Milw steeple cabs

[randgust]

You're still going to have really low torque and relatively high speed with most designs like that, so the issue is control.  Unless the motor is 12v and doesn't require a dropping resistor, you'll have issues there - that was a real problem with the original Kato 11-105 - they had a 100-ohm resistor on that circuit board tucked underneath and a 3v motor.  That went away when they got the 12v motor in the same case.

I've been OK with those tiny 3V motors as long as they had a gearhead to effectively have enough torque to not increase the current draw, a little resistor can deal with that well.  But man, those little early ones would get 'burn your fingers off' hot on the resistor under load, as well as be darn near uncontrollable as the RPM's increased as the current dropped coming off a grade or off load.

You also need equalized, end-axle pickup if you can get it, no wipers, no inside bearings.   

The last guy I saw really get excellent performance at slow speed without a gearhead was Ron Beardon's three-axle switcher, complete success, but I can't remember what motor he found.

The Japanese modelers have a ton now of really tiny 2-axle and 4-axle drives, more or less designed like that.   The Tomytec ED-01 and TR-01 are essentially what you are doing here.  The ED-01 is what I used on my last personal Whitcomb 65-ton build,8x8 drive and pickup, really worked well, but darn fast and relatively low torque.   The TR01 is inside-bearing (not as good) but basically same design.   The ED-01 has been out of production forever or I would have made it a standard mechanism for my Whitcomb kits, that was a sweet concept.

The best tiny, slow, powerful 8x8 power and pickup drive I've ever seen is the Bachmann 44-tonner, but it's in a fixed-length, cast-metal split frame.  But the design, components and execution of that mechanism are about as good as I've seen in end result.  That's another one to study.   You can get those motors, which essentially were the same 12V motor as in the Kato 11-105 but double shafted, which was sweet as well.    In a perfect world, you'd buy this chassis, tear it apart, fit it in a new metal split-frame that could accommodate your dimensions, and call it a day.
http://www.spookshow.net/loco/bach44ton.html

The slow-speed reduction is in the truck towers. 

This is the listing for the N motor, picture for the HO, trust me, it's as good as it gets.
https://estore.bachmanntrains.com/index.php?main_page=product_info&cPath=70_113&products_id=9995

[chessie system fan]

The last guy I saw really get excellent performance at slow speed without a gearhead was Ron Bearden's three-axle switcher, complete success, but I can't remember what motor he found.

This is it:

https://www.ebay.com/itm/284326072597

[AlwaysSolutions]

Well, looks like I've got a lot of considerations and thinking to do.  I appreciate everyone chipping in with their experiences.  Meanwhile, I wanted to keep motivation going so I modified the 3D model to make it print-worthy and printed a first draft of the chassis.  In my haste I screwed up the ride height but I've corrected it and will print another tonight.  I'm pretty happy with this little guy - while the printer is humming tonight I'll get to adding rivets and hinges to the shell.  Then I'll do up proper sideframes.  Anyway here she is in front of big brother Joe, Draft 1:

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 Cheers -Mike

[Jim Starbuck]

That’s looking quite nice Mike!

[u18b]

Aaron is correct- that was the motor.

But I have extensively used the coreless motors that Tramfabreik sells.

https://tramfabriek.co.uk/

I use the 7x16 in my Shay projects.  It is a fabulous motor, and it is double shafted.

If it will fit, I highly recommend.

[Jim Starbuck]

I fully agree with Ron on the 7x16 coreless.  I used it in my tiny Model 40 switcher among several others so there should be plenty of room in your shell.

[Iain]

You're still going to have really low torque and relatively high speed with most designs like that, so the issue is control.  Unless the motor is 12v and doesn't require a dropping resistor, you'll have issues there - that was a real problem with the original Kato 11-105 - they had a 100-ohm resistor on that circuit board tucked underneath and a 3v motor.  That went away when they got the 12v motor in the same case.

I've been OK with those tiny 3V motors as long as they had a gearhead to effectively have enough torque to not increase the current draw, a little resistor can deal with that well.  But man, those little early ones would get 'burn your fingers off' hot on the resistor under load, as well as be darn near uncontrollable as the RPM's increased as the current dropped coming off a grade or off load.

You also need equalized, end-axle pickup if you can get it, no wipers, no inside bearings.   

The last guy I saw really get excellent performance at slow speed without a gearhead was Ron Beardon's three-axle switcher, complete success, but I can't remember what motor he found.

