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Plaster Casts

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  • Member since
    May 2003
  • From: US
  • 148 posts
Posted by leewal on Thursday, October 21, 2021 9:07 AM

Thanks to all who replied.  Since I have all the interiors I need installed in other cars I can use them as guides to create what I need using the RIX seats and styreme sheets for walls as necessary. Little detail parts, like tables,  are easily obtained or made to create a diner.  Using the "originals" I can arrange the interiors to match the window design. Buying the interiors on eBay is another option but I can't find one seller that has all 5 that I need so shipping goes thru the roof instead of just up to it as it does now. Using the RIX seats seems like the easiest project with a lot less mess. 

  • Member since
    January 2017
  • From: Southern Florida Gulf Coast
  • 18,255 posts
Posted by SeeYou190 on Tuesday, October 19, 2021 10:44 PM

leewal
I've been wondering if it's possible to make plaster casts from the formed plastic Rivarossi passenger car interiors without damaging the original

Casting these in plaster would be a fool's errand.

However, it can be done easily with the Alumilite system. Wargamers have been using this product for a long time to copy all kinds of castings. It is an excellent product and the system works well.

-Kevin

Living the dream.

  • Member since
    August 2003
  • From: Collinwood, Ohio, USA
  • 16,367 posts
Posted by gmpullman on Tuesday, October 19, 2021 9:53 PM

Trying to make the entire interior in one piece would, IMHO, be an exercise in futility. Most of those Rivarossi/IHC interiors were molded using segmented plastic injection molds. 

I suggest using some commercial pieces with some of your own kitbashed creations as masters then making your own silicone-latex molds and using two-part resin to make your final interior components.

For a coach there are economical seats made by RIX that are quite suitable and can be cut up as needed for the car:

 PRR_Budd-Congo-seat-0 by Edmund, on Flickr

Partitions can be .030 styrene from Evergreen or others. You can make, scrounge or purchase parlor seats, berths, sofas and other appointments and use these as masters to make a latex mold.

 Parlor Chairs by Edmund, on Flickr

Palace Car Co. makes many pieces that can be used as masters for making YOUR clones:

http://www.palacecarco.com/categories.php?cat=25

I would make a pair of Pullman berth seats, back to back plus make a single to be placed against the bulkhead. This will fill the most common need for a heavyweight berth and the single one could be used in a lightweight roomette.

Tables and low partitions can also be made of styrene sheet.

 ATSF_10-6_Pine-King-BR by Edmund, on Flickr

This interior was cobbled together using several pieces out of the scrap bin and some commercial parts. There is no readily available interior for a PRR POC70R.

 PRR_POC70R by Edmund, on Flickr

 

Micro-Mark and others has mold making supplies and several types of two-part casting resin. MUCH stronger and lighter than plaster and it can be sanded and glued with ACC.

https://www.micromark.com/hobby-supplies/casting-molding-supplies

 

Good Luck, Ed

  • Member since
    December 2004
  • From: Bedford, MA, USA
  • 21,483 posts
Posted by MisterBeasley on Tuesday, October 19, 2021 7:31 PM

A couple of points:

A hydrocal casting would be heavy, and would add to the weight of the car.

Like I've done before, I would first make a rubber mold, and then use that to cast.  You need to get a negative of the model and then recast it as a positive.  This has worked well, but the plaster can weigh a lot.

It takes an iron man to play with a toy iron horse. 

  • Member since
    July 2006
  • From: Bradford, Ontario
  • 15,797 posts
Posted by hon30critter on Tuesday, October 19, 2021 6:57 PM

Can I suggest a couple of other options?

You can get the parts printed in 3D quite easily. You will need to find someone who can scan the parts for you, and then all you do is send the scan to a 3D printer who can make the parts for you. Note that you would not be able to sell the printed copies legally unless you made some significant changes to the design. Also note that you need to shop around to get the best price for the printing. Most commercial printers have a minimum charge which will make the cost prohibitive. Shapeways does not have a minimum charge (I believe).

https://www.shapeways.com/

Another option would be to use silicone to make the mold instead of plaster. The part will be much easier to separate from the mold if silicone is used.

Before everyone starts yelling at me, I will note that both of the above options would be more expensive than using plaster. The 3D printing would be much more. Whether or not you can justify the price is up to you.

I am currently in the process of having some kitchen cabinet handles copied in steel. I found a local fellow to do the scan, and I will use Shapeways to do the printing. I have done this before and the copies were almost indistinguishable from the original.

Dave

I'm just a dude with a bad back having a lot of fun with model trains, and finally building a layout!

  • Member since
    September 2003
  • 21,669 posts
Posted by Overmod on Tuesday, October 19, 2021 4:43 PM

leewal
I've been wondering if it's possible to make plaster casts from the formed plastic Rivarossi passenger car interiors without damaging the original.  Anybody ever try it?

I have not tried it, and I would assuredly use flexible (e.g. RTV) and not plaster molds, and a casting material other than plaster in those molds, if I were to do that.

If you use plaster as a mold, use a GOOD parting agent on your part, and keep your fingers crossed rhat Rivarossi shot the part with enough 'draw' to come out of the plaster mold easily once the mold has set.

Then coat the plaster mold with something impervious and slippery -- marine gloss varnish, perhaps? -- and liberally use an appropriate parting agent again in the cavity each time you pour a cast.

  • Member since
    May 2003
  • From: US
  • 148 posts
Plaster Casts
Posted by leewal on Tuesday, October 19, 2021 4:33 PM

I've been wondering if it's possible to make plaster casts from the formed plastic Rivarossi passenger car interiors without damaging the original.  Anybody ever try it?

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