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Casting; 1 piece or 2 piece?


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Hi,

So I was missing some parts from a newly purchased kit and thought to simply duplicate them.

Yea, boy, what the hell did I get myself into?!

At any rate, got my fancy shmancy Alumilte Super Cating Kit.

Is the part below (A7 and A8) a one piece or two piece?

Based on documentation in the kit, it sounds like this one would be one piece.

Thanks in advance.

post-14706-0-37772700-1434858167.jpg

Edited by aurfalien
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To get parts with all those undercuts, and to maintain that thin section, you'll most likely need to do two-piece molds, because the inner surface of the part has to be molded as well. Impossible to do those in one-piece molds...unless you don't mind the parts being very thick in the middle, and having to do a lot of grinding / trimming after de-molding.

This is a difficult one to start with, for sure.

You have to learn to think inside-out and backwards, and it can be frustrating, disappointing and tricky. It can also be very rewarding when your work pays off, and you get perfect replacement (or totally new custom) parts.

Edited by Ace-Garageguy
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If you don't mind them being quite thick, it's possible.

You'll be placing the detailed surface down for molding, meaning that in order to get those end panels, you'll have to fill the mold to the level of the edges of the long sides. This will mean grinding material away from the curves in the end panels after the resin is cured, but it will work.

Edited by Ace-Garageguy
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If you are missing the parts, what will you use as the masters? Usually you have an existing part either kit part or scratched and you make your mold around that.

X2...you must have a part to make a mold. Every once in a while, someone would ask me to cast a part they needed...I'd ask them if they had one, and they'd say "I've got the one for the other side" or something like that. Unless the "other side" part was exactly the same, it's of no use. It's not like you can turn the mold inside out and use it to produce a mirror image part.

Too, if you need only one of a particular item, in most cases it will cost less to simply locate another kit as opposed to making molds and casting parts.

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X2...you must have a part to make a mold. Every once in a while, someone would ask me to cast a part they needed...I'd ask them if they had one, and they'd say "I've got the one for the other side" or something like that. Unless the "other side" part was exactly the same, it's of no use. It's not like you can turn the mold inside out and use it to produce a mirror image part.

Too, if you need only one of a particular item, in most cases it will cost less to simply locate another kit as opposed to making molds and casting parts.

As Mark said, these parts are directional; casting them would be a waste of resin.

If you were casting this part, and it didn't matter that it was a thick part, you could get away with a one-piece cast but it might not clear body work or frame sections.

Edited by Relic_Models
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To carry this a bit further: An RTV rubber mold only captures the shapes and details of an existing part, "exisiting part" being the operative term here. It can reproduce that part exactly, but it cannot make the part if no original part exists. Think of it along the lines of a camera: A camera takes a picture of something it sees--if there is nothing out there in front of it, it cannot create something "from whole cloth".

As for whether a mold for casting in resin should be a one-piece or two-piece affair, virtually always a resin reproduction of a model kit part done in a simple one piece mold will not match the original exactly, as all injection molded model car parts have two sides to them, both from a two-piece steel mold. A lack of a properly reproduced side of a resin part will make that part harder to make work with when assembling on or into the rest of the model kit.

Making a two part mold for resin casting does take a bit more time, but the results are well worth it. In fact, any resin-caster out there in the "aftermarket" worth his salt does parts in 2-piece molds, for this very reason.

Art

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I'd post in the "Wanted" section of this board for a pair of them! You already bought an extra kit so you can build on, and still have time to find a pair.

Consider the cost of the casting kit, it's probably not worth doing them. I'd only be making molds for rare obscure parts or ones I want multiple copies of.

Edited by Tom Geiger
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Although it isn't too difficult, it is something that you'll want to take a few steps back & think about, look at a few SMOOTH-ON videos on Youtube for help.Oh, keep in mind the stuff has a limited shelf life, which means you may as well do a few more things at the same time, before it expires. Keep the stuff far away from your paint area, you may end up with silicone contamination, which will result in fisheyes for all paint work. Also, as mentioned, if it is a part, or parts that aren't expensive, or difficult to buy perhaps just do that. Plain & simple, It is a seperate hobby.Worse comes to worse, If there is someone out there willing to do it for you for a decent price & in a timely manner

- go that route. :rolleyes:

Edited by Krazy Rick
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Actually, not to sound flippant or dismissive but based on this video it looks pretty easy;

Problem is I got the super casting kit and will look to exchange at Hobby Lobby. Its more of a process with it vs the kit referneced in the video.

At any rate I will post my results and am doing it in 2 piece.

Edited by aurfalien
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Actually, not to sound flippant or dismissive but based on this video it looks pretty easy;

Problem is I got the super casting kit and will look to exchange at Hobby Lobby. Its more of a process with it vs the kit referneced in the video.

At any rate I will post my results and am doing it in 2 piece.

Ya, that looks really easy, go with that :)

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Ya, that looks really easy, go with that :)

Yep, thats what I was thinkin!

Hope practise turns out like paper.

My only stress point here is Hobby Lobby as I already opened the kit and messed with the clay. I didn't bother looking at videos until after opening it and should have done research prior.

I would not have gotten this kit, it seems more of a real casting kit were the molds take 24 hours to cure where as the refernced video is more of an instant mold variety.

Edited by aurfalien
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Just an update, I've decided to keep my current casting kit as for the price, it has way more use.

Its a bit more work, like having to build a mold box but I'm in no hurry.

Its a complete and thoruough kit and shoud prove very useful.

I've other fromage that would be cool to cast so who knows.

Here it's video;

Edited by aurfalien
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  • 2 weeks later...

So I've managed to dupe the parts via a 2 piece mold. It was fun as I planned and studdied the directions for a while.

 

The originals are already painted while the duplicated parts are still in resin color.

 

I'm very pleased however there were a few air bubbles which will be coverd up by primer/paint.

 

I rushed it being afraid the resin would dry quicker then it did. I'll take more time during the next casting as the resin doesn't dry that fast. Plus I even refergereted it based on the directions for increasing its "in-air" time a bit.

 

 

 

 

 

Edited by aurfalien
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Thank you Ace-Garageguy!

Notice the painted parts actually have the Metalizer Alumium on it. I'm going to give it a full day before lightly buffing.

I followed your queue on priming and then wet sanding. I did a test spray on bare plastic and didn't ike it much, so your method is the one to use.

I did notice Metalizer cracks when painted over putty even though that putty was painted over by primer. So I've elected to use Zap-A-Gap instead of putty to fill gaps that are being painted with Metalizer.

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Get the Super Cating Kit at HobbyLobby for 40% off and watch the video/read the enclosed directions and tips.

The tips in paricluar are very cool, like using talcom powder to ease surface tension, warming the mold, how to mix the resin like A into B in avoiding bubbles etc...

Very well writen all around.

Alumilite made it easy for us.

Edited by aurfalien
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