how to deal with an awkward void?

I'm restoring another camelback. Yesterday I cleaned the area around the raised lettering on the frame. A lot of big pits were exposed. One of them, a bit smaller than a dime but very irregular shape, goes all the way through to the inside cavity of the casting.

I didn't grow up fixing auto bodies and I'm no pro at Bondo. I can't get to the inside of the (hollow) casting at all except through that hole. The hole is adjacent to two raised letters, which makes any kind of sanding or filing problematic. I'll post a picture later today.

How do you fill such a void? Of course, the casting will be painted so any kind of patch need not color match.

metalmagpie

Poke a hole in a small bit of cardboard for a string....push cardboard in thru hole,pull back with string.....bog in around string against cardboard backing .

Melt some lead into it.

How do you fill such a void?

Click to expand...

I'll assume you want the hole to go away, not the "void" the hole leads to

Pound in wood plug somewhat below flush

Fill and finish to suit

It turned out to be way easier than I thought. I got the bright idea that maybe I could fish a wire through the hole, down the casting on the inside, and out the bottom of the column, then use that to pull something back through. I started fishing with a wire and lo and behold there is a 7/8" threaded hole exactly across from my void. So I can just cut out a 5/8" circle of pipe wrap tape and reach through the hole and stick it across the hole. After that I can fill it like any little pit, paint etc.

metalmagpie

More details on my approach to fixing this hole: First of all, the hole was nothing to do with a casting void. Directly opposite the hole is drilled and tapped 7/8" threads. When they drilled, they went a little too deep and slightly blew through. Since it didn't affect the letters, they left it apparently. Seen from the inside of the threaded hole, the bottom of the hole was domed somewhat.

Here is the bolt threaded into the machine frame on one side:



I took a piece of thin iron transformer lamination and cut it roughly into a 5/8" circle using tinsnips. Then I put my blank over the opening in a 5/8" nut and pressed a ball bearing down to dome the circular blank slightly. Then I applied some Gorilla Glue (hey, it's what I had) and pushed it into the threaded hole and adjusted things until the patch covered the blow-through hole, then kept some pressure on until the patch stayed in place. Then I put the 5/8" ball bearing into the hole and threaded the bolt in to clamp it in place. After a couple of hours the glue should have set up and I can then apply whatever filler to the blowout hole. Smoothed and sanded, it should be pretty invisible. Here's the patch sticking through the blowout hole:



So that's pretty much the end of my little story.

metalmagpie