CASTING PARTS???

[Seaboard Air Line Fan]

Just got the latest MicroMark catalog in the mail and spotted all the stuff they sell for mold making and casting parts.

I've done some mold making and casting using Smooth-On products, but have never tried casting using low temp metals.

Can the same mold be used to cast in resin or metal?

They show low temp metals that melt at 160 and 280 degrees, are there others and which one would be best to use?

MM usually has some high prices, any better place to buy low temp metal?

Things I'd like to cast (in resin or metal) are:

boxcar doors
roof walks
truck sideframes
bolsters
scenery parts (barrels, fences, signs, lamp posts)

MM also shows a product called Composimold which says can be heated in a microwave then pour over the master to make the mold, anyone ever tried it?

All this is on their pages 62-63 of the Spring 2017 catalog.

Oh for BobT...they also have plating kits on page 63, different kits for chrome, nickel, and copper.

[Rufus T. Firefly]

Can the same mold be used to cast in resin or metal?

In theory, yes, for low temp metals such as Cerrobend

They show low temp metals that melt at 160 and 280 degrees, are there others and which one would be best to use?

Hard to say.

MM usually has some high prices, any better place to buy low temp metal?

Can be expensive stuff - Cerrobend for example has cadmium in it and is mainly lead -- some of these alloys are just a bit on the nasty side and as such there are regulatory costs that drive up the price tag

Things I'd like to cast (in resin or metal) are:

boxcar doors
roof walks
truck sideframes
bolsters
scenery parts (barrels, fences, signs, lamp posts)

I already have molds for most of that list - just went through 2 lbs of resin this past week and starting in on the next 2 lbs - got 2 commissions that I am attending to now......

Why cast those parts In metal?

MM also shows a product called Composimold which says can be heated in a microwave then pour over the master to make the mold, anyone ever tried it?

Thermal setting? Probably not suitable for low temp metal casting,

[rrjjf]

Several years ago I used the Micro Mark products to make molds for passenger car under body ice box doors and battery box covers. I used one of the mid range temperature alloys to cast the parts and they turned out quite good. If I were to do this again I would use a lower temperature alloy because the higher temps damaged the rubber molds after a few uses. All of these alloys seem to be pretty expensive but maybe not if you really want to make some special items yourself. It is fun to play with.

Joe

[Rufus T. Firefly]

It is fun to play with.

Yes, indeed!

Someday I'm going to turn my hand to casting some parts in Cerrobend since I have a supply of that handy.

[Robert]

Always read through the casting stuff when I get my MM catalog. Still I never have been tempted to order any of it since I don't have any amount of casting to do other than perhaps to experiment with it for fun.

Now having said all that I have been curious as to the potential durability/flexibility of cast items, and specifically the spring planks that are found in Intermountain truck kits which I occasionally break while assembling the kit.

Robert

[Rufus T. Firefly]

..... the spring planks that are found in Intermountain truck kits which I occasionally break while assembling the kit.

Styrene, aren't they? Or. ABS? Either way, MEK would weld them back together.

Would a resin replacement be better? No idea, but the resin I use tends to be a little brittle when you get thin and expect it to flex very unlike styrene being a bit forgiving.

[Seaboard Air Line Fan]

Thanks guys!

There's a place nearby that sells Smooth-On products:

http://www.easternburlap.com/

Problem is Smooth-On offers so many types of rubber and resin it's hard to determine which products I want to use. In the past I've used the OOMOO 30 mold making material and Smooth-Cast 300 resin, but I need to email them to find out what would be the best for thin parts such as boxcar doors and if the OOMOO 30 will hold up to pouring hot metal into it.

[Rufus T. Firefly]

Thanks guys!

There's a place nearby that sells Smooth-On products

Drop me a note if you want to know what products I use, Bob.

[Seaboard Air Line Fan]

Will do Martin.

Here's what Smooth-On had to say:

Smooth-On Andrew Romano, Material Specialist 05-04-2017 9:22am
Robert,

Thanks for the inquiry.

Smooth-Cast 300 is a good overall resin but if your going to be casting thin parts, or pieces with thin walls I'd recommend doing a small scale test with our Task 4.

Task 4: https://www.smooth-on.com/products/task-4/

Oomoo 30 is a good starter mold material but If you plan to cast a reasonable amount of pieces I'd suggest using our Mold Star Series Platinum Silicone material. Better physical properties and library life.

Mold Star Series: https://www.smooth-on.com/product-line/mold-star/

Andrew Romano

[Rufus T. Firefly]

Task 4.

"Curing - Important: Use this product with at least room size ventilation or in proximity to a forced outlet air vent and do not inhale/breath fumes. Fumes, which may be visible with a significant mass concentration, will quickly dissipate with adequate ventilation. "

Interesting.... Not an issue that I've encountered before with resin casting, but makes sense as well that fumes are present and should not be inhaled. But visible fumes? Hmmmmmm........... I think that I'd be putting my casting work with that stuff into a exhausted hood to the outside.

Much longer cure time (and working time...) so you won't be popping out parts every 15 min. I've not had a need to use a 20 min working time resin..........maybe I should give it a try.

[CMorrill]

I've had very good luck with the CR-600 resin from MM and also the RTV they sold, but it has been four years since I last bought any resin or RTV so don't know if their present product is exactly the same. A SP caboose kit I produced for a short while using MM's resin and RTV has been in use on the layout for about 15 years now without showing any sort of degradation with walls and curved roof only 1/16" thick. The thinnest cast resin parts I've made with this material are probably the targets on signals (about .020").

So a spring plank for a truck or the whole truck exclusive of bearings for that matter could be cast in this resin. However, I doubt the resin material would take the bending stresses that are expected in assembling the inner springs in the IM truck.

Charlie

[Robert]

..... the spring planks that are found in Intermountain truck kits which I occasionally break while assembling the kit.

Styrene, aren't they? Or. ABS? Either way, MEK would weld them back together.

Would a resin replacement be better? No idea, but the resin I use tends to be a little brittle when you get thin and expect it to flex very unlike styrene being a bit forgiving.

Just tried gluing the broken spring plank using "Same Stuff" from Micro Mark. Not a chance. It is one of those slippery durable high tech plastics which apparently are adhesive proof. MEK is not something I get involved with, but those familiar with this "Same Stuff" are making an association of it and MEK. Who knows.

Robert

[Rufus T. Firefly]

..... the spring planks that are found in Intermountain truck kits which I occasionally break while assembling the kit.

Styrene, aren't they? Or. ABS? Either way, MEK would weld them back together.

Would a resin replacement be better? No idea, but the resin I use tends to be a little brittle when you get thin and expect it to flex very unlike styrene being a bit forgiving.

Just tried gluing the broken spring plank using "Same Stuff" from Micro Mark. Not a chance. It is one of those slippery durable high tech plastics which apparently are adhesive proof. MEK is not something I get involved with, but those familiar with this "Same Stuff" are making an association of it and MEK. Who knows.

Probably an acetal polymer plastic - MEK might or not work. And, it is nasty stuff. Making an association with is not equivalence....

[Robert]

Probably an acetal polymer plastic - MEK might or not work. And, it is nasty stuff. Making an association with is not equivalence....

Well I called Intermountain ( they have an 800 number ) in pursuit of a remedy for my broken part, the spring plank in question, and low and behold they had an odd parts box of this and that, and a spring plank is in the mail to me, as well as selling me several additional truck kits. He said no glue including MEK will touch the plastic they use in these trucks...so story had a happy ending.

Robert