How to machine this hex?

[5artist5]

I have a part that has an allen key hex in it and I am not sure how to machine it.
Any ideas on how it is done?
Here is a rough drawing of the part.

[SanDiegoCNC]

Originally Posted by 5artist5 I have a part that has an allen key hex in it and I am not sure how to machine it. Any ideas on how it is done? Here is a rough drawing of the part.

Broaching.

http://www.genswiss.com/rotarybroaching.htm

[Dick L.]

It could also be done with an EDM sinker. I agree though that most common way for production would be broaching.

Dick

[Dropout]

You can't broach it because it's essentially a blind hole.

[CaseyCAM]

Well, this can be broached, but not using a "broach" tool.

you can do this in the mill like on a bridgeport, take a lathe turning tool (one that is out of tool steel, not a brand name insert holder) and make a fixture to hold it sideways and pull down on the handle and work your way into the corners..

I'd rough this out and finish it with a small end mill, then use the lathe turning tool to create the sharp corners.

But the best way is it rough it out and finish as much as possible with a endmill, then EDM the rest.

EDIT:
.... Nevermind, I dismissed the sizes your working with, this will have to be done with EDM. Doing it like I said will require like a 1/8" Shank and thats not sturdy enough to hold anything, and typical tool steel lathe cutters are like 1/4" stock, and your largest opening is .200" .. So if EDM is not an option you might have to make it 2 pieces and weld it.

[davidw731]

This could be hex drilled with a Watts bros tool works hex drill, not sure if they go that small, we drill 1/4 hexs where I work, this is the basics of how it works. http://mathtourist.blogspot.com/2009...uare-hole.html
Watts Bros
412-823-7877

[garagefela]

Probably a long shot but could you find something that already has a hex in it already and machine it out of that. Dunno maybe a grub screw but not sure if the outside thread will have enough meat to machine off to get a clean diameter.

I had only thought of this as I had to replace the rear brake pads of my Mazda one time and had to back the pads away. Inside the caliper I had to place an allen key in a screw and to turn it. I pulled this screw out for a look and it was a long pin with a hex in one end and threaded on the other end.

Something like this would have been perfect for you, not sure if you are doing a one off or lots. Go and see some bolt people for ideas, might be cheaper than EDM or buying tools.

One possible pain is that a bolt like this will be hardened and difficult(ish) to machine but at least when it is complete it is already hard and tough.

That lower section has stuff all wall thickness.

Cheers M

[sti2011]

Talk to the engineer and see if you can undercut the bottom of the hex bore. Then you can simply rotary broach it or if the material is relatively easy to machine you can just force a stationary broach in. I broach hexes in my CNC lathe all the time in brass. Just push it right through...The undercut will allow the chips to break off and not destroy the part or tooling.
Always nice to have to deal with poor designing. The hex has no need to go to a flat bottom!

[Mcgyver]

there are lots of ways to do it, but you're not giving enough info.....do you need 1 or 1,000,000? what are the tolerances? what is the material?

the merit of any idea will depend on these three points.

off the top of my head, for a one of, I'd broach a through hole piece as an insert and loctite or silver solder it in place. for hundreds, maybe a rotary broach or edm. for millions, forging or casting, investment if it has to be super accurate

[5artist5]

Thanks for the input. I think I can get some leeway on the bottom of the hole.

As for the other specifics, I'm looking at between 25 and 75.

Material I some kind of steel. I will be sending it out for material analysis shortly.

I like the rotary broach idea.

[DareBee]

I grind hex broaches to do that all the time. As long as the hole is deep enough for the chips to stay in when done.
I shot, easy.

[SwissType1]

You CAN Rotary Broach this form, however the flat bottom aspect will be a problem as someone has already pointed out. You do need room for chip accumulation or you will break tools or stall the machine, etc.

Despite that, there are methods/processes for rotary broaching this successfully. Call Genswiss at 413-562-4800