SBS making moulds and casting resin

[Caranthir]

Hi all,

A few months ago a few of you asked me if i could do a sbs on casting resin. It took a bit longer than planned . But here it is

First of all, this is the way i learned it. Some of the moddelers who cast resin themselves may do it a bit different. And of course this is not the professional way . I hope that with the help of the text and pictures you have enough info to start casting yourself. And if not, you can always ask me. For the pictures i'm using different sized moulds. Makes it's easyer to make a sbs.

Second, there wil proberly be some words of wich i don't now the english translation.....sorry for that.

But before we start, safety first!


Hope that didn't scare you off LOL

It's always important to have a mouthpiece as on the picture and some thin rubber gloves. Resin is't that good for your health. With these things and a good ventilated room it should cause a problem. As you can see on the pictures i didn't use rubber gloves.....i need to buy some new ones.

Part 1, making the part ready forthe mould.

I haven't made pictures for this so i'll say it in words. The part wich you are going to cast needs a casting block. Not to big, not to small. Try to make these on the side of the part wich you won't see after it's glued on the model. But do remember the casting block needs to be big enough to get the part out of the mould.

Part 2, making moulds.

For this you need rubber and hardener. You should be able to buy these at model shops.
To make a mould i use lego blocks


and clay


I start with the lego blocks to make the size of the mould. The bottom is then filled up with clay. And on top of that comes the part sicked with bleu-teck on a piece of plastic. If you don't put the clay on the bottom the resin will go under the plastic card and if it works out bas the part you're planning to cast wil not be completely covered, I will show his later on.


Then some more lego blocks on top to make the final height of the mould, and take these of again.


When the mould is done you can use the legoblocks again to put the mould in when casting resin. This should reduce warpage.

In a metal cup i make a mix of the rubber and hardener. With a spoon i mix these two. When you're done making the moulds just leave the rest of the rubber in the cup. When it's dried you can pull it out. As you proberly make to much rubber for the mould(i always do) make sure you've got a few parts ready for making moulds. It's a waste to throw away that rubber. And if you've go a part wich is not completely covered with rubber....no problem, when it's dried you can put new rubber on top of it.


Now i'm using a wodden toothpick to put some rubber below the part. In this way i hope i won't get any airbubbles. As you can see i'using the radio wich i made for my YPR 765.


When the bottom is filled....


.......i put on the rest of te lego blocks......


.....and with the toothpick i put some rubber on the controlpanel of the radio to make sure there won't be any airbubbles.


For the rest of the mould i'm dropping in the rubber with the spoon


And done.As you can see the rubber tops out of the lego blocks. But that's no problem.


The rubber will find it's way through the legoblocks as you can see. And that's why i put some clay on the bottom of the mould.


The excess rubber can easily be pealed of.


And you're mould is finished.

Now you can also make two part moulds. I can't tell you anything about this because i haven't tried this myself. Maby sometme later.

[Caranthir]

Part 3, casting resin.

For this i'm using these tools:


The point of the needle is filed to minimise any damage in the mould.


I cut off the lower part of the plastic cups and going to use these for mixing the resin.


The resin(A & B) i've got in 1 liter containers. So i took two empty tamiya paint bottles and filled these up with resin. I do this because the resin needs to be stores at low temperatures, and it is told to me that opening and closing the large containers is not good for the resin. I don't know if that's treu but to be certain....... And it's easyer to use the small paint bottles than the large containers.

With the long plastic things(sorry, don't know the word) i put the resin in the plastic cup and stir it with a piece of spreu. With the needle i suck up the resin and start pouring it into the moulds. Do this very carefully. I wasted one of my shirts from my work as i pushed to hard on the needle. Nothing else happened as i used thin rubber gloves. But the shirt i could throw away.


And of course make sure you've got more than one mould ready as you would proberly make more resin then needed.

One mould filled up


I still haven't figured out how i could minimise the airbubbles. What i do know is it takes practise. This mould is for the seat parts of the YPR765 and i'm squizing them gently to get out the airbubbles.


This part isn't completely filled up. No problem. Leave it to hard, you can put new resin on top of it.


And when the part is hard, pull it out carefully. And as you can see this one got some airbubbles . Sometime on ML i read that a guy used talkum powder to reduce airbubbles. I tried it to with this radio and it didnt work. So i have to try this a few times.


Well, i think i wrote down everything you should know. Got any questions? just ask them.

Regards,

Richard

[Larry Bates]

Thank you Richard,

I have some wheels for an 8.8 cm pak 43/41 that I'm going to cast soon. I have already done the rubber mold and still need to cut in the passages for the resin and the air. I'll post when I have it completed. Wish me luck they are 2 part molds!

Larry

[tamigawa]

good tutorial! The "long plastic thing" is called a syringe BTW.

[MartinD]

Richard,
You might want to try a tupperware box, with a hole cut in the lid. Use a vacuum cleaner hose to suck the air out. I picked up this trick from an old article in MM, say five years ago.

HTH, M

[Caranthir]

Thanks for the comments guys.

@ Martin: Thanks for the tip, i'll try it.

Regards,

Richard

[Larry Bates]

Originally Posted by MartinD

Richard,
You might want to try a tupperware box, with a hole cut in the lid. Use a vacuum cleaner hose to suck the air out. I picked up this trick from an old article in MM, say five years ago.

HTH, M

OOOH,

I'll also be using that trick!!!!! Thanks Martin.

Larry

[Panzergrenadier]

Great reading and pictures, very informative.


Siim

[Sturmmann]

Very nice tutorial Richard.

Talcum powder does reduce bubbles, but it depends on the resin you are using. Since what talcum powder does is reduce the surface tension of the resin, it works better on some resins than others.

One thing I do (this is more complicated) is to make your moulds spin. I made a centrifugal machine out of an old record player. What happens is while the mold is spinning centrifugal forces act on the air trapped inside and literally pull the bubbles toward the center of the piece. That way they wont be visible on the surface. The only drawback is that it doesn’t work on thin pieces.

Dave

[Caranthir]

Thanks gents, and thank you Dave for the tip. It should'nt be a problem to find an old record player and turn it into a centrifugal machine. But i do have a question. Do you use the speed of the record player or have you made a modification for a higher speed?

regards,

Richard