A wagon turntable - construction
Taken from the forum 2018 - Bob Alderman
Following my question on the Forum about sourcing a wagon turntable I have selected the Kitwood Hill Models kit.
Choosing the motorised version all that I have to do is assemble it. To me it was the best value, just leaving me to supply the adhesives.
Before purchasing, a copy of the instructions were supplied; pdf by email. The only way they come. This helped make up my mind.
Assembly has started.
This is the base, three rings. As advised they were initially located using a contact adhesive. This gives the opportunity to move around to align. Superglue is used to complete the join.
Having jump d ahead a little here are most of the rest of the parts - lots!
I have assembled the shaft into the base of the turntable. Araldite for strength. The drive on the shaft is pre-assembled. I found it best fitted on the side the laser entered. There is a fine taper to the hole.
A slip ring followed. This is double sided pcb with the tracks linked top to bottom. The top is split into two pads, the divide used to align.
Now waiting for the glue to cure.
Bob
Bob Alderman - Mar 22, 2018 at 5:24 PM
A bit more progress, inhibited by a string of visitors and a minor disaster.
The track deck has been added. The two temporary pins, supplied, are used to align the parts. This time only superglue has used in the joint; two spots in the middle gap and a series of spots around the outside edge.
When the sleepers are stuck in further bonding will happen.
The disaster was breaking one of the plunger pick-ups whilst pressing it home. I slipped.
The pick-ups can be seen in the middle; two gold-ish spots. I have requested a replacement.
Nevertheless work should not stop. I can get on with the track - provided my track gauges can be found. After the demise of my workshop things have been scattered!
More anon.
Bob
Paul Bartlett - Mar 22, 2018 at 8:07 PM
What diameter is it please.
Paul
Bob Alderman - Mar 23, 2018 at 3:27 PM
Paul
The revolving deck is 114 mm diameter.
Grant18421 - Mar 24, 2018 at 9:18 AM
The actual hole in the baseboard is 122mm to accommodate the housing for the deck which is 115mm, the scored lines are set for in the centre Standard gauge 32mm or the outer 49.2mm Broad gauge.
Bob Alderman - Mar 30, 2018 at 12:27 PM
Further progress.
The replacement plunger pick-up, plus spare in case, arrived within 48 hours of requesting it. Part of the continuing good sevice I've had from Kitwood.
I've installed the rails and deck. Fitting the rails I found a little difficult. The sleepers were narrower than the recess and slipped around. I only glued them after I had a piece of track to install.
The deck was trimmed with my trusty Proxxon saw and fitted after link wires to the slip ring were fitted. Missed out photographing this in my enthusiasm to progress!
The connections to the pick-ups were made whilst they were accessible. The motor mount blocks them once fitted.
A second bearing is fitted to the motor mounting plate. This presses in more easily from the side the laser enters than the exit side. There must be small taper in the cut.
The bearing must have the bore square to the surface. To do this I fitted the assembly and checked against the turntable.
The motor mount parts were assembled onto the base. The turntable was fitted to the base so that I could use the shaft and the motor mount to jig the assembly.
The vertical parts were glued with the Zap-a- gap. This was recommended by my local aeromodeller's shop; that hobby glues a lot of wood.
The mount was not glued, it, with the motor and gear, is screwed to a plate later.
Bob
Bob Alderman - Mar 31, 2018 at 4:23 PM
Continuing after a small delay. I dropped the grub screw from the drive pinion and had to wait 'till my wife came home to grovel on the floor to find it!
The plate that locates the motor mount secured. Note the long tabs that also locates the mount. Good design point.
The motor with gearhead was fitted to the mount. I had a worry about this. The screws that come with the motor were a loose fit in their threads; a rattling good fit. However they tightened satisfactorily.
The drive pinion has to be fitted after fitting the motor, the hole in the mount locates the output shaft bearing. It was at this point the grub screw went walkabout.
A further “problem(?)” with grub screw is that it protrudes from the pinion, even on the shaft flat. If the pinion is low the grub screw fouls the motor mounting screw heads.
And for time being fitted to the base.
Turntable and drive shaft next.
Bob
DavidL - Mar 31, 2018 at 5:06 PM
Bob,
What are the dimensions of the grub screw (thread and length)? I may be able to find you a shorter one (or cut one down to suit). PM me if you prefer.
David
Bob Alderman - Mar 31, 2018 at 5:36 PM
Thank you David but I now have no means of measuring it besides struggling with my hands to hold it.
The location of the pinion isn't an issue. It has a face width of 8mm matching 4mm of the gear.
The problem I have now is that the gear has jammed on the shaft. It slid on perfectly in the trial fit, now barely moves. I've removed its grub screws in case they were a cause, but no.
Bob
Grant18421 - Mar 31, 2018 at 5:56 PM
I have built 3 without any problem but can you rest the gear over a vice and drive the shaft out with a punch or rod
Bob Alderman - Mar 31, 2018 at 6:14 PM
Not so easy in my situation.
I'll have to subcontract the job.
Bob
DavidL - Apr 1, 2018 at 1:06 PM
I'd be careful about using a punch in that situation; it risks swelling the end of the shaft and making it even more firmly stuck. In cases like this, it is better to press it out; a vice and a suitable backing plate with a hole in it will usually suffice if you don't have a press. Bob, I realise that might be difficult for you; hope you can find someone local to do it.
David
Grant18421 - Apr 1, 2018 at 1:38 PM
If you use the correct size drift then you should be ok.
I should of made it clear I did not mean a centre punch
Bob Alderman - Apr 3, 2018 at 3:22 PM
Thanks for all the suggestions. Drifting it was not possible in situ.
I had to hand it to friend to sort.
The gear was near the end of the shaft so the solution was to cut the shaft. Fortunately it is more than long enough.
The shaft was then drifted out.
Measuring the shaft and bore found them the same. this allowed a virtually exact fit, all well and good but…
The jam, I think, was down to the grub screw holes. A tiny feather of material from the end wedged it. From the thread finish? It was able to move away as the gear went on but doubled over in the opposite direction entering the tiny gap between shaft and bore wedging the assembly.
Whatever, with the gear released the bore was cleaned up, the shaft had an application of emery and the gear slides on freely now.
Now for the final assembly.
Bob
Bob Alderman - Apr 3, 2018 at 6:28 PM
After a walk around the village with my wife, or in my case a roll around, I have completed the assembly.
The gear in the correct position. Three ply washers on top. I'm not sure if they serve any purpose, the gear is against the deck bearing and the turntable against it the other side so there is restricted vertical movement in the shaft.
I found at this point the rotation of the turntable was slip stick. Close examination showed that cured superglue in the well, formed slightly raised patches and corner fillets that fouled the turntable. An application of a sanding drum in the modelling drill smoothed the way. I also used it around the peripherary of the turntable to remove superglue there and to produce a small chamfer on the bottom corner.
Rotation much improved!
The gear was refitted and the motor fixed.
The locating ring, the one that stops the assembly falling through the mounting hole, was added to complete the assembly.
All that's needed now is to weather the deck and build the layout it is destined for.
Bob
Grant18421 - Apr 3, 2018 at 11:55 PM
Glad you got it sorted. At York show this weekend ours was operated over 1000 times as it is used on every sequence