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Old Oct 19, 2010, 03:02 AM
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Hi MUTCAKE, i used a little olive oil wiped in with a lint free rag... not too much just enough to give it a glossy surface.. this a ghetto release.. as it doesnt really release, the molds are heated and the plastic gets soft and rubbery and its very carefully pulled out, this destroys the plastic part but leaves a perfect mold, there are a number of releases out there.. i havent tried them as i find the kits at this scale are cheap.. and i buy them just for the decals... so ruining a kit or two isnt a big deal.

Since i use JB-weld, it takes 24hrs to fully cure.

As for the heat... i use my kitchen oven, and i use a IR temp gauge.. got mine for 20$ with free shipping from some tea house place on ebay.

Pic of temp gauge.
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Old Oct 19, 2010, 12:11 PM
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wow this seems a lot better than using my sealing iron and wrapping foam plates around various size dowels and cans! :P I could probably shave half a gram off my builds using this method (my 1/72 models usually come in pretty fat at around 1.4 grams!). How many times can you use a mold before you have to retire it?
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Old Oct 19, 2010, 12:25 PM
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Southern Oregon
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Great info all!

Thank you!

Possible mold material instead of JB Weld: I use TC-1630 made by BJB Enterprises (Orange County, Southern California and distributed by Stephenson Pattern Supply in Portland Oregon(and others)... This stuff comes in a gallon kit (actually much more than a gallon) is pretty easy to pour, provides a fairly long pot life, holds GREAT detail, easy to pour, holds up to heat, is machinable (easily sanded) and hold up over time... and, it's under $100 for about a gallon and a half.... Obtainable in smaller sizes through Burman Industries in Van Nuys California (special effects supply house)...

Might be worth investigating...

Thanks again for all who are sharing here!

Best,
Richard
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Old Oct 19, 2010, 12:27 PM
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I had a very bad bring out through my first trials but I guess i did about 15 to 20 fuse parts out of the Uriol molds until the plug was finally adapted to work ... ( they are quite new!!) ... and I would say that the POM Molds would even take a lot more!
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Old Oct 19, 2010, 12:50 PM
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My molds have way over 100 stampings on them, some werent mixed properly and have gone brown, but the mold it still perfectly fine and continue to produce.

Richard, there are alot of different epoxy's out there, most need a post cure in the oven, others get hot during curing, and some shrink. jb weld doesnt need a post cure, it doesnt get hot while curing and has zero shrinkage...

Maybe someone can try some diffrent epoxy's and report the results... for the time being im happy with the jb weld... dont want to mess with what
works.


I should mention jb weld isnt cheap, so would be nice to find an alternative.

One thing i noticed is if you play with the mixing ratios you can get longer lasting molds, originally recomended to mix it 50/50... i found a 60/40 mix better, 40% hardner, 60% epoxy steel.
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Old Oct 20, 2010, 01:08 PM
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yeah I've worked with a few different epoxys and the recommended ratio is usually a compromise between a fast set that ends up too brittle or a slow cure that doesn't set up right and you end up with a tacky product. Finding the lowest ratio of catalyst to where you get a complete cure (takes longer and sets cooler) will give you a more durable product. If you guys are banging out 100+ pieces with your molds that's awesome! I need to go buy some models and wreck em!
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Old Oct 20, 2010, 01:39 PM
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You guys are doing great work. Have any of you guys thought about using the 1:18 scale war birds out there for molds? They have the P-47, P-51, P-38, JU-87, Zero, MiG-15, F-86, F-105 and others at that large scale that I may have missed. These planes usually run about $50+- more so for the P-38I think they could be used for making the molds without too much trouble. You'd just need a alot more epoxy etc. At that size you could then use small e-gear rather then micro gear.

Pete
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Old Oct 20, 2010, 02:07 PM
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Larger planes can be done with this technique, however i can see a couple of problems, for one the epoxy will cost an arm and a leg, second a big press would be necessary, a dinky arbor press just wont do, unless you use like 4 of them.
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Old Oct 20, 2010, 02:24 PM
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Pete ... do you think about copyingthe 20th century gems ... already thought about this .... doing this would probably need 4mm depron because of the depth of the details ... could be done but as Heliman said ... may cause some difficulties ... ( for me ... my oven is just 45cm wide....) the techniques work ... that is my main target... making series for a market ... for that you would need some more invest and regarding the amount of parts to be done by hand using the broken down technology to would have to produce in lets say Vietnam to get the costs down to a reasonable level!!!

I finally calculated the Material für a 45cm ws plane in the better/ Polyacetal mold Material is about 250 Euro
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Old Oct 20, 2010, 07:08 PM
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MY 1/32 scale stuka cost around 300 dollars in silicone that’s 3 gallons Most epoxy I have seen runs around 100 a gallon but I mold ever thing even the slightest detail like the throttle sticks…Will post some pics latter but it has around 50 something molds to it.. going to be hard geting them all in one shot.

FYI the 60 I use for my molds I can use foam plates derpon etc has a temp rateing of 450f..but I'm a sucker for detail and have not achived what PU gives me a resin like finnish does not matter how deep or how narrow the lines are I have to watch becuase it will even pick up my figure print on the plug if my hands have a little oil or dirt on them.
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Last edited by aerogel; Oct 20, 2010 at 07:20 PM.
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Old Oct 20, 2010, 07:50 PM
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All good advice, thats why i go over the master under a light to make sure there are no prints or any other imperfections, with the epoxy molds i have been able to achieve just as good of a finish and detail as pu foam, the drawbacks are, you cant get everything on certain planes, (undercuts) so those parts are separated and cast in pu foam.
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Old Oct 20, 2010, 08:32 PM
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Would have to see it Hillman, finished I have not come close enough to what I call resin quality useing db,dp,etc where one cannot tell plastic/ resin from foam…don’t get me wrong there are many disadvantages to PU weight being one of them it’s the skin but that also where the detail comes from.I can mold 1/144 scale and get the panel lines and rivets without any additional work a secret project I’m working on : )
Another great thing is its all ready pre shaded and painted I just do the final touch ups in the build.
Any hoot I was wrong around 75 molds for the Stuka lot of work here a few pics and some pilots note the flash has not been trimmed out yet…
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Old Oct 20, 2010, 08:43 PM
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Thats one reason i dont plan to do larger planes anytime soon... too many molds

I guess one would have to see it, never could achieve it with db, but have now with the depron, when say its like a mirror i mean it, cant tell the difference between a plastic part and a molded one, not a single microscopic dimple. Im not BS'ing i know what perfect is, Its basically just like light weight plastic part. Theres no way i can get a photo of it, i tried, camera wont pick it up properly.
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Old Oct 21, 2010, 01:19 AM
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one of the main reasons is that you are going veryx deep in detail - compared with the Alfa or FSK planes which are consisting of 2 bodyparts, 4 wing shells and 2 to 4 rudder shells ... bit plywood and that is all.....

Aerogel - how about the wing parts ... there is some stange line all over the plug ... did you apply the splitter camo schemme to the panellines section ???
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Old Oct 21, 2010, 01:23 AM
Build it again, Sam!
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one of the main reasons is that you are going veryx deep in detail - compared with the Alfa or FSK planes which are consisting of 2 bodyparts, 4 wing shells and 2 to 4 rudder shells ... bit plywood and that is all.....


- You use PU for forming ??? would be curious to see a detailed process description of the workflow which leads o a part !!!
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