# Twin 4J chuck keys



## PeterT (Feb 25, 2018)

I made a pair of identical chuck keys specifically for setting up my 4-jaw chuck. Not my idea, I saw it somewhere. But it works quite well because you can adjust the opposing jaws simultaneously in unison while watching the dial & just converge on the target with both jaws tight. Its easier to do than explain but saved me set dial-in time because normally I am slow as a tortoise.

I found a piece of mystery metal that was 0.750" & shiny - always a dangerous sign  It wasn't magnetic so I knew it was stainless. But this was some weird, tough sh*t for some reason. Long, hot, curly, razor sharp swarf came off at the lathe. Turning, drilling, milling & tapping the stuff was just brutal compared to mild steel & fighting me every step. It seemed much tougher than any stainless I've tried before. Hey is titanium non-magnetic? DOH! Oh well, used up the scrap & it wont rust. Initially I was going to make a knob but didn't like how it looked so went the tommy bar route.

Notice my goof up, the tommy bar is not aligned to the square facets. Oops. Then I looked at my other commercial chuck keys - neither are they! Haha. So its a design enhancement, not a screw up.


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## Alexander (Feb 25, 2018)

Titanium is super light. You know you are holding something special when it is in your hand.


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## John Conroy (Feb 25, 2018)

Nice work Peter, is that a Bison chuck?


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## PeterT (Feb 25, 2018)

John, yes Bison 8". Bought in '99 or so for a whopping $400-ish at the timed. I should have bought a pallet & stored them like gold bars, now they are 3X that. If you're in the market for euro chuck tooling, I see KBC is now carrying TMX (Toolmex), they recently had 30% off intro sale. I've never figured out the Toolmex/Bison relationship but supposedly is same specs, also Poland? but different marketing... anyways less $ than Bison brand.

Alex - just kidding, its stainless for sure, but I don't recall ever knowing the alloy or even where I got it. I think I had a similar experience with it before which is probably why its been at the bottom of the box with 'X' on it.  The valves on my radial are also SS so I was apprehensive about using it. But the few testers I made from 416 turned out quite nice, even 303 easier to machine. 

If anyone else is considering SS (purely from machineability standpoint, not other properties) here is a table I found somewhere. 
% is relative to 1112 carbon steel at 100% refeence.

416 annealed - _110%_
303 annealed - _78%_
410 annealed - _54%_
430 annealed - _54%_
302 annealed - _45% _
304 annealed - _45% _
316 annealed - _45%_
420 annealed - _45%_
431 annealed - _45%_
440A - _45%_
321 annealed - _36% _
347 annealed - _36% _


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## Everett (Feb 25, 2018)

Nice!


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## John Conroy (Feb 26, 2018)

I talked to the KBC guy about the TMX chucks and the price is pretty much the same as Bison. I don't want to spend that much money but I'm looking at buying a new 8" 3 jaw. It's gonna have to be Asian I'm afraid. I ordered an Atlas (PBA's economy line) chuck they have on sale, I'll let you know what it's like when it arrives.  My research tells me that even premium brand chucks like Buck and PBA are now made in Taiwan or mainland China. The 6" 3 jaw that came with my lathe holds under .002" runout so it will have to be good to beat that.


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## PeterT (Feb 26, 2018)

Dang. Maybe the Toolmex thing is more about distributorship then & its basically Bison through different middlemen? They are just plain spendy.

FWIW, I bought a smaller 5" Gator chucks for my rotary table setup. The legend goes they adopted all the Bison dimensions but produced in Asia, but to 'their standards'. I've heard both good & so-so opinions. I guess initially they were great, then they had teething pains when they scaled up & went fully cnc, now they are ok again. I didn't have high expectations & for this application it didn't really matter. But I'm satisfied with the ones I have for what they cost. I also got a D1-4 partial machined back plate included because it was inexpensive. Once turned in-situ & chuck mounted, the jaws are decently accurate 1-2 thou & repeatable. 

If I had to do a bigger chuck all over again I'd consider a Gator, but maybe go with their ?name? adaptation of Bison Set-Tru system. That way you can dial it in even further. The direct mounts are more compact than Set-Tru but you get what you get in terms of runout. 

I heard good things about the Atlas economy line too, but I couldn't see many CDN vendors. Travers was spendy I recall. Did you get it here or in USA?


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## John Conroy (Feb 26, 2018)

KBC has the flat back ones on sale right now. I ordered a no name D1-4 back plate on Amazon and will machine it already mounted on the spindle to get rid of any run out. That's why I stayed away from the direct mount ones, as you say, you get what you get for run out with those. The flat back chuck and the back plate were a couple hundred less than a direct mount model.


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## Tom Kitta (Feb 27, 2018)

I need to make like 4 chuck keys - almost all my keys are to short and I have hard time moving them when they hit back side of the lathe with handles. 

Stainless is hard to work with - just as 4340. 

Toolmex is supposedly distributor for Bison. Bison is expensive even in Poland - so no chance of getting it at the source for less.


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## Janger (Mar 17, 2018)

Those handles are a great idea Peter! More tools for the tools. My family keeps asking me when I am going to make something


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## Dabbler (Mar 18, 2018)

I have the same problem - I keep building the shop! Actually I do a lot of small repairs also, but I never get around to the big projects like PeterT (for example)...


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## PeterT (Apr 28, 2019)

Another set, this time for my little 5" Gator 4 jaw chuck. The mystery stainless I used on my other set was a bugger to machine but I wanted to use it up on something relatively simple. I didn't have the right diameter so this time I used some O1 drill rod for no particular reason. Its tough stuff too & was handy. I might heat treat the ends just for kicks but it probably isn't necessary. Some chuck key leanings to pass on if you decide to make yourself a set.

- I couldn't really figure out why the progressive necked down diameters on the stock key. I thought maybe it fit another scroll chucks where that was required but oddly I also have a 5" Gator 3J and it uses a different key. Maybe its a generic key design & they just scaled it? If you can think of a reason let me know. Anyways I kept mine simpler with just a short reduced round section which forms the boss of the 4 milled key facets. Notice the underside of the jaws has a curved recess so the 0.5" stock easily fits in there.

- I wanted these to be stubby so I could get on either side of the chuck. That's the whole idea is being able to turn them in opposition to dial in a setting simultaneously without going back & forth on either side with a single key. But on a RT its also possible to bump into other things so I stayed with my short Tommy bar handle retained by a set screw. So you can cinch them down pretty good or remove the tommy bar or locate off to one side, whatever the situation calls for.

- I made my first one copying the square dimension of the original key. I was only a couple thou off but it wasn't the best fit. I rechecked the original, also not a great fit. Guess I never noticed till now. Then I got the bright idea to actually measure the chuck female square. I tweaked the dimension & increased the size, they engage much better now.

- O1 machines decent enough but I noticed in tapping, especially fine threads, the typical recommended pilot drill size (what is the number again 77% thread engagement?) can be a bit tight. So sharp taps, lots of oil, yada-yada. Since in this case its just to hold a non critical set screw, it would have been smarter to go up one numbered drill size. You lose very little in terms of thread engagement but tapping is usually less drama. I have to remind myself of this all too often. I think I'm going to make a little chart for common tap sizes. If it loos useful I'll post it.


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## YYCHM (Apr 28, 2019)

Please make that chart.  I always end up drilling and then drilling 1/32 larger every time. Gets kind of annoying.

Nice keys BTB.  Need to make a stubby set myself.  Mini Lathes and 4JS are a PITA space wise.


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