Question Rokuhan Z Shorty?

Raytl Dec 3, 2016

  1. Kurt Moose

    Kurt Moose TrainBoard Member

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    OMG!!! That is spot on!! (y)(y)(y)
     
  2. southernnscale

    southernnscale TrainBoard Supporter

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    With all that weight it should pull really good and handle inclines great! Well done Outstanding model! you might think about cutting out windows. that would also bring a little off the price in the shell! then it could be lighted!
     
    bostonjim likes this.
  3. Heay Equipment Designer

    Heay Equipment Designer TrainBoard Member

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    That came out really great! Two quick questions, did you print the handrails in FUD? And are those trucks with the larger ALZ locomotive wheel sets or with the 36" wheel sets the shorty came with?

    -Jon
     
  4. bremner

    bremner Staff Member

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    Not happy with you...the wife will kill me if I get another scale
     
  5. shortpainter

    shortpainter TrainBoard Member

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    hi Jon,

    The handrails seen in the photos were ripped off a Micro Trains GP35. I am working on custom photo etched hand rails for future versions. The wheels are the regular wheels that come with the shorty. For a time, I wanted to add AZL 40" locomotive wheels. However, the shorty's axles are too close to each other by 2 scale feet. So I decided to use the smaller wheels and hide them behind the trucks to trick the eye into seeing a wider wheel base.
     
  6. ZFRANK

    ZFRANK TrainBoard Member

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    I am looking forward to see the this switcher in action.
     
  7. SJ Z-man

    SJ Z-man TrainBoard Member

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    Can you pop the shell so we can see inside? I don't see how the second trucks are mounted.
     
  8. SJ Z-man

    SJ Z-man TrainBoard Member

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  9. woodworker19

    woodworker19 TrainBoard Member

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    I made the assumption looking at pictures of the Rokuhan Shorty slow speed control wire that there was a resistor hidden under the shrink wrap. I figured if one can be put under the shell in series with the motor it should have the same effect. With a little experimentation I found that about 1,000 ohms slows a Shorty down nicely. My test case has two 470 ohm resistors in series because that's what I had on hand. It runs reasonably well with a MTL GP-9. I unsoldered the black wire from the circuit board and spliced them in there. Once the Shorty is moving the speed matching stays pretty consistent through the speed range. At full switcher weight the resistance value may need adjusting but, I think it's promising. I've attached a picture of the Shorty. I tried to upload a video of it running with the GP-9 but, that didn't seem to work. I'll look for some help and try again.
     

    Attached Files:

    shortpainter likes this.
  10. Mark Watson

    Mark Watson TrainBoard Member

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    I've been following this thread and loving all the great stuff you guys are doing with this. Hope you won't mind me sneaking in something of my own.

    Here's a quick comparison fo the ZShorty truck to the Kato N Scale Power Chassis truck.
    [​IMG]


    Ignoring the wheels in the middle, the Kato N Scale wheels fit perfectly into the ZShorty geared axle sleeve (right side).

    [​IMG]


    I now have the smallest power truck in N Scale. :)

    [​IMG]


    So, I'm making a hi-rail truck.

    [​IMG]
     
    Kurt Moose, tjdreams, ZFRANK and 4 others like this.
  11. shortpainter

    shortpainter TrainBoard Member

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    Here you go. The trucks are both mounted exactly as they are on the original shorty frame. To mount the unpowered truck, you use the same screw that comes with the shorty.

    [​IMG]

    Here it is in action!

    <iframe width="560" height="315" src="" frameborder="0" allow="autoplay; encrypted-media" allowfullscreen></iframe>
     
    Last edited: Apr 9, 2018
    Garth-H, sboyer2, Kurt Moose and 7 others like this.
  12. southernnscale

    southernnscale TrainBoard Supporter

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    Really great video of the SW. It seem it can handle more then it need to be as a Switcher. It seem to have good power and smooth running! Well done!
     
  13. SJ Z-man

    SJ Z-man TrainBoard Member

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    Watch out for the wattage on the resistors. Stall the loco to test, before their under the shell.
    Even with a 9-12 power supply, if you use a PWM controller, like the Snail, Jöeger or the classic $5 putty-colored LED dimmer, you should be able to keep the speed down with reasonable speed steps.
    That Hi-Railer is going to be a Winner ! Whose truck ?
     
