7mm Turning The Table

Discussion in 'Area 51' started by Lancastrian, 20 September 2017.

  1. Lancastrian

    Lancastrian Western Thunderer

    This turntable has been on the workbench for quite a while now, due to some issues, but I have had to resort to making new parts to get it finished.

    [​IMG] by Ian Allen, on Flickr

    [​IMG] by Ian Allen, on Flickr

    Two of each of the above outriggers and handrail stanchions have had to be made so they are the correct hand. The outriggers and handrails are quite flimsy until the decking and handrails are fitted, so it's difficult to clean them up thoroughly.

    [​IMG] by Ian Allen, on Flickr

    Above image showing another outrigger in place.

    [​IMG] by Ian Allen, on Flickr

    One side being populated with outriggers.

    [​IMG] by Ian Allen, on Flickr

    End two outriggers with plates attached.

    [​IMG] by Ian Allen, on Flickr

    Second side outriggers being installed

    [​IMG] by Ian Allen, on Flickr

    Decking plates fitted on one side. There are some slight variations with dimensions, and the centre plate needs to be cut down to fit the space.

    [​IMG] by Ian Allen, on Flickr

    Meanwhile at the SR7mm Group I cut out slots in a baseboard to take inspection pits from KS Designs. We decided on three with brick walls and three with concrete, the concrete ones being a later addition after the turntable was enlarged by BR.

    [​IMG] by Ian Allen, on Flickr

    [​IMG] by Ian Allen, on Flickr

    Back to the turntable and today has seen the control cabinet built and installed, albeit with sparse instructions. I decided to have wrapped round handrails rather than them just terminate outside of the stanchions. The four on the control deck area were a pain to fit as there are no guide marks so everything has to be done by eye.

    Anyway, it's coming along slowly.

    Ian
     
  2. Lancastrian

    Lancastrian Western Thunderer

    More progress with the turntable, almost complete now.
    [​IMG]by Ian Allen, on Flickr

    The turntable well had the race rail installed today, and the segments which represent the concrete slabs of the base. Gaps have been filled and the two Dremels are providing a little weight as two of the segments had a slight curve to them. Hopefully the tape behind and the filler will hold them in line with the neighbouring pieces.
    [​IMG] by Ian Allen, on Flickr

    Ian
     
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  3. Yorkshire Dave

    Yorkshire Dave Western Thunderer

    Is that a 2 EPB in the background of the top photo?
     
  4. Lancastrian

    Lancastrian Western Thunderer

    Hi Dave,

    Yes it is, from Peter Clark's range.

    Ian
     
  5. Lancastrian

    Lancastrian Western Thunderer

    Test fitting of the turntable today...
    [​IMG] by Ian Allen, on Flickr

    As can be seen above, there is a bit of a gap between the well side and the deck. However.....

    [​IMG] by Ian Allen, on Flickr

    [​IMG] by Ian Allen, on Flickr
    That sure isn't right ! An afternoon's work wasted as the setting bar provided in the kit is obviously incorrect. Not impressed to say the least. It'll all have to come out and be re-laid.
     
  6. Martin Field

    Martin Field Western Thunderer

    Those "bolts" look a bit hefty on the chairs.
     
  7. adrian

    adrian Flying Squad

    Doesn't look right does it. :'( :'( Sorry to mention it but shouldn't the wheel be moved inboard as well, I don't know the prototype but intuition says the wheel should be in the middle of the ducting/channel.
     
  8. Lancastrian

    Lancastrian Western Thunderer

    Martin, they are pins to hold the chairs in place on the MDF, as supplied with all these manufacturers turntable kits.
     
  9. Lancastrian

    Lancastrian Western Thunderer

    Adrian, Yes I agree. Possibly another issue with the etches or an error with the dimensions of the side plates. The carrying wheels cannot move inboard any further due to the design, and it would involve cutting away the deck side plates. The kit originally provides etched parts, but there has been a problem in sourcing/producing trapezoidal bearings so machined parts have been provided from another kit. I believe this is the first time this particular kit has been offered up to a well. SteveB allegedly has one of these kits to build too.

    Ian
     
  10. Martin Field

    Martin Field Western Thunderer

    I realise that, but it seems odd to provide a very accurate looking chair and then hold it down with huge brads!
     
