Vac-u-forming a Vac-u-formed Canopy

Don Stauffer

 

No, but....  The plaster is not sticky when hardened.  But, it is very brittle.  If there is any undercutting, you will break the mold.  You have to inspect the mold to see if the plaster mold will remove freely.  Most of the canopies and other parts I have done this too did not have any undercuts, but with some of the new slide molding technologies we may be seeing more parts that do.  For parts that have an undercut one could try making an rtv mold, but I don't know if that would mold well in vacu-form.  RTV is a pretty high temperature material, but may be too soft  Experimenting might be a good idea.

 

 

Don,

If a mold is made from RTV, from the outside of the original canopy, a plaster or resin cast can be made using the RVC mold.

No, but....  The plaster is not sticky when hardened.  But, it is very brittle.  If there is any undercutting, you will break the mold.  You have to inspect the mold to see if the plaster mold will remove freely.  Most of the canopies and other parts I have done this too did not have any undercuts, but with some of the new slide molding technologies we may be seeing more parts that do.  For parts that have an undercut one could try making an rtv mold, but I don't know if that would mold well in vacu-form.  RTV is a pretty high temperature material, but may be too soft  Experimenting might be a good idea.

P o P is kind of old school, but it has it's merits.

When I was making model railroads I used to buy the stuff by the 25 lb bag. Freshness was a deal, having to do with the setting time.

Model railroaders would make an entire building or car in a single mold as it holds great detail.

If you buy a bag, and use some of it, keep the rest in an airtight bag. 

I have not.  If the plaster sets properly, the plug should come out with no problem.  Wash the original vac canopy out gently with soapy water.

Can't hurt.

Don Stauffer

 

 

Linebacker

I've never used plaster. Which kind would you suggest for this purpose?

 

 

 

 

I use plaster of paris.  Be sure to get water to plaster ratio right, and mix thoroughly.

 

 

Do you need a release agent on the original canopy? 

You can get the stuff from craft stores.  I think hardware stores also carry it.

What I've done in the past is to make a slightly watery mix to slush into the cavity to get good coverage, followed by the mix ratio recommended by the manufacturer to fill the mold.

Linebacker

I've never used plaster. Which kind would you suggest for this purpose?

 

I use plaster of paris.  Be sure to get water to plaster ratio right, and mix thoroughly.

I've never used plaster. Which kind would you suggest for this purpose?

Real G

Fill in the backside with quick set plaster, pop it out when it hardens, and you have a durable master “buck” to form new canopies.  Make a couple and use them instead of the original.  If you mess up, you can practice until you get good results.  if you cut a decent set, use it!  The original can be your back up plan in case all else fails.  HTH

 

Fill in the backside with quick set plaster, pop it out when it hardens, and you have a durable master “buck” to form new canopies.  Make a couple and use them instead of the original.  If you mess up, you can practice until you get good results.  if you cut a decent set, use it!  The original can be your back up plan in case all else fails.  HTH

Hi,

I have had similar thoughts before as well.  One potential idea would be to maybe get some clay to make a "dummy" plug off the original canopy, and then use that "dummy" plug in your vacuformer.  I haven't tried it yet, but it might be a possibility.

PF