Making Protective Bellows

I have been trying to find a supply of very small plastic/rubber bellows to protect linear bearings on an 8mm shaft. The movement only needs to be about 25mm, but I have been unable to source such an item.

While browsing the internet I came across a supplier of liquid latex which can be used for dip moulding and was thinking of trying to make my bellows by dipping a shaped former in this stuff. Has anybody used this technique for making things and if so was it worthwhile?

Doug

Doug,

Sorry I can't offer any eperience at his stage; but I would be very interested to know how you get on.

Meanwhile; these guys seem to know how.

MichaelG.

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Edit: Just found this supplier ... looks useful.

Edited By Michael Gilligan on 31/10/2013 20:39:49

Arc Euro?

You need the bellows off a clutch or brake master cylinder.

Similar to this ?

**LINK**

Or this ?

**LINK**

We had a chap on the Stirling Engine Forum the other week who had made a corrigated rubber tube using a form made of a rod for the minimum diameter, and washers spaced along the rod for the maximum diameter. He just used the liquid rubber on its own, some else suggested maybe some sort of fabric interlayed between layers of rubber, looked a bit crude, but serviceable. Ian S C

Edited By Ian S C on 01/11/2013 11:39:34

There seems to be a wide variation in our understanding of the size of bellows you require! If I understand correctly, some car handbrake cables have rubber/neoprene bellows of a size which might suit your need. Maybe a trip to the nearest car breakers is on the cards.

John

Thanks for the suggestions, I will follow them up to see if I can get anything of the required size (needs to fit over an 8mm rod ). I think the brake or clutch cable boots may be too small, but a visit to the nearest car scrappy might be fruitful.

I have also sent for a bottle of the liquid latex to see if that idea might work and I will report back after doing some experiments.

Doug

I have been messing about with the liquid latex and the results are mixed. It does work but there are a number of problems to be overcome. Making a decent former that the latex will build up on is the first one, the latex is quite thin and each dip results in a very thin layer on the former and then a wait of an hour or so before dipping again.

Once the sequence is complete it can be quite tricky to remove the cured latex from the former. The removed rubber is quite tacky and needs to be dusted with talcum powder before use otherwise it will stick to itself. I have only done some simple experiments so far (coating the bottom of a test tube ) but will make a former for my bellows and do some more trials later. The weather has been rather cold for working in my workshop of late so this could take some time.

Doug

The chap on the Stirling Engine Forum use a mandrel for the minimum dia. wrapped in paper (I think, maybe something else), over this was slid washers to the maximum dia. and at the pitch required, it might take some experimenting to find a compound that is not sticky. Someone on that site suggested incorporating some sort of flexible mesh in the rubber compound. Ian S C

People do make their own latex pen sacs that way, sometimes dipping 15-20 times & allowing to dry off between. It does work, but is usually a very slow process. Do note that latex is not very resistant to most chemicals...

Regards,

Richard.

I'm tending to look more toward Silicon/ Silastic, it can be obtained in an uncured form, and vulcanised in a similar way as rubber. It can also come as RTV, or as a two part liquid, ie., Mold Max 30, a10:1 silicon rubber for making moulds. Ian S C

Might be worth looking up Auto Factors (car spares) In your local area, some of them enjoy a challenge, and as others have already mentioned some car part bellows sound similar.

Edited By V8Eng on 08/11/2013 11:36:47

Jason:

I easily found sugru, but not Home Brewed "ougoo". Is this the proper spelling ?

BTW, I am looking for a pourable polymer / rubber-like material that will cure in a mould (without excessive exposure to air) and can have it's hardness modified (goal = 25 Shore A).

Paul

Paul,

This looks promising.

MichaelG.

Thanks for the suggestions.

Instructables.com (with 500 postingst) on the subject of sugru and "oogoo" made from cheap 100% silcone purchased in tubes from a home repair materials store.

VERY interesting experiments and samples are discussed and pictured.

A bellows tube or sheet could be made from fiberclass cloth or screen and coated with oogoo.

When we construct engineering models, there are needs for rubber-like material that could be cast or formed for gaskets, plugs etc.

Instuctables.com has examples of oogoo used to make a mold and then oogoo rubber can be cast in the mold. This would be good for making multiple parts. One poster used oogoo to make a mold and low-temperature metal cast in the oogoo mold.

Paul