1/12 scale R-40-23 reefer Dreadnaught end
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I am not a tool maker and have never played one on TV (Ha HA). Most of what I know is just from listening to actual toolmakers talk. I have had a fair amount of resin casting experiences and those traits i can speak about more informedly. The only work I was involved with those 3 ends I sent pictures of was the resin HO end, I poured that casting in a mold I poured with RTV about 16 years ago.
Even further back in time, I once saw the work from another old-school tool maker. This guy had the acrylic 4-1 sized positive of the Athearn Blomberg EMD truck which Athearn had commisioned for the replacement styrene sideframe for the BB Zinc out side bearing early Athearn Blombergs. That plastic sideframe is still held in ultra high regard decades later. That original toolmaker has since passed away. I wish I had bought that acrylic pattern from him when I had the chance.
I think that in some very important ways the old-school methods of panto reducing down over size patterns with a pantograph can produce parts which the best of CNC tooling has not shown an even match.
On Wednesday, December 11, 2019, 8:08:23 PM PST, mark_landgraf via Groups.Io <mark_landgraf@...> wrote:
If you have a Deckel photograph available, wouldn't it have been easier to make the first generation master rib and then use it to panto all 5 ribs, using an offset method into a ABS sheet?
I model in 1/8 scale and have done steel tooling for 5 rib Murphy end panels. Now insert a piece .030 thick steel and apply 40 tons.
Are you envisioning resin or vacuum formed or fiberglass sides and roof?
What ever your choice, I'd recommend making sure it is UV and age/heat stable.
Sometimes it is easier to make your master 2 or 3 times larger and then panto it down to the correct scale.