GE 23 ton boxcab in 7.5" gauge / 1.5" scale

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Jawn
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GE 23 ton boxcab in 7.5" gauge / 1.5" scale

Post by Jawn » Fri Oct 09, 2015 3:01 pm

Earlier I had inquired about power for a small locomotive and settled on battery/electric for such a small critter. I've settled on a design and now it begins.

http://www.cnwhs.org/ageir/ageir40.html

They're neat looking little critters. Tiny, but I hope to put enough weight in it to give it useful tractive effort.

I just received some wheels (four destined for this locomotive, four probably for a bobber caboose). I have some 4130 steel rod I plan to use for axles (what size should it be? I have an assortment), and 26mm OD x 9mm ID x 8mm wide ball bearings.
20151009_125915 (Small).jpg
I'll get a suitable electric motor online if one doesn't show up from the junk business soon. I have a pair of old deep cycle batteries I'll use as core replacements for new ones. Still working out the details of control, not sure if I'll go tethered or R/C. Either way it'll probably be something homebrew (I like messing with electronics).

As for construction, I figured I'd follow prototype and use a thick steel slab (in 1.5" scale, that's 7/16" steel plate) for the deckplate and build up/down from there.

Glenn Brooks
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Re: GE 23 ton boxcab in 7.5" gauge / 1.5" scale

Post by Glenn Brooks » Fri Oct 09, 2015 3:10 pm

You can add a bit of weight by going with larger diameter axles and turning down the part that fits in the wheel - maybe anywhere from 1/2" to 3/4", even 7/8" diameter axles with the axle stub in the wheel being 3/8" to 7/16" maybe?? Probably doesn't matter much what size you make the stubs so long as they fit the scale of the wheel hub itself and the ID of the bearings. 3/8" axle hub O.D. is immensely strong for the actual size of the loco you plan to build.
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Motive power : 1902 A.S.Campbell 4-4-0 American - 12 5/8" gauge, 1955 Ottaway 4-4-0 American 12" gauge

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steamin10
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Re: GE 23 ton boxcab in 7.5" gauge / 1.5" scale

Post by steamin10 » Fri Oct 09, 2015 11:17 pm

I use 1" and 7/8 for axles, as that is what fell into my lap. The 7/8 make a nice 'hourglass" tapered axle for cars, with a shoulder to hold the wheels in one direction, and journals of whatever size needed. 1/2" being a common center dimension for me.

The 1" stock I have is keyed down the side, so it is a natural for drive components, chain gears, and the like to be slid in place with no sweat. With drive chains around the axles, the choice of motor position, is fairly straight forward. A mounting plate can have a screw to adjust the tension, and kill that bird right there, swing arm style.

So the rolling platform becomes fairly easy to assemble. For me, I use metal from discarded window air units, and build the cabs of cardboard, then cut metal to suit my eye, and what is available.

Added weight can be put in the frame ends under the floor with lead blocks or steel slugs.

Just throwin' ideas out for you to consider.
Big Dave, former Millwright, Electrician, Environmental conditioning, and back yard Fixxit guy. Now retired, persuing boats, trains, and broken relics.
We have enough youth, how about a fountain of Smart. My computer beat me at chess, but not kickboxing
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Bastelmike
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Re: GE 23 ton boxcab in 7.5" gauge / 1.5" scale

Post by Bastelmike » Sat Oct 10, 2015 12:32 am

Jawn wrote: I have some 4130 steel rod I plan to use for axles (what size should it be? I have an assortment), and 26mm OD x 9mm ID x 8mm wide ball bearings.
Hi Jawn,,

just for reference some data from the prototype. Modern fullsize locomotives, axle load 20-25 tons, have typically an axle Diameter between wheels around 200mm = 8". With 1/8 scale thats 1".

Ball bearing ID 120-150mm = 5-6"- In Your scale ~3/4"

The 23ton doesn't have These axle loads, so Diameters should be less.
Axle Diameter 3/4 or 7/8 is okay, for bearing ID I would prefer 12mm respectively 1/2".

