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Plunge Moulding Primer: the good and not so good


DMC

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9 hours ago, Courageous said:

In my view, I think that vacforming and heat has its limitations and detail is one of them and the detail needs to be added.

 

Stuart

 

Agreed, Stuart, at least as far as DIY is concerned.  The vacuum forming kit makers, however, seem to be able to pull quite a bit of detail out of their moulds.

 

Dennis

 

 

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  • 2 months later...

I've made some forays into home Vac forming and after a few trials, I think i'm getting the hang of it. The results I find are a much better than plunge molding

 

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Pfalz DR1 Fuselage sections

 

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Ju87A wheel Spats

Edited by Marklo
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Well, @Marklo, I have done a little of both and I agree with your findings.  With plunge moulding, your Pfalz for instance, the center of the mould contacts the hot styrene first and doesn’t stretch it as much as the sides as it is plunged.  In Vacuum forming the soft styrene “blankets” the fuselage mould and gives a more uniform thickness.  Also, with plunge moulding you need both a male and female mould but with vacuum forming only a male mould is required.  But then a rig of some sort is required and vacuum cleaner, or similar, is needed.  Both methods require a little practice and mistakes will be made.  But with perseverance.......

 

More later about this later as I am getting ready, coincidently, to vacuum form replacement VC10 engine pods on my homemade rig. 

 

Cheers

 

Dennis

 

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The Airfix VC10’s engine pods don’t quite match up with the 1:1 pods. This overhead shot of the VC10’s engine pods shows them to be a little bit wider apart and flatter towards the rear.  Also the kit ‘wing’ attaching the pods to the fuselage is incorrect as has been pointed out here on BM. 

 

When I first bought the kit I thought I’d be able to modify the kit pods to suit but then thought I might be able to make replacement pods by vacuum forming them.  I’d carved a male mould for the pods some weeks ago and thought now might be a good time to try my DIY rig as @Marklo had brought the subject up on this thread.  Plunge moulding wouldn’t work because of the ‘valley’ between the engines. 

 

Top left is the Airfix kit pod showing them to be a little too close together and with a bulge where it should be flat.   Top right shows a comparison between the kit pod(s) and my balsa mould.  Bottom left is the mould on the rig.  It is Blue Tacked to a hardened clay cradle which is itself B T to the metal platform.  First attempt turned out surprisingly well, they usually don’t, and I think there’ll be no need to modify the balsa mould at all.

 

Thanks for your interest.  As always, happy to take advice or answer any questions.

 

Dennis

 

This OGL photo by Sgt Laura Bippy 

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  • 2 weeks later...

After studying the results from using the first balsa mould I decided I could do better and carved another pod mould.  On this one the pods are closer together and more closely resemble the 1:1 ones.

 

This time, however, I seperated the mould into two halves with a thin slip of veneer thinking that I’d separate then and vac them individualy.  However, as they exactly the depth of the mould I would need to thicken each half so that I would have a little extra styrene to work with when matings them up.  

 

I re-worked the clay cradle a bit and went ahead and vacuum formed a new pod, upper and lower.

 

Probably one of the most difficult things to do when using a homemade rig is placing the rack holding the hot styrene exactly on the rig.  

 

In the bottom right photo I was slightly off center and nearly had to do it over, but it is usable.  I could, if I’d screwed it up, however, re-softened it up in the oven and had another go as the styrene would have reverted to the “sagging” stage.

 

The bottom set of four is more or less the same process being used for the stub wing.

 

Should probably start  WIP on this kit as I’ve done so much preliminary work.

 

Thanks for your interest.  Questions and suggestions more than welcome.

 

Dennis

 

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