Making casts, casting pieces

[Hidronax]

*sorry for any grammar mistake, English is not my mother language.

Hello everybody. So, I've always been intrigued with the idea of making pieces in colors that LEGO hadn't released. Painting or dying pieces wouldn't satisfy me though, I want as few differences from the original pieces as possible. So, I was considering making castings with silicone (there are many videos on YT) and melting LEGO pieces for the plastic.

I know, LEGO has plenty of expensive machines that inject hot plastic at high pressure, but I wanted to try nonetheless.

I wanted to ask you if you have any tips or information, or if you know of someone who tried something like this. There are many persons who tried making lego pieces, but I know of noone trying to do it with actual lego plastic.

At what temperature do lego pieces melt? (here they say 105°C)

Will they burn before they melt?

What are differences between the different plastics used by LEGO? (Like transparent pieces not being made of ABS plastic)

What are the dangers (like poisoning) when attempting something like this?

How much will it take to the plastic to cool down and solidify? Will it solidify while casting it in the mold?

Is there any reason why the result might be not satisfactory?

I heard of someone who melt lego plastic with acetone and then used it for castings, it didn't end well.

I wanted to try a purple Miru Mata (worn by Damek the Matoran), post your thoughts.

Edited July 30, 2015 by Hidronax

[emilstorm]

I have had the same idea often :) it is definedly possible not as easy as it sounds. I don't know what temperature is required, but if you google ABS plastic it should come up. You will need to do injection molding and silicone molds will not do for that, you will need metal ones. Having molds made will be really expensive unless you know somebody who does CNC. Last time I searched the web for manual injection molding kits I could only find one, I forgot the name but it should be easy to google it. Once you have everything together the process itself looks quite easy, and the melted plastic hardens up almost instantly. Actually brickarms started out doing it this way, grinding up black 1x2 bricks and manually injecting their little guns in one single mold. And they are doing pretty good now :)

http://www.easyplasticmolding.com here it is:)

[Hidronax]

I was thinking of putting the pieces in a metallic funnel connected to the mold, and then heat everything up to about 120° in the oven. Plastic should remain liquid and enter the mold, or so I hope.

The silicone I'm going to use to make the mold can stand temperatures of 250°.

I can't afford injection molding sadly, that would be way out of my budget.

[emilstorm]

The problem with silicon is not the temperature but the pressure from the injection. Unfortunately you can't just pour it in because it is too thick and it would start to harden before it fills up the mold. Instead of pure metal molds you can make molds in epoxy encased in metal, much cheaper and you can just have one metal holder thingy and different epoxy inserts. But you can't really get around the injection if you want to use ABS and have good quality. Another solution could be resin casting which is much easier to do at home :)

[TheOneVeyronian]

Sadly I can't offer any advice with casting in ABS as I've never attempted it, but funnily enough I'm also attempting to mould custom Kanohi using silicone moulds, and I'm using resin casting methods instead, which is relatively cheap (well, the resin I'm about to suggest retails for £12 for 150ml and the silicone paste I use is another £12 so it depends on what your definition of cheap is ) and definitely easier than casting with ABS. If you ever want to cast translucent pieces in the future, I can recommend Pebeo Crystal Resin to do a good job, if you can wait the 24+ hours it needs to set that is, and you may have to repeat it in order to get a complete mould (though that might not be a problem with a Miru). It sets completely solid and the end result is very durable. Similar resins should do solid and pearl colours, and my advice would be to do some research into how to mix your own colours so you can try to match LEGO's colours as much as possible.

But if you want to use ABS then it's really as emilstorm says, and I'm sorry I couldn't be of much use. Either way I wish you luck in your project and would like to see what you can get out of it. I always love to see custom Kanohi

[Hidronax]

Yeah, if I can't get to use ABS I guess I'll try to use some resins and mix colours to get as close to LEGO's as possible. Still, I liked the idea of making pieces in the same material as the original ones :(

I was also considering painting/dying, should I fail to obtain an acceptable color.

I wish you good luck with your mask too TheOneVeyronian, may I ask which one you're going to make?

Emilstorm, why would the plastic harden? I'd pour it in the mold while it's in the oven. It should work just like a normal resin, wouldn't it?

Just imagine mold, funnel and pieces inside the oven. The oven is turned on, then the pieces melt and the liquid ABS enters the mold, while the temperature is 120°. Eventually the temperature lowers and the plastic hardens.

I have no experience at all so I trust you if you say it's not gonna work, I just wanted to know why.

Also, I don't know if LEGO in the oven could release toxic fumes.

BTW thank you for replying.

[TheOneVeyronian]

I wish you good luck with your mask too TheOneVeyronian, may I ask which one you're going to make?

I'm trying to make some of the 2015 masks in blended gold / trans, and transparent varieties that LEGO haven't done. So far I've only made moulds for the Gali, Tahu and Skull Spider masks and have only tried to make them in transparent, because my money at the moment could only stretch to buying clear Crystal Resin and 100ml of silicone moulding paste. Still need to buy some coloured varieties of resin, but don't want to invest lots of money into coloured resins until I've perfected the casting technique

[emilstorm]

If you do it all inside the oven it will probably to harden, I just am not sure you will be able to get it in there and get a good result. I think the melted plastic will be to thick and you will get massive bubbles in there.

But it is worth a try of course, maybe try and shake it a little and bang it against the oven bottom to get rid of bubbles. I wish you the best of luck with it and really hope you can make it work, I will definedly have to try too if it works :)

[Hidronax]

Thank you :)

I will post when I have some news, for now I don't even have the silicone. If anyone wants to try / has tried / knows of someone who tried something like this, leave a post!