Peco Turntable electrics

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D605Eagle
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Peco Turntable electrics

Postby D605Eagle » Sun Jan 07, 2018 12:54 am

I have a Peco turntable, with a Locomotech motorising kit and indexing add on kit (both expensive and not very impressive) but neither Peco nore Locomotech provide any system at all for wiring up the various roads that I've come across. I've an idea using neodymium magnet on the turntable and magnetic reed switches on the outside of the turntable well. Before I embark on such a project am I missing something easier but automatic?

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TimberSurf
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Re: Peco Turntable electrics

Postby TimberSurf » Sun Jan 07, 2018 9:16 am

It is assumed your DC, as on DCC this would not be required. Magnet and reed switches is certainly an option. A magnet and FET's would also work, both would be best, feeding a relay to switch the power. A second slotted disc and photocell could also be used, or an up/down counter using the pulses from the existing one.
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D605Eagle
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Re: Peco Turntable electrics

Postby D605Eagle » Sun Jan 07, 2018 1:18 pm

Yes I am on DC. It's been an absolute nightmare to get the thing to work properly and stop where my sidings are, so I'm hoping I can put the magnet somewhere discreet without having to dismantle the table at all. Unfortunately I've gone about this project the wrong way round. I should have thought about all of this before I started but........ :(

Mike Parkes
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Re: Peco Turntable electrics

Postby Mike Parkes » Sun Jan 07, 2018 1:53 pm

I still work mine by eyeball, have not got the indexing kit - it only has a solitary entry road entry road so I did try to make it autostop using a pair of rods clamped to the central pivot bearing on microswitches; worked once then I found that the torque applied by the motor resulted in the microswitch contact arms getting bent. Thinking of trying a infra red detector instead. Not sure why you are unimpressed with the motor, compared to other turntable motors its a very efficient quite mechanism.

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D605Eagle
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Re: Peco Turntable electrics

Postby D605Eagle » Sun Jan 07, 2018 7:53 pm

Actually the motor is fine, although there is rather a lot of backlash in the gearbox, which is inevitable by its gear design. A much lighter, faster motor with a double worm reduction would have been better IMO. It is the other parts that come with it, especially the indexing system. They don't tell you that its pre set for 10 sidings, whether you want them or not, and it's incredibly tricky to alter the position or number of the sidings and the instructions are pure pants. Also the method of attaching the motor to the turntable is not secure enough and allows the table axle to turn in the coupling even with the grub screws tightened to the point the allen key rounds them off.

Bramshot
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Re: Peco Turntable electrics

Postby Bramshot » Tue Jan 09, 2018 3:10 pm

I motorised a couple of N gauge Peco TT’s using very cheap geared stepper motors (less than £5) and an Arduino UNO. The fake moulded rollers on the bridge ends need removing and replacing with real rollers. I used some spare part Bachmann BR Mk 1coach bogies glued underneath with one wheel pulled off each axle. I spun the axle and remaining wheel in a drill against a file to remove the flange, making a roller.
These cheap gearboxes have quite a lot of backlash, so any attempt to automatically align track would have been very difficult and expensive and complicated, so I opted for a system that drives the TT to about the right place, then let’s you manually inch into perfect position. Only problem is, you need to be able to see the rails to do it.

I use dcc, so no problems of the sort raised by the OP, I think the original idea of a magnet and reed switch sounds simplest and so probably cheapest and least likely to give problems. I guess you only need to switch one of the dc poles at each track and the other can be permanently wired and commoned. Just make sure you get the rail polarity right to match the bridge rails at each position. I think you will get a direction change I.e. L to R loco side polarity change.

ianjeffery
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Re: Peco Turntable electrics

Postby ianjeffery » Mon Jan 15, 2018 9:56 am

hi,

This is aimed at the OP : D605Eagle

"I have a Peco turntable, with a Locomotech motorising kit and indexing add on kit (both expensive and not very impressive) "

I make and sell Turntable indexing systems with DCC capability -http://www.dccinterface.com and i would be interested to hear what issues you encountered, and how you would improve it - so that I can improve my own product.



Ian.

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D605Eagle
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Re: Peco Turntable electrics

Postby D605Eagle » Mon Jan 15, 2018 1:58 pm

Hi Ian. The main beef with the locomotech system is backlash in the gearbox and the indexing system. The gearbox is a beautiful piece of engineering but because is uses a chain of straight cut gears even with precision manufacture and construction play is inevitable, and the length of the tuntable amplifies it. The index system is a brass disc with ten slots in. An IR transmitter and receiver stop the turntable when the disc slot is detected. The this works ok, you can adjust the turntable speed and motor brake to take account of the motor backlash. But what if you want a different arrangement of sidings?
Another point is neither peco nor locomtech make any reference at all to making the siding selected live. I know this isn't an issue if you use DCC, but DC it is a major problem. As I stated in my PM to you I have successfully overcome this with magnets and magnetic micro switches.

ianjeffery
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Re: Peco Turntable electrics

Postby ianjeffery » Mon Jan 15, 2018 3:14 pm

i too encountered the gearbox backlash issue when i had a stepper motor with a 100:1 gearbox on the top - it became quite inaccurate.

in the end i swapped it out for a 0.9deg ( 400 steps per revolution ) stepper motor, and an A4988 stepper controller that i set to 1/64th steps - this does very well and means its a direct drive.

in terms of DCC - yes your right - usually all the tracks would be live as people would still want their stationary trains to be live if they are sound locos.

glad you got it sorted.


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