table a la carte

[beeman]

The original was built some 20ish years ago, this was an Airfix kit [now Dapol]but built to the well type structure. It only rotated thro 180' being on a single track.This has been recently updated after spending many years boxed in the attic.It now has 6 usable outlets, this could be 12 but due to its location 6 are buffer stops.It was built using chipboard to profile the shape[see cross section dwg.]and 'let in' to the baseboard from the underside so should it be nescessary it can be removed.I gather many modellers aspire for a turntable, but be under no illusion that you can buy a proprietry built kit and simply motorise it to work. The worm gear drive sold by certain outles would rotate it but no stopping accuracy would be achieved. My finding are that a robustly engineered mechanism is nescessary with no 'backlash' is needed. I found after modifying mine a website 'Turntable at Malfunction Junction on the Teton Short Line',My link this was very similar in the way I contructed, but their electrics are over complicated and can cause it to 'hunt. when stopping. I have attached pics and dwg's to illustrate.The drive is from a discarded VCR cassette loading motor and worm unit supplied from a wall wart dc supply of 6 v.the drive to the plywood 'gear' is by a toothed belt from a pc printer.The drive gear on the worm from the same printer stepper motor. To operate it is only nescessary to choose the outlet on the rotary switch you wish to go to , choose the direction, clock/anti, press the 'Start' button and leave it to it. The stopping accuracy is less than half a mm. I must stress that there is no 'backlash' in the setup at all. The electrical circuit also slows themotor prior to stopping by using the two oposite 20mm targets operating the appropriate position micro switch. The final stop by the slot opto switch. Full rotation of 360 takes around 1.5 minutes so quite realistic. After numerous circuit ideas and alterations it really does work as it should. some further details on the build are on the attachments Beeman

[eldavo]

That is seriously cool. Like it. Even enough information for an electronics numpty like me to understand.

 

Cheers

Dave

[jamie92208]

This looks great. I've got a turntable to build for my Lancaster Green Ayre Loco shed and this looks like suitable way forward. What exactly is the slotted opto unit. I presume it's a photoelectric cell that the wire interupts.

 

Cheers

 

Jamie

[Miss Prism]

Excellent circuit, Beeman. I had been planning something similar for a sector plate, with 'slowdown/speedup sections' being optically detected/activated rather than your mechanical 20mm targets, and the 'final position' detector also being a collimated opto. I do have a couple of those interruptors somewhere (from an old printer), but it never occurred to me that they could have that kind of accuracy (0.5mm). Presumably, your limiting final position accuracy is given by the diameter of your paperclip wire targets?

 

Btw, a couple of minor queries on the circuit:

 

[Oldddudders]

Excellent, innovative work. Only one disappointment - when I looked at the record label, I assumed the layout was set Down Mexico Way! Seriously, the TT looks the biz in its setting, too. Cottages along the back are pretty tasty, too! This is the sort of stuff I come here to see, frankly.

[beeman]

Excellent, innovative work. Only one disappointment - when I looked at the record label, I assumed the layout was set Down Mexico Way! Seriously, the TT looks the biz in its setting, too. Cottages along the back are pretty tasty, too! This is the sort of stuff I come here to see, frankly.

Thanks for your comment, I thought you were going to reprimand me for getting the title of the song wrong, should have been 'South of the Border' the lyric continued 'down mexico way' , think Ambrose was aroun in my childhood years cheers Beeman

[ZAR]

Greetings.....As a newby, where do I find the detailed article and schematics of the "Table a la carte" as published by Beeman (the little genius).  Many thanks

[KeithMacdonald]

On 07/10/2019 at 18:10, ZAR said:

Greetings.....As a newby, where do I find the detailed article and schematics of the "Table a la carte" as published by Beeman (the little genius).  Many thanks

 

Seconded. Have the pictures disappeared?