¼" hex holes?

N

Nap

Joined
Sep 9, 2015
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I am obviously a novice in this area. My dad was an industrial electrician, and I worked with him throughout my teens some *cough* years ago, so while I know my way around a machine shop and can drill and tap, I don't exactly know the answer to this:

How does one go about putting a ¼" hex socket in an arbitrary piece of metal? Is this a job for a milling machine, or best outsourced, or what? Have I not googled hard enough to find a tap set (which wouldn't go through much anyway), and am just being an idiot?

The reasons for wanting this should be obvious, but even if I am just stupid, please be constructive when pointing it out.
 
Option 1 is punch, press or broach (all similar operations) - requires a hex-shaped tool. Option 2 is cut (laser, waterjet, jewlers saw, etc). Option 3 is machine (mill). I'm assuming you're talking about a hex-shaped through hole rather than a blind hole.
 
What Patrick said. I have made hex broaches from Allen wrenches in the past. Essentially you want to drill a hole the size of the inscribed circle of the hex size you want, and then broach or punch with your form tool. Design of the form tool follows any cutting tool, you need sharp edges with rake and relief angles, and it's nice to have a pilot the size of your predrilled hole.
 
I done it much like Kuraki method excepting done hot. The tool a tapered hex drift under a flypress.
Finished part needed minor cleanup of displaced material & scale.
 
I've done it making custom screws in 310 stainless. The method used was to drill to the size of the inscribed circle then tap in a broaching tool made from an Allen wrench.

The Allen wrench was cut down and torch annealed, centre drilled in a lathe to give a cutting edge at the corners and rehardened (torch, case hardening compound, mainly to avoid scale, and oil quench: rough and shop-expedient).

I turned up a guide to keep everything aligned and hammered the Allen wrench bit in with a light hammer.

To get it out, the Allen wrench was held in the vide and the guide used as a slide hammer to get it off.

It was a long time ago, but I seem to recall getting 6 sockets from 2 tools. The sockets were not very deep and 310 is a free-cutting stainless. Getting the shavings out of the bottom of the holes was the longest part of the job as they were still attached. I used a scribe for this and it was never the same again.

The hex size was 6mm, so just under 1/4".
 
If you know anyone with the technology, EDM is very good for making odd shaped holes, blind or through... you can buy 1/4" hexagonal electrode online.
 
If you;re just doing one and it's a through hole.

Drill a hole and file the corners in.


Broaches and punches are nice, but go look at the prices of the tool and the press.
 
Thanks, guys. I have a much better idea of how to go about it now. (And yes, I'm talking about a hex-shaped through hole.)
 
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