Mike

Jawn
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Re: GE 23 ton boxcab in 7.5" gauge / 1.5" scale

Post by Jawn » Sat Oct 10, 2015 7:59 am

Bastelmike wrote: Axle Diameter 3/4 or 7/8 is okay, for bearing ID I would prefer 12mm respectively 1/2".
I'd like to use what I have if I can. I figured as long as the turned-down stub for the bearing ID is not longer than the bearing itself, the small ID wouldn't be that big a deal.

Do you normally use a press fit to keep the bearings on the axle and in the journal boxes? Or do you let one "float" for flexibility?

Bastelmike
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Re: GE 23 ton boxcab in 7.5" gauge / 1.5" scale

Post by Bastelmike » Sat Oct 10, 2015 9:59 am

Hi Jawn,

it depends. In this case the seat axle - inside ring should be a tight fit. outside ring -bearing box more a loose fit.
Always remember through temperature the axle might grow. Do not fix both bearings completely in axial direction, one bearing should have the freedom to "creep", either on the axle or in the bearing box, the other bearing is usually fixed in axial.

Mike

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Joe Tanski
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Re: GE 23 ton boxcab in 7.5" gauge / 1.5" scale

Post by Joe Tanski » Sat Oct 10, 2015 11:51 am

Why not just use the Plum Cove powered axles & their electronics .i have them on my 23 tone ge
Cab switcher.with two deep cycle batteries it runs all day long ,
Joe

Jawn
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Re: GE 23 ton boxcab in 7.5" gauge / 1.5" scale

Post by Jawn » Sat Oct 10, 2015 12:35 pm

Joe Tanski wrote:Why not just use the Plum Cove powered axles & their electronics .i have them on my 23 tone ge
Cab switcher.with two deep cycle batteries it runs all day long ,
Joe
Because I want to build it. Cheaper and more fun.

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steamin10
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Re: GE 23 ton boxcab in 7.5" gauge / 1.5" scale

Post by steamin10 » Sat Oct 10, 2015 2:24 pm

Thats the spirit! On my critter the axles are fitted tight to the bearing blocks, (journals) and they slip and slide with some clearance in the outside frames. They actually rattle. Some conflict arises that the axles tend to pull together on powering up or coasting down from the 'grip' action of the drive chains, but it doesnt seem to be a problem. If you have two independent axle-motor assemblies, this action would be eliminated. free motion of the axle-motor assembly would take a bit of creation to get flexible to follow the small axle motions.

Critter frame is 33" long on the floor plate, with the journal box slides cut out of the four inch channel. Similarities end there as my design is for a 3 HP gas engine drive.
Big Dave, former Millwright, Electrician, Environmental conditioning, and back yard Fixxit guy. Now retired, persuing boats, trains, and broken relics.
We have enough youth, how about a fountain of Smart. My computer beat me at chess, but not kickboxing
It is not getting caught in the rain, its learning to dance in it. People saying good morning, should have to prove it.

Jawn
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Joined: Wed Apr 09, 2014 12:39 pm
Location: Canton, GA

Re: GE 23 ton boxcab in 7.5" gauge / 1.5" scale

Post by Jawn » Wed Oct 14, 2015 4:07 pm

Here's the basic layout I have in mind. Should be able to fit two decent size deep cycle batteries. Motor in between, chain drive, and control electronics above it.
23tonner.jpg
23tonner.jpg (19.12 KiB) Viewed 2696 times

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Fender
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Re: GE 23 ton boxcab in 7.5" gauge / 1.5" scale

Post by Fender » Wed Oct 14, 2015 6:19 pm

That's pretty much the configuration I used on my Davenport loco. However, it turned out to not have enough speed reduction between the motor and axles, so I had to add another jackshaft and sprockets/chain into the drive train. You'll need to have some way of tensioning the chain between the sprockets. I also found that I needed a fan to cool the motor.
Dan Watson

chooch
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Re: GE 23 ton boxcab in 7.5" gauge / 1.5" scale

Post by chooch » Wed Oct 14, 2015 6:45 pm

I wonder why you couldn`t add 2 different size sprockets on the lower shaft and Then a chain to each wheel axle??
I think if a "tensioner" is needed, a spring loaded fixture might be made fairly simple. Maybe even a lawn mower belt part would do.

chooch

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