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6' Fiddleyard turntable


2ManySpams

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I'm trying to work out how big i need to make the base plate for a fiddleyard turntable of the following requirements.

 

Gauge: OO

Min Curve Radius: 800mm

Deck Length: 1650mm (+150mm lead in = the 6' in the title)

Min Track Centres: 55mm

Number of Lines: 6

 

Is there anyone who could work out the track curves at either end to give me the overall width of the deck if it is pivotted in the centre? I know it's a chunk more than 330mm (6x55) but how much?

 

Any help nuch appreciated.

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  • RMweb Gold

Why not reduce the track centres at the ends if you need to sace space. I tried to work out the maths. Found it easier to draw out. Try 1/4 size on A3 paper or else full size on a roll of lining paper.

Donw

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I'm trying to work out how big i need to make the base plate for a fiddleyard turntable of the following requirements.

 

Gauge: OO

Min Curve Radius: 800mm

Deck Length: 1650mm (+150mm lead in = the 6' in the title)

Min Track Centres: 55mm

Number of Lines: 6

 

Is there anyone who could work out the track curves at either end to give me the overall width of the deck if it is pivotted in the centre? I know it's a chunk more than 330mm (6x55) but how much?

 

Any help nuch appreciated.

 

 

If you have 6 tracks then there will be 5 gaps in between them, plus 1/2 a gap on the outside of each outside track. 6 x 55mm = 330mm. You may want to add a bit more for a bit of extra leaway.

 

Its a dood idea to draw it out on a full size piece of paper. But the maths are quite simple, its just how much overhang you will need to cater for on the 2 outside tracks on the entry curves if you have saftey walls. This will depend on your loco with the largest overhang and the radius ou the outside curves. If it is wrong just cut off the end parts of the side walls and add extra spacers and re attach the side walls

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As suggested I drew the turntable up last night and was very suprised at how little curve was required at the end of the outer tracks. I think this is down to the length of the table meaning the angle shift is relatively small. I think i had in mind a layout from years back which had a 3' long table and significant curves to the tracks.

 

The question now is... is there enough room infront of the layout to rotate the table through 180deg? Will the table have to slide back first??

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Just researching how to build the turntable fiddle.....

 

Found this site that shows the elements of one built by someone else. Not a lot else (other than talk of the version built by Mr Denny).

 

Also found this website that sells various rollers and central pivots - would a simple vertical bolt be enough though?

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Update - i resorted to Excel last night and some advanced (?) trigonometry just to check what I'd sketched up was OK....

 

I've revisiting the requirements and amended them to:

Gauge: OO

Min Curve Radius: 850mm

Deck Length: 1500mm (+curving 300mm lead in = the 6' in the title)

Min Track Centres: 60mm

Number of Lines: 6

 

The results are that to align the outer-most tracks you need to turn the deck through 13.39deg which results in a curve approx 200mm long (ie a 1100mm straight on the deck (1500-200-200)) which widens the track centre by 23mm each side. The deck will therefore be around 400mm wide plus sides.

 

Unless i've made the same basic mistake on the drawing and calc methods, this settles my fears that the table would end up very wide with large curves each end.

 

Job done!

 

Interestingly amending the spreadsheet to a 900mm deck, with 600mm min rad curves results in a deck 600mm wide with only a 100mm long straight on the outer roads...

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  • RMweb Gold

Hi Chris,

 

 

(Happy birthday btw)

 

How will you be supporting the ends of the table when rotating it 180 degrees ? 1500mm (or approx 5 ft-ish) gives quit an overhang each side of the main supporting lags.

 

Stu

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Hi Chris,

 

 

(Happy birthday btw)

 

How will you be supporting the ends of the table when rotating it 180 degrees ? 1500mm (or approx 5 ft-ish) gives quit an overhang each side of the main supporting lags.

 

Stu

 

Stu - still waiting for the card and cake!

