# Casting tips.



## FOSTBITTEN (Aug 1, 2013)

I wanna try & see if there any tips out there with you all that can help us all.

My Mother gave me an idea a week or so. She said to put a little baby powder in the mold just enough to dust it. This seems to help with bubbles & getting your casting out a little easier. She has a friend that makes jewelry/beads & does this every cast.

She also told me to heat the mold everytime I cast. She told me to heat the mold the 1st time in the microwave for a minute & then 30 seconds everytime after that. 

Also do not cast on a rainy day, I dunno if this works or not never tried it.


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## FOSTBITTEN (Aug 1, 2013)

Also I would like to know how do you put chassis mounts in a body? I have some ideas on how to do it but, I am just puzzled on this one.


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## 60chevyjim (Feb 21, 2008)

are you using a 2 part mold , what chassis are you using.. for tjet chassis I use 
plastruct # 90863 styrene rod 4mm. I get on ebay ..
and I use super gel glue from dollar tree to install the screw posts.
mount your posts to the chassis adjust the height then superglue the body on them.
make shure to clean and skuff the body and the posts. if your making 2 part molds then put the mounts on your master and then every body you make will have mounts. 
if your using a afx chassis hilltop has a post that shows how to make afx body mounts
happy molding !!


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## bobwoodly (Aug 25, 2008)

First off I am far from an expert but do occasionally cast small parts.

Both heat and baby powder are suggested by the resin makers. Mine suggested a few seconds in the microwave as a way to warm up the molds. I think the baby power helps to make the resin flow better to reduce bubbles.


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## FOSTBITTEN (Aug 1, 2013)

60chevyjim said:


> are you using a 2 part mold , what chassis are you using.. for tjet chassis I use
> plastruct # 90863 styrene rod 4mm. I get on ebay ..
> and I use super gel glue from dollar tree to install the screw posts.
> mount your posts to the chassis adjust the height then superglue the body on them.
> ...


I think the bodies I have made will work on a t-jet. I don't know for sure because I do not have any t-jets. I am making 2-piece molds.

I need to get more molding rubber because my mold ripped pretty bad in several places yesterday.


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## Hilltop Raceway (Feb 12, 2006)

Still learning here myself... What is the principle behind warming the mold??? I know the resin itself produces heat during the chemical process when you mix it...
Also if you need some posts, take a soda straw, clamp one end, then pour resin mix into the straw. Pour at an angle to let the air out. After it dries, carefully drag a blade down the tube to remove the plastic straw. Makes good posts in various sizes...RM


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## FOSTBITTEN (Aug 1, 2013)

I do not know what the science is behind it either. But I know my castings that did not go in to a warm mold seem really flexible & thinner than the other ones. Almost like they never set up & harden. Maybe it has something to do with the different types of resin used. I use the resin from a Alumilite kit.


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## slotcarman12078 (Oct 3, 2008)

Starting with a warm mold gives the resin a kick start in the curing process. If the heat generated by the resin itself gets absorbed into cold silicone, the resin won't cure completely because the heat is an essential part of the curing process. .


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## FOSTBITTEN (Aug 1, 2013)

slotcarman12078 said:


> Starting with a warm mold gives the resin a kick start in the curing process. If the heat generated by the resin itself gets absorbed into cold silicone, the resin won't cure completely because the heat is an essential part of the curing process. .


:thumbsup:


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## pshoe64 (Jun 10, 2008)

I use a pressure pot to pressurize the silicon as it cures as well as the resin casts. I make my mold walls at least 1 inch thick on all sides so they do not distort under the pressure. I make 2-part molds and include vent lines on the sides and middle of the "male" portion of the mold. I usually pressurize the casting at 30 PSI. That crushes any air generated by the mixing process or pockets in those hard to reach spots of the mold. The vent lines allow that air a place to escape. I also use a mold release spray to coat the silicon molds before pouring. OooMoo30 is my silicon of choice and Hobbycast resin (tan) for my casting. Which reminds me, I need to order silicon....

-Paul


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## FOSTBITTEN (Aug 1, 2013)

Nice tip Mr.Shoe! I got a friend that has a pressure pot & he owes favor too.

