Model resin casting starter kit options?

[Dave V]

I discovered that at some point a press-fit piece on one side of the rear truck from one of my Galloping Geese disappeared. Already checked the HO scale detail casting catalogs and nope, not available. I doubt Con-Cor has any parts left.

Anyway @Ed Kapuscinski suggested this would be a fine excuse to start resin casting. I have three Geese, which means I have 5 of these parts still on hand to serve as a master. And if one fell off, more might fall off some day in the future.

So, Micro-Mark's resin starter kit (because the 2-part mold rubber is out of stock). What else have folks used? A starter kit would theoretically be ideal, but if I need to mix n' match, I can do that too. Happy to take recommendations. And is it worth it to use black resin dye for a part that needs to be black?

[Chris333]

I cast resin in my printer     I do remember casting and it kinda sucked. Had to have the right weather or it came out all sticky.

[Rasputen]

First of all, what does this part look like??

Although you can tint resin, making parts that are truely black can be problematic.  There are some products that are already black, but they contain a lot of filler and are somewhat strange until fully cured.

Usually, casting resin needs to be used within 21-30 days of opening it, depending on the humidity.  Buying a whole kit for one small part sounds wasteful unless you really want to learn to make other things.

[Scottl]

Smooth on products are great.  You can get dyes to make castings any color you like. 

[Jim Starbuck]

I’ve successfully made small parts using Oyumaro mold making compound and Milliput epoxy putty.
The mold compound is a reusable thermoplastic that’s about the consistency of very strong pencil eraser until placed in boiling water for a couple minutes when it gets  to warm bubble gum softness. Press your master part into the compound and let it cool to make the mold. The compound won’t stick to your part.
I’ve made open face molds for truck side frames and the cab faces for my Model 40.  You can also make two part squish molds with it for more complex shapes like Milwaukee Road spark arrestors.
It’s cheap, has no odor, reusable , quick and great for making one-off parts. Although I’ve never tried it, I think you could make a two part mold with filler gates cast in like a silicone mold and use liquid resin.
There are plenty of YouTube videos on it.  I got mine online but I think it’s available at Hobby Lobby.  I’ve also used JB weld two part epoxy as my resin with good results.

Jim

[peteski]

Over the years I've used resin and RTV from Alumilite, and ore recently from Smooth-On.  ALumilite originally only sold few products, but tat this point, bot companies have a wide range of casting products available.  Alumilite  used to see la small  casting kit which included the resin and RTV.

I've heard that Micro-Mark resin is just repackaged Smooth-On resin.  Like Rasputen mentioned, if resin is not fresh, it will not produce good castings. It will be full of micro-bubbles.  Moisture (humidity in the air) gets absorbed into the liquid resin and causes the bubbles.

I only cast simple one-piece open mold parts, but if you need a 2-piece mold, then you will likely have to get into vacuum or pressure castings.  You will need a vacuum pump and (air compressor and a vessel which can withstand vacuum/pressure. I suspect that is how Rasputen casts his amazing N scale vehicles.

If that's the case then you would likely be better off trying to find someone with the equipment whom you can hire to cast the part for you.

[Dave V]

This is what I’m trying to reproduce:

[ Guests cannot view attachments ]

[JeffB]

I cast resin in my printer     I do remember casting and it kinda sucked. Had to have the right weather or it came out all sticky.

Agree...  Zero humidity.  Don't try casting in your basement during late spring (especially if it's a very wet spring), summer and early fall (same applies).  Make sure the temp in the area you're casting in is fairly warm as well.

Had good luck when the air was real dry.  Also make sure that if you're using baby powder to coat your molds, that's bone dry too, even if the air is dry, any moisture in the baby powder will result in the resin having a lot of bubbles, which is counter to why you use the baby powder to begin with.

Lastly...  If you're mold has too many flaws (usually air bubbles or tears), make a new mold.  You don't want to have to fix every casting that comes out of a bad mold, most especially if you're making a lot of castings.

Jeff

[Jim Starbuck]

Dave,

The Oyumaro / JB weld would work very nicely for that. Leave the part on a flat hard surface then press the soft compound over the top. This wouldn’t stress the delicate part. When cool, flex the mold a bit to release the master and you’ll have a mold to make as many of those as you want. Quick cheap and easy.

Jim

[Dave V]

Dave,

The Oyumaro / JB weld would work very nicely for that. Leave the part on a flat hard surface then press the soft compound over the top. This wouldn’t stress the delicate part. When cool, flex the mold a bit to release the master and you’ll have a mold to make as many of those as you want. Quick cheap and easy.

Jim

Um...how do you then make a part with detail on both sides? The only thing I care about on the side that faces the Goose of course is the mounting hole.

Agree...  Zero humidity.  Don't try casting in your basement during late spring (especially if it's a very wet spring), summer and early fall (same applies).  Make sure the temp in the area you're casting in is fairly warm as well.

Had good luck when the air was real dry.  Also make sure that if you're using baby powder to coat your molds, that's bone dry too, even if the air is dry, any moisture in the baby powder will result in the resin having a lot of bubbles, which is counter to why you use the baby powder to begin with.

Jeff

LOL, humidity is literally never a problem in Colorado Springs. Ever. Seriously. Never ever. Today's about as humid as it gets with an indoor relative humidity of 26%.

So now that we're not worried about moisture in the air, does that make my prospects better for doing this in resin?

[Jim Starbuck]

Ah, I see it now. I wasn’t clear on your photo. I thought the part was flat on the back but it needs the post that presses into the truck.
You could do a two part squish mold and use epoxy putty or make an open face mold for both the front and back then glue the two pieces together. It might take a little rub on some 400 grit to make the backs nice and flat so they mate together well.

[Sokramiketes]

Low humidity helps, but never a problem once you start using a pressure pot. 

Where did DKS post all of his pressure pot casting advice when he was doing NZT products?  That's the threads/posts to find.  Buy a real pressure pot, buy the trial size Smooth On rubber and resin straight from Amazon.  Enjoy casting. 

Open face molds, no pressure pot, lots of casting bubbles, aggrevation, give up... 

[Dave V]

Yeah, lots of new words here that I've never heard before.

You guys did accomplish your mission of dissuading me from even attempting, LOL.

[chessie system fan]

I used smooth-on products and had good success even though I basically lived next to the Gulf back then. The trick was turning a Harbor Freight paint tank into a pressure pot.

But that part is so thin, that might be too fragile for resin casting anyway.  3D printing with the new flexible resins available would be what I would do if it were mine.

[Jim Starbuck]

Where else but Railwire can you ask what time it is and receive multiple instructions on how to build a watch? HaHa