 

The idea at the moment is for the table to sit on a 2' wide board supported on a 1' diameter circle of bearings (with additional rollers further out) and with a BIG bolt holding it down to avoid tipping. There will be 18" of overhang each side at mid turn. The table itself will have over-girders down the sides to prevent bending and i'm hoping that the whole lot will be fairly stable and robust.

 

That's the current idea anyway!

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Stu - still waiting for the card and cake!

 

The idea at the moment is for the table to sit on a 2' wide board supported on a 1' diameter circle of bearings (with additional rollers further out) and with a BIG bolt holding it down to avoid tipping. There will be 18" of overhang each side at mid turn. The table itself will have over-girders down the sides to prevent bending and i'm hoping that the whole lot will be fairly stable and robust.

 

That's the current idea anyway!

 

 

You could use a 'Lazy Susan' bearing that are available from Squires, these screw to the top and bottom plates ie. the baseboard and the turntable. I think that you can get them up 12" dia. You would sill need some support at the rail ends of the table thought. Axminster do or did a low friction tape or strip. Don't forget to have some sort of stop at both ends of the table to stop any stock rolling off when turning and some sort of locking device for the entrance roads. Then it comes to getting the juice to the tracks?????

 

HTH

OzzyO.

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  • RMweb Gold

Hi Chris,

 

Card in the shop, cake eaten...

 

Sound like you've got it sussed. Will the 18" overhang in front of the layout impede the viewers ?

How will the fiddle yard be hidden ?

 

I ask as I've seen a layout with removeable fiddle yard walls - these were lifted as the table was turned, then replaced afterwards.

 

Another possible solution would be to make the fiddle yard board at a slight angle to the main ones, giving you necessary turning space without extending beyound the front edge of the layout.

 

post-7025-127142373797_thumb.gif

 

Stu

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Stu

 

Hope cake was nice.

 

Now that i've worked out the table dims I'm going to have a look at how it sits in relation to the frontage. One idea is to accept that the fiddle yard will be open to public viewing - adds interest to the viewer and an opportunity for audience interaction. The layout has display boards along the scenic section that end about 6" forward of the layout and the barrier is generally set up about 12" beyond that. If i can get the pivot point more than 12" back from the front edge of the boards i don't think turning will be an issue with impeding viewers. If it is i could always put fending off spikes on it!!

 

Need to dig out the layout in the garage to do some curve and clearance testing me thinks.

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What do you need to turn? If it is just the locomotive [plus break van] why not a sector plate with another sector plate on the end long enough to turn the loco and b.v.?

 

See http://www.rmweb.co.uk/community/index.php/topic/11678-traverser-and-sector-plates/page__p__116566__fromsearch__1entry116566

 

Merely make the loco sector plate pivot at the centre of it's length, not at one end. Depending on your locomotive, that need be no longer than 12-14"

 

Hope this gives you an idea,

 

 

Doug

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2ManySpams, I have two 5' 360deg turntables, 7 tracks....

One has a single track onto it, the other double (up, down lines),

the double track electrics were a pain with cab control, DCC would be a lot easier.

 

Do you need the information before Taunton, or shall I bring one along?

They were there last year :D

 

Penlan

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What do you need to turn? If it is just the locomotive [plus break van] why not a sector plate with another sector plate on the end long enough to turn the loco and b.v.?

 

See http://www.rmweb.co.uk/community/index.php/topic/11678-traverser-and-sector-plates/page__p__116566__fromsearch__1entry116566

 

Merely make the loco sector plate pivot at the centre of it's length, not at one end. Depending on your locomotive, that need be no longer than 12-14"

 

Hope this gives you an idea,

 

 

Doug

 

Doug

 

Thanks for the link - I do like the idea with the sprung ball and hollows in perspex for track location / indexing. Got me thinking there.

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2ManySpams, I have two 5' 360deg turntables, 7 tracks....

One has a single track onto it, the other double (up, down lines),

the double track electrics were a pain with cab control, DCC would be a lot easier.

 

Do you need the information before Taunton, or shall I bring one along?

