# G1 driver pattern test



## Jack - Freshwater Models (Feb 17, 2008)

Please bear with me as this is my first post with a pic


This pattern was digitally modeled in Rhino4 and then 3D printed. Next this pattern will be molded in RTV rubber to produce Britannia metal production patterns. The Britannia metal patterns will be used to produce a vulcanized silicone rubber mold. The drivers will be cast in zinc-aluminum alloy. This is an experiment to come up with an easier and more cost effective way to produce wheels and drivers for G1. The prototype is an 0-6-0T shunting/goods loco. The model will be based on LBSCs Chingford Express but with some improvements I hope.

Jack


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## Jeff Livingston (Jan 2, 2008)

Jack, 

I'm not sure I understood much of your description but that's one fine looking wheel. Did the class have outside counterweights? 

Jeff Livingston 
Kaneohe, Hawaii


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## Jack - Freshwater Models (Feb 17, 2008)

Jeff, 

Thanks! No, this particular loco didn't have counterweights as is fairly common with locos like this in the UK. The passenger version of this loco had 10 spokes instead of 12 and did have counterweights. 

To simplify, this plastic wheel was computer generated. It will be used to make molds to produce metal wheels. Hope this clarifies a bit. 

Jack


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## Dwight Ennis (Jan 2, 2008)

Today's technology is amazing! Good job!


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## Gary Armitstead (Jan 2, 2008)

I saw this technology used at Cal State Los Angeles during one of my MasterCam seminars about ten years ago. Is this the unit that is "somewhat like" an ink-jet printer? Less expensive than Stereo Lithography. That will be a beautiful pattern. Thanks for sharing.


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## Jack - Freshwater Models (Feb 17, 2008)

Gary, 

Thanks for the compliment. The digital model, a 3dm file, is saved as a stereo lithography (.stl file) and sent to the printer. The printer is based on ink jet technology but laying down plastic in 3D. The goal is to test the viability of zinc-aluminum drivers or driver centers which are relatively cheap and easy to produce. I've given up on having small quantities of cast iron drivers made. 

Jack


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## Gary Armitstead (Jan 2, 2008)

Jack,

Does Rhino4 do surface modeling or solid modeling. Many years ago, at a local college, my professor and I built seven 1/8 scale Baldwin Electric locos. All the sheet metal parts for the cab and floor, the trucks and wheels were drawn in MasterCam. The wheels were all done using surfaces. We then made our patterns and had them cast. Lot of work!


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## Jack - Freshwater Models (Feb 17, 2008)

Gary, 

Rhino is a surface based, solidmodeling software. It's similar to Solidworks which is "feature" based. Rhino is very affordable and has almost a "cult following". Mastercam is awsome but increadibly expensive. I use Rhino with Rhinocam (Visual Mill) to accomplish almost the same stuff. I hope to someday get Visual Turn for CNC turning. 

This driver was developed mostly from revolved surfaces and lofted surfaces. First the spoke was lofted. Then the various surfaces were revolved. Next the spoke was coppied and revolved. Finally the hub was lofted and all the surfaces were joined/trimmed. The last step was to make sure that the model is water tight using an analysis feature of Rhino and correcting any problems. 

I have a small mill which I retrofitted with CNC but accuracy is limited due to acme screws rather than ball screws in the X-Y axis. 

I did all this because because I have the capability and it is fast but the same could have been done with wood or plastic using manual machining/fabrication methods. 

Jack


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## Pete Thornton (Jan 2, 2008)

the viability of zinc-aluminum drivers 

Jack, 

The wear characteristics should be interesting, or are you planning to add a steel tire? 

When you've done that, Kevin has a 48" EBT driver that we need in 1:20.3.


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## Jerry Barnes (Jan 2, 2008)

Nice to see someone doing wheels. Where are you located?


