TheRailwire
General Discussion => N and Z Scales => Topic started by: Jim Starbuck on August 25, 2023, 10:38:51 PM
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The latest addition to the critter fleet is this GE 25 Tonner.
The shell is Damin Keegan’s excellent design from Shapeways and the mechanism is a modified 12mm axle space geared turnback drive from Narrow Garage Japan. Thanks @Chris333 and @u18b for the links to the mechanisms. The chassis is 3D printed and nicely done.
I’ve had this shell for well over a year and had started powering it using a Bachmann 44/70 tonner truck. The axle spacing was right but the gear tower was centered and I was trying to use a shorter motor without much success. When I saw the link to the Narrow Garage chassis and his drawings showed the main part of the drive at 6mm width I knew it would work. The inside of the shell measures just over 6mm.
The drive comes with a 10mm motor so I remotored it with a 6x15 coreless. The shaft on the coreless is smaller than the stock one so I made a bushing that ended up only .004” wall thickness but it worked.
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I shortened the chassis and added a styrene cradle for the new motor. Photo shows the stock chassis on the left.
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I changed the stock wheels to ESM at first but ended up changing those to Tangent 36”. The stock wheels have a metal hub which rides in the 3D printed frame so I turned down bushings from brass stock to go over the now half axle wheels.
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I needed a way to hold the shell to the chassis so brass angles were glued to the squared up ends of the lower chassis section. The notch in the brass is where the coupler screw passes by. I milled the shell so the bottom of the angle was flush with the top of the coupler opening. Screwing the coupler to the shell traps the brass angle holding everything together and establishes shell and coupler height. The shell is printed with the screw holes already in it so I tapped them for 00/90 screws.
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The ground pad on the ESU Lokpilot Micro is about the size of a pinhead and it’s difficult to keep the solder joint from breaking. My remedy was to lay the wire so it exits the decoder opposite the stock wires then hot glue the capacitor side of the TCS KA-N1 keep alive to the decoder. This traps the ground wire to avoid breaking the solder joint and still makes a compact electronics package.
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Some thin double sided tape holds the decoder and keep alive vertical and it just fit up in the cab after scraping some thickness out of the cab ceiling.
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Since I was freestylin’ this one anyway I used elements from multiple prototype photos. I thought the external air cleaner on the hood was cool so I made one from brass. Railings are .008” phosphor bronze wire and the air whistle is a piece of brass wire drilled to accept an .008 wire “pipe”.
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The shell was primed with Mr Surfacer gray. The paint is Tamiya Flat yellow with some orange mixed in. The black is Tamiya NATO black.
Decals were printed on my Alps then everything was sealed with Mr Hobby Matt clear.
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A few added details were brass wire for the exhaust stack, brass trainline hoses, BLMA windshield wipers and scratchbuilt cut levers.
The lights are 0201 LEDs.
A huge thanks goes out to John @oakcreekco for hooking me up with the Kato semiautomatic couplers. They fit up beautifully.
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It runs nicely albeit a bit noisy. I suspect from the extra gearing but is slows down well and crawls through Unitrack switches. It will move 5 or 6 cars without problems.
Here’s a short video:
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Jim
Here’s a short video.
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WOW!
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Damn , and thats over turnouts .
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Impressive is an understatement, Jim!
And to think I'm proud of my abilities when I assemble an MT coupler :facepalm:
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I love it Jim.
Very well done.
And the cab is still open.
What a great locomotive.
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Absolutely incredible!
When are they going to be available? (JUST KIDDING!)
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After your last tiny loco I thought you needed a harder challenge, I had the 25 tonner in mind but here you have done just that. I'll have to find something smaller for you to make :D :D
Massive ups to you for doing this so well!!
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Jim, this is the best I can come up with:
http://www.northeast.railfan.net/images/bnsf_trackmobile.jpg
Probably not smaller but it is trickier :D
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Thank you for kind words gentlemen. Hi praise indeed coming from this group.
This was just my own spin on a 25 tonner. @randgust scratch built his probably 15 years ago. He also has a Trackmobile and Burro crane that run. I’m also inspired by Ron’s hi-rail truck, Max’s Stephenson Rocket and @Chris333”s various critters. @bbunge recently posted photos of his 25 tonner as well. I’m wading into some very good company here.
@kiwi_al, I’ve got several more smallsters in the queue. Stay tuned…
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Rereading my original post I realized I left out a couple photos.
The motor turns an intermediate gear that in turn drives the worm shaft
The shaft rides in bushings at either end.
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There was some room in the shell above the motor which got filled with tungsten powder. I also fit wafers of lead in the cheeks of the cab.
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It weighs in at .463 ounces/ 13.13 grams. It will handle 3 or 4 40’ MT gondolas and 5 or 6 empty 33’ two bay hoppers.
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Looks and runs great! :o
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Looks and runs great! :o
Thank you Russ!
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Dang, he does it again! : :o
Just beautiful, Jim
Otto
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Dang, he does it again! : :o
Just beautiful, Jim
Otto
Thank you Otto!
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I bet that new motor was an upgrade besides making room. It is very smooth and slow!
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I bet that new motor was an upgrade besides making room. It is very smooth and slow!
Absolutely!
The Tramfabriek motors play extremely well with ESU decoders. With the gearing this little bugger will slow to a crawl and the TCS keep alive makes it rock solid through switches.
