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Old Nov 19, 2010, 05:00 PM
aerogel is offline
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Molding and Casting urethane rigid foam Pilots


Now for the pull, Peel off the big junks of splash then one by one open and pull the parts trim and put together and paint away...Weight with the flash is 1 GramWill be around .3 .4 grams trimmed.
This concludes the A to Z how to..hope you all enjoyed the show but its time for me to go..
All I have to say is..

So Long and Thanks for all the Fish (2 min 35 sec)
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Old Nov 19, 2010, 05:16 PM
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That was way cool and a lot of work but so appreciated! Wow!

Fred
Old Dec 05, 2010, 10:00 PM
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Has anyone ever tried this with method with EPP, or is it a depron only thing? It probably wouldn't work well, and you wouldnt have the same level of detail, but you never know.
Old Dec 06, 2010, 02:41 AM
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My planes are from depron only - but that stuff is not THAT FLEXIBLE to shape a small face from foam plate --- from the not cured styrene foam it would be possible but I - for my person would not experiment with liyid styrene in my living room!

For EPP . there is a possibility to work with, in a special way but this is not that secure regarding your health for you work with high pressures and 140C HP steam more like working on an armed bomb


Aerogel - I was off this area for some time - but the way you use that liquid stuff is amazing, helpful and absolute worth sharing!!!! Thank you very much!
Old Dec 06, 2010, 02:57 AM
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I have thought about epp and blue foam molding...

I have tried blue foam and it sticks like mad im glad i tried it on my old mustang molds.... as for epp since we use steam to fix dings and dents.. why not use the hot water techique that epilot showed for depron... no sticking.. so it should work, although one would have to compensate for the predicted shrinkage...


The idea i had was to mold the parts out of super thin depron and then use some blue foam or epp to mold the "backing" basically go to do a second pressing but lay in a piece of epp or blue foam and press for the second time, this would reinfoce the piece making it very strong and lighter, if thicker depron was used. Problem is with the sticking.. but i think one can use baking soda or something along those lines to coat the male to prevent it from sticking.

Something to think about
Old Dec 06, 2010, 03:05 AM
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I thought about the following ... using a EPP block ( very low density) roughly cut to form, suck this full of water like a sponge . Shut the very solid aluminium mold and heat all the thing up about 145 C so the Water is vaporizing but due to the sealed mold it raises pressure and Temperature ... teh EPP is changing density but not weight and is reorganizign the structure.... but as I mentionned 145 C @ some 20 BAR is no kids gaming ... the mold could explode due to the pressure ... - I stick with depron, but I'm sure that bluecor is also useable in Uriol molds ( next plane I want to go for is a ARADo 96 ) q heliman - the Stuka I did is made vom 0.6mm fOAM which is best formed when first preheated and afterwards pressed in heated state
Old Dec 06, 2010, 03:16 AM
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Interesting... This is another reason this thread is good... exchange of ideas!

I do not preheat the foam, just the molds and then press, ive been wanting to try that for awhile now but building the frame and getting it sized.. just seemed like to much work.. and the current technique was working perfect.. will have to try that now. Flybob did originally mention the technique for deepdraw molds ... using DB... i just never bothered to try it....


As for epp i noticed it forms just fine in boiling water, and thats around 100C so 147 might be too much.... unless your using fresh beads and a real heat compression mold...
Last edited by Heliman420; Dec 06, 2010 at 03:30 AM.
Old Dec 06, 2010, 11:01 AM
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EPP is heat welded expanded pellet granulate - the raw grains are brought into a chamber and then blown up using pressure steam .. the pressure is needed to get steam over the welding temperature of 140 degree so the blown up pellets bake together .... same as talked bout ... Taking a preexpanded block of low density epp .... sucked full with water to expand the foam form block shape further into the mold.... two shells of a mold where the block is forced in.... the heat and the steam to blow the compressed areas into the not filled gaps of the mold .... and the heat to weaken the material do do this in easier way to get the epp material from elasic to plastic constitution.

On the thin styrene foam .. I tried both ... but the pre warming process had a much better yield and a much better result!!!
Old Dec 06, 2010, 11:23 AM
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The EPP thing sound interesting for sure. Aluminum molds, and a way to make them is so specialized that few 'modelers' could have that available, and I have a conventinal machine shop set up (non CNC).

In pre-heating depron for forming, there becomes a point where the depron will expand in the heat. I've seen 2mm depron get to 4mm in an oven. Stays the same weight, but is bigger, and stiffer. Are you talking about pre-heating in water or an oven type enviornment (controled temp of course)? I find different thickness depron forms at different temps too. Thinner types take less heat.

Thanks

Fred
Old Dec 06, 2010, 12:32 PM
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It does expand with heat, thats one of the reasons it molds so well, from what i understand you do it in an oven and use a frame to keep it from curling up, although it probably can be done with water as it doesnt take much heat to get it to start expanding.
Old Dec 06, 2010, 01:01 PM
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I often take two fairly heavy floor tiles and heat them in the oven. I can sandwich the foam inbetween to temper it, pre-heat it, or flatten out a 'curly' piece I want dead flat. An idea anyway to avoid a frame to build and 'screw' around with.

The foam also cools so quickly, that handling speed is important!

Fred
Old Dec 06, 2010, 01:29 PM
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On my method the handling speed is too slow - I will have to go for a more massproduction like process ... perhaps same as richard had chosen - in combination with some necessities for depron molding...!!
Old Dec 07, 2010, 02:36 AM
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Quote:
Originally Posted by Freddie B View Post
I often take two fairly heavy floor tiles and heat them in the oven. I can sandwich the foam inbetween to temper it, pre-heat it, or flatten out a 'curly' piece I want dead flat. An idea anyway to avoid a frame to build and 'screw' around with.

The foam also cools so quickly, that handling speed is important!

Fred


the problem with the floor plates is their weight... so the foam never has a chance to reach maximum expansion, thats where the properly sized frame comes in... it makes up for the lost shrinkage without allowing the sheet to curl.. one can then flatten it using tiles or glass.

Yes the cooldown time is very quick and a fast and properly aligned stamping machine will be needed to press fast. what i was thinking is expanding the foam in the frame, then pressing it using just the heated molds.. might make for a more rigid part...
Old Dec 07, 2010, 10:45 AM
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My daughter sent me 3 rolls of wallfoam from UK when she lived there. I still have them and wonder if it can be formed using any of the methods here. I know it can be heat formed, but due to its thinness finding the proper range with out melting is a bit of a challenge.
Old Dec 07, 2010, 11:17 AM
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If it is styrene the weakening temperature is about 10XC melting temp is much higher


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