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Molding small parts

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  • Member since
    January 2019
  • 2,227 posts
Molding small parts
Posted by John-NYBW on Wednesday, June 15, 2022 4:40 PM

The roof vents on one of my engine houses have taken a beating over the years and I've decided to replace them. One of the problems is they are too tall and prone to getting knocked off with a clumsy elbow. I thought it would be better to replace them with a lower profile vent. I went to my drawer of spare lead castings that I have accumulated from other projects over many years. I found a perfect replacement both size wise and the fact they perfectly match the pitch of the roof. The problem is I could only find three and I need four.

I got the idea to try fabricate a fourth vent from the existing vents but I have never tried such a thing. I was thinking of pressing the existing vents into some modeling clay to make molds, pressing both a left half and right half. I could then fill them with a substance that would harden, then glue the two halves together and paint them to match the existing ones.

I'm wondering if there is a better material for making the mold than modeling clay. The two materials I'm thinking of using to fill the molds are either plaster of paris or casting resin. Is there a better choice than those?

  • Member since
    September 2003
  • From: Omaha, NE
  • 10,439 posts
Posted by dehusman on Wednesday, June 15, 2022 9:52 PM

Check out Alumilite products.  Many of them are available at Hobby Lobby.

Dave H. Painted side goes up. My website : wnbranch.com

  • Member since
    September 2002
  • 7,387 posts
Posted by ndbprr on Thursday, June 16, 2022 7:42 AM

an alternate to turbine style roof vents could be to get round burs for tools like dremels.  there is one made that is round except the shaft.

  • Member since
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  • From: Dearborn Station
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Posted by richhotrain on Thursday, June 16, 2022 7:48 AM

dehusman

Check out Alumilite products.  Many of them are available at Hobby Lobby.

 

I will second that suggestion. Mel put me on to Alumilite. Works great.

Rich

Alton Junction

  • Member since
    January 2019
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Posted by John-NYBW on Thursday, June 16, 2022 12:36 PM

Most of the Alumilite products I looked at on Amazon look like they are similar to Famowood Glaze Coat which is also a 2 part resin product and which I also have a small amount left over from using it on water features on the layout. If this type of product is the best choice to make the vents, the question then becomes what to make the molds from. In searching for Alumilite on Amazon, this product also was listed:

Environmental Technology 1/2-Pound Kit Casting' Craft Easymold Silicone Putty : Arts, Crafts & Sewing (amazon.com)

That looks like it would easy to work with although a bit pricey just to fabricate one small part. I could probably vacuum seal it and use it later if another need arises. 

  • Member since
    September 2004
  • From: Dearborn Station
  • 23,318 posts
Posted by richhotrain on Thursday, June 16, 2022 1:22 PM

Alumilite makes a 2-part kit. The mold is formed over the part to be cast. Then, the casting material is poured into the mold.

Rich

Alton Junction

  • Member since
    September 2004
  • From: Dearborn Station
  • 23,318 posts
Posted by richhotrain on Thursday, June 16, 2022 1:37 PM

richhotrain

Alumilite makes a 2-part kit. The mold is formed over the part to be cast. Then, the casting material is poured into the mold.

Rich 

Here is a short Alumilite video on the making of the mold.

https://www.alumilite.com/silicones/amazing-mold-rubber-3-4-lb/

The resin mix is then poured into the rubber mold to cast the needed part or parts.

Rich

Alton Junction

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