exspanding cast resin kit.

Re: exspanding cast resin kit.

Postby ConducTTor » Tue Feb 28, 2012 10:33 pm

Well damn. I honestly thought very negatively towards this process. It appears that I may have jumped the gun.
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Re: exspanding cast resin kit.

Postby TTTerrific » Wed Feb 29, 2012 2:52 am

I spent some time on the SMOOTH-ON site. Pretty d--n impressive. I think I'll shell out few SS dollars and get some mold-making material ansd casting materials and give it go,
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Re: exspanding cast resin kit.

Postby Rob M » Wed Feb 29, 2012 10:51 am

ConducTTor wrote:Well damn. I honestly though very negatively towards this process. It appears that I may have jumped the gun.


Yep, the possibilities are pretty exciting.
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Re: exspanding cast resin kit.

Postby Rob M » Wed Feb 29, 2012 11:20 am

TTTerrific wrote:I spent some time on the SMOOTH-ON site. Pretty d--n impressive. I think I'll shell out few SS dollars and get some mold-making material ansd casting materials and give it go,


Go to http://www.reynoldsam.com/, they are their offical distributors. Their prices are the same but they may have a location nearer to you to save on shipping.

For expanding N scale you will need a regular silicone mold, Coleman fuel (solvent), Smooth-Cast 300Q, Ease release 200 and some Zip-lock freezer bags. You will also need some mixing cups and stirring sticks.

Make your mold in the normal manner and once it is setup remove it from the mold box and put it in the solvent. When it has expanded close to the size you need take it out of the solvent and place it in the zip-lock bag while it is still wet. Don't worry if the mold is warped at this point. The zip-lock bag will keep it from drying out and allow the solvent to even out within the mold.

Depending on the thickness of your mold it will settle itself into the propper shape in a few hours. From there you may need to soak it some more or let it dry out and shrink a little.

Once you have it to the propper size you can make a casting with the Smooth-cast 300Q. Don't bother trying anything else, it won't work. This stuff sets up in about 30 seconds so you need to have everything ready to go. And don't forget the mold release, I seem to have a mental block with that stuff!
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Re: exspanding cast resin kit.

Postby TTTerrific » Wed Feb 29, 2012 12:45 pm

Thanks Rob for the info on how to do this. I found a Smoothon dealer in San Francisco which is about 85 miles from where I live. Coincidentally, I'll be attending a NMRA Coast Division meet--in San Francisco in about 10 days. How convenient! Also, the primary reason I'm going to make this trek is because one of the top-dog modelers in the area is going to give a workshop on resin casting techniques. Looks like the MR modeling gods might finally start smiling on me--just a little.
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Re: exspanding cast resin kit.

Postby Rob M » Wed Feb 29, 2012 1:09 pm

Just keep in mind that I only have about 3 hours of experience with this stuff. There may be better methods. Maybe Elmer will find this thread and have some tips as he's the master-caster around here.
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Re: exspanding cast resin kit.

Postby scaro » Thu Mar 01, 2012 7:06 am

very interesting, rob.

i suppose the question is knowing exactly when to take it out of the solvent to get to TT size from N. is there a set timespan for this? can you take it out and put it back in multiple times until you get to exactly the right size?

regards, ben
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Re: exspanding cast resin kit.

Postby Rob M » Thu Mar 01, 2012 10:26 am

For that side frame it was just a one sided mold that was about 1/4" thick. It took about 5 hours for it to grow to where I needed it. At first I didn't have the quick setting resin so I put a light bulb about 2" above it to make it cure faster (didn't work) and that made the mold shrink quite a bit. I put it back into the solvent for about an hour and it came back to the correct size.
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Re: exspanding cast resin kit.

Postby jmass » Thu Mar 01, 2012 10:37 am

im gonna give this stuff a try on maisto boxcars and maybe the gp 40. being their not to far off the mark it might only take a couple of hours to exspand to full 1/120.
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Re: exspanding cast resin kit.

Postby scaro » Thu Mar 01, 2012 10:49 am

i've got an atlas GP40 that i've been taking measurements from for a GP40 shell in TT. got the basic hood shape and walkway assembled, but maybe i'm being a bit stone-age in my approach.
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