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.

.

Edit: Just found this supplier … looks useful.

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

Arc Euro?

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

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.

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

And push bikes use small bellows so might be worth a look

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

Hi Doug

I made some latex parts along the same lines, but with thinner wall section, for an inventor a couple years back, so sorry I can't post a photo.

I made the mandrel from aluminium and because I made around 25 identical parts for him, I built a motorised rig to dip slowly and repeatably. Dipping cycle was around 3 minutes. The long time is just to get a thin even coat as it flows off the mandrel on the way out of the latex. If you only need one off, you don't need to be quite as careful.

I made another rig to dry each layer by rotating axially, keeping it horizontal not vertical so that the liquid was spread evenly as it dried. I forced the curing with an IR heater and from memory it was still an hour between dips to cure in all the ridges, which is when the latex goes clear.

The lathe with slow speed would work just as well for the drying.

It was normal liquid latex that I used and it takes quite a few layers to build up a good thickness if dipped slowly. I found that the mandrel needed a mirror finish and needed to be cleaned with isopropyl alcohol (Maplins) to prevent pin holes on the base coat.

Like you, I dusted with talc and rolled the parts off the former, making sure the surface coming off the former is also covered with talc immediately. It doesn't stick to the mandrel, just stays put because of friction – but it sure sticks to itself !!

The finished part is strong, but not like neoprene – more like silicone as it will tear easily from a cut or nick. But if its for an application that isn't treated badly, it could work.

Nice Christmas project and good luck.

Cheers – Will