Making cutouts for thru-chassis transformers

[EETStudent]

I am currently working on a 6G9 Tremolux build, and I need advice on the best way to make a square cutout for the power transformer. I would normally use my nibbler tool, but the chassis is just too thick. Any recommendations?

[black_labb]

i've used a drill for the corners and a jigsaw to roughly meet the holes, then clean it up with a file.

i havent used this with steel, but i've used it with 3mm thick aluminium

[EETStudent]

Ok I already had the cutout marked off and the holes in the corners. Youre saying to use a jigsaw to to close things off? Do you recommend a specific type of blade?

[defaced]

The finer the better. Wear ear plugs, it will be loud, the chassis is like a big sound baord (think of how a piano is constructed). If you can back up the your cuts with a piece of wood, it will make the cutting easier/more controllable because you'll have something to stabilize the chassis on that's right under the cut.

If it were me, I'd use an abrasive cut off wheel, but honestly you've got the same amount of work either way.

[tubeswell]

I use a 1/2" chassis hole punch for the corners, which is big enough to get some lopsided sheet metal cutters into for the straight bits with a file to tidy up

[fyl]

I am currently working on a 6G9 Tremolux build, and I need advice on the best way to make a square cutout for the power transformer. I would normally use my nibbler tool, but the chassis is just too thick. Any recommendations?

A small plunge router fitted with a carbide bit, a template and 5 minutes of your time. Check the tuto: Power Transformer Cutout

[J M Fahey]

I only use aluminum
Iron is my foe, I hate it.

[Michael Allen]

I've done it with a Dremel cutoff wheel. It takes a few to get the job done. This is on Aluminum though.

Now that i have a jigsaw, i'd probably drill holes in the corners like recommended and use the jigsaw to connect them. If you don't have a dremel/jigsaw/router, then just drill a series of holes all the way around the cutout and use a small file to connect the holes, and then to clean up the edges.

[defaced]

I've done it with a Dremel cutoff wheel. It takes a few to get the job done. This is on Aluminum though.

It's actually easier on steel because it doesn't clog cutting wheels like aluminum does. But with steel, you will chew through dremel cutoff wheels. Keep the arbor as close to the surface as possible so you minimize the contact area with the metal, this will speed up the cut and probably reduce wheel wear, but I can't really back that up with experience.

[Diablo]

You probably don't have these in your workshop, but a water jet or laser would be the easiest method.