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## Jack - Freshwater Models (Feb 17, 2008)

Pete, 

Yes, I will be interested in the wear characteristics as well. As you may know Aster used ZA on their little oscilator 0-6-0 for the wheels as are Mamod wheels though they are diecast. They had problems but I think they were mechanical fastening to the axle not the fault of the alloy. If the ZA wears too much I'll remake with CI tires. Interestingly, in industry ZA is used as a replacement for CI for all sorts of parts including bearings. The EBT wheels might be reasonable if you use tires for such a heavy loco. I would have to see a drawing. 

Jack


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## Jack - Freshwater Models (Feb 17, 2008)

Jerry,

Thanks! Actually this driver isn't exactly as it should be having fillets too small and spoke cross section not entirely correct but close. 

Ideally I would like to make CI wheels but it is beyond my capability and small quantities are tough to get investment or shell cast. ZA may be a reasonable substitute. I am going to try to model some nice wheels for both British and American rolling stock. 

At this time I still have a lot to learn about digital modeling. I especially need to learn more about how to join two surfaces together with proper fillet as done in full scale patternmaking. It all gets very complicated very fast and the learning curve is monumental for me.

I'm in Rochester, NY a couple of blocks from Lake Ontario and the Genesee River. Once a very important railroad area with the NYC, HoJack, and BR&P (B&O) not to mention a couple of trolley lines.

Jack


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## Gary Armitstead (Jan 2, 2008)

Jack,

If you are having problems with the filleting, maybe you can send me the file in DFX and maybe I can import it into MasterCam, do the fillets for you and send it back. Does Rhino have the capability to import from MasterCam? It might be worth a try. Let me know. I have a buddy in Ventura, CA that is familiar with importing from Rhino to MasterCam.


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## Jack - Freshwater Models (Feb 17, 2008)

Gary, 

Thanks for the offer! If I get stuck I might take you up on it! 

Actually I just have to learn more about Rhino! The fillet on the tire end of the spoke is there but too small (next time). The spoke/hub is the tough part and I will be playing with it on the next driver I design. I don't have any formal training and have been learning through tutorials and trial by fire! One reason the spoke cross section isn't the correct pear shape is that it is easier to cast the way I designed it. Drivers are nasty things to cast! Thick sections like the hub and tire next to thin sections of the spokes. Any cross section I can gain in the spokes makes it easier to cast. I will be adding a feeder on the back of the driver from the gate to both the tire and hub in an effort to feed both during solidification. Yes, I have to consider how the part will actually cast in designing the part. I am always trying to design taking into account progressive solidification. 

Jack


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## Jack - Freshwater Models (Feb 17, 2008)

This is the first try at a production pattern. Sadly it ended up about .010" out of round due to centrifugal force. Will try another method! 

 


Jack


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## Semper Vaporo (Jan 2, 2008)

Cast it too big and turn it true on a lathe.


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## Jack - Freshwater Models (Feb 17, 2008)

Hi CT, 

I wish it were so simple! Actually, it isn't far off and if it were cast in zinc-aluminum it could be used as a driver since the casting is oversized and .010" isn't too bad. Thickness was held within .003" which surprised me! The pattern has to be very accurate because it will be used to produce another mold that will be used to produce the actual driver castings. If I were to use this one the error would be multiplied in using the second mold. The idea is to do everything as accurate as is reasonably possible to produce quality driver castings. 

My plan is to make another mold and gravity cast the pattern which will be more accurate. 

Jack


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## Jerry Barnes (Jan 2, 2008)

Jack, 
If you get going on this, put an ad in Steam in the Garden magazine, one of the best places to contact builders. Published right there in New York! 
Jerry


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## Gary Armitstead (Jan 2, 2008)

Jack,

That "shot" of the wheel looks real nice! Is your process similar to die-casting? Is there a "shrink factor" used in your process. Is there a thin layer of "scale" on the surface of the casting after cooling? With my limited experience with zinc-aluminum and die-casting, you should be able to hold tolerances of plus-minus .001 without a problem. Thanks for the update on this.


