The joy of metal working is directly proportional to the number of metal working tools you can access. At least that’s what I tell me wife.
Not that I have much. A decent drill press, a good nibbling tool or two and some chassis punches are, for me, pretty much the minimum requirements for enjoying, or at least tolerating, vacuum tube chassis prep.
Of these tools, the radio chassis punch is my favorite. Typically from Greenlee, and made years ago, these are plentiful on eBay for 10-30 bucks. Happily, you only need a few to cover common sockets. I’ve got seven mostly random punches, I think, slowly acquired through the years as targets of opportunity at hamfests or more recently, from the Bay, in anticipation of retirement.
A picture is worth a thousand words here.
To use the punch, you drill a guide hole the size of the bolt, place the smaller cutting blade portion below the chassis, push the guide bolt through the larger portion and the drilled hole and thread the bolt into the cutting portion til it’s tight. You then turn the bolt head with a wrench until the lower portion cuts completely up through the chassis. There is no muss, little fuss, and if you’ve ever made a large hole by drilling small holes and filing, you will know that you never want to do that again.
The chassis hole punch is especially important if you are recycling a chassis, as I am. There will be large holes you will need to make, often in areas where some metal has already been removed. Drilling a hole overlapping an already existing one can ugly. But the chassis punch works in this situation as if it was designed for it. Buy a couple. But make sure they are radio chassis punches, not conduit punches. A 2 inch conduit punch is sized to make a hole for 2 inch conduit, which won’t be exactly 2 inches. The radio chassis punches make a hole the size they say they are.
I won’t bore you with the details, but below you can see the results of a couple of annoying days of heavy metal work. There’s a hole for everything I need. The stray hole near the transformer was pre-existing, but ideally located for either a second IF amp stage, or I hope, a 6V6 second audio stage. But I’ve got to make the stock radio work right first. If I do neither I’ll make a plate and it will look fine.
The panel fit-up went well too. After filling and priming, the old hole areas look smooth, and everything mounts up as it should without any clearance issues. What do you think, Cosmic Blue paint, perhaps?
There may be a hole or two left to drill as I move forward – there always seems to be – but none that I’m aware of now.
So it’s time to melt some solder.