Hi all,
For my layout expansion, I’m doing a dual-gauge turntable to basically just turn a loco so that it’s been ‘flipped around’. As I’ll only really need the turntable to make a half-circle each time, I was wondering if it would be possible to modify the Geneva drive of the Atlas turntable to have less stops? I’m thinking of something along the lines of cutting a new drive wheel based on the old one, with just four slots.
Cheers,
tbdanny
Might be a bit of a project, but that’s how you would do it. Maybe instead of a whole new disk, fill in the unneeded slots in the stock one. Not having one to look at, perhaps there’s enough room to make fillers that scew into place that could be removed to return the turntable to stock condition, or alter the number of stops.
–Randy
Below is a photo of the bottom of the TT.
Rih
I don’t think you can (yet again, i haven’t tried[:S]). depending on the length of your engines, you could probably just buy an N-scale turntable.
Thanks for the replies. Based on that photo, I’d say it’s undoable - the slots are a bit more spread out than I thought. Looks like I may need to start from scratch.
The current Atlas turntable indexes at 15 degrees. If you can find an old one, they only indexed every 30 degrees, so you can cut down the stops by a factor of 2.
The actually stopping points are the deep slots - seems to me that if you purchased a spare table you could simply fill the deeper slots with a piece of styrene so the escapement mechanism couldn;t drop in the ones you didn’t want. For smoother operation a little more surgery would be required, to cut back the depth of the unwanted slots to it can transition more smoothly across the ones it’s not going to stop in.
The pictured one is a 30 degree one since there are 12 slots.
–Randy
Blocking the slots will most likely cause the mechanism to bind and stop. See the illustration at: http://en.wikipedia.org/wiki/Geneva_drive
Joe
Isn´t it possible to go around the electrical circuit instead? Maybe use two microswitches or reeds and some diodes?
Thanks for the link. I had a misunderstanding of how a Geneva drive worked - I thought the slots were for the stops, not the motion. So plugging the slots would stop the motion completely. Also, studying the diagrams, anything less than 4 slots would be difficult to make work properly.
Fred W