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General Aircraft: Tips & Techniques
Discussions on specific A/C building techniques.
Vac Canopy cutting
rdt1953
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New Jersey, United States
Joined: February 06, 2015
KitMaker: 1,094 posts
AeroScale: 896 posts
Posted: Wednesday, March 29, 2017 - 06:58 AM UTC
As a continuation of my earlier vac canopy question post and a sub topic of my Hayabusa build I thought I might post my results of casting canopy support for trimming using Durham's water putty.
As this was my first experience with vac canopies I sought the advice of others and received much very helpful advice including stuffing Blue Tac or Silly putty in the canopy to support it while trimming away the matrix.
This worked well but still allowed the canopy to flex to a degree.
in an effort to provide more rigid support I have tried making both male and female forms using Durham's water putty. This is a very inexpensive easy to use water mixed plaster based powder that can be mixed to a pourable consistency with little to no shrinkage.

I simply placed the vac canopy upside down in a plastic cup and filled it with a poured mix of Durham's. Save the remains in the mixing cup and place it next to the canopy while curing- when the remains are hardened you can carefully flex the canopy away from the male form . No adhesion or marring of the canopy itself.

Next step is to place the canopy upside down in a second plastic cup and tape it down. This time pour around the exterior of the canopy to create a female form.

Same as before, save the remnants as a gauge for curing. When hardened you can remove the canopy from the female form and while it is in a green state the casting has a cheese like consitancy that can be carefully cut and carved away leaving clear access to the bottom edges of the canopy for final sanding and fitting.



http://i1175.photobucket.com/albums/r638/richardtool/image_zps6pfuf8ye.jpg









This is a very rapid process - depending on drying conditions ( temp./humidiy) the entire project can be done in an hour or two - then left the castings cure for another day and they should be good to go .

Happy modeling - Richard
Jessie_C
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British Columbia, Canada
Joined: September 03, 2009
KitMaker: 6,952 posts
AeroScale: 6,239 posts
Posted: Wednesday, March 29, 2017 - 09:03 AM UTC
The possibilities of using this process to make masters for vacuforming can also be explored.
Kevlar06
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Washington, United States
Joined: March 15, 2009
KitMaker: 3,662 posts
AeroScale: 832 posts
Posted: Wednesday, March 29, 2017 - 10:09 AM UTC

Quoted Text

The possibilities of using this process to make masters for vacuforming can also be explored.



Interesting-- I just made a bunch of vac canopies for my modeling friend Patrick Nance for his TBD project-- and I always start my vac projects with a Durham's Water Putty master-- but I just cast it from a styrene vac of the original-- making a "male" mold, then I just pop the clear vac over it and cut away-- exactly the opposite of this technique. I think my method is easier, because you don't have to make cuts "down inside" the "female" mold, but this negative mold has some real promise too. Folks often overlook Durham's Water Putty for molding, because it resembles plaster, but it hardens as a durable, resin like material that is pretty hard and dense. Glad somebody else is experimenting with it.
VR, Russ
rdt1953
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New Jersey, United States
Joined: February 06, 2015
KitMaker: 1,094 posts
AeroScale: 896 posts
Posted: Wednesday, March 29, 2017 - 03:13 PM UTC

Quoted Text


Quoted Text

The possibilities of using this process to make masters for vacuforming can also be explored.



Interesting-- I just made a bunch of vac canopies for my modeling friend Patrick Nance for his TBD project-- and I always start my vac projects with a Durham's Water Putty master-- but I just cast it from a styrene vac of the original-- making a "male" mold, then I just pop the clear vac over it and cut away-- exactly the opposite of this technique. I think my method is easier, because you don't have to make cuts "down inside" the "female" mold, but this negative mold has some real promise too. Folks often overlook Durham's Water Putty for molding, because it resembles plaster, but it hardens as a durable, resin like material that is pretty hard and dense. Glad somebody else is experimenting with it.
VR, Russ



Russ - Thanks for the input . The trimming of the base material is done on the male mold - I made the female mold to support the trimmed canopy while tuning up the bottom edges while fitting to the fuselage . I guess I didn't make that clear.
BTW - off topic -did your Camel ever arrive ?
Richard
Kevlar06
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Washington, United States
Joined: March 15, 2009
KitMaker: 3,662 posts
AeroScale: 832 posts
Posted: Wednesday, March 29, 2017 - 09:29 PM UTC
Richard,
That's brilliant! now I see what you need the female mold for. I never thought of using that to refine the edges. By the way-- I usually hang on to these molds, marking them up with a marker on the bottom for the kit they go to--so if I ever need to vac another canopy they're handy. No-- Camel has never arrived-- a very sore spot for me. I've sent two emails to Weta which have gone unanswered. I'd go to Sprue Brothers (I see it's back in stock there and elsewhere, for the third time since release) but our credit card info and the $11 charge "pre-order charge" are still hanging out there at Weta. My wife received an "robo" email some time ago from Weta (she ordered it January 2nd as a belated Xmas present) saying the shipping was "pending". This is really poor service on the part of Weta, and I will never be using them again. But I note Sprue Brothers does not carry the complete WnW line. if you want a newer kit from Weta it isn't going to get here quickly. I don't understand why WnW went with them over one of the established model distributors. If you look at Weta's own products, many are "sold out" too. They list the Camel as shipping in "early Q2" whatever that means-- it could be as late as June by those standards-- six months after initial release and terrible for "pre-order" service status. My next step is to send another message to Richard Alexander-- he's answered the first two at least, but I think my only recourse is to wait and see what happens. Strangely, I'm having a similar experience with HobbyLinc, as my daughter ordered the new Revell-Germany 1/32 ME262B (also a belated Xmas gift). It was promised in late March, but I don't see it either, and now it's just been taken off pre-order and listed as "out of stock". I think the "god of new model kits" is punishing me for some slight-- maybe not spending enough time at the workbench!
VR, Russ
bzak
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California, United States
Joined: June 07, 2006
KitMaker: 264 posts
AeroScale: 87 posts
Posted: Wednesday, March 29, 2017 - 09:39 PM UTC
I too have been waiting for a Camel from WETA. I emailed them about canceling my order, a week ago. They replied with a series of emails in which they say it will ship in a couple of weeks when they get their shipment.

Brian Riedel
rdt1953
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New Jersey, United States
Joined: February 06, 2015
KitMaker: 1,094 posts
AeroScale: 896 posts
Posted: Thursday, March 30, 2017 - 01:06 AM UTC
Here are a couple of shots that will hopefully illustrate the use of the male vs female molds-

Here is the canopy on the male mold for the removal of the matrix - note the windscreen has already been cut away -



Here we can see the windscreen taped to the inside of the female mold -



and the bottom edges of the windscreen being tuned up -



So far this seems to work very well - easier to hold these fragile small pieces and lessens the risk of deforming them while working.

Cheers - Richard