Re: RPM History -Toolmaking


soolinehistory <destorzek@...>
 

One more go-around at this... I've taken the liberty of combining Chuck Yungkurth's posts below, as I want to speak to his points here.

I have nothing but the greatest respect for Chuck and the service he has given this hobby over the years, but I'm going to disagree with him. Even when everything he mentions below has been accomplished, it STILL isn't everything the tool shop needs. What Chuck described are PART design drawings. What the guy at the bench, or the guy programing the CNC needs are TOOL drawings. The guy building the tool doesn't need to know how the parts fit together; he needs to know how the cavity that makes that part relates to the mold insert, it's parting line, runner, gates, ejector pins, core pins to make any required holes, and all that stuff has to miss the water lines that run through the mold to remove the heat of injecting plastic at 400 deg. F or so. Draft has to be designed into the cavities, material shrinkage accounted for, and if any undercuts are required, the mechanics of the side actions need to be drawn and dimensioned. In fact, the part of the cavity that is on the slide is likely on a completely different drawing sheet than the rest of it, as is the core that makes the detail on the opposite side. By the time the design and drawing work for the mold are completed, NONE of it is very recognizable as a model railroad part... it's lost in the details of the mold.

This is where small (and some not-so-small) manufacturers get into trouble when looking for a "toolmaker". Go to a large commercial concern, and they take your part drawings and send them up to engineering, who will quote you to design the mold. Not build it, but simply design and draw it so it can be built. Go to a little shop, and if they're smart, they'll send it out to a design service, and add the design work to the price. Designers have this rule of thumb that the design work is worth about 10% the total value of the mold, so if they figure there's $50K worth of work, they are going to add $5K. Complain about the price and insist the toolmaker should be able to do this at the bench, "cocktail napkin" style, and you'll be in trouble for sure. It's easy to initially overlook details during the design process, and if steel has already been cut, sometimes it's costly to recover when things just don't quite work out. Tools are traditionally built with a hefty down payment. When the cost of fixing the boo-boo looks like it will exceed the quoted price, often the shop will simply stop work and cut their losses to what has already been paid. Yeah, you can threaten to sue, but as they say, you can't get blood out of a turnip. Win the suit, get a judgement, and the shop will simply go bankrupt.

Since several people have brought up the CB&T Santa Fe reefer, I guess I can tell my story. I ran into Dick at one of the NMRA Nationals, and he wanted to show me a test shot. The only thing on the body was the door hardware, and it was upside-down. How in the heck can you put the door hardware detail on upside-down? Well, the cavity insert it goes on is just a rectangular block of steel, and if the features that orient it and key it to the mold aren't well defined, or worked out so that it can't be assembled correctly, I suppose it can happen; it obviously did. There really isn't any good way to recover from this, other than to start over. At the time I was dumbfounded that 1) something like this could happen, and 2) it required assembling a partially completed mold and hanging it to discover the error. What a waste.

Dennis

--- In STMFC@..., "drgwrail" <drgwrail@...> wrote:

I think it is time for me to chime in on this. For one thing I have to defend Irv Athearn who was guilt of all the warts and pimples, like mirror image underframes, thick doors with claws, overs size cast on grabs, etc. etc. Ironically some of the most vocal critics who continue to blast "blue boxes" are the same guys who put our products to upgrade or kit bash the Athearn plastics. Irv provided the basic materials, no matter how bad.

His 99 cent box cars and rubber powered F unit revolutionized the industry, killed Varney, pretty much drove Mantua into the toy business.. Irv's only sin was not recognizing that he needed to upgrade.

Without going into my "life & hard times" to far, I got my first HOW engine in 1941 when I was 11. Needless to say HO was a disaster back then. But I was fortunate in that here was large hobby shop in my home town with a very large model railroad department. Plus the owner was involved in model manufacturing of several type. From about 1944 through when I got out of college in mechanical engineering I worked in the shop part time and summers. So I pretty much had an insight into the evolving model railroad business.

Up until Irv came out with the plastic freight cars, Silver Streak(ugh)Varney pressed metal, and Mantua kits was pretty much tops in equipment. And Irv's metal car kits.

The I spent over thirty five years in the on the drawing board design , engineering management and subcontract building of precision equipment.

Until CAD came along about 40 years ago, most small model railroad manufactures did as Athearn did, copied a page from a Cyc and found a die making shop that would build the molds. I know of one present day RPN type manufacturer who was operating in this mode as recently as 8 years ago.
Most of these manufacturers knew nothing about die making or manufacturing and the die makers knew nothing about railroad practices. There were of course exceptions like Gould, etc. where the owner was a die maker / model railroader who went into business. The other trap for these would be manufactures was that they fell into the trap of producing models that they wanted for years, but fortunately things changed when CAD became available to small users. For 25 years now I have been doing engineering design for almost every HO manufacturer. This was all unsolicited, word just got around. The mode today is you make a CAD layout of the prototype car, then a detail drawing of every part. The detailed parts then can be assembled into another drawing of the completed model so all fits, interferences, errors are visible. Now the "client" can see exactly what will come out of the model and he can go to any good die shop and tell him he wants dies to a make exactly that. And revision are simple before metal cutting starts With modern (but very expensive) 3D CAD the inputs to numerically machining the die can be done directly from the CAD data base.

All unlike the old days where the guy who paid a die shop never really knew what he was getting until the first test shot into the die.

Almost all the defunct manufacturers cited so far on this topic failed because of this die problem. Recall one out of business manufacturer who gave a clinic at an NMRA national about going into the business. He started by saying you would should put $30,000 in dollar bills in a pole and light it.... thereby saving your mind and health and save yourself the suffering before the inevitable end!

I worked with Dick Schweiger just before he got ill. He wanted me to redesign the entire line stating with the SFRD reefers so he had a decent set of drawings to define exactly what he wanted.

So there is more to this long story, including inside horror stories for which a client paid for a design that really would be a disaster. but when he pays you you do what he wants and respect his privacy!

Chuck Yungkurth

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