to get a clean cut in thin metal- - - -attach a piece of 1/2" plywood to the metal where you want the hole to be with 2 or 3 sheet metal screws in the area that's going to be cut out, and make the cut with a fine-toothed jigsaw from the wood side. The wood will reinforce the metal and give you a clean cut with no distortion of the sheet metal.
Jerry

Got er done. I found some good blades at my local old time hardware store. I bought 2, but only took one to cut the 4 holes with my jigsaw. I did use a support backing out of paneling. Only took a few minutes. I was amazed at how fast they cut. I only did a little finishing up with a dremel tool.