making hex or torx "holes" at home?

[king nero]

I'd like to know whether it is even possible to make hex or torx drive "holes" at home.

I normally take the pieces I need done, to a shop where they die-sink EDM them. This is normally in quantities ~100 to a few 100's.
This goes great and relatively cheap, especially when you pre-drill the holes (making them remove less material).

I am now making some prototypes, one-off's, and I would like to know if this was possible @ home.

I have seen a sink-EDM setup some 10+ yrs ago, which you just install the thing on a large drill press or a mill, where you manually feed the EDM head.
It was fed from a battery if I remember correctly.


Anyone have one of those, or has some other solution or out-of-the-box ideas?

 

[laser3kw]

you could try "broaching" them. pilot hole is undersize, the broach shaves the features to net size. You could make a decent broach out of HSS shor short runs.

 

[king nero]

they are not through holes though... and cutting blind holes like you describe is not easily possible for small sized holes (size is upto 5/16 hex, maximum, mostly smaller). The chips get in the way fast.

 

[2mJps]

I saw a simple EDM in a magazine. It used a lightbulb. The guy that made it cut a torx like hole in a hack saw blade. I think it was in Home shop machinest.

 

[2mJps]

What are you building?

 

[kazlx]

Look up rotary broaching if you have a lathe.

 

[justanengineer]

Sounds like you need a shaper, my personal favorite machine tool.

 

[king nero]

2mJps: thanks for that, will search for it...
kazlx: rotary broaching is indeed an option for hex holes.
justanengineer: I do that sort of thing on my lathe, but that has certain disadvantages. and also, I won't be buying a shaper for some one-off's. Also as I said above, for small blind holes, this is not the best option.

I am actually looking for an EDM, as I have more use for that. I haven't tried yet, but I do believe Torx profile cannot be achieved with rotary broaching. At least not with the ancient tools I have used at a previous employer.

No-one with a DIY or modified EDM at home or at work? I know it exists, I just regret that I didn't take pictures of it or that I never wrote down the name/manufacturer... When working with one, you just take things for granted...

 

[theoldwizard1]

If it is blind, then it will require cold forging.

 

[deere2210]

I did a lot of checking/reading on doing the same.. If you have a lathe, rotary broaching as has been mentioned should work. Some of the broaches get expensive and have limitations on depth.. I originally wanted to figure out how to do the splines on HD gear shift levers but went a different route after looking at the cost of the specialized broaches.

 

[kmacht]

I built the sinker EDM machine from home shop machinist. It works surprisingly well and is about as cheap as you can get. The thing is comprised of a few light bulbs, the capacitors from old camera flash units, and a few small electronic components you can get from radioshack (or at least used to be able to). The thing is very slow and probably only good for holes that are less deep than they are wide but it does work.

Keith

 

[rsanter]

There are such a variety of bolts available that I have to ask what you what you are doing that you can't find an existing bolt you can use or modify to use

Bob

 

[mvptrukin]

I am not a pro machinist or anything close but have seen links to this company on different machine shop type forums and if I understand the rotary broaching process correctly they sell tools to do what you want but are not cheap:
http://www.buybroaches.com/How-Broaching-Works_ep_7.html

 

[king nero]

Thx for the replies so far.
Current options are rotary broaches (new) and buying a second-hand die-sink EDM as they do not appear to be that expensive. Making my own is probably doable, but I just don't have the time. I did check home machinist, and it sure seems like an interesting project, but I've found some online starting at a few 100 EUR. Counting my own time, I do not think I can make one cheaper. I can however convert a manual to an NC, which seems the most reasonable option. That would also allow me to make larger series if I can make an automatic feed system.

@ rsanter, there are other things that might need a hex or Torx drive besides bolts. Once I get a working prototype, I might (or might not) post it on here, depending on the customer's wishes. I can say however I'm working on an addition to an existing machine, which needs rotating for adjustment.

 

[theoldwizard1]

I built the sinker EDM machine from home shop machinist. It works surprisingly well and is about as cheap as you can get.

Pictures ? Plans ? Links ?

You are holding out on us !

 

[justanengineer]

I did check home machinist, and it sure seems like an interesting project, but I've found some online starting at a few 100 EUR. Counting my own time, I do not think I can make one cheaper.

I think that is your answer then. With the low price and high number of EDMs on the used market Id agree they arent really worth the effort building unless you really want a project. The only problem with EDMs is theyre like shapers, theyre handy for occasional projects but do take up room otherwise.