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Casts from original plastics

Old 03-23-2019, 07:26 PM
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solentlife
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Default Casts from original plastics

OK.... I have a complete spare set of HK Lanc plastics ..... so I am now experimenting to see if I can cast Plaster in them to create plugs.

First is the Tail gunners turret ...sprayed with Silicon spray as a release agent and then plaster poured in.

A ply stick as a handle of course.

The 'radiator' is not on ... its purely its close to the sink /water supply. The bottle of course keeps the turret upright while the plaster cures.

Fingers crossed I haven't ruined my spare turret !
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Old 03-23-2019, 09:26 PM
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Not easy getting plug out even with the pliable plastic .... air cannot get in behind ...



But it worked.
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Old 03-24-2019, 06:54 AM
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Wildflyer
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I have used a product called "Fix-it-All" to do similar things. I think it cures much harder then the plaster I have played with.
I cast the entire inside of a canopy I liked in case I messed up the first one. Haven't tried to vacuum form it yet.
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Old 03-24-2019, 07:17 PM
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Originally Posted by Wildflyer View Post
I have used a product called "Fix-it-All" to do similar things. I think it cures much harder then the plaster I have played with.
I cast the entire inside of a canopy I liked in case I messed up the first one. Haven't tried to vacuum form it yet.
I made a vacuum forming rig from junk materials about three years ago. I used the Fix-it-All for most of the molds I created. Loved the stuff. Cures hard and very smooth. I ran out of it and tried plaster of Paris and just wasn't as happy. It seems to end up with too many bubbles on the surface and overall surface smoothness is not there. Aside from the bubble (low spot) areas the other abnormalities likely won't show through to the final product. I just prefer the ready to use surface of a Fix-it-All plug. I need to get another box and continue making plugs for all the cowls and canopies I have. Then I need to get MUCH better at getting the plastic temp just right before pulling the parts. I don't have a good success rate yet (see the pictures for the worst one and a success) and it's soooo expensive to waste the plastic...

Joe
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Old 03-24-2019, 07:28 PM
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One of the problems here .... Fix it All .... dunno if its over here. But will see if I can find it.
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Old 03-24-2019, 07:47 PM
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Originally Posted by solentlife View Post
One of the problems here .... Fix it All .... dunno if its over here. But will see if I can find it.
I just checked the Custom Building Products manufacturer website and you can buy it virtually anywhere on the planet EXCEPT Europe. It is available on Amazon though if you use them over there.

Joe

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Old 03-25-2019, 11:25 AM
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I tried the 'external' casting but it was really only good for very small item.



So I went back to pouring into the item to create plugs. The Baby Oil really made a difference instead of the silicon spray.

Here are :

Cockpit canopy Hk Lanc :





Front gunner :





Upper turret and bomb aimer :







Tail gunner :





All with plywood holding sticks in .....

Now to learn how to hot form the plastic bottle over them !
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Old 03-25-2019, 05:25 PM
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I wonder about pulling plastic over a balsa built buck. Of all the threads I've seen about vacuum forming I haven't seen anyone using balsa. Maybe one or two using hardwoods but never saw reports on their results. The worry for me would be mold release as I wonder if it would just be absorbed by the balsa and likely not be effective. Not sure.......

I'm finishing up a scratch built balsa cowl for the Airtronics Jetfire .20 laser cut kit that Andy Kunz of Horizon Hobby/Spektrum fame gave me a few months ago. The cowl is turning out much better than I expected. While it's not all that heavy a plastic cowl would still be much lighter. I'm not willing to risk damaging the cowl or having the plastic fuse itself to the wood in a test pull though. I wish I had a 3D scanner. Then I could just create a file and make it on the 3D printer!

Joe
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Old 03-25-2019, 09:14 PM
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Looking at it online ..... seems to be a nose cone style ..... plenty on Thingiverse ....

Why not external cast the cowl you make (wrap in sandwich film first) then cast a plug from that ?
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Old 03-25-2019, 10:23 PM
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Originally Posted by solentlife View Post
Why not external cast the cowl you make (wrap in sandwich film first) then cast a plug from that ?
I've been thinking about doing that. I still have some plaster of Paris left. I won't waste my time using P of P for making plugs again as the bubbles render them needing more finish work needed than they're worth. I may try using it to make a plug from my balsa plug. I still have a lot of final sanding and finish work to do on the balsa part. Since leaving RC Groups and the thread on this bird I have been working on it at a snails pace. All that is left is to make the canopy frame (90% done) and build the entire cowl from scratch. (80% done). I have an old sheet of acetate that will work fine for the canopy. It's just a glue and wrap process....

Joe
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Old 03-26-2019, 06:50 AM
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Fix-it-all is just a repair filler sold in paint departments. There should be a substitute for in in any paint store in the world.

When I was a contractor, I kept needing a little Fix-it-all, at different jobs, then after I started cleaning the workshop I found boxes of it all over the place. Dumped them all in one 5 gallon bucket and almost filled it.
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