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Old Nov 25, 2012, 03:22 PM
Registered User
Brownsburg, Indiana
Joined Aug 2005
1,017 Posts
Question
I need How-to help vacuforming canopies

I have a Lancaster bomber build that needs canopy and blisters vacu-formed, but I've never done it before. I have a pretty good idea of what the vac box should look like, and the hobby shop has the plastic. But from what I've read you have to carve every mold from balsa? Large pieces are getting pretty expensive. Anyone have any tips for a first timer?
Jay
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Old Nov 25, 2012, 03:33 PM
Airplane crasher
CapMike's Avatar
USA, CT, Shelton
Joined Jan 2008
2,732 Posts
Get in touch with Keith at Park Flyer plastics. He goes by Sparky here on RCG. He does great work and can make the molds and then pull the plastic for you. He is reasonable on his prices too. Plus it saves time from having to do all of this when you could be building
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Old Nov 25, 2012, 05:19 PM
The "pro" in procrastination
Steve85's Avatar
Canada, ON, Kingston
Joined Mar 2004
2,893 Posts
I'm in exactly the same boat, with a Lancaster needing canopies and cowlings, and never having attempted vac-forming myself. I've heard that MDF (medium density fiberboard), the stuff made of sawdust and glue, is a good material for building forms out of. It's a lot harder than balsa (and a lot cheaper, too), so some power sanding tools will probably useful, along with a bunch of hand files and rasps. When I get around to it, I'll be trying MDF for my forms.

Steve
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Old Nov 25, 2012, 05:34 PM
Airplane crasher
CapMike's Avatar
USA, CT, Shelton
Joined Jan 2008
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Steve and Jeep if your both doing the same size it might go well to split the cost to have a set of molds done by Sparky then have him pull a set for both of you
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Old Nov 25, 2012, 07:49 PM
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wizard of odd's Avatar
Australia, WA, Kalgoorlie
Joined Apr 2011
1,435 Posts
Dynamic Balsa makes a vacforming machine (in kit form) that takes the pain out of re-inventing the wheel. It works really well. You can get the plastic from them too. Here's a link to a picture I posted in my blog.

http://static.rcgroups.net/forums/at...g?d=1318934679
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Old Nov 25, 2012, 08:37 PM
Scale Builder
United States, AZ, Litchfield Park
Joined Jul 2002
2,603 Posts
Vac forming is not difficult, just takes a bit of playing around. Below is a link to a short tutorial I wrote a few years back on the very basics of the process. As noted by Steve above MDF makes a good plug material because it's cheap, carves easily, and has no grain. The biggest draw back to MDF is the limited thickness which means having to laminate to get a large enough block for your plug. When laminating be very careful not to apply glue where you will be sanding later as it is impossible to blend the two dissimilar materials together and you will always see the joint in your finished part. This is not as critical on opaque parts which can be sanded to alleviate any imperfections but on clear parts it is of premium importance. In fact everything about molding clear parts is substantially more difficult than opaque parts. There are techniques for simplifying the process though and a bit of "googling" will provide lots of information. I do a considerable amount of vac forming as well and would be happy to answer any questions to the best of my ability as I'm sure would others here who have experience. (Sparky being the "guru" for sure!) It's actually great fun once you get the hang of it and opens up lots of new doors. Give it a try!

Basic Vacuum Forming Tutorial
http://www.rcuniverse.com/forum/m_81..._1/key_/tm.htm
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Old Nov 25, 2012, 08:43 PM
KE your cub.
Curare's Avatar
in the gutter, again....
Joined Jun 2005
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Anyone who's tried messing with large chunks of MDF for moulds will tell you that:

a) it's a pain as it's not a consistent density all the way through, the faces are harder than the core.

b) it's a dog to sand.

c) the sawdust is potentially carcinogenic.


I prefer making my plug/buck out of balsa as it's easy to carve (remember this is a hobby and it's meant to be fun), and will pull a decent canopy. If you're struggling to find lumps of lumber big enough, then you may want to consider jelutong. I used to make fishing lures out of it, as it's a little harder than balsa, but still good 'whittlin' wood, in that it can be shaped with hand tools.
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Old Nov 25, 2012, 09:05 PM
Scale Builder
United States, AZ, Litchfield Park
Joined Jul 2002
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If you can afford the stuff then high density foam tooling board such as Renshape or Chemiwood is the ultimate in plug making material. Just be sitting down when you go to order!
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Old Nov 25, 2012, 10:31 PM
KE your cub.
Curare's Avatar
in the gutter, again....
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Hehe, yes, also check out Obomodulan, which is what I've used in the past.

not cheep but great stuff.
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Old Nov 26, 2012, 08:29 AM
Bleriot's R Us
xairflyer's Avatar
Ireland, Donegal
Joined Nov 2003
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Quote:
Originally Posted by Chad Veich View Post
Great tutorial but unfortunatly all the pics are missing, you must have used a photobucket or similar third party host to store them rather than uploading direct to the forum.
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Old Nov 26, 2012, 11:15 AM
Scale Builder
United States, AZ, Litchfield Park
Joined Jul 2002
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Quote:
Originally Posted by xairflyer View Post
Great tutorial but unfortunatly all the pics are missing, you must have used a photobucket or similar third party host to store them rather than uploading direct to the forum.
All the pics were there yesterday. This morning RCU is all jacked up for me and I can't even get into the thread! It's possible that a new post added to the thread will make the pictures reappear. I'll do that just as soon as I can get RCU to cooperate with me.
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Old Nov 26, 2012, 06:15 PM
Since 1952
Harry D's Avatar
Canada, AB, Edmonton
Joined Oct 2004
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Everything you need to know: http://www.build-stuff.com/001book_vacuum_forming.htm.

Highly recommended.
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Old Nov 26, 2012, 06:18 PM
Scale Builder
United States, AZ, Litchfield Park
Joined Jul 2002
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Quote:
Originally Posted by xairflyer View Post
Great tutorial but unfortunatly all the pics are missing, you must have used a photobucket or similar third party host to store them rather than uploading direct to the forum.
They are showing up for me just fine. Anybody else having trouble?
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Old Nov 26, 2012, 08:03 PM
The Prez....... again
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United States, IA, Rockwell
Joined Jul 2011
4,267 Posts
"Pattern" pine is not to bad to work with. It is used by mold makers to build plugs for castings, steel, aluminum, etc. Any "clear" pine should also do the trick. It might need a finish on it if some of the grain comes through. Clear pine does not have much grain though.

I do have to admit I've never use pine for a vacuum mold, so I may be speaking out of turn.

Ken
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Old Nov 26, 2012, 08:35 PM
KE your cub.
Curare's Avatar
in the gutter, again....
Joined Jun 2005
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I have, it wasn't pretty, the oils that came out of the wood stained the canopy.

The only way I got it to work in the end was to pull a sheet over the buck, trim it off, and then hit the sheet with 600 and get rid of all the blemishes, and then pull a clear sheet over that.

Incidentally, that method works pretty well for most canopies, provided you don't heat the sheet on the buck up too much when forming, or it'll pull and pucker and drive you bananas.
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