  11. Lancastrian

    Lancastrian Western Thunderer

    I've done a quick bit of research and it seems the kit might be blown up from 4mm to 7mm. The prototype is residing at Kidderminster ! I may have to make a visit.

    Ian
     
  12. Steph Dale

    Steph Dale Western Thunderer

    Ian,
    What a nuisance. Your problem is caused by the way the basic geometry for the turntable has been developed. The designer has made a simple geometric error in developing parts from the centre line of the bridge.

    An easy mistake to make and a bit of a pain to resolve. As, in essence, all parts worked in plan are accurate, those worked from the side are out by a consistent geometric error.

    Steph
     
    Last edited: 9 October 2017
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  13. Lancastrian

    Lancastrian Western Thunderer

    Steph,

    The other issue of course is if I move the carrying wheels in so there is a greater clearance under the cover plates the radius will mean they aren't running parallel with the rail :(. Only option is to move the rail out.

    All these problems, and more, will be included in a review for publication, and Dave is aware of this.

    Ian

    P.S. I'm not building another one !
     
  14. simond

    simond Western Thunderer

    How frustrating! It does indeed look like the rail will need to be re-laid.

    I do wonder if moving the wheels inboard a few mm might centralise them in the "splashers" which would improve the appearance. As you note, you might want to adjust the angle of the wheel relative to the girders on which its trunnions are fixed, to ensure that its axle is radial. You'd want to do that, before doing the rail, as that would define the radius you'll need to lay the rail to.

    I don't know if this will be of help, but I made a daft mistake whilst making mine - I forgot that DCC (sound) requires that the loco is permanently live, so rather gormlessly split the rail in the fashion of a commutator and arranged the carrying wheels as pickups, which would be perfectly satisfactory for DC. Of course, the carrying wheels shorted the commutator out, and the booster tripped. Homer "D'oh!" moment. My solution was to join the rail electrically and to provide a slip-ring type connection at the axle to provide the other track feed. Obviously better not to make the rail in halves to start with. The track feeds are reversed by a pair of SPDT relays on my t/t but could easily be a "juicer" or a simple dpdt switch if preferred.

    best
    Simon
     
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  15. Lancastrian

    Lancastrian Western Thunderer

    Simon,

    Adjusting the wheel position would be ideal, but achieving the correct radial angle will prove difficult as the bearings are bolted to the girders. It was a bitch of a job getting that completed due to the difficulty of getting to the bolt heads of those on the inside. :confused:

    Ian
     
    Last edited: 9 October 2017
  16. Lancastrian

    Lancastrian Western Thunderer

    Finally, the turntable is installed, warts and all. Just the electrics to wire up and then it'll be time to paint it, ready for this years running sessions. With a little jury rigging (two screwdrivers) we ran a loco on and off the turntable today.

    [​IMG]

    [​IMG]

    Ian
     
  17. john lewsey

    john lewsey Western Thunderer

    Very impressive
     
  18. SteveB

    SteveB Western Thunderer

    Hi Ian

    This is the first time I've seen your thread on the turntable construction. Not sure how I missed it because it certainly would have been of interest. Your comment on my post makes a lot of sense now. This is probably far too late for you now, but I did some LWC brass bearings for the carrier wheels. I did them through Shapeways, so I could get some more if you wanted them.

    TT1.jpg TT2.jpg

    Regards

    Steve
     
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  19. Lancastrian

    Lancastrian Western Thunderer

    Well, we finally ran a loco onto the turntable under it's own power, and without the need for screwdrivers, and I've started to lay the shed roads too.

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    Ian
     
  20. Lancastrian

    Lancastrian Western Thunderer

    The turntable has had a coat of primer now and yesterday I started on painting the turntable well. For some reason the well was wider than the turntable so the walls have been lined with two rows of 1mm lime strip.

    [​IMG]

    [​IMG]

    [​IMG]

    I also removed the chequerplate between the running rails as it was too high and locomotives were catching the centre raised section. Having found some photos online I noticed the chequerplate should be at the same level as the foot of the rail and not the head. Therefore, the cheesehead screws supplied, as can be seen in the photos, will have to be replaced with countersunk versions.
     
    Last edited: 18 April 2018
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