Has anybody used Legos for a mold box?

Has anybody used dyes before? Anything you would like to share?

I tried green food coloring once only one drop it made the cast the color of key-lime pie. It casted really good. So I tried 3 drops & it was not good at all. This was also the casting that I ripped my mold. So DO NOT USE FOOD COLORING! It foamed a lot too, it looked like a green volcano.


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## alpink (Aug 22, 2010)

I use LEGOs for custom size boxes.
and yes, oil base hobby paints make good dyes along with dyes available from most resin providers.
if you use white or tan base resin, your colors will be like pastel.
if you use clear or dye ready resin you can get brilliant colors like Randy(hilltop) has been exhibiting.
always make sure you use mold release (can be PAM or even Vaseline) between mold halves when creating the second (usually male) part of the mold.
I have forgotten more than once and destroyed perfectly good molds because

water does NOT get along well with resin, thereby food coloring being a problem

Oh Yeah, tints, dyes, powders designed for candle crafts usually work well with most brands of resin


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## FOSTBITTEN (Aug 1, 2013)

I started making the 1st half of a mold today. So it is a good reminder for me to use the release. 

Prepping your piece that is going to be casted is also very important. I spent about 2 hours today getting my new body cleaned & sanded down so nothing will transfer into the mold. I use clay for the underside and you really have to make sure it is clean before you pour that mold.


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## 60chevyjim (Feb 21, 2008)

micromark and hobbyloby sell the same resin tints , but if your using white resin you will get pastel colors with them . if you use clear resin with them then you will get translucent colors .that's good for tinted windows .
I think my buddy kirk told me that uses smooth on tints and says they will give you much darker colors even with white resin. like the colors hilltop is doing !!


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## FOSTBITTEN (Aug 1, 2013)

alpink said:


> always make sure you use mold release (can be PAM or even Vaseline) between mold halves when creating the second (usually male) part of the mold.
> I have forgotten more than once and destroyed perfectly good molds because


I almost forgot to put the release agent on my mold this morning. Then I almost forgot to to put it on the open section for the windows. I guess that is a product of being in a hurry. So slow down when you mold, is one tip I cam pass along this time. 

I also wrote down how much silicone I used & what size the box was that I used. Along with times between molding. And the date. I probably will not remember any of this unless I write it down. So keep notes is another tip I have.


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## bobhch (Apr 22, 2007)

Quick and dirty...






I searched Google: casting slot cars video

http://www.alumilite.com/howtos/SlotCarCast.cfm

casting slot cars video

A Hobby Talker did this video:






You never know what you will find until you search.

http://www.ask.com/youtube?q=casting+slot+cars&v=S-P6IID9eTg

This last video shows a 2 part rubber mold being made by mixing 2 color rubber mold material in your hands. 
This is a real fast way to make a part and does not require a mold box and 
you can pour your liquid resin into the mold in a very short time as these molds set up FAST!! 
I like to use a very smooth surface and push material around item being casted. You can cut off any part of this mold with an X-Acto Knife if needed.
This type of mold material can be found at Hobby Lobby. I believe it may or may not be with the pourable stuff? It may be in a different area. Sometimes people use this to make jewelry beads and the sort.

I use Legos for my mold boxes to make a 2 piece mold. 
Starting with a large flat lego base I build my box and clay up my body to be molded and then insert it carefully in my box

Have found out the hard way that Square type bodies (like an Honda Element) come out harder from the mold so, I built a Pyramid under my body to be casted up from clay. 
This allows room for the casted resin body to come out of the mold.

Before I mix my resin I hang some strips of masking tape from my table edge.
These strips of tape will be used to wrap around my mold to keep it together.

I heat my mold in the Microwave for a min. before starting the first time. If I am molding more then I just keep going and let the resin heat up the mold. If I take a break then the mold gets heated up again.

I always wear gloves and put clear packing tape on a large piece of cardboard for my work area.

For me casting has been a neat way to have slot cars that I have made and have in my collection, my friends here on HT get my extra bodies to have fun with also. 

Building slot cars from resin cars that others have casted is a rush too. 

Bob...I was born to have fun...zilla


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