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T O P I C    R E V I E W
carolina Posted - 09/21/2017 : 16:47:19
My oven is like this: 4x4 , 32" tall inside. Can do many of my molds for curing better and make some windows.



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25   L A T E S T    R E P L I E S    (Newest First)
harv Posted - 05/31/2018 : 07:16:33
Doug, you're right and you're wrong. 250°F is hot enough. Lower temps making the time required impractical. I'm attaching a link to a technical article about forming PC and there are many to be found. http://tinyurl.com/y7mh3z4s
carolina Posted - 05/30/2018 : 14:46:56
But i cook cell cast acrylic; its 320 for 10 mins. This is no blown, this is simply dropped into a female mold for this oven.

My petg is straight or almost in a window frame, i don’t use polycarbonate, i like petg. Also i use only 0.30 which sometimes haf to order.

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DougC Posted - 05/30/2018 : 13:39:30
quote:
Originally posted by harv
...You have to dry polycarbonate ie 375f for 24 hours in an air circulating over. It's hygroscopic and will release entrained moisture as steam bubbles in the part.

Warning: I may not know what I am talking about. And I've never made any canopies.... -But I have heard about the entrapped-moisture issue. And I've seen it myself when bending plastics with a heat gun.... The solution I was told was to pre-heat the plastic at 150F for 2+ hours in an oven before you actually form it (either by heat gun or by oven).

It would seem that heating it to over 212F would be counterproductive. The reason the bubbles form is because water trapped inside the plastic boils. So to drive the water out, you don't want to heat it hotter than boiling...?
carolina Posted - 05/29/2018 : 19:45:08
How high will AirCrete go in temperature? Some inch thick panels would line an oven great if it would do 320 f degrees. Gotta find a local company that sprays AirCrete (youtube: type it in) and maybe get them to spray some in a wood mold.

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carolina Posted - 04/25/2018 : 17:58:33
Harv: l did buy 0.30 petg for side windows and that worked out great. These windows are not heated or bent. 0.30 is really all i need to use in front windows also, (used 0.40) if l build another canopy top.

The 0.30 can be hard to find in alot of areas which makes shipping and purchasing high$$.


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carolina Posted - 03/17/2018 : 12:49:26
Thanks harv! Want need, as u can see the pics. They just set in place in frame. I will finish my oven with more $$$$. And may not use it much but Wanta finish it anyway. Now it runs great @145 to cure parts but need the ceramic fiberboard and another element. Even if i leave frame out and install a full heated one-piece molded windshield, iam worried bout pedal clearance up front there with this bd5 canopy. Really goes down in front.



Your idea is great for trike or 2 wheeler, one who just wants a windscreen. Thats what lognotching (youtube channel) does on his nice trike tops.

Nice channel: ed miller, https://youtu.be/vAlKhBO_b2U
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harv Posted - 03/17/2018 : 10:36:10
FWIW .032 polycarbonate can be cold bent in a sheet metal bending brake.
carolina Posted - 03/15/2018 : 18:10:15
Trying this polycarbonate i bought today in raleigh. Lil’ thinner than 1/16” as u can see. Feels like great stuff.

4 x 8 foot sheet $75 out the door.

These 3 frame windows will not haf to be heated but will go in frame below nice l hope. Polycarbonate is very flexible.



5 windows will go in canopy below. I hope the side windows do good without heat. Fun to experiment.



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carolina Posted - 03/14/2018 : 09:26:18
Saving up funds for my oven completion. Need another element and some ceramic fiber board from ebay.
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carolina Posted - 01/27/2018 : 10:16:04
Useing this large oven , tweeking my techniques. I lay acrylic on top of heat resistant sheet rock then 100% cotton. Heat to 320 and lay into female mold. I trim acrylic to shape of window and extra inch. Then the acrylic is totally laying down in the female mold with no krinkel around perimeter. Try to find some polycarbonate local tomorrow. Test it too.

UPDATE:
This powder coating oven want do the trick, need to finish my home style oven one day (1 more element & 1 ceramic board). Sheet rock is ok for small oven but tile stone is best, like pizza stone(maybe Larry will find me one large stone). Oh if my kitchen oven was larger, it makes good smaller windows.


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carolina Posted - 01/15/2018 : 14:00:04
Update and shopping for this ceramic board 1” thick liner, its high $$ on ebay. But l love it! Line my oven with it if found discounted at mcmaster-carr or Alibaba express.

https://youtu.be/JAoxsDYFhdg

https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F182420607998

Still a fan of the foam to build my oven from Home Depot with liner in it of the ceramic board.
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carolina Posted - 01/07/2018 : 09:34:05
My first oven turned out great for curing all components molds at 145 degrees.

