Filling holes in a chassis?

[mlp-mx6]

How do you fill holes (even big ones) in a chassis when you are doing restoration/repair/redo work? I have an aluminum ODS-style chassis that I am completely rebuilding and need to fill several holes, including up to the size of a FP-style cap can. There are several mounting screw holes to fill as well.

Thanks for your suggestions,
Michael

[Phil_S]

There is no solution that is really good. I have used several recycled chassis and so, I've got some experience with this. Typically, I cut a square of sheet metal (or sometimes I use old PCB material which cuts with a snips) and mount it to cover a hole (like a can cap or octal socket) and mount it with two #4 screws. I nearly always mount it on the inside as I think a circle looks OK and you don't have to make your cover plate all that neat. I don't bother closing unused screw holes. If you are really set on doing that, I suggest a bit of tape on the inside to create a "wall" and some epoxy filler from the auto parts store (for body work). When I'm done closing the holes, I usually paint the chassis.

Here are a couple of examples of my less than professional handiwork:
http://home.comcast.net/~psymonds/JTM45.htm
http://home.comcast.net/~psymonds/6SN7amp.htm

[Dr-Joned]

I always liked the Keystone nylon plugs. They should be available at Mouser, Allied, etc.

[selloutrr]

The mounting screw holes are probably not worth trying to fill what ever you use will stand out more then if you left them. suppliers like Weber and Tubesandmore offer socket covers like the ones Dumble used on 50W versions of 100W chassis to cover the Octal sockets. if those are not the correct size, you could go to a metal fabricator and ask for scrap material and measure out and cut a larger version. This way the hole cover would look purpose done and not a cover up. they used to make plastic caps that would fit inside 1/4" holes pressure fit. sometimes gromits help close up holes enough to get by. If you have welding skills and the chassis is bare you could fill the hole.

[KellyBass]

Anyone remember those infomercials for something called "allumalloy"? I've wondered about this stuff for plugging chassis holes.

[TheGimp]

Put a screw through the hole and a nut on the bottom. Looks like it is functional from the top.

[Phil_S]

+1 on what TheGimp says about running a screw into it. If you use the right kind of screw, you don't even need a nut. If they have sharp points, the mill file is your friend. Those store bought hole covers are expensive. For what you pay for those, it will take the fun out of a recycled chassis.

[tubeswell]

I make sheetmetal covers for the bigger holes, and usually just leave the teency holes.

[daydreamer]

If it is on the face and you are redoing the paint/lettering, you could do what panel beaters do; sheet metal behind the hole with 'epoxy' glue, then '2 part' body filler, sand and repaint. It's a long way round though and wouldn't work if not painted obviously. I use it when fixing steel door frames to cover screw holes, patch dents etc.

[dynaman]

Add more tubes!

Or, fill the holes with something similar to what used to occupy them. Dude recently sent me a gorgeous vintage Webster amp to be converted to a 5F6A kinda thingy and wanted it to at least appear somewhat stock. I pretty much just filled holes with whatever fit or used a plate.

Since the transformers were OK in their existing locations, I wound up only having to drill about a half dozen holes to accept 4/40 screws. Fortunately, I was able to relocate the input, lamp, jacks, power tubes, etc., to other existing holes.

Note that there are a lot of weird connectors, unused sockets and a can cap. They're connected to nothing and only serve to fill holes. One hole was covered with a homemade plate. The input transformers stayed, but their sockets are wired to nothing. The back of the amp had four large 4-pin sockets that I salvaged and used to fill holes on the top of the chassis. To cover their original holes, I fashioned an adapter plate out of scrap black phenolic and located the speaker jacks and power switches in the center of the existing holes.

I guess what I'm trying to say is that you can use those holes to host other vital components or at least appear functional if you get creative. Stuff like external bias pots, spare fuse holder, etc. That's why I never throw anything away! Yeah, I even have a bin filled with nasty scrap flat stock that I use for making cover plates.

Eh...or just gut the whole top of the chassis and replace it with a blank plate if that's easier.

Or just don't look at the darn holes and be done with it!