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## Jack - Freshwater Models (Feb 17, 2008)

Gary, 

Not as precise as diecasting. The molds are silicone rubber. The casting is very clean as it comes from the mold. One advantage is that flaws that are usualy hidden in a diecasting are out in the open in spncasting. On the down side spincasting in rubber molds doesn't have the mold pressure as in diecasting. Though the molds don't hold up well they are cheap so they can be easily replaced once the mold shows signs of ware. 

Jack


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## Jack - Freshwater Models (Feb 17, 2008)

Gerry,

Yup, Ron's magazine is where any G1 advertising will be done though I may eventually try the G1MRA newsletter. I met Ron and Marie a couple of years ago at their annual get-together. 


The wheels are just part of the story!










These parts were cast from a pattern I made about 22 years ago. I plan on redoing these patterns in the next few months.

I plan on offering cast detail parts for both American and British rolling stock and possibly locos. The first parts I am working on are for a British wagon and will be working on an American flat car. I am always open to suggestions! 

Jack


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## Pete Thornton (Jan 2, 2008)

I am always open to suggestions! 

Jack, 

_I was wondering about your intentions after I looked at the On3/30 stuff on your website..._ 

There are a couple of threads here (in the Rolling Stock forum?) with a 'wish list' topic. Unfortunately, this crew are all over the shop in terms of G-1 interests; standard gauge rules in Nebraska (see NTCGRR,) while eastern narrow gauge is my focus. It gets worse with driving wheel - the narrow gauge ones had few spokes (10-12) while the standard gauge locos have many more, making it tough to satisfy a wider market.


We have some flat cars in Fn3, so I hope your's will be an interesting variant.  There's a dearth of 1/32nd scale american outline stock to run behind those Aster locos, so that's a potential market.  As I've noted before, freight cars get bought in multiples - the live steamers always seem to be trying to pull the longest train possible! 

Dave Queener has some experience in the wheels arena, though not with the techniques you are using. He has some nice steel tires ready to ship - maybe your wheels could be fitted inside them?  Here's some of Dave's tires set on a flatcar as a load:


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## Jack - Freshwater Models (Feb 17, 2008)

Pete,

I model in a variety of scales and prototypes! I do casting for other model and model kit producers. Right now I am finishing up two projects for an antique model outboard builder with one project in 1:4 scale and another in 1:8 scale. I do this for a living so models really boil down to creating scale parts. You'll likely see some O and HO scale stuff on my site in the future but also some G1.

Way back in the dark ages of the early 1980s I did a test run of 1:32 box car kits. They were NYC&HR RR Grain Line Transit box cars. Therre were about 75 kits sold. To my knowledge these were the first G1 1:32 scale kits produced in the USA. At the time I didn't have the experience to equipment so I farmed the castings out. Back them there weren't many 1:32 modelers and sales was slow. Offering G1 kits has been on the back burner for the past twenty some years. After doing this for 6 years and having the business free and clear as of this summer I will be persuing G1 parts and maybe kits. I still have to do the other stuff to keep the business alive but if the G1 community has a need for what I offer I'd certainly continue to serve as long as I can.

I am unaware of Dave Queener's tires???? Got an email address or web site for Dave????

Jack


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## Gary Armitstead (Jan 2, 2008)

Jack,

I just did some look-up of info on spin-casting. That really is a great way to cut the cost of castings in zinc or aluminum. The cost of tooling is REALLY reduced! I learn something new everyday here.


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## Jack - Freshwater Models (Feb 17, 2008)

Gary, 

Yes spincasting is useful but is to a degree limited. Not the precision of investment casting and limited to tin alloys and zinc-aluminum alloys. Mold material costs are pretty reasonable though going up but the cost of quality equipment is pretty nasty and alloy prices have been volital for the past 18mo. 