My friend owns powder coating bizz here and invited me to use his oven at 320 degrees.

I made a great miniature frt canopy windshield. [PHOTOBUCKET DOWN]. So i have some confidence.

I can use male or female mold, i have both. I choose to drape down into female mold with plastic on acrylic. And i have thin layer of felt on female mold. Windshield is 33” x 33” and pointed taper at front.

Start another oven with fire shield sheet rock, like in youtube above.
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harv Posted - 12/09/2017 : 06:35:39
link to a vac forming guide for polycarbonate. http://tinyurl.com/yahtpnla
carolina Posted - 12/07/2017 : 17:02:00
But iam not use air, i use drape molding. Actually 320 could be lil high, probably even 300 f would work. This is very difficult. But l have plane B to start next week. A 3 window straight window frame plug of wood and bondo/duratec. Airplane plastics of ohio worked on this drape 2 piece mold method for over 10 years. Proprietorial & jeff want give any info out. And my buddy todd crashed and died. He would of helped me.

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warren Posted - 12/07/2017 : 15:51:31
According to my notes while blowing bubbles in Bill's basement, Lexan Polycarbonate can be blown at 350F.
harv Posted - 12/07/2017 : 14:27:54
You have to dry polycarbonate ie 375f for 24 hours in an air circulating over. It's hygroscopic and will release entrained moisture as steam bubbles in the part. IIRC PC has a forming temp 450-500deg and would probably melt any poly cling film.

I think aircraft canopy fabricators would use greased felt covered molds for forming acrylic. The grease (crisco?) is softer than the hot acrylic and traps debris before it can leave a mark in the hot plastic.
carolina Posted - 12/07/2017 : 13:48:52
Harv, your version is best, just tried another. I might b able to do it correctly with your idea because the real mold for frt windshield is not compound at all compaired to this lil 10” sample mold i made. And its possible the polycarbonate will do a better job along with your idea of leaving the film on. Thanks. Every tip helps. This molding is very secretive. Will get some polycarbonate soon.

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carolina Posted - 12/07/2017 : 11:03:19
Harv, gonna try leaving film on next one like you said. Tried 3 will felt and cotton based mold. Cotton best. Will post later today.

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carolina Posted - 12/06/2017 : 16:05:45
Much better without felt,, but not good enough: hunt more info. My buddy who could have helped me was killed in his plane months ago.


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This is the way l cut all plastics now:

https://youtu.be/XPlbZdwQ2AM

Another molding of acrylic:

https://youtu.be/pgtwAPWraZE
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carolina Posted - 12/06/2017 : 12:32:09
Learning curve mini mold l made. Both pieces covered in felt.







1) 320 for 10 mins. 1/16th inch thick.
2) was simple.
3) cools in minutes.
4) layed acrylic on pizza stone, parchment paper, then 100% cotton piece (t-shirt material) in oven
5) textbook except for the felt impression left on acrylic.

My next hurdle is the felt left imprint on the lil mini piece. What to do next?? Maybe cotton??, or just the clean plain molds.
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Took felt off of the lil’ molds. Start over with some new ideas.

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Speedbiker Posted - 12/04/2017 : 19:51:25
Excellent video Mike.
carolina Posted - 12/04/2017 : 15:47:56
Yea, will get some poly next run. Never any vaccum forming here. I will try video above or use solution B as wrote above. Oven was built to cure part too. I am making part B or starting on that plug next week. I can use all 3 situations with the oven.

Ill check for UV harv, thanks. Piedmont plastics is a average supplier.

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harv Posted - 12/04/2017 : 12:36:35
UV resistant PETG sheet is available. A tip: to help prevent scratches when handling AND vac forming petg, leave the blue cling film on and remove it after the vacform/trim operation.
warren Posted - 12/04/2017 : 11:01:51
PETG is the best option I found. It is inexpensive, melts at low temperature, forms well, and it optically clear. It is reasonably fracture resistant and does not shatter. Like most plastics, it will discolor or gt brittle if left in the sun. I have personal experience with blown PETG bubbles that are close to 20 years old and are still being used.
carolina Posted - 12/03/2017 : 15:25:08
1)Video again (below) has great technique but i use female mold instead of male mold.
2) my small test scrap mold for learning curve.
3) ya have to learn how first. Gotta start somewhere.
4) Speedbiker if l can do this with poly and be able to see thru it. Yay!



[Watch]
https://youtu.be/VlzfPzQXACY
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