threaded collet to put in the middle of something to attach a rod to? - Page 1
Forum section: electronics / general

author: coppercone2
author_rank: Super Contributor
timestamp: May 22, 2021, 03:50:19 am
content: 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

author: penfold
author_rank: Frequent Contributor
timestamp: May 22, 2021, 11:33:51 am
content: 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.

author: beanflying
author_rank: Super Contributor
timestamp: May 22, 2021, 12:41:43 pm
content: 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 pasthttps://www.stauff.com.au/index.php?id=5690

author: bill_c
author_rank: Regular Contributor
timestamp: May 22, 2021, 08:10:03 pm
content: Maybe a few more ideas here, but not cheaphttps://www.mcmaster.com/collet-fixtures/

author: coppercone2
author_rank: Super Contributor
timestamp: May 22, 2021, 08:11:56 pm
content: 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 equipmentI 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 comparisonIt'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.

author: beanflying
author_rank: Super Contributor
timestamp: May 23, 2021, 01:33:13 am
content: QuoteNope what it is is simple and practical and it works. In particular when it is a setscrew on a keyway I have machined and had couplings/pullies machined to handle over 100kW at 2900RPM.Only other option might be to take something from the R/C aircraft range and drill out the shaft bore. We run these at 20k RPM+ without an issue but the diameters won't get to 3/8"8mm (5/16") here

author: SparkyFX
author_rank: Frequent Contributor
timestamp: May 23, 2021, 08:33:54 am
content: Quote from: coppercone2 on May 22, 2021, 03:50:19 amThe ER collet system would fulfill these needs and is available in various ranges and various collet holders. 3/8" stock size is covered by ER 16 and up.There is also the 5C collet system and plenty others, but each have their own holders and might require the stock/shaft to be precise to begin with.Should you not need the concentricity have you considered a chuck? Either a drill chuck or a very small lathe chuck? Much of what you ask depends on how it should be attached to the motor, can you provide more details on that?

author: coppercone2
author_rank: Super Contributor
timestamp: May 23, 2021, 09:00:49 am
content: I am not sure, I wanted to have it in mind when thinking about building something. The one I have seen in something is built kinda thin, its not a heavy duty chuck, think collet in a dremel (not a proxxon), but made of something magnetic.I am just wondering if you are doing something with shafts is it a part that you can get some where without alot of custom machining. The ER collet system seems huge, it has a big nut that fits over it, and compresses the top, this just had a maybe 3/16 thick with 3/8 thread nut that goes on top to compress it a little, standard thin nut, not anything special for compressing a collet. Its very compact, low profile, etc. I was not even sure if there was a collet there until I inspected it closely, I was looking for a set screw when I was trying to take it apart. It's very elegant.It would be useful for gears, so you put a gear on the shaft, tighten a nut over it and you are done. I am not talking a machine tool here, more like a weak clockwerk positioning mechanism. everyone here is suggesting stuff for like metal working, and it should be fairly precise (even if its weak). So then I could put it on something like an acrylic shaft if i wanted to.I.e. take any gear you want, drill the correct size hole in it, then attach it to any shaft you want made out of any material without a set screw or glueI guess it must be a custom part since no one here has any idea. thought it would make a good parts series****In short: really flat bored through collet without a special nut that can be press fit or threaded into whatever you want to attach to a shaft. some might say its over complicated but that can be said about anything greater complexity then the flathead screw.. who ever thought torx can take off?

author: Andy Watson
author_rank: Super Contributor
timestamp: May 23, 2021, 10:17:22 am
content: Potentiometer shaft locking collets perhaps?https://www.secsinc.com/pdf/SHAFT.pdf

author: PlainName
author_rank: Super Contributor
timestamp: May 23, 2021, 01:56:39 pm
content: How about something like Speedfit (there are several other brands and styles, but these are the ones typically stocked everywhere).https://www.johnguest.com/speedfit/They are for plumbing and typically join plastic pipes, but also fit copper. Standard plumbing sizes, and 15mm is about 5/8". I was initially thinking you could replicate their mechanism since it doesn't look too tricky under the bonnet, and you don't need a water-tight join. But maybe something like the photo attached would do without any dicking about.

