My 6" 4 jaw seems to need a 9/32 hex key, anyone know where to get a T handle for it?

[gellfex]

A chuck gifted to me seems to have an odd size hex key, the smallish L key I've been using measures 7mm. The chuck is a 'Power Companion' and marked USA . But McMaster doesn't have anything in 7mm nor 9/32 nor does anyone else! What am I missing about this?

[rickyb]

Just make one from drill rod. Easy-peasy

[Rich Carlstedt]

https://www.amazon.com/EKLIND-64970-...82&sr=8-8&th=1

Rich

[gellfex]

Just make one from drill rod. Easy-peasy

I don't have an indexer but I guess I could drill a piece of AL 1/2" hex and pin or set screw a rod in to mill the flats. I'm not so good at hardening, It'd probably snap right off the 1st try!

https://www.amazon.com/EKLIND-64970-...82&sr=8-8&th=1

Rich

Hmm, funny how that didn't come up when I was searching, I didn't try directly on Amazon because the search engine is so sloppy as to be unusable for something like that. I think the key probably is actually 9/32 since it's USA made and not young, but Eklind does not seem to a make it. I guess a good quality 7mm should work.

[oxford]

You could always get a 9/32” hex socket and use a 1/4” drive T handle.

[Ian B]

Oxford,

This is exactly what I do. I have a 4 jaw Pratt Burnerd with hex sockets, I bought a long Allen key 1/2" socket and a cheap extension & tee bar. Works perfectly. It also means that with an adaptor, i can spin the screws with a battery drill.

Ian

[BCRider]

Just make one from drill rod. Easy-peasy

Eggzacklee ! ! ! !

You have a mill, right? And a hex collet block? Or some other way to index 6 sides? Making your own specific size hex chuck key is super easy. Turn up down the end of a piece of 1/2" drill rod then hexify it. Super easy.

Heat up the hex end and quench then temper it back to a dark straw to brown color and then polish it up and yer done.

[true temper]

I had a bunch of 5/16” t handles and needed a 1/4” cut it down easily with a carbide end mill.

[old mart]

Tee handle hex sockets should be easy to obtain in both imperial and metric.

[lynnl]

Interesting how the eye deceives. Given that the original hex in that first photo is 5/16," the milled down part looks considerably smaller than 1/4' to me.

[gellfex]

I had a bunch of 5/16” t handles and needed a 1/4” cut it down easily with a carbide end mill.

Well, that is an idea. I'm confused by the pic, is that a 30 deg end mill?

BCRider You're definitely more confident with the heat treat than I am! I have some 304 SS 3/8 hex rod, I guess I could mill it down and see if it holds up if I didn't want to try the 7mm T handle from Amazon.

[mattthemuppet]

no need to heat treat the key at all. It's not a precision part and if it wears enough to cause problems just make another. If anything unhardened drill rod will be tougher and less prone to breaking than a hardened one.

[oxford]

no need to heat treat the key at all. It's not a precision part and if it wears enough to cause problems just make another. If anything unhardened drill rod will be tougher and less prone to breaking than a hardened one.

I have to agree. I have a plain piece of CRS that I milled a square on that I use in my 4 jaw. Granted it doesn’t see hard daily use but I have been using it for years now.

[BCRider]

If you don't trust yourself for the heat treating then I'd say go with the T handle mill down using a good stout hex key to start. I'd say at least 3/8 to start so you don't have any twisting flex when using it as a chuck key.

Well, that is an idea. I'm confused by the pic, is that a 30 deg end mill?

It's just a regular end mill. He's holding the hex shape on two vertical sides. So a point up and point down. And then side milling the flats down parallel to the one jaw. This is how I turn round into hex too. I only turn on the top if I want a sharp transition. In your case you'd want the lower stress shape of the side mill with radius at the transition.

You can nail the size by knowing the target dimension (for tool hexes I like -.005 from the size of the socket at that size range. Tighter if smaller and up to .007" at around 1" and bigger to fit up around 1") How you do it is measure the existing hex or round. Make a skim cut to get a reading and do some math to see how much more you need to remove half of the two sided total material. Do the second cut to size needed. Flip to the next hex and do the same cut. Repeat until done. The hex will be your final target size to within a thou every time thanks to the measurements and bit of math. Easier than using an edge finder in fact since there's no need to change the tool. Just back it away to permit reaching in with a mic or calipers then back into the cutting area.

Another option is to make up a proper design of chuck key to a proper chuck key size from mild steel. But instead of a hex on the end you make a hole for a length of 5/16 or 3/8 allen key to push into the end needing the hex. You want the hole to be a pretty heavy press fit against the 6 ridges. Like .02 to .025 smaller. This would be my own preference since it would give me control over the length of the chuck key and the length of the arms. Looking around there are in fact 9/32 hex keys available. But they are not common at all. So buying a carbide end mill if you don't have one and using it to shave down a length of 5/16 or 3/8 allen key and then press fit it into a mild steel body is certainly an option.

As an example I've done this cut down hex key trick a few times. The one I can post easily are the two tool post "T" wrenches I've made. The bigger of the two in 3/16 hex for my shop made lathe tool posts for about two decades now. And the little 4mm one for the new Aloris style post is only just over a year old but doing just as well. The thumb turn section is for rapidly spinning the tool post screws in or out. You wouldn't need that of course. Plus the hex sections are a lot longer on these to ensure easy clearance in all cases. You would only need a short stub sticking out the end of your chuck key.

[BCRider]

no need to heat treat the key at all. It's not a precision part and if it wears enough to cause problems just make another. If anything unhardened drill rod will be tougher and less prone to breaking than a hardened one.

It certainly wouldn't break. But 9/32 is not far off 1/4" and this IS for a lathe chuck key. That size of mild steel or annealed drill rod would easily twist out of shape in that sort of use given the typical length of the "T" handle on even a small chuck key. So I think at least a pre-hardened alloy that is still machineable would be needed. And frankly the cheap allen "L" shaped keys are just such a handy source of heat treated stock which has good known durability that I think in this case it's the better option just due to the small size.