  14. woodworker19

    woodworker19 TrainBoard Member

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    I'm actually more worried about how much weight the motor can haul around for the long term. My trial piece is running at 9VDC and it's pulling 2 ma. during normal running according to my meter. Using P=I^2 x R, I'm calculating 0.002 watts per 470 ohm, 1/4 watt resisters. Stalled with the wheels slipping I get 5 ma. which should give 0.01 watts. Stalled with the wheels stopped I read 8 ma. or 0.03 watts. If I reverse the calculation, 1/4 watt resisters should be good up to 23 ma. of motor current. Pulling a couple cars didn't move the current meter much. Hopefully the weight add doesn't either. i don't know what the limits of the motor are.
     
    Garth-H likes this.
  15. bostonjim

    bostonjim TrainBoard Member

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    WOW!!! You've made it look so easy. Bravo!! I really like the sham trucks. I thought the same thing would work for the PCC. You've shown that it can be done without sacrificing realism. There are a lot of possibilities. Thanks for sharing all of this with us. Jim
     
    jdmter likes this.
  16. shortpainter

    shortpainter TrainBoard Member

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    I have to admit the video is somewhat misleading. While it pulls plenty of cars in the forward direction, it only pulls 1/3 of that in reverse. From what I can tell, it seems the gears mesh better in one direction than the other. At first I thought it was due to me taking the thing apart and reassembling but I tested a new unmodified shorty and it acted the same. To test, put your shorty on the track and slightly push down on it with your finger. In one direction it works smoothly but the opposite direction causes the truck to rotate and one of the axles may start to skip. This problem only occurs if the loco is pulling too many cars in the weaker direction. Of course, there are no such issues if the loco is not pulling any cars or if a second locomotive can help. That works for me because I plan on running these in pairs.

    I can't wait to try this. So if I buy some 1k ohm resistors as seen here;

    https://www.amazon.com/Projects-25E...33675&sr=8-1-spons&keywords=1k+resistor&psc=1

    would those work?
     
  17. woodworker19

    woodworker19 TrainBoard Member

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    Those should work and simulate what I did.
    Did the weight of the body seem to slow it down much ? If it did, then 1k maybe a little too much. Space for resistors doesn't seem to be an issue. You could consider going with three 330 ohm, 1/4 watt resisters. Then you could drop one off if the 990 ohm total was too slow (can a switcher run too slow ?).
    One 470 ohm did slow it a noticeable amount but, it was still too fast. I think the sweet spot is still going to be closer to 1000 ohms.



    Sent from my 2PS64 using Tapatalk
     
    jdmter likes this.
  18. shortpainter

    shortpainter TrainBoard Member

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    The brass frame and shell don't seem to have slowed it down at all. I ran a brand new shorty on the same track as SW and they stayed at the same distance from each other. I'm not too familiar with circuitry so I got a newbie question. Do resistors need to be spliced in a certain direction? Does the order of the colored rings matter? OMG, if it really runs like an MTL GP9 I'll be in heaven. :D:D:D:D:D
     
    jdmter likes this.
  19. woodworker19

    woodworker19 TrainBoard Member

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    Resister do not have a direction requirement like diodes. The color rings do have an order because they tell you the value of the resister but, it's not something you need to worry about for the installation. I put mine in the black wire side of the motor. It will work in the red wire side also. Since I was experimenting I didn't shorten the resister leads either. They can be cut to the needed length. They are pretty robust but if you're still improving your soldering skills, I'd recommend using a heating between the resister and your solder connection to avoid burning it up. Self closing tweezers work great. Google "resister color code" if you want to learn more about how to read the rings.
    I've been running mine more. The GP-9 starts moving a little sooner but, not by much. Some of that could be the wheel to rail contact that I hope a little weight will help. I'm pretty happy with it.
    Alot of us will be in heaven when we have a nice switcher on our layouts so thanks to you for all your efforts. I'm glad I could contribute a little.

    Sent from my 2PS64 using Tapatalk
     
    jdmter likes this.
  20. woodworker19

    woodworker19 TrainBoard Member

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    Should be "heatsink" not heating. Spell check got me.

    Sent from my 2PS64 using Tapatalk
     

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