How do they do it?? 1st Casting

Hey Joe, I'm pretty sure that the dies are CNC machined from CAD drawings on the computer.

Joe check it out: 

http://www.youtube.com/watch?v...youtube_gdata_player

Will,

 

I expect that you are correct, but I think what would be of interest to Joe (and myself), is how they did stuff before computers, or how can a guy do it without all that sophisticated gear?

 

As I think about some of the older models, the EMD E and F units really got butchered quite a few times, but there were also some pretty darn good ones made on occasion, and all those curves on the nose would be a real challenge!

 

So I guess the question is, how would you make an accurate model without all the technology that is available today? I think that is what Joe might be looking for.

 

Simon

The old time "tool and die maker" was as much an artist as a machinist. It was/is a highly skilled profession, turning engineering drawings into the tooling to produce them. 

 

Jim

Hi Joe ,

Jim is right tool and die makers were artists, I make 86ft hy-cube boxcars , I painstakingly spent countless hours making the masters , 6 parts , ( 2 sides , roof , frame , ends ) I spent maybe 200  hours , I used blueprints or drawings lots of photos and probably got 95 % accuracy , I used styrene just as you are on your G scale diesel . You have to work slowly and make sure as you go you are precise as possible because your castings are only as good as your master. I must say it is tough sledding .I work for a few hours and then stop, patience and stopping when you are not feeling it . I usually do my best within 30 minutes of waking up , brain fully charged .

It is tedious and I imagine , back in the day , tool and die makers were the most important guys in the plants , kind of like surgeons . I have been mold making and casting for many yrs , it is an acquired skill , the more you do the better you get .

On complex parts I make mini parts , to make a bigger part .

I added a couple of photos , to get the 3 dimensional effect , you have to layer the castings . I lay out the basic side with reliefs for the add-on parts , then add the parts . Basically casting is 2 axis , and you can't have undercuts .

Just my 2 cents

 

Bernie

Not only did you have the tool and die makers, but you had the talented draftsmen creating the drawings required to cut the dies for the various parts.  Each part required a separate drawing with every distance, radius and angle spelled out.  I remember doing some of that in my high-school drafting class.  It is meticulous work.

 

There was also a model maker involved that would make a sample, sometimes using existing parts to build a representative "proof of concept" model. 

 

As I recall, the proof of concept model for the New Haven EP5 was cobbled up from two F3 bodies. 

 

The Touhy-McComas MPC book has a photo of a proof of concept old-time 4-6-0 based on a Disney park locomotive that never made it into production.  Pity, it looked pretty nice.

 

Rusty

 

Yes you had a pattern maker from a wood model. It had the proper shrink in the model based on the material you were going to shoot in the die. The tool maker used this model to cut the steel.

I would add that even today, it still requires skill, talent and patience to draw and dimension the parts on the computer to create the files the CNC machine will use. 

 

And, it ain't no iPhone app.

 

Rusty

I have seen a CNC make wood parts from a picture. There is a little more to it then that. I think they need to set some  parameters for X- Y -Z

Bernie, for your two cents, don't short change yourself. That is fabulous!

I used to be a draftsman back in the 70s.  What always amazed me was that 4-5 of us could be working on 1 project and have all the parts fit together after the machinists made them.  We had a "Checker" draftsman that would double-check our work before it went to the machine shop (man we use to call him names) that would catch all the mistakes we made.

 

In today's model world trying to make a model of a no longer in existence piece of rolling stock can give you heartburn.  Building something that perhaps the PRR used is one thing, but try finding enough data on building a car of which there were only 10 of is almost impossible to do.  Even with a great photo, sometimes there's just not enough to go on.

 

I see some things folks built and have to wonder if they had a 1:1 prototype to measure from.

 

When I was into 1/6 military modeling I would often use 1/48 scale models to take measurements from, but at that scale if there's a blob of plastic on the model you can't identify, it ends up as a bigger blob of plastic in the larger scale.

 

In our scale, 1/32" in actual size is 1-1/2" in 1/48 scale.  A missed measurement can throw a model way off to the point it just won't look right.

Thanks Guys, great stuff!! Sure makes me appreciate these models even more.

If you want to see some really good techniques for scratch building with styrene or brass check out http://www.scalemotorcars.com , granted its a site for building model cars, but the technique and skill used to make these is amazing. some guys are building model cars that have all the working parts as the real sized counterparts its amazing.