Bill & All,

 

Most brass castings you see are a result of a 2 cycle casting process. A
brass master is created - about 4% larger than the needed item. The master
is cast as individual items maybe 10 times - possibly more for smaller
items. Those items are cleaned up and assembled into the production master.
Another mold is made and cast. Those parts are the saleable items we buy.
Having many of that item on a tree makes the casting feasible.

 

So with about a 2% shrink per casting cycle that is why original master
patterns are 4% oversized. This was old school before RP where you only
wanted to make 1 original master pattern.

 

I have never done the 2 cycle casting. The castings are crisper that way.
The items I wanted were always for my own use and only did not need to make
hundreds of them intended for public sale. As a cost per piece it was pretty
chunky so selling them was really never an option any way. In some cases
like my PRR steam loco handrail stanchions I made the original master a tree
with about 20 stanchions each. That is the beauty of RP!

 

Finally at least with my caster I have found 2% shrink to be really accurate
to within thousandths! Maybe the 5% shrink you heard about is because things
are bigger in Texas? (;->)

 

Thank You,
Bill Lane

Modeling the Mighty Pennsy & PRSL in 1957 in S Scale since 1988

See my finished models at:
 <http://www.lanestrains.com/> http://www.lanestrains.com
Look at what has been made in PRR in S Scale!

Custom Train Parts Design
 <http://www.lanestrains.com/SolidWorks_Modeling.htm>
http://www.lanestrains.com/SolidWorks_Modeling.htm

PRR Builders Photos Bought, Sold & Traded
(Trading is MUCH preferred)
 <http://www.lanestrains.com/PRRphotos.xls>
http://www.lanestrains.com/PRRphotos.xls 

***Join the PRR T&HS***
The other members are not ALL like me!
 <http://www.prrths.com/> http://www.prrths.com
 <http://www.lanestrains.com/PRRTHS_Application.pdf>
http://www.lanestrains.com/PRRTHS_Application.pdf

Join the Pennsylvania Reading Seashore Lines Historical Society
It's FREE to join!  <http://www.prslhs.com/> http://www.prslhs.com 
Preserving The Memory Of The PRSL

 

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