reviving shaft gripper topic

[boslab]

I had a really old book by Percival marshals who had a line drawing of what you describe and called it a bell Chuck, it was a bell shape, small end to headstock wide end to bed, three screws threaded into the bell, screw version of a three jaw independent, it said a 4 or more screw version could be made from an iron pipe fitting.
mark

[darryl]

Yeah, I have a camera- had it for years now. Problem is it won't stay in focus. It will auto-focus, then for seemingly no reason it goes way out. I find that to make it work ok I have to back way off, like 3 ft or more, then zoom in to get a close-up. Even at distance, it will home into focus, then off it goes. Could be operator error, but my other camera doesn't do this, it just works. Problem with it is it eats batteries very quickly. Now I have an Iphone, but I'm not very far along on the learning curve. Once I get the hang of transferring pictures to my computer I should be ok.

[garyhlucas]

I made pulley mounts with ER collets and a compression ring with 3 screws. Taper bore in the pulley.

[Mcgyver]

Darryl got a camera! Nice, looking forward to getting to see more of your creative projects.

[darryl]

This shows it all. The brass bar in front has been pre-drilled for the set screws. It gets cut into 5 pieces, which are machined to make the pins. A finished pin sits on a collar just above it. Might be hard to tell, but the pins are smaller in diameter than the holes they sit in. I shimmed the pins with 4 layers of paper towards the set screw, then snugged them up before boring to fit the shaft. Each pin can then move inwards by around 12 thou once the paper is out. Call that the wear allowance I suppose.

The two collars on the left are finished, the ones on the right haven't been fitted with pins and bored yet. I mentioned earlier that this was a mostly drilling project- and after careful layout and punch marking it pretty much was. Tapping was a bit tedious, but having the pin holes in first gave the tap somewhere to break into, so that was easy enough.

These things are made thicker than necessary, but that keeps the screws that go through those holes in the faces going straight. That should help keep the wooden sanding drum from weakening where the screws go in. I will need to make sure the ends of the drums are square.

I'm also going to shorten the screws, make them all the same length, and grind a profile on the ends to suit the divots in the pins.

[darryl]

I want to say 'now I've seen it all'- but I'm sure I haven't. So many ways to do the job- I settled on a way, and now I have two out of four clamping rings made. Pictures a bit later-

[BCRider]

Video from the Ringfeder site showing the principle of how it clamps.

RINGFEDER® Locking Assemblies – How to Use Them? - YouTube

Darryl, in your case it would need a fairly stout outer bushing in the wood pulleys you mentioned. But there's no doubt that the principle of two split tapered rings like this would give a very solid locking action.

[Illinoyance]

Check out Ringferder.

https://www.ringfeder.com/products/locking-assemblies/

[darryl]

I don't mind lace-

[BCRider]

Well. Perhaps I should just give up this hobby and get into something like that instead. Could get expensive though-

It's not for just the leather. It's that other part that goes with the leather

[darryl]

That was my last best option. I liked BCRiders idea of a compression ring pinching down on hub fingers, but the hubs on my existing flanges just aren't wide enough to make it work.

[darryl]

Well. Perhaps I should just give up this hobby and get into something like that instead. Could get expensive though-

[Doozer]

...McMaster Carr has these.



--D

[Doozer]

I just searched google for Locking Collar and this came up.




-D

[darryl]

I have not yet resolved the method I'm going to use to make a flange grip onto a shaft without marking the shaft. My first idea was to use 3 keys with set screws behind them. Someone said use a nylon nub in front of the set screw so there's no marking. Now I'm thinking of using that same basic method, but in a different way. The idea now is to drill three equally spaced holes such that they overlap into the subsequent bore that fits the shaft. The 'keys' in this case would be short round sections of brass rod that would be a slightly loose fit into the holes. Each piece has a slot cut into one side, which is where the set screw would nest into it. This means that even when loose, the parts can't go anywhere and get lost.

Because these short brass sections are slightly loose in their holes, I can use some paper to wedge them towards the outside of those three holes. With the set screws snug I can machine the bore, which means I'll be taking material off the brass pieces, leaving them with the exact curvature of the shaft. With the paper removed, each piece is now free to move inwards by a few thou, which means it can grip.

A couple things I like about this method- it gives grip every 120 degrees, which could mean that the flange is kept fairly well centered- it's also much easier to make as it's mostly drilling- and the parts don't fall out when loosened. Another thing I like is that the brass rides the shaft for the most part, not the aluminum bore in the flanges.

For the flanges I'm making, the thing that does the work is the screws I'll use to attach each flange to the sanding drum. I really don't have to make a flange out of it at all- I can just leave the aluminum discs their full thickness. All that means is I use longer screws to attach them to the drum. That helps anyway, as those screws will have less tendency to tilt and rip out of the wood. The set screws can be centered in the thickness of the disc, which probably means the disc will run more true.

I'm really kind of liking this idea- which could mean there's a flaw in it which I haven't considered yet. Ok, flame away-