Mounting a free spinning U-bracket

Hi all

I'm hoping to mount a metal U-bracket on a 5mm steel rod so that the bracket can freely rotate on that rod.

The rod should protrude about a few millimetres into the bracket. Does anyone know of a good way to mount the bracket on the rod so that it won't slide along along the rod? Would some kind of a stopper be needed?

Any help appreciated.

Thanks

John

Hi John,

How about a collar with a set screw?

Ed.

Hi Ed,

Do you mean a collar on each end or just on the back? Will a set screw apply enough pressure since the surface of the rod is round?

Thanks

John

Without knowing the purpose/loading of your application its hard to be specific. The simplest method would be two circlips in grooves close to the end of your rod.

Ian P

As Ian says the design of the retainer will depend on how much load the bracket will see in use, and from what direction.

If collars are used one could be silver soldered on, the other setscrewed or split and cross drilled / tapped to make a clamping collar. If setscrewed a flat could be cut on the rod to a) assist holding/prevent slipping b) prevent a divot being raised on shaft that could make disassy a problem.

Cross drilling 0.5 mm in two places and use of two washers and small cotter pins a set each side of bracket may suffice if loads are very light.

About 50 ways and combinations of ways to do it. Tell us more. JD

.

Subject to Ian's caveats

These may be even simpler

MichaelG.

Hi Ian,

Actually, my original plan was to use two e clips. Do circlips and e clips serve different applications? The bracket is rotated and the torque is around 0.3N-cm.

My current idea is something like this

(bracket end) E clip, washer, teflon washer | teflon bushing | teflon washer, washer, E clip (rod end)

where | xxxx | denotes the bore in the bracket.

I wonder if a washer is needed between E clip and teflon washer? The clip is held fixed by the groove, so it wouldn't exert much pressure on the teflon washer, right?

Edited By John Munroe on 16/03/2016 14:47:52

Hi Michael,

Do you know how these fasteners are different to circlips/e clips?

Thanks

John

Hi Jeff,

The bracket is turned with a torque of roughly 0.3N-cm. The speed is around 20RPM. With the cotter pin idea, should the washers be standard ones or teflon ones? Also, wouldn't a bushing be needed to avoid the bracket from wearing out?

Thanks

John

.

Yes

.

.

They don't use a groove ... They push on, and lock by friction

MichaelG.

Michael's will be easiest as no groove is needed provided you can get to the other end of the rod to slide the inner one on.

If not stick with your idea of E-clips, large flat washers and then teflon washers if you make one washer a "top hat" one with a spigot then that will bush the hole in the bracket too.

Edited By JasonB on 16/03/2016 15:08:38

I used the term circlip in a generic sense.

Since you know the operating speed, loading and presumably other details, what you end up using is going to depend on what materials are involved, what engineering facilities you have and also how much you want to spend!

Mainly though its the end use or purpose that will determine what is the best approach.

How much play/looseness can you tolerate in the joint, does it matter if it a rattling fit, there might even be a rattle (noise) that detracts from the final product's acceptability, Slightly preloading the already mentioned PTFE washers would prevent noise.

Ian P

Hi Jason,

Right. How come flat washers are needed to sit in between of e clips and teflon washers? Can the e clips not push against the teflon washers directly? The grooves should stop the e clips from moving - right?

Well you obviously thought they were needed as you thought of it first!

My current idea is something like this

(bracket end) E clip, washer, teflon washer | teflon bushing | teflon washer, washer, E clip (rod end)

My thoughts are that E-clips are quite small dia so could start to cut into the teflon washer. What was your reason for suggesting washers?

Hi Jason,

Well, there really wasn't a clear rationale, but I thought it might be better for a piece of irregularly shaped metal to press on a metal washer rather than plastic (teflon). I haven't used teflon washers before, so I'm not sure how durable they are.

How many rotations does it have to do in its' life?

Can it be lubricated with grease?

Is there much dust present where this device will operate?

These questions will help answer whether using PTFE (teflon) washers is practical or useful or not.

You have had some excellent responses with many good ideas for construction. Now will you tell us what this is for?

JD

Changing fuel rods in a nuclear reactor.

EDF have decided they need to make a few savings on the design costs for Hinckley C.

Neil

So, what us this mechanism going to do? What is it? Or what is it part of? If it is going to be doing 20rpm for extended periods you probably need some kind of bearing or at least bronze bushing in place if you don't want it to wear and flop about all over the place.

I think it may be a homework question for a mechanical engineer ??