Some interesting ideas… I’m not making the mold, just the master. I don’t think my caster would like me to make the mold anyway. I send the master to the caster (not in ME) and he does the rest. Plating seems interesting – now I need to find someone who does plating --. Yes, I have looked into larger rail to compensate for the shrinkage but have found only one candidate – Peco .142”, but the head width is so far off – and I did try filing it… the 4% shrinkage isn’t too bad just using the rail I normally use. Still it would be nice to get rid of the shrinkage altogether.
My main problem with producing a master is the shrinkage of the material I use to sculpt the insert – and that is do to the high temp, vacuum vulcanizing – again, my caster says it is 350°F. It is not so much shrinkage in size, but rather shrinkage that breaks the bond between the material and the rail (also the bottom – I build these things on a brass plate). It has to be solid and stable for the mold making process.
Yesterday, I was thinking - why are we using the high temp, vacuum vulcanizing instead of RTV? I am under the impression that hi-temp induces more shrinkage (4%) than RTV (about 2%). RTV would also eliminate the hi-temp problems I am having with the material I use for the insert.
I did have some work done by a local jewelry caster, but they were not up to the volume I require or I might add, quality. My caster is in CA and is in the model railroad casting business. He can do production volume and his prices are good. However, I am paying the cost of not being able to interact with him and he is not forthcoming with information. I would love to have someone in Maine, but I’ve been down that road without any luck.
I’ve been posting on the brass casting list and I think I should really be in the investment group. I didn’t realize this when I first signed up… I hope it is ok to cross post.
Thanks,
Tom Stoltz
Tom’s Turnouts & Trackwork
www.tomsturnouts.com
