vacforming canopy resin - some info required

[Troy Smith]

Thread title may not be the best phrased question.

 

Ages ago  I discussed this with @Colin @ Freightdog Models  

He mentioned the material for canopy moulds was a resin with added aluminium, some googling got me this

http://www.easycomposites.co.uk/#!/resin-gel-silicone-adhesive/casting-resin/vac-cast-epoxy-vacuum-forming-casting-resin.html

 

Vac cast is an aluminium filled epoxy casting resin designed for high temperature tooling applications such as vacuum forming tools.

which looks to fit the description,  but you will note in the link that the small tub is 5.3kg,  I'm wondering if anyone knows if smaller quantities of a similar material are available?  

 

 Looking at vac canopies, eg Falcon, Rob Taurus,  I note they use female moulds.    

 

Part of the reason I'm asking to make use yellowed vac canopies as masters,    google is not turning up many answers.    When I talked to Colin about this, a long time ago, he said he'd had problem because he'd not made airhols, and the resin was very hard to drill due to the metal content,  so would casting in airholes,  ie adding pins with mould release to the master work? 

 

Anyone know more, or can add some links?

I've not seen @John Aero  on here in a while, but perhaps a notification may get through, as I think he'd know more.

thank in advance

 

 

[Alex Gordon]

Sorry Troy,I've only just seen this thread.I've got away with Plaster of Paris quite happily for the few bits I've had cause to replace.I would think that the mould would be good for a handful of pops at least.

 

I like the idea of female moulds (cavity moulds is what I tell my little dears at school,I have no wish to explain the difference) if you are making a copy it makes the external dimensions the same as the original.

 

Airholes,I've found that it is easier to drill through the mould after casting rather than inserting pins that are difficult to remove once the mould has set.On a cavity mould this makes life interesting keeping the drilling dust out of the of the cavity,something always sticks,fully conversant with that at this end.

 

I've no piccies to show now but leave it with me.

[Troy Smith]

I'm going to bump this,  in case now @John Aero  as posting again he could add some information, or if @Alex Gordon perhaps turned up some info in the menawhile.

cheers

T

[Pin]

Simple question, are you going to form one canopy to replace yours yellowed one or to mass produce them?

The reason to use fillers such as alluminium for resin forms is to harden them so that the formd could withstand multiple (several dosens) cycles of vacforming being in contact with hot plastic. If you only going to form a single (or a couple) replace canopy you don't need to harden the form. 

This is what I have done:

 

Here I have tried to make a negative form, but I'm not quite happy with the result, I suspect I have applied silicon  release agent incorrectly

 

 

[Plasto]

Troy,

 

I made a resin master to vac form a canopy for my ongoing 1/32 Typhoon.

 

 

Here you can see the RTV mould the vac form ‘buck’ and the PETG canopy I vac formed.

 

I used regular casting resin and a home made vac table for the job.

 

I think you would want reinforced resin on the vac form master if you were running many many copies. I vac formed around 20 canopies on my resin master without any issues. 

 

If if it’s a commercial venture then I have no experience of reinforced resin casting..

 

 

HTH..

Edited January 13, 2019 by Plasto

[Black Knight]

For just one or a few copies I've used Keramin moulding plaster or Polymer Clay for the buck