Peco OO turntable

Discussion in 'Computer Automation' started by Andy_Sollis, Oct 17, 2018.

  1. Andy_Sollis

    Andy_Sollis Full Member

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    I’ve done a search, but other than a few passing mentions I can’t find anyone has posted that they have motorised the Peco OO Turntable with a stepper motor? I’m wondering Audiuno board?

    If you have, what stepper motor did you use and how did you mount it? Direct or via a gear train/gearbox?

    Andy
     
  2. redpiperbob

    redpiperbob Full Member

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  3. Toto

    Toto Staff Member Founder Administrator

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    I know Paul has ideas on this as we discussed the eventual automation of my O Gauge metalsmiths turntable. He's laid up with a knackered back at the moment but I'm sure he'll catch up with your post at some point with a suggestion or three.

    Cheers

    Toto
     
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  4. Andy_Sollis

    Andy_Sollis Full Member

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    Cheers Bob, will have a read through. Trying to figure what the Perspex is for. Will need to read further when more time.
    Thanks
     
  5. Andy_Sollis

    Andy_Sollis Full Member

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    Yes that was one that the search picked up, but it stopped. I’m guess progress has stalled?
     
  6. redpiperbob

    redpiperbob Full Member

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    Hi Andy
    if you want to see the turntable running there are a couple of videos on my you tube channel.


    be seeing you
    Bob
     
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  7. Paul-H

    Paul-H Full Member

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    I used the MERG turntable controller with my Peco n-gauge turntable but it will work Just as well on the 00 version, it uses a stepper motor and gearbox so loads of oomph to it. I used the recommended motor and gearbox from RS Components so it worked out a little pricey but I am sure a better value option would be available if you knew what to look for, I didn't so that's why I stuck to the one recommended by MERG.

    Paul
     
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  8. paul_l

    paul_l Staff Member Administrator

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    Hi Andy

    Bob's is a very sound and professional solution and well worth a good look at.

    If you're wanting to play with the arduino then this tread may be of interest

    Arduino 101 Lesson 3

    Toto's turntable thread will be picked up again in the new year - he needs to mount the turntable onto something that I can then build the rest onto.

    For a turntable I'd recommend a Nema 17 1.8 degree (200 steps per rev - as per Bob) or preferably a Nema 17 0.9 degree (400 steps per rev) this will give a smoother less notchy drive. And also stick to full steps, disabling the motor after each move, this stops the heat building up from the coils being energised holding the current position.

    The above example works through a simple spinning turntable to including a homing routine, worth a play just to get an idea of the basics, for less than £10's worth of bits, which may also provide the solution you are looking for.

    If you want any of the stl files to print off the parts just ask.

    Paul
     
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  9. Gary

    Gary Will the real Gary please stand up... Staff Member Administrator

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  10. Andy_Sollis

    Andy_Sollis Full Member

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    That is super. That’s about what we will be doing (two roads on and a head shunt?)

    I will have to look in to this in more depth.. thank you very much.

    Is it installed yet? (I keep looking and wondering if the deck needs a little weight to hold it down, but once it has a loco on it I think it’s going to be ok.
     
  11. Andy_Sollis

    Andy_Sollis Full Member

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    Sounds a very good price.. just up my street. (When it’s for Grandad/grandsons layout)

    I may say yes to the STL files. Have to weigh up between yours and Bobs options.
     
  12. Andy_Sollis

    Andy_Sollis Full Member

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  13. redpiperbob

    redpiperbob Full Member

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    Hi Andy
    Yes mine has been installed all summer now and I have had no problems.
    I made the hole in the baseboard a good tight fight and just dropped it in no fittings and it works perfect.:thumbs: :thumbs:
    let me know if you need more info.
    Be seeing you
    Bob
     
  14. TimberSurf

    TimberSurf Full Member

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    I looked at turntables for years, none of the DIY designs inspired me, I did come up with an idea to drill holes at each outlet and use them as an optical encoder, but getting the holes drilled precisely would have been a nightmare! Motor and gearboxes will always suffer from backlash. I like the timing belt and stepper idea (it was never an option until arduino's came along) but direct drive sounds like it will be lumpy, though with sub degree stepper resolution and fractional step software, it does give smooth rotation. In both cases the stepper 'singing' would drive me nuts and turning the stepper power off after a move will allow a tiny misalignment (stepper will relax to nearest step). Looking at the RM web parts cost, I only paid £80 more for my Heljan, which took 10 mins to install, no construction and has worked perfectly for 3 years.
     
  15. paul_l

    paul_l Staff Member Administrator

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    Bob's is definitely the more professional solution, and timbersurf's comment regarding the stepper singing, (or over heating) is only an issue if you leave the drive enabled, on an A4988 based stepper controller (e.g. Big Easy Driver or 3D printer driver), there is a builtin enable switch, allowing the outputs to be switched off.

    A4988 Modules x 5 £6.14

    Big Easy Driver £25.65

    Big Easy Driver (Chinese Clone) £2.42

    I have used all three types, and as they are A4988 based solutions, using the Accel Stepper library, gives ramp up and down speeds, to give really smooth movements.

    Me, I enjoyed the challenge, but am also open to buying a ready made solution as well, at least with DIY solution if any compromises were made in the design / build you know what they are and can sort them later :avatar:

    Good luck

    Paul
     
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  16. Andy_Sollis

    Andy_Sollis Full Member

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    Paul, looked through your other thread... did you just do a 180 swizzle in either direction, or did you do any intermediate stops? (It was 3am on a night shift when I was reading it)
     
  17. paul_l

    paul_l Staff Member Administrator

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    The test just did the 180, but any number of intermediates can be added, just need to avoid the zero position, so it doesn't foul the limit switch.

    I suppose the logic / method of work would be, a push button at the entry road (A), 180 degrees (B), and any intermediate positions (C, D & E)
    The turntable A end has a wheel house (or any other identifiable feature), the B end does not have the wheel house

    The test just did the 180, but any number of intermediates can be added, just need to avoid the zero position, so it doesn't foul the limit switch.

    I suppose the logic / method of work would be, a push button at the entry road (A), 180 degrees (B), and any intermediate positions (C, D, E & F)
    The turntable A end has a wheel house (or any other identifiable feature), the B end does not have the wheel house

    upload_2018-10-19_22-22-14.png

    Loco enters at position A, pressing the button for any intermediate position, turntable rotates to the position, loco moves to storage track.

    When required to exit the storage track, press the button for the track, turntable rotates into position. Loco enters the turntable, depending on which way the loco is required face to exit turntable - if the front is at the A end (Wheel house end) press A button or if the front is at the B end press the B button

    Paul
     
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  18. Andy_Sollis

    Andy_Sollis Full Member

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    I think I missed something. What was the reason for a limit switch? There isn’t one on a real turntable? Is it down to the stepper motor?

    (I think I need to learn more before I start on this project)
     
  19. paul_l

    paul_l Staff Member Administrator

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    The limit switch acts as a zero or homing switch. When powered on or reset, the turntable rotates to the limit switch, as soon as the limit switch is made, turntable stops, then rotates very slowly in the opposite direction until the limit switch changes state. The count is then set to zero. The turntable then rotates end A to position A. All moves are relative to the zero position.

    Hope that explains it clear enough
    Paul
     
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