Author Topic: Old Fart Ramblings - Steam Critter drives  (Read 405 times)

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kiwi_al

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Old Fart Ramblings - Steam Critter drives
« on: July 30, 2020, 04:26:49 AM »
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I must have too much spare time on my hands, thinking about how we currently have 3 manufacturers making critter chassis.
Kato with it's B shorty mechanism, Tomix with a variety of lengths and Green Max with short and long mechanisms. Between those 3 manufacturers we can make a wide variety of small diesel engines.
When you look at steam we have to buy a fully built locomotive then strip it down and use the bits we want and put the other bits in the parts bin.
I was thinking if the 3 manufacturers above built modular steam mechanisms say 0-4-0,0-6-0 and maybe a 0-8-0 with a variety of wheel diameters, it would lower the cost in kitbashing our favourite (yes I'm from the British Commonwealth eh) steam locos. We could chop them up, make them longer, add more wheels etc. Then the problem would be the siderods but it would be a better starting point. :D
What do you guys think?

ChristianJDavis1

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Re: Old Fart Ramblings - Steam Critter drives
« Reply #1 on: July 30, 2020, 04:46:59 AM »
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Check some of the Japanese manufacturers for small steam mechanisms. TGW comes to mind, but I know there are others. They are usually used to power kits or other scratchbuilt motive power, and they sound exactly like what you want.
- Christian J. Davis

kiwi_al

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Re: Old Fart Ramblings - Steam Critter drives
« Reply #2 on: July 30, 2020, 06:26:39 AM »
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Check some of the Japanese manufacturers for small steam mechanisms. TGW comes to mind, but I know there are others. They are usually used to power kits or other scratchbuilt motive power, and they sound exactly like what you want.

How did I miss that, yes that's kind of what I was looking for!! I'll be a great start

randgust

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Re: Old Fart Ramblings - Steam Critter drives
« Reply #3 on: July 30, 2020, 09:17:39 AM »
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The problem with the one that's out there (the little 0-4-0 with the vertical pager motor) is multiple.

First, it does work.  But, those are all little rockets.   There's usually either a 3.5 v. or a 6v. pager motor there.

And because of the motor size, there's really no torque to speak of, direct worm gear to a spur on the axle.

Then you get into the pickup issues with non-equalized, short-wheelbase 2-axle drive.   Only solid frogs will work at all.   And, although it's tempting to turn the wheels, if you drop in a frog with a wheelbase that short, you may rock completely off.

Then there's the wheels.   Some of the manufacturers have really terrible wheels; no fillet, sharp-edge flanges that pick any irregularity and derail.

I've had several of these mechanisms tinkering with my 25-tonner drives and the most success was taking one, putting a Kato 11-105 motor in place of the pager motor (twice the size and 12v) and swapping the wheels out for better Kato wheels.  I started with a TU-7T   That worked, but you still have a rocket that takes an excellent throttle to control at all.   See Youtube for my running video of that.   This mechanism plus a Shapeways shell has proven to be a repeatable build.
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  But if you take that drive, and add side rods and cylinders, you've got a steam critter drive and that's what they've already done.    If you can get a gearhead in there (even the Robotshop GM15A) with the 25:1 reduction, you've then got something, but I haven't made one work yet.

The 4-wheel drive for the N/Nn3 kits that's been expirimented with are expensive but really well engineered.   The one that Walter Vail (Showcase) does for his Nn3 geared steam kits is well evolved, hopefully he'll offer in in N at some point.     I had an early one from another manufacturer and all it had was Z wheels regauged and didn't work well at all.    But the combination worm/spur gear reduction is what you need.  Walter's done various overlays on the wheels as well for spokes and counterweights. 

Bottom line, it's almost there.... keep an eye out.
« Last Edit: July 30, 2020, 09:30:53 AM by randgust »

sd45elect2000

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Re: Old Fart Ramblings - Steam Critter drives
« Reply #4 on: July 30, 2020, 12:33:01 PM »
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I just bought one of these drives for a trolley car. I do not like the wheels on any of the Tom drives I have, looking for a solution.

randgust

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Re: Old Fart Ramblings - Steam Critter drives
« Reply #5 on: July 30, 2020, 12:52:52 PM »
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Tomytec drives have a split-axle just like a Kato.    If you have a Dremel, or even a drill, you can pull the wheels apart and turn the flanges and easily reassemble them.     I just used a file, and referenced the depth with a micrometer although you can also just eyeball it.  I've had to turn a lot of them for customers on my Whitcomb kits.    Probably easiest flange-turning job around.

mmagliaro

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Re: Old Fart Ramblings - Steam Critter drives
« Reply #6 on: July 30, 2020, 01:41:17 PM »
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Where are these TGW mechanisms?  I can't find them.
Thank you.

DKS

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Re: Old Fart Ramblings - Steam Critter drives
« Reply #7 on: July 30, 2020, 02:22:40 PM »
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Where are these TGW mechanisms?  I can't find them.
Thank you.

They are difficult to find. Here's a listing, although they're all out of stock. Sometimes you'll find them on the 'bay.

https://www.1999.co.jp/eng/list/750/0/1

Or here:

https://banzaihobby.com/train/tgw-tsugawa-yokou
« Last Edit: July 30, 2020, 02:25:05 PM by DKS »
“Everyone leaves unfinished business. That's what dying is.” —Amos, The Expanse

Chris333

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Re: Old Fart Ramblings - Steam Critter drives
« Reply #8 on: July 30, 2020, 02:59:29 PM »
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Ah TGW home of the 1:1 gear ratio  :lol:

sd45elect2000

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Re: Old Fart Ramblings - Steam Critter drives
« Reply #9 on: July 30, 2020, 03:13:05 PM »
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Tomytec drives have a split-axle just like a Kato.    If you have a Dremel, or even a drill, you can pull the wheels apart and turn the flanges and easily reassemble them.     I just used a file, and referenced the depth with a micrometer although you can also just eyeball it.  I've had to turn a lot of them for customers on my Whitcomb kits.    Probably easiest flange-turning job around.

I am using some Proto 87 girder rail, i also have issues with width. As soon as I get the machine I am going to do exactly what Randy suggests.