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Vertical lift device for HO scale train storage

Discussion in 'Concepts and Ideas' started by KiloWhiskey, Feb 24, 2019.

  1. KiloWhiskey

    KiloWhiskey Well-Known
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    I am designing a vertical storage transfer elevator for my model railroad. This would allow lets say a 1.3m section of train cars on a track be raised /lowered to other storage track feeds. The speed of the transfer would need to be closer to 5 seconds per inch as to avoid launching locomotives and more realistic.
     
  2. David the swarfer

    David the swarfer OpenBuilds Team
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    Hi
    I make that about 300mm/min which is quite easy to do.

    I would use M6 threaded rod each end of the track for the drive to give a smooth low speed drive with a relatively high stepper motor speed which will give less vibration (you may need some sort of friction patch on the track to stop the train rolling away). Maybe drive both screws with one motor and a belt the way 3d printers do it to avoid out of sync situations..

    I would put adjustable hard stops at the bottom of travel making finding 'home' easy.

    What are you planning for a controller? I can see it as either a custom Arduino unit or an Arduino running GRBL with another Arduino or a Raspberry Pi feeding it Gcode for the motion.
     
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  3. KiloWhiskey

    KiloWhiskey Well-Known
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    I was looking at a longer lift , as my railroad is going to be running along 2 edges of my wall. The elevator will remove them from a display storage on the wall to the railroad. As far as control, until i find a way to index at stops and run slow enough to look realistic .... manually may be the way to go....
     
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  4. KiloWhiskey

    KiloWhiskey Well-Known
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    Controllers.... are you familiar with the DCC train systems? Each item to be controlled is equipped with a digital decoder board that exploits the abilities of the item
    On a locomotive it would be speed, lighting effects sound effects ect. I have heard that some people have added arduino or Pi boards for automated controls...
     
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  5. KiloWhiskey

    KiloWhiskey Well-Known
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    And i looked at the C-Beam screw drive in the catalog. The longest was a meter long and may work. I may need to learn how to use code.
     
  6. GrayUK

    GrayUK Openbuilds Team Elder
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    Just had a look on YouTube for DCC rail systems, things have certainly moved on since I and my son built model railways. :)
    It is seriously tempting. I know my son is planning to build an "N" gauge layout soon.
    Trouble is, I've just filled up the only space with a rather large CNC machine!! :banghead:
    I liked the Faller car system as well. :thumbsup: But really expensive. :jawdrop:
    It has given me the idea to produce Faller road sections for sale though. :rolleyes:
    I could knock them out fairly fast once I've made the master drawings.
    I'll give it some thought. :rolleyes:
     
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  7. KiloWhiskey

    KiloWhiskey Well-Known
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    The control system i plan on using is called Railpro. It uses rf instead of the rails to send the control packets.
     
  8. David the swarfer

    David the swarfer OpenBuilds Team
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    oh, you said 1.3m of train so I assumed the entire lift would not be much longer.
    but length is not a problem, only getting the ends to stop accurately can be a problem.
    height is also not a problem, one of these V-Slot® NEMA 17 Linear Actuator Bundle (Belt Driven) can be 1500mm long and 2 or 3 of them could lift quite a long section of track. (though I do prefer screw drive over belts for this.)

    In our CNC machines we use stepper motors because they are relatively cheap and very accurate for the price.
    They have 2 coils and take a step when one or both are energized in particular ways, the stepper driver takes care of this for us. (you wont need one that big, just an example). We give the driver a direction signal (5v on or off) and a step signal which is a pulse of 5 volts. The driver/motor takes a step each time it receives a pulse. Stepper motors cannot start instantly at a high speed, so our series of pulses have to take care of acceleration and deceleration.

    So it boils down to giving the motor the exact number of steps needed to move from one track level to another. That is where GRBL comes in. GRBL is software written for the Arduino Uno that accepts simple text commands and translates them into controlled motion. So a command like 'G1 Z400 F300' will cause the Z axis to move at 300mm/min to the position 400mm from the 0 point. This is called G-code. GRBL takes care of remembering where it is, acceleration and deceleration and calibration. GRBL does 3 axes, X, Y and Z but for a track shifter you would only use one axis.

    So given 2 or more vertically oriented Vslot rails which are supporting a platform with a length of rail on it we need some way of telling the Uno what to do. I will assume that you don't want an entire PC cluttering up the landscape so I would use a Raspberry Pi, maybe with a touch screen. Then I would look at using Python to create a simple application to send commands to the Uno. The application can have an onscreen button per track level. Tap the level you want and it will move there. The only critical thing to always do is to turn it off with the track at the zero level, and turn it on again at the zero level. This is the point that GRBL will use for 0 and while it could be calibrated after turn on why bother when you can just park it properly (-: A secondary display in the program can allow for calibration for each track level.

    ok, so I write software for a living and it all seems easy to me but you might feel overwhelmed. I suggest you do some more browsing here at Openbuilds to become more familiar with the CNC control systems, and also do some Youtube watching on the topic as background. There are many projects here that are not strictly CNC machine that use Vslot in creative ways. and there is bound to be someone in your club who can write the code or at least help you to get going.

    oh, RailPRo.... I see Railpro has an accessory module. I have not looked at it in detail but it should be possible to wire one of those to the Raspberry Pi (which has general interface pins which a PC does not have) . Then you can tell the lift to go up or down from the Railpro controller. This is an addition to the touch screen software so you can still move trains around directly but have the option of using a Railpro command as well.
     
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  9. KiloWhiskey

    KiloWhiskey Well-Known
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    Cool.... I'll look into this further. Before I found the openbuilds community I was looking at using a tv lift unit for this project.
     
  10. MaryD

    MaryD OpenBuilds Team
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    Very interested in this project. Please keep us updated!
     
  11. KiloWhiskey

    KiloWhiskey Well-Known
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    I wonder if a hall effect sensor would work to position the gantry units at the appropriate locations.....
     
  12. Alex Chambers

    Alex Chambers Master
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    Hi @KiloWhiskey, I doubt if a hall effect switch would be precise enough if you are trying to match rail heights - in HO scale much more than 1/2 mm risks derailment, which could be disastrous 1/2 way up the wall. Stepper motors and cnc software through would probably be accurate to +/- 0.2 mm or better.
    Good luck with the project.
    Alex (also a railway modeller) ;)
     
  13. Alex Chambers

    Alex Chambers Master
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    Just a thought - if you used say 3 leadscrews connected together with a belt and drive pulleys, driven by one stepper motor/driver, all you then need is a means of sending "x" steps to the driver plus a direction signal. You wouldn't need a relatively expensive controller board - just something like an arduino and stepper shield. You might find some help with that on an arduino forum.
    Alex.
     

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