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Modeling in General: Advice on...
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Need help with Resin Casting
csosus
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Texas, United States
Member Since: March 21, 2011
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Posted: Saturday, October 01, 2011 - 03:42 AM UTC
Hello all,
I need some help/advice on resin casting. I am copying some resin interior sets for my Pz IV interior. I am using Alumilite casting resin (white) and I'm having problems getting the resin to flow down into the smaller parts such as the 1/35 scale 7.5cm ammo and the turret basket support bars and other small parts. The resin, when mixed, has the consistency of very thick syrup and traps the air in the mold and won't flow down into the mold. I have heard of cntrifuge machines and pressure pot casting but I was hoping to maybe find some other type of resin that is thinner when mixed, some type of resin that will flow similar to water. I would rather try a thinner resin if available before I invest a lot of cash into a pressure pot and/or centrifuge machine.

If there is a thinner resin on the market that anyone could direct me to that would be great. Otherwise, I need some advice on which other methods I could try. I've read about centriguges and pressure pots but I'm not sure that either of these methods will solve my problem.

Any suggestions and advice will be most welcome.
Thanks in davance,
Cory
Red4
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Posted: Thursday, October 13, 2011 - 11:47 AM UTC
Check Smooth On products. They have a huge assortment of resins to choose from. Barring that, pressure casting is your best bet and would be the route to go even with a thinner resin. Small pockets of air will be trapped regardless of how thin the resin is. Pressure casting will force the resin into these little pockets so that you have more consistent castings. I found the Alumilite cured far too fast for my tastes and gave up on it years ago. I only use Smooth On now. Your mileage may vary
Something that goes hand in hand with pressure casting is putting your mold material under vacuum prior to pouring it so-as to remove as much air from the mold as possible. It is another step, but it helps reduce the amount of voids introduced into your molds by air trapped when it is pored.
I did a quick tutorial on pressure casting several years back. If you look under my profile, it should still be visible. It might help and answer some questions for you. Good luck with your castings.... "Q"
ps. You can assemble a workable pressure casting system for well under $100 if you shop around. I got everything I needed for mine for about $50 or so...minus the compressor which I already had on hand. I have since revamped my set up since I posted the pressure casting tutorial...
oldbean
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Virginia, United States
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Posted: Thursday, October 13, 2011 - 12:23 PM UTC
I helped out a friend who had an aftermarket business a few years ago and here are a few of the things we did. Heat up the mold. Put it in the oven at about 275 for around 5 minutes or so. You can also coat the mold with corn starch/baby powder. Pour some on, work it into all the cracks and crevices and then turn the mold over and dump it our so there is only a thin layer in the mold. The powder helps draw the resin down into all the lower areas. You can also put the mold under vaccuum after you pour the resin. This draws out all the air in the resin and the mold.

HTH,

Jesse
matt
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New York, United States
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Posted: Sunday, October 16, 2011 - 11:54 PM UTC
I will also second Smooth on's resin.

As well as Matt's other Ideas. I too also pressure cast. the other Idea is to try a and have a void or some vent lines for the resin to flow into and help.
slodder
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Posted: Monday, October 17, 2011 - 01:08 AM UTC
One thought is vibration? Never tried it, never heard of anyone using it. Maybe you could put the mold on top of a hand sander with no paper on it and vibrate the freshly poured resin into the nooks and cranies.

Cheap and easy (if you have a sander)
PunyViking
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Akershus, Norway
Member Since: November 02, 2008
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Posted: Monday, October 17, 2011 - 10:07 PM UTC
I use a rumble-part from a old playstation controller. If you have a old controller somewhere, disassable it, remove the motor and wires, connect to 5V and press it to all the sides of the mould. The bubbles would make it's way to the top of the mould in no time!

I have a friend who used his girlfriends "toy" to vibrate away the airbubbles with good results!...
ludwig113
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Posted: Thursday, October 20, 2011 - 07:18 AM UTC
i had a look at the smooth-on website, there are some good tutorials on there, i can get the stuff in the uk so i'll be try it as well.

paul
jasmils
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Queensland, Australia
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Posted: Thursday, October 20, 2011 - 01:31 PM UTC
Cory,
http://www.ammsbrisbane.com/newsletter.htm#
Go to August 2009 and see my casting workshop.
The product I use is not from the same place you got yours, but the principals are the same.
Also there is plenty of casting advise here on Armorama.
https://armorama.kitmaker.net/forums/182041#1528643
https://armorama.kitmaker.net/forums/172767#1452139
Or if it is all to hard, here is another option.
http://www.armscorpsmodels.com.au/Custom_Casting.html

Cheers Jason
csosus
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Texas, United States
Member Since: March 21, 2011
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Posted: Friday, October 21, 2011 - 01:58 AM UTC
Thanks to everyone for thier advice. I am going to give it another go this weekend. I want to try the pressure casting method, but that will have to wait until I can afford the equipment.
@Jason - really liked your tutorial and thanks for the link (other good stuff there too). One question. The Alumilite instructions say to heat the mold in the microwave or oven before pouring the resin. I know you are using different products, but do you think that skipping the mold heating might help? I think that part of my problem is that the resin starts to cure before it can get down into the mold. I think that when the mold is warm it speeds up the resin curing. The parts I am trying to cast are small, like 1/35 7.5cm ammo. The resin is too thick and traps air in the mold (not flowing down into it at all past the "neck" of the casting block) and starts curing in under 1 minute. I am going to try and use a "cold" mould and try and prick the resin down into the mold with a piece of wire or something.
I will post my results next week
Thanks again everyone, much appreciated.
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