Stevenson Preservation Lines?

Unless he is on vacation it should be pretty quick.  He is a one man show.

Thanks Bob!

I can't wait to see what the parts look like, I ordered a bit over $100 worth.

I just wanted everyone to know that I got my order T-O-D-A-Y!!!

That's pretty fine service if you ask me.

Every time I see stuff like this I think "The casting part can't be that difficult, but making the masters needed to make the castings has to be", but I think that casting them in brass is a lot trickier than the liquid plastic or fiberglass resin I usually use.  I have no idea what a lost wax casting is or how to even make one

Thanks Bob!!!

A lost wax casting is a good description of what it is.   The wax pattern is placed in a molding material.   then the hot metal burns and melts the wax away to make the casting.   the wax pattern is made in a mold that is easier to deal with than one that can handle metal.

Some companies - GM is one, make engine blocks and heads this way with "lost foam".   They cast foam parts and than place them in sand molds for casting metal.   The foam is burned away by the metal.  

I think it is easier to make much more complex castings this way.  That is why it is used.   

And making masters is complicated.   You have to allow for the shrinkage in both casting processes so your final part comes out to the proper dimensions.   I understand there can be as much as 15% shrinkage.

prrjim,

Thanks!  I can't imagine all the trial and error one has to go thru to get a master just right in order to reproduce a detailed, scale item in any scale, and SPL has hundreds of brass items!!!

We plan on 4% shrinkage for the entire process, or about 1/2% for lost plastic.  It is great fun to take a plastic model and convert it to brass!

A lot of Bob's masters were made a long time ago, and gathered by Henry Pearce and others.  The most famous maker of masters was Ray Waller, and his SP and UP parts are legendary.

Considering the advent of stuff like SolidWorks and 3D printing, it appears that made to order parts are not too far off. If the Part needs to fit an existing model perfectly, how does one come up with the EXACT magic number for shrinkage, or are we talking trial and error?

Simon

Simon,

3D printing is going to be "The Stuff", I just hope I'm around to see it produce some rare O-scale items that a manufacturer using the old methods simply won't offer.

We need more sources for parts, although it would be nice if there was a "Co-Op" that had supplies of all the parts from different makers.  SPL has at least done us a favor by gathering up a lot of the older molds made by the craftsman of the middle of last century.

It bothers me that PSC STILL hasn't got the O-scale Steam Locomotive catalog ready for sale yet.  They need to put a PDF file (with photos) online so folks can buy a copy, rather than wait for the printed version.

Bob Stevenson said he was going to be closed for 2 weeks after I got my parts.  I need to go ahead and place another order soon!

Simon

 - my numbers are far from exact,but we depend on them and they work.  When I say "we" I do not mean to imply that I know what is really going on.  I make the masters 4% oversize, and the brass comes back more or less where I want.

I believe the 1/2% will apply to 3D printing.  The real shrink in lost wax is the rubber mold and injected wax.  Dentists have known of ways around that for a long time, but it is very expensive.

Picture having a perfect locomotive frame with cast-on cylinder block and pilot in brass or even steel.  It is now possible, although still quite expensive.  With the standard rubber mold and wax, it is just not possible.