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Absolutely!
The Tramfabriek motors play extremely well with ESU decoders. With the gearing this little bugger will slow to a crawl and the TCS keep alive makes it rock solid through switches.
I'm assuming the Tramfabriek motors are basically the same as the Bachmann coreless motors like we used in the SW9/1200, right? If so, then yes, they are magnificently smooth motors and I really hope that more N scale loco manufacturers consider moving to them, as they also make more room available for sound decoders, etc.
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I believe the 7x16mm double shaft motor from Tramfabriek is the same as the Bachmann.
The 6x15mm from the same source is a single end shaft which is what I used in the 25 tonner and the American crane.
These slim, smooth and powerful motors have been an absolute game changer for building these small locomotives.
Jim
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Bachmann motors, while coreless, they are really low-end motors with only 3-segment commutator. I took one apart, so I know. Kato coreless motors have 5-segment commutator, and some other coreless motors I have examined have 7-segment commutators. Those are really smooth with lots of torque. Think of the number of segments as number of poles in a standard open frame motor. I have no knowledge of the Tramfabriek motors.
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Thank you for sharing. Amazing work. Excellent ideas!
Bob
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Bachmann motors, while coreless, they are really low-end motors with only 3-segment commutator. I took one apart, so I know. Kato coreless motors have 5-segment commutator, and some other coreless motors I have examined have 7-segment commutators. Those are really smooth with lots of torque. Think of the number of segments as number of poles in a standard open frame motor. I have no knowledge of the Tramfabriek motors.
@peteski,
Thanks for the motor information.
Is there any way to tell by the specs what’s on the inside of the motors? As in are there particular specs to be looked for other than just physical dimensions when sourcing motors?
Jim
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Well Done!! 👍👍
Jerry G.
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@peteski,
Thanks for the motor information.
Is there any way to tell by the specs what’s on the inside of the motors? As in are there particular specs to be looked for other than just physical dimensions when sourcing motors?
Jim
No, I have never seen any detailed specs for those low cost coreless motors. The manufacturers probably list them (if you know the manufacturer), but sellers usually do not include them. High-end motor manufacturers like Maxon or Faulhaber provide all their specs, but those motors are quite pricey.
There is no way I know how to tell looking at the outside of the motor. That is why I disassemble one (they are inexpensive enough to sacrifice one). The low-end motors will still work, and are good for where very small motors are needed. I just wanted to mention that they might not have the torque or longevity of Maxon motors (but still plenty good for a typical model locomotive usage. There seems to be this belief that a coreless motor automatically means superior performance and long life, but that is not the case for every coreless motor. Low-cost coreless motors became popular when Chinese manufacturers started producing large amounts for inexpensive radio controlled flying toys, and spread to other types of electric powered toys and models over time. Before that, coreless motors were usually made in Germany and they were all top quality and longevity.
(https://www.therailwire.net/forum/gallery/14/2700-030220002800-147442388.jpeg)
Here is a photo of a Kato coreless motor showing the commutator and brushes. It has 5 segments. Will be smoother and have more torque than a 3-segment one.
(https://www.therailwire.net/forum/gallery/2700-120717040818.jpeg)
This one if from Arnold S1. Similar to Bachmann coreless motors. It has a 3-segment commutator.
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I use the Tramfrbriek 7x16 coreless. I place them in all of my Shays. By its very nature, a Shay probably requires a bit more torque. I have found these up to the task. They barely feel warm when running continuously. Of course, my Shays have eventually been tuned to reduce friction.
I love these motors.
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Maxon 8mm motors use 5 commutator segments. The 10mm and larger use 7.
As for specs, Tramrabriek does show complete specs for a lot of their motors on their website.
Example: Their 0816D18, which is an 8mm x 16mm dual shaft, and is the higher-rpm, more powerful version that they offer.
I say more powerful because it is, not because it has a higher max RPM. Its stall and continuous rated torque are much
higher than their 0816D lower-speed version.
The 0816D18 continuous rated torque is 5 g-cm (gram centimeters)
A comparable Maxon 8mm x 16mm 12v motor #118391, rated continuous torque is 7.6 g-cm (you have to convert from
mNm to g-cm because Maxon specs all their motors in mNm units). Still, that's a whopping 50% more powerful., with a no-load speed of only 11,600 vs the Tramfabriek's 17,800. I would argue that getting more torque and lower speed is much more
preferable. The Tramfabriek lower-speed version (speed comparable to the Maxon) is only 3 g-cm rated torque, so the Maxon is 250% more powerfulthan that one.
That's not to say this doesn't come at a high price. The Tramfabriek motor is about $22 USD. The Maxon is $78, nearly a whopping 4x more expensive. So that boost in performance is expensive indeed. Of course, there are big unknowns like precious metals, bearing quality, lifespan, etc. For model train use, who can say whether any of those will matter? We're not putting these motors into a space satellite that has to contuinuously operate for 20 years, after all.
One final thought. My impression is that getting Maxon and Faulhaber motors on eBay or other surplus sources has become a lot harder in a post-Eldon-Shirey world. I have no idea whether his passing away and the loss of his micro-loco-motion business had an impact on this, but it does look to me like the periodically available stashes of relatively cheap surplus Maxon and Faulhaber motors has really dried up since we lost him.
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This is excellent information.
Thank you gentlemen.