Large Scale Central

Jawn Henry - a slow moving project

Modeling
#1

I have been working off and on developing a 1:32 model of N&W’s Jawn Henry. My first task is to create a power truck that does not exist. Using AutoDesk Inventor I have been modeling what I think will work. The truck is a Baldwin AS-616 (or so I have been told). I have not been able to verify that. I have been working from the drawings published in October 1976 issue of Railroad Model Craftsman. Below is a pic showing what progress I have made.

I see it as several castings, some laser or water jet, and lots of machining. The project direction is to power two trucks with a Pittman motor, two motors for the engine. Many more details to work out, but being able to develop it in model form first will hopefully eliminate most of the false starts in building. Bob C.

#2

Oh boy, I can’t wait to follow this. I love those of you that can cut/mill/cast/etc at this level.

#3

No kiddin…not to mention a “home road” prototype

#4

Cool!
Good Luck Bob and keep us posted!!!
:slight_smile:

#5

I’m another who will follow along

#6

This was titled ‘slow moving’ because this step from decision to attempt this project to where we are now is about 3 years. Took the drawings from RMC (done to 3/16"=1’0") and had them doubled at the local drafting supply store. Then spent a bit of time generating a rough working side elevation of the truck in AutoCAD. The original drawings gave little evidence of the thickness of the trucks, so that part is all interpolation from photos I located on the web. I will still need to contact a spring company to assist in sizing the springs for the weight distribution I am looking for. Other details such as brake cylinders, etc are not forgotten, just set aside while the major stuff is worked out. For general reference the truck parts will be brass for most of it, and stainless steel for fasteners and a couple of small parts. The gears will be steel worm and brass gear, with the box relatively sealed and greased. For those interested the original drawings are located here:

http://www.gscalejunkie.com/GeneralPics/CatchAll/Jawn_Henry_Scan_RMC_10-76.pdf

Next up is to work out how the span bolster is going to work. 20 foot diameter track is awfully tight for this size locomotive. Loco and tender will be over 5 feet when completed. Clearance allowances for the curves is going to be another real challenge. I may do a mock up using four truck and some 1 by material to see what the offsets are going to be on the centers of the trucks vs the span bolster. I am not too worried about overhang in the middle, I can just ‘take off what don’t clear’. Goal weight is to be about the same as the USA Bigboy, something in the 90-100 lb range.

@Bart - I have always been a fan of the eclectic, and this surely fits that description in many ways. The most catching thing to me is the boiler is a water tube type in lieu of the standard fire tube used on almost every other steam powered locomotive I know of. The concept of using a steam turbine was not new, but the turbine was not fond of the jostling a railroad generated. As for the turbines, I believe the C&O experienced similar maintenance failures with turbine bearings that N&W did. It is sad that the loco was so short lived and so little information is available about it.

#7

It’s huge :open_mouth: Here’s a photo:

(http://www.divisionpoint.com/photos/N+W_JH/N+W_2300_17.jpg)

Also a few other photos on the site, including their model, and a list of some reference books. Ralph

#8

Bob,

have you considered having the intial parts made as solid models? Will save time over machining and can get you directly to brass castings. the economics of doing eight sideframes alone I think will justify it. And you may find someone else who wants the same truck along the way. Check out Lee spring www.leespring.com/ for spring sizing. Looks good overall. I have used Inventor but am now a Solidworks guy myself, and I have done many 1:20.3 solid models.

#9

Al,

That is the primary direction I am headed. And for most conditions SLA directly to lost wax castings will be acceptable. I have found a company that I can work with on the finger of Florida that can do exactly that, plus post processing if required. I am not comfortable with tolerances in areas such as the journal box/frame, and the shaft/gearbox mates to rely solely on the castings. The model as shown would be considered in a ‘finished’ state. Any areas that will need machining will need to have some additional material added in that area. Another factor I need to resolve before going to any sort of production will be how much to allow for mold shrinkage for making the ‘lost waxes’. I had also considered water jetting all the main side frame parts from bar/plate and finish machining myself, which is still an option. Costing will be a big factor. When all is said and done I cans see the final price tag for this being in the same range as the USA Bigboy.