There is a major learning curve with little specific info written on the subject. The equipment dealers make it look easy but there is a lot to the process. When you get down to the nitty gritty of it is WORK and actual casting, once set up, is pretty boring. 

I chose the process due to the relatively environmentally friendly nature of the materials available and since it allows me to amortize the cost of a mold on a short run of parts. The alloy I use doesn't contain lead or cad so is pretty safe to use and handle. 

Jack


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## Pete Thornton (Jan 2, 2008)

Got an email address or web site for Dave


Sure do: 

http://cumberlandmodelengineering.com/


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## Jack - Freshwater Models (Feb 17, 2008)

Pete,

I found David just after I asked. Sadly, he doesn't do turning and those tires came from South Africa. Daves strong suit is in wire edm for cutting frames and patterns. Daves capabilities in house are not as I would have imagined from the look of the web site. What he does have on his web site appears to be of excellent quality.

I may eventually look into having tires cnc turned but there has to be enough demand.


Jack


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## xo18thfa (Jan 2, 2008)

Jack: Very nice work on those drivers. Can't wait to see the finished product.

I have to do a shameless plug for the Chingford Express. It is a really sweet little engine. I built one a few years back and she runs like crazy. Mine easily tows 3 David Leech Bullied coaches. Here's a little series I did on the construction. 


http://archive.mylargescale.com/forum/topic.asp?TOPIC_ID=30544

Don't do what I did for quartering wheels. It's better to use the "old school" LBSC method and press them on the axles. 

I am thinking about building another. Someday. What I will do differently is to use the original LBSC "Smithies" boiler arrangement, but put the oiler in the cab, like on a Ruby. Pushing the cylinder as far forward as possible is a big help, I think. My boiler is way more complicated than it needs to be, but it steams like crazy. LBSC's simple alcohol burner will work fine with the Smithies boiler.

Looking forward to seeing more of your drivers. Bob


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## Jack - Freshwater Models (Feb 17, 2008)

Bob,

Interesting version of Chingford Express! Very nice to see someone interested in loco building.

I have some info on the prototyoe and hope to be able to cram the meths tank in the coal bunker. I will probably use a smithies boiler but have also been considering a Project type boiler. I hadn't consider a tender but it does make sense. I would want to disguise it as a wagon for a J67 or Coach for J69.

About 20 years ago I built a Chingford chassis that was complete but never got arount to the boiler and superstructure. It ran on air very nicely. I sold it and it ended up in Canada.

LBSCs locos are a bit "basic" but they do run well. If I get Chingford done by summer I plan on starting "Girton" a Schools based loco.

Jack


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## mocrownsteam (Jan 7, 2008)

Jack, 

Lots of laser cut "goodies" are available for GIRTON. I have a set of the frames and rods and they will save a lot of time. 

Looking forward to having drivers available from you for my projects. What you have done so far looks really good! 

Mike McCormack 
Hudson, Massachusetts


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## Jack - Freshwater Models (Feb 17, 2008)

Mike, 

Tell me more about the Girton goodies???? Making frames isn't too bad if you have a large enough mill. We really need CI drivers and that is my ultimate goal but Z-A drivers will do for Chingford and maybe some other projects. 

Jack


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## Jack - Freshwater Models (Feb 17, 2008)

Here's a picture of the zinc-aluminum driver casting for _Chingford Express_. They came out nice and I hope to machine a sample shortly. The inside of the rim is very round being within .003" and the finish is very nice. The outside of the rim is not as concentric with the inside of the rim as I would like but is within useable limits and better than some CI drivers I have had.


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## Jerry Barnes (Jan 2, 2008)

Glad to see you making progress. Jerry


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## Jack - Freshwater Models (Feb 17, 2008)

Hi Jerry, 

Ya, only wish the outside was as round as the insixde which would make machining easier. I cast a bunch of these pretty fast and just need to work on making round and concentric wheels. 

Jack


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