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  #11  
Old 12-29-2009, 05:04 PM
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kurtschachner kurtschachner is offline
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Quote:
Originally Posted by tbzep
Kurt,

Where did you order the polycarbonate? It's expensive at Tower Hobbies.


I didn't order it, there's a nice plastics supply house near where I live. It's called Midland Plastics, and once I told the guy I only needed some for my hobby they bent over backwards to accommodate me. He said they had some "scraps" they'd give me at a discount, which turned out to be relatively large pieces. I don't recall what I paid but it wasn't over $30 or so.
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  #12  
Old 12-29-2009, 05:09 PM
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That gives me some ideas.

Why couldn't you make the mandrel out of wood?

300 degrees won't bother red oak.
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  #13  
Old 12-29-2009, 05:11 PM
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Quote:
Originally Posted by GA_Bar
I ordered mine from Horizon Hobby (www.horizonhobby.com)



Thanks. Unfortunately, it's a little more expensive per square inch than Tower.

You get two 7.5x11 sheets from Tower and one 11.5x13 from Horizon.

I just re-read Kurt's post and saw he got his from a local plastics supplier. That's one of the few disadvantages I have living in rural America.

Edit: I posted this as Kurt explained in more detail what I missed.
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  #14  
Old 12-29-2009, 05:14 PM
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Quote:
Originally Posted by sandman
That gives me some ideas.

Why couldn't you make the mandrel out of wood?

300 degrees won't bother red oak.


That's what I was thinking about, myself....along with wondering if I had to go all the way to 300 deg to make the stuff relax.
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  #15  
Old 12-29-2009, 05:16 PM
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These are designed to just friction fit over the main body tube, right?
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  #16  
Old 12-29-2009, 06:31 PM
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Well, it may take some experimentation on your part to see what temperature is required. Looking back at my notes (and the picture I posted of the mandrel) I may have only gone to 270 degrees. If you don't go high enough the plastic will still have a spring to it, and if you go too high it will get a mottled appearance that isn't very nice looking.

I thought you had to take it above its glass transition temperature to affect a permanent shape. But if it is only 270 degrees then that isn't high enough. On the other hand, my oven (a standard kitchen range) may not be that accurate either, so who knows exactly what the temperature is. If I were doing it again I would start with 270 and see if that works. If not, just reload the same piece in the assembly and try again. A low temperature causes no effect on the plastic. I do know I heat treated it for about an hour and then let it cool before removing the plastic strip from the mandrel.

Could you use wood as your mandrel? Maybe, it wouldn't hurt anything to try. I don't know what affect moisture in the wood might have. Too much will of course cloud the plastic. But you could do a couple "dry runs" by just heating your mandrel first. This might help.

Quote:
Originally Posted by tbzep
That's what I was thinking about, myself....along with wondering if I had to go all the way to 300 deg to make the stuff relax.
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  #17  
Old 12-29-2009, 06:37 PM
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Quote:
Originally Posted by tbzep
These are designed to just friction fit over the main body tube, right?


Yeah, but on mine (the GT-3 one at least) I glued a couple of little wood blocks behind the aft end of the body tube. I then use a couple of nylon screws to attach the fin to the model. You can see the holes in the body portion of the fins if you look closely enough.
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  #18  
Old 12-30-2009, 06:43 PM
GA_Bar GA_Bar is offline
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Ah yeah I see them. That is a great idea. I think I will steal that one too.
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  #19  
Old 01-06-2010, 02:09 PM
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Anyone know what commercial adhesives work best with polycarbonate? Will CA work? Epoxy? JB Weld? Thoughts?
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  #20  
Old 01-06-2010, 02:25 PM
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Plastik Welder or Tenax 7R
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