shaft gripper

[darryl]

Looking for something that is quickly adjustable to grip a shaft and turn a drum or whatever. What I have is the need to move something along a shaft and grip the shaft wherever it suits. Sort of a backwards chuck in essence. The shaft diameter is fixed at 3/4 inch. I can use a cross pin, but that means that I need a hole through the shaft- or many holes so I can choose a position. I don't want to cross drill the shaft, thus I'm asking for a grip of some kind instead.

If you imagine a sleeve with three keyway slots in it, with set screws behind them- that would work. I can always bore through with the keys in place to round out the keys so they have an area contact with the shaft. The idea is no marking of the shaft, therefore no hang-ups with anything that needs a close sliding fit to the shaft. The first mark from a set screw would already screw this up, and I got bit with this yesterday. Had to force a collar off the shaft, which made some damage, etc. I think we've all probably been there at one time or another.

To use an actual chuck for this would be overkill. Perhaps there's an idea with a one-way clutch that I could make to do this job. The direction of rotation won't change, so for me to move the drum I could just rotate it against the shaft in the one-way direction, then it would tighten as required in the 'drive' direction. This could be two jaws, or three- three preferred I think, in the aim of keeping the mechanism in balance. Just looking for ideas.

[Richard P Wilson]

A grub screw with a tiny brass or copper plug under the end will grip and won't mark the shaft. Simples.

[SVS]

Could do a threaded shaft and double nut idea.

[Guido]

Spraig clutch bearings, checkout Amazon.

[tom_d]

Perhaps there's an idea with a one-way clutch that I could make to do this job.

For a one way clutch, picture a collar on a shaft where only the collar is broached for a keyway. Rather than a key, insert a round dowel pin. Rotate the collar or shaft and the pin rotates similar to a needle in a needle bearing. If the slot holding that pin is widened, but only on one side of the slot, then, depending on direction of rotation, the pin will continue to free spin against the side of the slot or it will roll into the widened side and get wedged between the shaft and the outer portion of the keyway, such that the collar rotates with the shaft.

A grub screw with a tiny brass or copper plug under the end will grip and won't mark the shaft. Simples.

Yes. Delrin tipped set screws are readily available.

[mikey553]

How about a cheap ER32 collet block? Like one of these.

[metalmagpie]

Spline the shaft.

[J Tiers]

Just have a setup that looks like a huge pin chuck. 3 tapered "petals" that are just a turned and split cone, with threads behind it., and a relief to allow them to close somewhat. Matching coned nut. To grip, turn nut to tighten the "petals" down, to loosen, turn the other way.

Could be made for hand or wrench operation.

If you key it (one key) you could use that for power transmission, and the "pin chuck" mechanism would just lock it against sliding.

[darryl]

I'm not touching the shaft- no splines, no cross holes, etc. I'm liking the ER32 collet idea- that could be my best option.

[metalfixer]

Might take a look at quick clamping shaft collars.

[reggie_obe]

Electricians rubber cord grip?
McMaster just one of many sources: https://www.mcmaster.com/Cord-Grips/...-cord-grips-8/

[Tobias-B]

I was thinking shaft collars or similar, too. They grip pretty tightly with no distortion.

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[darryl]

I can make a shaft collar with a larger diameter, then turn down a portion to leave it look like a flange. Holes through the flange let me attach it to the drum. Then I drill and tap for two clamping screws and then saw away half of the collar part. That leave a loose half-collar that can be tightened down on the shaft. That would work for me-

[Tundra Twin Track]

Maybe a smaller version of this could work.

[darryl]

If I make these from steel, I will definitely want to check the balance- it will be spinning at 3450, so even a small imbalance will be felt. I don't have any problem making these from aluminum- after all I'm screwing them to wood. I don't want them slipping, but I don't think they'll have to be all that tight. If I make a pair, they will share the load as well. One for each end of the drum.

I can see where I made this mistake- I should have bypassed the idea of the simple flanges with a pin and done it right in the first place. Oh well, this will be better solution, and if I can use these socket head, countersink bolts for the tightening, I'll be sticking with one size of allen wrench for when I'm mucking about changing drums, or repositioning them, or doing anything with the motor shaft coupling. I see I have a couple of drill bits ground to the 82 degrees or whatever it is for these heads to sink. Normally I'd use a socket head cap bolt, but I think I'll be alright with these. This results in a larger bolt but with the smaller socket size. I think I'll be happy with that.