TO-3 Drilling Jig

[BrianDonegan]

I am thinking of producing a jig for drilling the heatsink holes needed for TO-3 devices.

It will be a CNC-milled piece of aluminum roughly the size of a TO-3 device with four drill bushings (will make it as close as possible, may be larger to accomidate the two end bushings). You place the jig where you want the device on your heatsink and use a hand drill to drill the holes. Simple as that.

Would anyone be interested in these? Not sure of a price yet, but probably in the $15-20 ballpark each. Also, any feedback on the design? Could include a 1/8" drill bit as well.

If there is interest, I will post in the Marketplace forum.

[acenovelty]

Sign me up! Would also work for those of us who own a drill press?

Prosit

[BrianDonegan]

Don't see why not.

[Stuart Easson]

I'll take a couple...would you consider getting the same thing done out of steel? or are the bushings steel?

I have used aluminum jigs for other purposes and they work perfectly for a while, but I always seem to slowly enlarge the holes, a steel version, or steel bushings would make this process slower.

Of course I am assuming the cnc process can be applied to any material...

Stuart

[BrianDonegan]

The bushings are hardened steel drill bushings, so that shouldn't be a problem. I may actually make the jig out of plastic, depending on costs, but aluminum would be nicer.

[Mr Evil]

Could you lop the top off an actual TO3 case and use that instead of milling a piece of aluminium?

[BrianDonegan]

Would still need to mill it for the drill bushings. Plus, most TO-3 cases have one bog hole in the bottom for the pins rather than two small holes.

[Zen Mod]

Originally posted by Mr Evil
Could you lop the top off an actual TO3 case and use that instead of milling a piece of aluminium?

that solution is proved in praxis
cheap and simple and-what is most important- works.

[pinkmouse]

I have some flat aluminium plates used as heatsinks from a Crown Powerbase amp that I use as drilling jigs. Just about the only useful thing that I could get from it!

[BrianDonegan]

You can use an old TO-3 case, if you have one, but it won't do much for guiding the drill.

My initial idea was a simple jig and a metal punch to be followed by drilling, but I figure there are a bunch of people out there without drill presses, and drilling straight into a piece of aluminum with a hand drill can be tricky.

The drill guide bushing will keep the drill perpendicular to the surface you are drilling. It also will not wear out (hole get bigger) over time. These things should be the last tool you need for it, which is the way I like things.

I'll make a couple and post some pics.