Off Topic Hobbies > Mechanical Engineering

threaded collet to put in the middle of something to attach a rod to?

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coppercone2:
I want a collet that you can extend a rod through. I took something apart and it had something like this, so you thread the collet into a part, then you put your shaft through, then put a nut on top to tighten it to the shaft.

I see ones that screw in, but I wanted a through hole one. Like a cable gland thats precise and made of metal. So it has two threads on it, one to tighten and one to fix into something (say with retaining compound). It can be really compact. I imagine maybe someone sells a series of them, I need something in 3/8, but I am swamped by results about lathe collets and stuff like that, this is for a structural reason. I don't want set screws. I suppose it can be non threaded too (press fit), but I would prefer threaded. Is this a name for a part series like this? It is to make something spin on a motor slowly

penfold:
I was looking for something similar recently, I didn't find anything off-the-shelf, but along the route I had some ideas...

If you have a bit of fabrication-ability, it's possible to use tapered pipe thread style fittings (slitted into 4, collet style, so that they can close up when tightened), and then there's a load of couplings and reducers which can provide the internal and external thread for securing to something else. Inspired by some potentiometer knobs.

There are some taper-lock bushings that are available in relatively small sizes, or that can be used with reducers and collars to get the fit better.

I think there might also be some mileage in Dremel style collets (opposed to the ER series) since they fit into a parallel bore and seat against a shoulder, so in all, there's nothing too fussy to machine, just need to have descent co-axiality, so lathe would be a must. Even the nut could be something like a dome nut drilled through, the internal taper would probably work out similar to the included angle of a drill bit or center drill.

beanflying:
Why no set screws? That is just 'standard' on couplings, couplers and bushes of all sorts. If it is for cosmetic reasons then I can understand but otherwise - why?

One option will be to take a cable gland remove the rubber and make a split delrin plastic collet for it. Downside is they are light duty and generally will be brass.

Your other alternate is to go to a Hydraulic company and buy rigid pipe fittings unlike the water and most cable glands you will get Steel or Stainless bodies in most cases. The olives (the bush) are crushed slightly into the pipe for form the seal. To help support the shaft better you might want to look at two so a male outside your (plate or surface?) and a female screwed into it to give two bushes separated by 20-30mm.

I used to work for another division of these guys way back in the dim dark past https://www.stauff.com.au/index.php?id=5690

bill_c:
Maybe a few more ideas here, but not cheap https://www.mcmaster.com/collet-fixtures/

coppercone2:
well it holds better and its nicer, I have one I took out of some custom equipment but it was mega seized so I actually just cut it in half to free the shaft You can make it about 0.4 inches tall and 0.4 inches wide for a 3/8 shaft no problem, just I wonder if anyone sells this stuff, they made it real thin, unfortunately its soviet MIC equipment

I don't need the size they had anyway, but I was hoping that it was some standard part you can buy in different sizes, because its cool. set screw is barbaric in comparison

It's basically not much bigger then the hole used to fit the shaft and its held on buy like a 3/16 nut, quite a bit more beefy then a panel switch nut but not a full sized nut by any means, more like a set nut.

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