author: coppercone2
author_rank: Super Contributor
timestamp: May 23, 2021, 07:13:01 pm
content: the potentiometer locking collet maybe, the speedfit is way too big from the looks of it, it is supposed to still look like a gear when you are doneBut if it was made of steel it would be better, somewhat stronger.

author: bill_c
author_rank: Regular Contributor
timestamp: May 23, 2021, 11:42:01 pm
content: Does it look something more like this then?https://www.mcmaster.com/bushings/bushings-for-chain-and-belt-drives/quick-grip-screw-clamp-bushings/

author: Gregg
author_rank: Super Contributor
timestamp: May 23, 2021, 11:45:23 pm
content: search for 5C collets and holders; the collets themselves are threaded on the outside and allow through holding

author: coppercone2
author_rank: Super Contributor
timestamp: May 23, 2021, 11:55:34 pm
content: yeah, that looks like it would work. I need to look at it more closely but damn, that price is high. I thought this part might be $10-15, not $60, I mean the bushing, I have one of those 5c collets but they are giganticI think that collet is still a bit tall though, 19mm for a 3mm shaft, the equivalent of the one I saw would be like 4-5mm for a 10mm shaft.

author: artag
author_rank: Super Contributor
timestamp: May 24, 2021, 01:30:40 am
content: You can buy a simple drill collet like thishttps://www.ebay.co.uk/itm/393315638013then just cut an M4 thread (or whatever your local units are - 3/16" ?) on the part that has the setscrew

author: coppercone2
author_rank: Super Contributor
timestamp: May 24, 2021, 01:39:15 am
content: they are all still tooo tall, let me dig through the trash the find the remains of the one I have to give you a spec, but its cut in half and mangled

author: bill_c
author_rank: Regular Contributor
timestamp: May 25, 2021, 11:34:07 pm
content: Yeah, if you NEED it, McMaster has it. I haven't seen them beat anyone's price in 50 years.This also looks similar and may not be much cheaperhttps://www.fennerdrives.com/micro/But maybe an image search will list some competing devices.

author: BrokenYugo
author_rank: Super Contributor
timestamp: May 26, 2021, 01:12:56 am
content: Brass compression fitting from the plumbing aisle?

author: JohnMc
author_rank: Contributor
timestamp: May 30, 2021, 01:02:30 am
content: A SS Swagelok would probably work fine. A friend had a spotting scope stand made out of stainless tube and rod with a SS Swagelok fitting for height adjustment. Light finger tight it had no problem holding a old heavy Bushnell Spacemaster.

author: coppercone2
author_rank: Super Contributor
timestamp: May 30, 2021, 01:07:22 am
content: I thought about it, their all bulky, the part I have is steel and measures0.9cm tall(when fully tightened, so the nut fits flush with the collet at 1cm), 1.1cm wide, the nut on top is 1.6cm (so its wider then the collet), it goes into a smooth bore btw, and it works greatfits on 1/4 inch shaftso when I put it on 2 stacked gears, it protudes 2mm from the top and 2mm from the bottom through 5mm of gearsso it just looks like a gear with a small thin nut on top when its seated, and the bottom of the gear has a bit of a lip, it does not thread into the shaft, you just drop it in the gear, put it on a shaft, tighten the screw and its mated.I have one of the collet shaft potentiometers (just came in on ebay in old equipment), its actually taller then this thing I am describing, and also made of brass, for a much more thin shaft (1/8)swagelok would be like a wart lol, and that works on deforming tube, I don't know how well it holds on to a solid shaft, certainly without its specificationAlso I was wrong to call this one a collet, its not really a collet, its just a split tube, the other one I destroyed (which I still need to find on the bottom of a trash can some where) was split in 3 regions, the one I found on the gear just has 1 slit down the side, but it works OK for the big brass gear, its for alignment of radio parts

author: JohnMc
author_rank: Contributor
timestamp: May 30, 2021, 10:21:19 pm
content: Sounds like some make of Trantorque bushing. Have a look at the links Bill C posted.