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Casting- what to get to get started?


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I'm looking into getting into casting parts, seems like this is what I need to get to the next level of modelling. Copies of scratch built details/parts, whatnot and am wondering what do I need to get started and where ot get it? I've seen, and I forget the name of it (Aluminite or somehting), sets at the local Hobby Lobby, but don't know anything about it.

Does anybody have any recommendations or directions they can point me in as a newbie to get started?

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Alumilite has a starter kit for about $30. It'll provide mostly what you need to get started, including 2-part resin, 2-part RTV silicone, mixing cups, clay (IIRC), and some basic instructions. Other things you'll need:

  • disposable latex gloves
  • flat styrene sheet for making mold boxes
  • Legos (not absolutely necessary, but handy for creating mold boxes)

I think both Alumilite and Smooth-On have tutorials on their websites. You can do some searches on ARC and Google for tips. Smaller pieces are often harder to cast without vacuum chambers/pressure pots due to the volume-to-air bubble ratio. You might use up your entire starter kit just on trial/learning, but I don't recommend getting large bottles of resin because it has a short shelf life.

Good luck.

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Fine Scale Modeler did a good article on resin casting a couple years ago (2007?), it was probably recent enough that you can get it from their past issues if you are patient enough to search through them.

Model Cars magazine is supposed to be doing an article on casting later this year.

Other than that Alumilite's tutorials are a good place to start.

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I am going through all of this right now. The stuff is expensive, but will pay off in the long run. TS is right about using up a starter kit figuring out what to do. I will give yo some pointers based upon what I have learned so far.

Forget Aluminite except for very simple casting. Aluminite resin has about a minute or so of open time before it starts setting up. Once it starts setting, that's it, your flow is gone. You have to work really fast.

I use Micro Mark RTV rubber. You can get two pounds of it for $30 plus shipping. It is a 1/1 two part RTV. It has about 10 minutes of stir/pour time before starting to set and will be ready for molding in about four hours.

For the resin, it is best to use the hardest, slowest curing stuff you can find. Micro-Mark CR-900 takes 16 hours to cure. You can de-mold in about 12. It is a 1/1 mix.

There are lots of molding tips/techniques out there if you search a little on the net.

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I would agree the Alumilite kit is only appropriate for starting out. It is really intended as a fairly inexpensive way to see what you are getting into. There are dozens of casting supply companies out there each with their detactors and supporters.

I use redicast from TAP Plastics a local supplier. The silicone gives me around 20-30 minutes of working time and cures in about 16 hours. The resin gives me about 3 minutes working time and is fully cured in about 15 minutes.

Once you start to understand what you are doing you can shop around for a resin that meets your needs.

I found the FSM article, it was May 2005 and FSM does still list it as available.

http://www.finescale.com/fsm/default.aspx?c=ma&id=1

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Fine Scale Modeler did a good article on resin casting a couple years ago (2007?), it was probably recent enough that you can get it from their past issues if you are patient enough to search through them.

Model Cars magazine is supposed to be doing an article on casting later this year.

Other than that Alumilite's tutorials are a good place to start.

I think I might have that article...... Do you want me to see if I can fing it?

- Brad :P

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http://www.modelingmadness.com/others/feat...fordhamglue.htm

Has anyone tried this? it seems promising...

Brad :thumbsup:

I've seen a number of cheap solutions, household silicone for molds, 5 min epoxy for the resin being fairly popular. These methods work fine for one off parts but can not compare to the quality you can get with actual casting silicone & resin.

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Prolly the biggest problem with starting up resin casting is simply Fear.

Knowing you only have one chance to get that Silicon mold right or getting each cast right turns a lot of people off from even starting, and to top that off the seemingly high up-front cost of the Resin and RTV scares a lot away.

Your best bet to start learning is the Alumilite kit that you can get at hobby lobby. Wait for the %40 off coupon and pick one up at a total of around 18 dollars. It gives you enough RTV to do some small molds and enough Resin to pop out quite a lot of pieces. It does not, however, include Mold Release so you'll have to buy that separately if you're doing a 2-piece mold. Just keep in mind the starter kit is aimed at a one-shot project so they don't tell you how to measure out the RTV and save some for later. Just do a 10:1 Silicon to Catalyst mix and you'll get the right ratio.

