Cutting a hole in sheet metal

[Cruiser804]

I am a real rookie when it comes to this stuff. I want to cut about a 6" diameter hole in the rear deck of my truck for an access hole to a subtank. (before I install the tank)

I also need to cut two small square holes for the plastic nuts.

How should I do this? I want to to look good when it is done.

 

[DanS HJ-45]

You want a round hole?

I'd probably buy a hole saw (make sure you have a pilot bit). Any hardware store should have them. You could also take the truck to a welding shop and have them cut the hole for you--it'd be like 15 minutes of work with a plasma cutter.

What are you going to cover the hole with? Is this in the ribbed section of the floor?

Dan

 

[Dieseler]

post some pics of location of hole and the plastic nuts,this may help with ideas for accomplishing this.

 

[Cruiser804]

Non-USA 80 series trucks with subtanks have an access door in the rear floor deck. The stamp is already there so you can see where it belongs. See picture. I have the door, packing and plastic nuts. The nuts are basically the same as the nuts for the headlight adjusting screws on a late model 40 series.

I have access to a plasma cutter. I don't think the guy who owns it is pro but says he'll give it a shot. He suggested making a jig somehow. I just want it to look half assed when we're done.

 

[Gumby]

6"? I think I would use a body saw. It's a little reciprocating saw. A jig saw would work too.

You could do it with a plasma, but it might be tough to get in there and clean up the edges.

A 6" hole saw wouldn't have very many uses for a fairly expensive tool. Looks like they are about $50. You could buy a body saw for half that.

 

[Dieseler]

You should be able drill the nut holes with a drill bit smaller than the nut shoulders and tap them in,I have done this in the past for body moldings.
X2 on the body saw if you have one a jigsaw would also work you have the room to rotate it.

 

[Cruiser804]

I have a jigsaw. I suppose I need a blade made for steel? What is the best way to clean up the opening? File and sand?

 

[DanS HJ-45]

I have a jigsaw. I suppose I need a blade made for steel? What is the best way to clean up the opening? File and sand?

Exactly. You're going to want a blade for steel (it will have very fine teeth), then take some high quality masking tape and cover the whole area. Once that's done, I'd take a marker and carefully draw where you want the cut to be. Then take the jigsaw and cut the hole roughly. Then slowly work your way to the actual cut line you want. Once you've got it cut the way you want, file the rough edges, and take a little paint with a brush or Q-tip, and run it along the bare metal of the cut. Once that's dry, remove the masking tape.

You'll have a clean cut, protected from rust, and no scratches from the jigsaw/metal chips (that's what the tape is for--to protect the paint).

Dan

 

[Cruiser804]

Drill it and fitted with nutts

Huh?

Thanks Dan. That helps a lot. When you say high quality you mean like green 3M?

 

[DanS HJ-45]

Huh?

Thanks Dan. That helps a lot. When you say high quality you mean like green 3M?

Yep. Green or blue. I pretty much stick with 3M because I've never had a problem with it, and it's available everywhere.

Dan

 

[turd]

we have used bi-metal hole saws on sheet and stock up to 1/4" before,,
best on a drill press,,but possible with a hand drill,,,
use lots of cutting oil and let the bit do the drillin,,,
good to back up thinner stock with a piece of wood,,,