Casting epoxy resin in a nylon mould

[Matty F]

I have discovered that epoxy resin doesn't stick to nylon. That doesn't seem to be a property of nylon that is well advertised, but Google found a number of people complaining that they were unable to glue nylon.

For my purposes this is ideal, since I want to cast some insulators from epoxy resin, and I am able to make a mould out of solid nylon. I used to tape up bits of plastic drainpipe for a mould but the epoxy tended to leak through the joints, and the plastic would break when taking the mould apart.

Here's an old insulator and the finished new insulator:

old insulation is some horrible mixture of asbestos and something else. I carefully cut it all off and cleaned up the brass insert that I will reuse.

Here's the nylon mould which I turned up in a lathe.

cut the mould in half because I wasn't confident that the casting would push out later. How right I was. I didn't make a very smooth job in turning the mould and there are small grooves that the epoxy clings to. The white powder is filler that I used to add a bit of strength.

Here's the brass insert in one half of the mould:

white washers I made out of nylon and tapped them to suit the brass thread. The epoxy will run through any little hole and I didn't want it on the brass thread.

I put a couple of Jubilee clips around the mould and poured in the resin. If you pour slowly on one side it pushes all the air out and doesn't leave bubbles:

a few hours the resin is set and I can open up the mould: careful not to touch the sharp edge around the top. It's so sharp that you can't feel it cutting your finger!

I put the casting in the lathe to trim off the end:

also skimmed along the sides since the mould was not perfectly round after I had cut it in half.

I imagine that I can make a nylon mould for almost anything small. It cuts and drills quite well.

[Dave Plowman (News)]

It doesn't work with most flexible plastics.

[Roger Mills]

Very nice! Is this another tram project?

[The Natural Philosopher]

The word you want is 'polyolefins' the 'oily' polatics.

Polythene is the easiest one to strip it off.

I use polythene food boxes to mix it in.

[Matty F]

Yes. But it could be for trolley buses too!

[Matty F]

Can I get solid polythene or make a mould out of melted food boxes?

[The Natural Philosopher]

[Adam Aglionby]

insulator:

> The old insulation is some horrible mixture of asbestos and something

lathe.http://i49.tinypic.com/20jfvr6.jpg>> I cut the mould in half because I wasn't confident that the casting

mould:

The white washers I made out of nylon and tapped them to suit the

mould:

> Be careful not to touch the sharp edge around the top. It's so sharp

end:

> I also skimmed along the sides since the mould was not perfectly round

Your work, as ever is just incredible, thanks for sharing.

Usual to cast rigid items in flexible mould and vice versa.

Thought about silicone, 2 part mould making stuff is nice but expensive, but have seen sculptors use tube upon tube of glazing silicone to make a mould.

Really good book on casting:

[Matty F]

Thanks. Usually someone comes up with some ideas I have not thought of.

40 years ago I used to use Silastic 2 part rubber to make moulds, but I don't know where to buy it now. The advantage of nylon is that the mould is very accurate. And nylon is all I've got lying around.

[Anna Kettle]

South Western Industrial Plasters

01380 850616 They haven't yet joined the 21st century but are very nice people and will send you an excellent catalogue if you phone them

Anna

[Dave Liquorice]

To New Zealand? B-)

[dennis]

If you need to make lots you could make recyclable moulds out of wax,

[Andy Dingley]

that's the production quality of the book, but also the content looks a bit antiquated.

Andy Wilson's "Making Stage Props" was much more fun. Not as specific on casting, but a great read.

Bentley chemical company (silicones) are a delight to deal with and very encouraging to small-scale prop makers.

[Dave]

Do a google for your local industrial sealant shop and ask them for some, or an equivalent. That is what I did in order to get some black silicone adhesive that I couldn't find outside of the aerospace industry.

Dave

[Adam Aglionby]

Read that criticism on Amazon as well TBH bit lost as to the meaning, nothing much has changed in basic moulding and casting, some of the moulding materials urethanes and epoxies have advanced but principles are the same.

Can`t see where this `modern` content was going to come from...

Great book but very light on casting detail.

Glasplies do quite a silicones and casting resins, in depth in silicone

repeat fine enough detail to copy cell walls..

For the OP, Dow Corning one of big names in silicones ,

[Jules]

Nice "report" - do keep 'em coming! :-)

cheers

Jules

[Andy Dingley]

Obviously they weren't covering the web, and the vast amount of information that's out there these days.

What I found lacking though was any detail on materials beyond the broad types: particularly silicones, where Bentley were happy to advise on a vast range of mixes with different mechanical behaviours. The book seemed a bit of a closed book on this, as if you bought one sort of goop, that was your lot and you ought to be grateful.

[geoff]

In message , Adam Aglionby writes

[Adam Aglionby]

Personally hate books with large amounts of links , they always end up with things like geocities....

True, but there are whole websites on just silicones, but silicones aren`t beginner friendly, expensive and expensive and easy to make mistakes with. Ditto with urethanes, plus messy... Advantage of PBMCHB is the basic techniques, plaster is cheap and simple to use, gets a beginner encouraged to go further, also has one of best explanations of vac forming in a book. Basic techniques of taking a mould and casting an item are the same, materials may be advancing but theyre used in pretty much the same way.

For the more advanced Amazon recommends

if you had the machining skills of the O.P. and you didn`t in a country where simply to posess such information would be illegal, hence have to order it from Amazon U.S., project for the weekend ;-)

[Adam Aglionby]

Never come across Jordan, just thought of DC as big player,presumably with representation in NZ, other supplier thought of`s NZ distributor is in Australia :-(