The Japanese modelers have a ton now of really tiny 2-axle and 4-axle drives, more or less designed like that.   The Tomytec ED-01 and TR-01 are essentially what you are doing here.  The ED-01 is what I used on my last personal Whitcomb 65-ton build,8x8 drive and pickup, really worked well, but darn fast and relatively low torque.   The TR01 is inside-bearing (not as good) but basically same design.   The ED-01 has been out of production forever or I would have made it a standard mechanism for my Whitcomb kits, that was a sweet concept.

The best tiny, slow, powerful 8x8 power and pickup drive I've ever seen is the Bachmann 44-tonner, but it's in a fixed-length, cast-metal split frame.  But the design, components and execution of that mechanism are about as good as I've seen in end result.  That's another one to study.   You can get those motors, which essentially were the same 12V motor as in the Kato 11-105 but double shafted, which was sweet as well.    In a perfect world, you'd buy this chassis, tear it apart, fit it in a new metal split-frame that could accommodate your dimensions, and call it a day.
http://www.spookshow.net/loco/bach44ton.html

The slow-speed reduction is in the truck towers. 

This is the listing for the N motor, picture for the HO, trust me, it's as good as it gets.
https://estore.bachmanntrains.com/index.php?main_page=product_info&cPath=70_113&products_id=9995

I once went through the effort of drawing up a split frame to use the 44 ton components to power a whitcomb and even had a test 3d print done.  The kicker is I was in a car wreck and the hard drive got trashed, but it's on my to-do list to replicate that work (someday).

[Jim Starbuck]

I once went through the effort of drawing up a split frame to use the 44 ton components to power a whitcomb and even had a test 3d print done.  The kicker is I was in a car wreck and the hard drive got trashed, but it's on my to-do list to replicate that work (someday).

@Iain Inquiring minds want to know…which Whitcomb were you working on? A 44tonner has been on my want list for quite a while.

Jim

[Iain]

@Iain Inquiring minds want to know…which Whitcomb were you working on? A 44tonner has been on my want list for quite a while.

Jim

75 ton, for Beaufort and Morehead

[TinyTurner]

Looking forward to this.
It's nice to have a vision and watch it follow through.
When do we put the advance orders in?

Works for the big name products releases   

[AlwaysSolutions]

Over the last week I struggled with the ride height since I had to drop it considerably from my first draft, I ran into physical constraints but finally figured out a workaround.  While my many chassis iterations were printing I updated the pantograph, designed the truck sideframes (still in progress), slightly modified the main shell which I haven't printed the updated shell yet.  I also ordered a couple more Tramfabrieck motors with dual shafts, hoping those will be good performers.  Anyway here's a pic with the aforementioned updates:

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Cheers -Mike

[Jim Starbuck]

My experience with Tamfabriek motors has been game changing. I’ve used over a dozen in various scratchbuilds and remotoring existing mechanisms. The double shaft 7x16 as well as a couple of the 6x15 have proven to be reliable, strong and excellent performers. I’ve not had any failures or any problems with them whatsoever.

Jim

[randgust]

Thanks guys - that's a huge resource I'd never really explored.

I have one remaining hill to climb I've never conquered, a scale-size, scale wheelbase, 47-ton Heisler with a working crank.   This may restart that effort.

You pretty much have to work backwards off the trucks on that one.   The 5' wheelbase is the killer there, along with 42' wheels and inside pickups.

Mind you, my original 1976 "Bigfoot" version (9' wheelbase) is still going strong, but I've successfully scratchbult everything else I've wanted including the PRR D16, the Climax B, 25-ton Shay, Lima 2-6-0, rebuilt Trix decapod.... this is still the one I've never figured out.

[nkalanaga]

I don't know of any available truck with a five foot wheelbase.  Probably the shortest I've see is the MT Z F7, which is just under half an inch, or a little less than 80 scale inches.  It could be modified with longer axles and larger wheels, but would still be too long.

[AlwaysSolutions]

Could this thing possibly have any more rivets?  Why yes, yes it could!  I haven't had a lot of time this last week to work on it, and next week appears to be shot as well.  But, I still tinker at night when I have a spare moment or two.  Besides adding the rivets, I had some fun with the one small motor I do have.  I 3D printed a worm gear and motor coupler just to see if it was worth anything.  After a couple additional measurements I produced a worm gear that matches dimensions of the brass ones.  The first couple drafts I thought, no way it's going to work.  They "kind of" worked, but were bumpy / noisy.  By the third draft it was quite smooth.  Can't wait to get the motors I have on order to do it properly.  Anyway - updated model with rivet detail.  Still more to do:

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Cheers -Mike