Moulding

[Nigel Herron]

Hi gents,ladies has anybody used air dry clay to form mouldings.

Im trying to make a plug to vaccum form an engine cowl for an AT-6 Texan

I have a basic plug of foam sealed with a primer then a coat of PVA to seal and act as a bond then built up with air dry clay 2 layers approx 5 mm thick overall I cant stop it from cracking any ideas.?.

[Plummet]

I spoke nicely to my dentist, who introduced me to his dental technician, who gave me some dental moulding stuff. You can heat it in a microwave and place the object you want to mould into it and let it cool.

Then you can use plaster of paris to make a solid rigid copy.

Does this help?

Plummet

[Nigel Herron]

Sorry plummet but no not what i was looking for

My Idea of using clay was that it can be moulded into virtually any shape you want it's the 1st time i have used this material its very easy to smooth out.

So back to my original question has any one used air dry clay for mouldings.

would it be better to use a full plug of clay instead of trying to build it up in layers granted its only 2 layers on top of a foam base plug that im having problems with.

[cymaz]

The thread below is about some trying to vac form from a blue foam plug.

There might be something you might find useful

[Denis Watkins]

There is much going here Nigel, and you want a simple answer. If you are experienced with air drying clay, then yes, make the full plug from clay, and do not lay it on to another material.

A few points though. An AT 6 cowl is a cylinder, and apart from being able to buy, and copy one quite cheaply, from a forming point of view, the cylinder of plastic will grip the former so tight that you may not be able to part it from the mould.

I use dry clay moulds to repeat form tapered cowls, such as the Mascot, in previous times, and currently the Wot 4.

Forming a cylinder can be a waste of time, due to the damage inflicted on parting the job

[Peter Miller]

I have made a large plug from cement covered with plaster. I use it to heat shrink a 5 litre plastic bottle over it.

It worked.

This was described in the instructions for my Fletcher Defender which has been recenty republished in Flying Scale models so you should be able to get a copy fairly easily.

[Nigel Herron]

Thanks all unfortunately i cant find the part on H/K web site so presume no longer available and you are probably right would onlyhave been a few £'s but that takes all the fun out of restoring this plane as its a trial for another project that i require to form a larger cowl for a piper cub @ 2.2mtr w/s

So will try a full plug of clay with various methods of releasing agent (trial and error and beats corrie and the rest of the soaps on TV).

Good job i got a 12.5kg pack of clay.