They were there last year :D

 

Penlan

 

Hi Penlan - you're making a habit of helping me out! (Par Inn photos...)

 

Are you able to post any shots of your turntables on this thread? I'm interested to see how people do power supply and track indexing.

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  • RMweb Gold

Two simple methods of power supply

1. two brass bolts one either side of the approach track two brass fittings at each end for the bolts to connect to for each road. Feed from each fitting to the track. Provides alignment and track feed in one non connected tracks all isolated.

2. two pole jack plug on a wander lead, a socket for each track at either end. Note the sockets are wired to the opposite rails at opposite ends. Provides feed and isolation for the other tracks.

for DCC a single socket at either end will work for all tracks and also isolate all tracks whilst being turned.

Wiper contacts can work well but are more fiddly to set up and are also more prone to damage.

Donw

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Two simple methods of power supply

1. two brass bolts one either side of the approach track two brass fittings at each end for the bolts to connect to for each road. Feed from each fitting to the track. Provides alignment and track feed in one non connected tracks all isolated.

2. two pole jack plug on a wander lead, a socket for each track at either end. Note the sockets are wired to the opposite rails at opposite ends. Provides feed and isolation for the other tracks.

for DCC a single socket at either end will work for all tracks and also isolate all tracks whilst being turned.

Wiper contacts can work well but are more fiddly to set up and are also more prone to damage.

Donw

 

 

I think i'm erring towards the brass bolt option at the moment. Worked on a layout years ago that had wiper contacts but these, as you say, were prone to getting damaged.

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Are you able to post any shots of your turntables on this thread? I'm interested to see how people do power supply and track indexing.

Will do, but we have a major plumbing problem at home from last night, so once I've replaced a couple of toilets and sorted out a leaking shower, re-tiled one of the toilet rooms and other general stuff - I will have a go......

 

Penlan (was happily retired :angry: )

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Penlan,...Best of luck with the plumbing. Just goes to prove that there's no such thing as retirement - just different work to do!...

Think's, right another day or two, new flooring in too, just finish the new tiling around the whb's etc, and that's all done when, SWMBO "...as your fiddling about in there :( I think those taps are looking a little manky and could be replaced, my friend Sue has some really nice gold plated ones...".... Now I'm not saying the taps are difficult to get at in the built in vanity units, or that my really bad back is a problem buuuuuttttt

 

Meanwhile, the track on the 6' fiddle board WILL NEED some expansion joints in the track, remembering the ends are fixed - I have used some 'plug-sockets' from a DIY plug and socket kit, source RS or Maplin's, will bring samples on Sunday.

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Pelan, just re-read your posts and they refer to Taunton and this weekend. Sadly I'm not actually able to go to the members event so won't be able to meet up. (it's a bit of a trek and i'm prbably better off building the TTs rather than talking about them!) good news is the rollers and bearing spiders arrived yesterday.

 

Good call on expension joints - thanks.

 

Regards

 

Chris

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Just researching how to build the turntable fiddle.....

 

 

Also found this website that sells various rollers and central pivots - would a simple vertical bolt be enough though?

 

 

Flash of inspiration for the center pin, how about a jack pin and socket, if using DCC just power up to all lines, also has the benefit of being removable.

 

OzzyO.

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Flash of inspiration for the center pin, how about a jack pin and socket, if using DCC just power up to all lines, also has the benefit of being removable.

 

OzzyO.

 

interesting thought ozzyo - that idea would work very well in dcc (i think?) as the chip would sort out the direction when the table was turned. Would there be a problem with shorting out between the layout and the tt if polarities of the rails didn't match?

 

I'm part way through the build of these new fiddles now and i've gone for a long m10 bolt and washers as the pivot with a 12" dia spiders web plate of bearings around that in the centre and some additional rollers near the edge. The table deck is 1.6m long and considering its weight and 6 tracks worth of stock i decided the robust approach was best.

 

Will post some photos at the weekend.

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