Is there a consensus of opinion re: Bison lathe chucks?

[cazclocker]

so probably trying to lose weight on a small lathe like that. I imagine the key is like the key on a drill chuck.

Yeah, that was my guess too. Without a solid body to enclose the back, it probably loses 20%-30% of what it would otherwise weigh. And yes, the key is exactly the same scheme as a Jacobs chuck key. That's what the large hole on the chuck's side in the last Bison pic is all about. The key fits through those holes with about 0.010" to spare! Tight fit...

 

[cazclocker]

+1 on Bison stuff.

So I guess the Bison line of stuff is regarded pretty highly. Thanks guys. Y'all are more experienced than I am, and I'm addicted to learning whatever I can. That's why I like coming here.

 

[Toolmaker51]

Here, purchases of new and far more often used, are based on suitability, condition, fitment, can it be opened and tuned up, just about everything before brand is a factor. It's about impossible answering the first qualities with inferiority. As such, there is aversion to things coming from certain a specific location. If, for no other reason than spending twice (or more) to undo discontent with an article.

Bison is not one of those; having their chucks, collets, endmill holders, fixtures mixed among domestic pieces with no qualms what-so-ever. I'm confident they ramped quality with demise of ENCO (the importer, not EMCO), near certain that is how they gained production footprint to start with. Also certain, other brands followed that game plan.
Versus the 'specific location', unlikely to occur.

 

[rwm]

If you are getting .005 runout on your Sherline chuck there is something wrong. They are well made and typically more accurate. Take it apart and clean it. Check the jaws for damage. Check the mounting arbor for runout. I have 2 Sherline chucks that have .001 runout at most scroll positions. I also have 3 Bison chucks that are excellent.

 

[pdentrem]

My 3J that came with the Atlas had 2 sets of jaws. Inner and outers. I believe that the PM lathe we have for some specialty work also came with 2 sets.
Pierre

 

[cazclocker]

If you are getting .005 runout on your Sherline chuck there is something wrong. They are well made and typically more accurate. Take it apart and clean it. Check the jaws for damage. Check the mounting arbor for runout. I have 2 Sherline chucks that have .001 runout at most scroll positions. I also have 3 Bison chucks that are excellent.

I suspect it's the mounting arbor that's the culprit. I've had the Sherline 3-jaw apart for cleaning several times, and it never makes any difference with respect to runout. I actually had 4 mounting adapters made for me, and one of them has less runout than the others - it's permanently mounted to my Sherline 4-jaw independent chuck. Of the remaining 3 adapters, they all create different amounts of runout and the best of those three is the one I keep mounted on my Sherline 3-jaw scroll chuck. I no longer have any hope of having a "perfect" Rivett-to-Sherline adapter made for me, so I'm stuck with what I've got.

 

[rwm]

I suspect it's the mounting arbor that's the culprit. I've had the Sherline 3-jaw apart for cleaning several times, and it never makes any difference with respect to runout. I actually had 4 mounting adapters made for me, and one of them has less runout than the others - it's permanently mounted to my Sherline 4-jaw independent chuck. Of the remaining 3 adapters, they all create different amounts of runout and the best of those three is the one I keep mounted on my Sherline 3-jaw scroll chuck. I no longer have any hope of having a "perfect" Rivett-to-Sherline adapter made for me, so I'm stuck with what I've got.

I agree that is sounds like the adapter. It should not be that hard to make a concentric adapter. I am not familiar with the Rivett but that arbor seems pretty small compared to that small chuck. Have you checked the runout of your spindle also?
I would mount the worst arbor on the 4 jaw. That way you can compensate and get the runout to 0. Use the best arbor on the 3 jaw. If you really have .005" runout I would have a new arbor made by someone else.
What is the largest collet the lathe can accept? You could have a simple adapter made to convert 3/4-16 to a straight shaft and hold that in a collet. That should have minimal runout and would avoid the complexity of machining the taper. For example. I made this 3/4-16 to 3/4 straight arbor for my Sherline chuck. It has great concentricity.

 

[cazclocker]

I agree that is sounds like the adapter. It should not be that hard to make a concentric adapter. I am not familiar with the Rivett but that arbor seems pretty small compared to that small chuck. Have you checked the runout of your spindle also?
I would mount the worst arbor on the 4 jaw. That way you can compensate and get the runout to 0. Use the best arbor on the 3 jaw. If you really have .005" runout I would have a new arbor made by someone else.
What is the largest collet the lathe can accept? You could have a simple adapter made to convert 3/4-16 to a straight shaft and hold that in a collet. That should have minimal runout and would avoid the complexity of machining the taper. For example. I made this 3/4-16 to 3/4 straight arbor for my Sherline chuck. It has great concentricity.

View attachment 438978

The runout in my spindle is close to zero except for 0.0008" (eight tenths) front-to-back.
Your idea of keeping the worst adapter in the 4-jaw is sound reasoning - as mentioned, I've kept the best one for my 3-jaw, but I haven't paid much attention to which one is in my 4-jaw.
I have a complete set of collets for my Rivett watchmaker's lathe, and the largest one (designated #1 in the series of 80 collets) is made for 0.227" stock. BUT....
I need to take some pictures of my Rivett-to-Sherline adapters and show a couple of them here. No use trying to describe them here, since I'll post photos of them here in a little bit. I'll warn you, though, one glance at them will make you run for the hills...nobody in their right mind would want to hand-turn them themselves. Nice work on your arbor! It looks beautiful.

 

[cazclocker]

Here's one of my two unused Rivett-to-Sherline adapters, next to an actual Rivett collet. The whole thing is turned on a Myford Super 7 from one chunk of steel. My friend in Oregon (who made these, and other projects for me) told me that it was actually easier to make two of them at once compared to just making one. He must have started with a piece of steel rod and began with turning the 3/4-16 in the middle, and then made the Rivett collet-clones on the ends. To compound matters, the physical dimensions of the Rivett collets are proprietary - my friend Tom got extremely proficient at duplicating collet blanks for the Rivett watchmaker's lathe, but that was because he and another fellow were (as far as I know) the leading experts in Edward Rivett and his mechanical genius. The lathe I use every day was manufactured around 1897 or 1898, according to serial number records, and it's still capable of incredible accuracy (too bad I'm such a dam* hack).

I'm also attaching another adapter that Tom made for me, specifically for my Sherline 4-jaw chuck. Two things to notice - the circular (rather than truncated) register plate with four allens holding it onto the chuck. Also, notice the mass that Tom hogged out of the chuck itself... it really saves some weight.

OK enough blabbing from me... onto the pics...

 

[rwm]

Those are small! I feel like .227" (collet size) is too small to be used as an arbor. It would flex too much, so scrap that idea. Your arbors appear very well made. What do you think the cause of the error is?