Lee Spring and Stock Spring are both suppliers I am considering for the springs. I have worked with both on a professional level in the past. I am not confident enough with my abilities to try to balance the spring sizing for that on my own, plus I have a goal for a slight pre-load at assembly, but am not sure how much would be ‘right’.

As for the software, i am using Inventor Suite 2006. I purchased mine when AutoDesk was running a bargain basement pricing structure to get folks into Inventor. I had AutoCAD 2002 and was really only looking to upgrade the AutoCAD. At the office I now run primarily Solid Works, but also use Solid Edge, and some Pro E (which I despise). We have the latest Inventor, but our primary client (the Navy) uses very little of it. We are starting to to more work with the Marines, and they just love their Pro E.

#10

Very cool project!

#11
Quote:
My first task is to create a power truck that does not exist
Bob, Fantastic project!

We have the same issue with our M-1 railcar, which has an 8’ wheelbase and 33" wheels. We fould that the Aristocraft FA-1 truck is a nice self-contained power unit with removable sideframes and one rigid axle plus one ‘floating axle’ on a universal joint. The exploded diagram is here (page 3) http://aristocraftforum.com/NewDocs/explodedDiagrams/FA1new.pdf

Our plan is to make up new sideframes and move the floating axle with a metal frame/extension.

#12

Pete,

It is not clear in the graphic, but the truck is designed to be fully strung and equalized with all axles having full motion. Not the easiest with the limited space and the availability of commercial parts that can be used as is or easily modified. There are a couple of alterations that will require some ‘not common’ tooling.

Looking at the Aristo exploded view gives me a couple of ideas for a ‘next generation’ try at this truck, but for now it is forge ahead with the current design.

Thanks for all the positive comments, the encouragement is appreciated.

Bob C.

#13

Very Impressive! Will be following this one closely!

#14

A little more work last night. Roughed out the front span bolster and mounted the two forward trucks. The trucks are shown at the approximate angle they would be traversing a Wide Switch (10’ diameter). As best as I can tell from the models it should work. The picture below shows the trucks at angles with the front of the engine in the upper left corner. Next up is to develop the sliding ‘U-Joint’ that will join the two trucks. Not much space in between. May have to get real creative. I am considering one of the ball/socket styles. We’ll see…

Bob C

#15

You might want to have a look here

http://www.sdp-si.com/

for any kind of drive products you need.

#16
Quote:
I am considering one of the ball/socket styles
The Shays have square sliding joints + U/Js and are readily available as spares, I think.
#17

@Bob - Stock Drive is where the worm and gear for the gearboxes are from. The gear will be significantly altered in order to work (remove the hub, increase the bore and add a keyway). I only have 5/8" min. in between the ends of the shafts exiting the gearboxes to work with. In that space I need to have the flexibility of a universal joint and the expandability of a slip joint. I searched the net for miniature universal joints, found several manufacturers, none were any shorter than the SDPI ones and most were larger. That joint is going to be a real challenge! Here is a shot of the bottom showing the limited space.

@Pete - I had thought about them, but I don’t believe they (those by Bachmann) will have the strength to handle the torque, although cloning the design concept might work. The motor of choice is the Pittman 9237 24VDC, 11.5 oz-in of torque. A fairly sporty piece. One motor per pair of trucks. Eating the elephant, one bite at a time. :slight_smile: Bob C.

#18

Hi Bob
Have you considered driving the two trucks from above with the drive coming down through the bogie pivot point, using gears and a drive shaft from the one motor. Could be complicated but it might be simpler than the required flexible coupling.
Mick

#19

another thought - steel flex cable like they use on those flexible wrenches? Remember the old erector sets? Square the end of the shafts, one end fixed to one truck, the other a slide joint to compensate for the changing distance between the trucks as they swivel.

#20

@Michael - Yes, that was the first concept. The 2.375 diameter of the motor is too large to accommodate the amount of swing the trucks will be making, not to mention the additional 90 degree turn and associated losses. I might have had better luck all around by using a rigid frame in lieu of the sprung and equalized frame, but I feel the extra effort is worth it.

@Steve - A flexible cable would work for the 7 degree angle between the trucks, but to get the flexibility I need the current length just for the flex, I still need to allow for a slip fit to allow the trucks to move.

My next venture is to model what I think will work for the slip/universal joint. Probably won’t get to it until Sunday, family obligations. More to follow …

Bob C.