SP GS-4 Drive Wheels

Re: SP GS-4 Drive Wheels

Postby Rob M » Wed Apr 22, 2015 11:23 pm

HP 2-10-2 ------------->>
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Re: SP GS-4 Drive Wheels

Postby j p » Thu Apr 23, 2015 10:54 am

Last edited by Anonymous on Thu Apr 23, 2015 12:56 pm, edited 2 times in total.
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Re: SP GS-4 Drive Wheels

Postby areibel » Thu Apr 23, 2015 1:05 pm

Getting the castings done isn't hard, there are a couple places besides the place JP posted that will cast from your master. The tricky part (for most, anyway- Bernd, you don't count on this!) is the machining. The gent that is mentioned at the bottom of the page on the PLW website sounded familiar so I dug back through my old emails. I contacted him in 2006 about turning driver, and again in 2008 but nothing ever came of it. I have a small quantity of drivers that were done by Garn Smith probably 10 years ago. He just copied the HP large driver so they're a hair smaller than the originals (they're cast in nickel silver). The original plan was to do an axle insulated driver just like the HP's, but the better plan would be to have the complete wheel turned, then use a stainless tire along with rim insulation (like most other steamers use).
Mr. Hanson had a fire in his garage and shop in 2006/2007 so he was out of business for a while, he said the only thing he would need was a profile tool to cut the proper taper and flange onto the new tires. But I didn't hear back from him and I forgot about it myself, I don't know if an email to him would jog his memory or not?
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Re: SP GS-4 Drive Wheels

Postby Richard-B » Thu Apr 23, 2015 3:49 pm

Bernd wrote:What's the NMRA say about TT scale flange size?
See sheet 2... excerpted from NMRA RP-25.
NMRA TT-scale.pdf
selected NMRA TT-scale standards
(82.64 KiB) Downloaded 165 times
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Re: SP GS-4 Drive Wheels

Postby Richard-B » Thu Apr 23, 2015 4:11 pm

j p wrote:<snip> or ask PLW to rescale to TT:
http://www.pacificlocomotive.com/catalog.php
I have been discussing this with Bill Brisko (PLW owner).

Interesting story: Bill obtained his commercial-quality 3D printer from a jewelry-maker in New York City... They were re-organizing and the machine had some alignment issues, so Bill got a good deal. He works in Silicon Valley technology... and was able to determine how to slightly modify the machine to maintain alignment and increase reliability. Bill's major problem is time... he is still fully engaged as a corporate executive.

We discussed doing a full set of TT-scale drivers (4 counterweight types) in one print pass. After some hand detailing, these 3D prints can be passed along to one of several metal-casters... who burn-out the printed material, and cast a first generation master. This is inspected and hand polished where needed, and then a female mold is made from which wax 2nd generation masters are made. The waxes are burned-out... and you have driver centers.

That was the EASY part!

Now you have to give the rough centers to a machinist, who will center bore them for the preferred axle size, turn them true to the correct diameter, and fit previously machined tires (often 12L14 Ledloy - a free-machining steel alloy), with or without an insulating material between tire and center.

This is all a non-Trivial undertaking...
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Re: Espee GS-4 drivers

Postby Richard-B » Thu Apr 23, 2015 4:42 pm

gerhard_k wrote:I'm an SP modeler also, citrus industry emphasis - R40-23 reefers anyone? (sorry, off-topic) :silent:
I would take a GS-4 also!
Hmm... sitting here on the shore of the San Francisco Bay... I thought everyone was an SP Modeler... (or should be!)
Bernd, you may get some help by putting in a query at the discussion boards at
http://www.southernpacificmodelerssocie ... portal.php
Actually... the more active discussions are on the Yahoo! Espee Group https://groups.yahoo.com/neo/groups/Espee

There may be GS-4 driver engineering drawings in one of the industry "Car and Locomotive Cyclopedias" from the 1940's;
or they can be purchased at: http://www.livesteamlocomotives.com/drawings/sp_gs-2_3_4_5_6_4-8-4.htm
  • DL 19920 Driving Wheel Center (3rd) Intermediate
  • DL 19921 Driving Wheel Center (1st) Front
  • DL 19922 Driving Wheel Center (4th) Back
  • DL 19923 Driving Wheel Center (2nd) Main
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