The resin that comes with the kit is fair. It can get a lot of good detail but one problem is that you can get a lot of air bubbles even if you follow the precautions (heating up mold, proper pathway to minimize bubbling). The reason this happens is because it cures so darned fast (~90 seconds) and it does not allow sufficient time to fully de-air.

Despite those short-comings, buy that kit and use it to learn, and then after you have the hang of it go for the good stuff like Smooth-on

Edited by Duymon
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I've seen a number of cheap solutions, household silicone for molds, 5 min epoxy for the resin being fairly popular. These methods work fine for one off parts but can not compare to the quality you can get with actual casting silicone & resin.

That is true. Unfortunately, not everyone can justify the high cost.... :woot.gif:

- Brad

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Casting to get good results is spendy. Good equipment and good resin/RTV are a must. Also, if you can't vacuum and pressurize the moulds you will have a lot of issues with degassing and thus creating air bubbles, voids, short casts, you name it!

It is a lot of fun once you have the correct set up, it is just getting their through trial and error that may put some off. RTV is massively expensive for good stuff and even when you buy in a good quantity, it does not go very far.

Cheers

Mike

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Really the only way to learn how to do it is to jump in and start. If I can cast, than ANYONE can! I really mean that, too. I'm not a risk taker, and I don't like trying new things. But I decided to do it because I needed parts. Using a starter kit is a good idea, but if you don't succeed with it, don't be discouraged. I was not impressed with Alumilite. It was okay at best. I had a very bad expericence with Smooth-On, so I'm somewhat turned off by them, even though I hear good things. It might be that I used one of their cheaper products. This was years ago. I use Vagabond resin and Circle K RTV, which I get from CRM Hobbies in St. Louis. I find it to be very easy to work with, and the resin is very thin when being poured into the molds. You'll also learn how to get rid of air bubbles using toothpicks and popsicle sticks. I don't have a vacuum chamber or pressure pot (see the first part of this post! :worship: ), but I still can get pretty good casts using the above mentioned "tools". Of course, I only do relatively small stuff. If you're going after something bigger, like fuselage halves or something, then the pressure pots will definitely be needed. It does seem scary at first, but the more you work with it and understand the mixing ratios and time limits, it starts to get easier.

Edited by Darren Roberts
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Forget Aluminite except for very simple casting. Aluminite resin has about a minute or so of open time before it starts setting up. Once it starts setting, that's it, your flow is gone. You have to work really fast.

Here is the proof!!

100_3302.jpg

100_3303.jpg

I think I'll try a different resin next time!

Steve

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One other piece of advice I would like to give is make sure to let your RTV cure for at least 24 hours, even if the box says 16 hours etc.... Allow that RTV to cure completely so your first pulls come out nicely. I have had more than one initial pull come out sticky in a mould left to cure 18 hours. The same "pour" was with another mould that had been used many times over and I had zero issues.

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Moldmaking and casting is a lot of fun once you get the hang of it. I've casted thousands of parts (no joke) that my spares boxes are always full. It doesn't take a genius to do it, but you gotta make sure its justifiable to yourself. Resin and RTV are expensive, with the latter eating the biggest chunk of money. Starter kits aren't a bad idea if your doing small, limited runs. More often than not, you'll run out of rubber before you do resin in those things. Other drawback is they don't give you enough rubber to practice/ get comfortable with.

I get mine in the 10lb container. Costs about a hundred dollars. Thats cheap comparing to buying rubber at Hobby Lobby for $30 a pound. They never carry more than 1 or 2 at a time also. I also have 10 gallons of water thin resin on hand. Resins come in different setting times, but you can mix and match those chemicals to suit your needs. Small, quick production stuff, I find that 2-3 minutes is enough. Larger pieces like hulls, and fuel tanks, 5 minute resin works best. Again, this is what works for me.

If your inclined to try on the cheap, a better choice than Alumilite is another product they make. I've seen it at HobbyLobby in the clay section. It comes in a yellow box I believe is called Cast n Craft. It comes in 2 8oz bottles, and flows like water. Only negative is it cures white, which I hate.

I'll second Darren Roberts on the products he mentioned; I used those said products in the past from CRM, and they work great. I currently use products from MPK Enterprise now. A vaccum pump and pressure tank are great to have, but not completely necessary.

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