Hi folks,
I thought I would step into this discussion and maybe clarify a few things about the mold industry and how a company decides whether to use 3D printing to actually make the part needed OR use 3D printing to form a part and then have it cast. Take a look at this link I have provided here:
https://www.shapeways.com/shops/backyardtrainco
This is a 1" and 1.5/1.6" scale vendor who builds ride-on diesels. He also provides 3D printed details for these locomotives. Some of the parts are ABS or other "plastics" materials. Other parts are 3D printed "sintered bronze" or cast bronze that are lost wax impressions made from 3D printed molds. It all depends on the resolution of the printing process. The faster the printing is, then you have a courser (rougher) resolution. Lots of hand work to make it presentable (process is called "Benching"). You make up time in the 3D process AND less cost, but there is added cost to the benchwork it takes to smooth things up. When we did our aluminum castings for the louvered panel doors for our 1/8th scale Baldwin electrics, the part was 3D printed in a "rough resolution". We would have paid quite a bit more for this part to make the mold. The foundry that printed the part did the final bench work by hand and then they used the printed mold part to press into the "sand mold" to make the aluminum sand casting. Scroll down the page on the link above and look at the cost of some of the parts. Most are relatively inexpensive. But take note of the two steam generators.....one is 1-1/2 inch scale and the other is 2-1/2 inch scale. These are NOT cheap mainly because of the fine resolution of the 3D printing.
We are working with our foundry in Kent, Ohio to make scale model trolley poles. The man I'm working with is using Fusion 360 software (as I am) and we are deciding how best and economically to go forward with combinations of 3D printing and making sand casting molds. So far, it will be much more cost effective to 3D print the parts in a semi rough finish, do the benchwork to smooth the parts and then produce the sand mold for aluminum castings. The cost of these parts to 3D print in a fine resolution would be prohibitive (at least 10-15 times the cost of the castings.
Also on this Shapeways page, you will find full 3D printed bodies of SD60 shells for HO scale and they are almost $300 each. Multiple that cost for a 1/29th body shell and I very much doubt ANYONE on here will be doling out $700-$800 for a shell. And I also know that those on here using home 3D printers will not have the capacity to print an entire shell, much less a seqment of a shell. These would require 3D printers in the thousands of dollars. All of these devices talked about here whether 3D printers or the software to design the parts needed (also the experience to make any part in the software). 3D Solid Modeling and drawing is not for the faint hearted. Remember you pick the "tools" to use to make your parts that are the most econmical and appropriate. One "tool" won't do everything and some of this discussion above sounds like that is waht is expected of 3D printing. Not necessarily so :).
