Hello,
This is the ten degree Geneva Drive for turntables that I have been developing. It is rock solid and can be mounted under the table for either a pit or a flush turntable. It has been indexed with a two pound weight on the Geneva Wheel. The next item is the bridge. The center pivot shaft is 1/2 steel.
A gentleman on the forum stated that many modelers would not like the pause that the Geneva Drive generates as it cycles. I have designed another inexpensive turntable drive that will not hesitate. It will have a solenoid and require human intervention to start and stop it. The location will be self indexing. It will use some of the principles of the Rivarossi turntable.
Jerry
Loathar, I don't know when they were originally designed. But they are used to increment a shaft in degrees of rotation. I know that over 60 years ago, IBM was using them to increment punch cards through machines and each time the card stopped the machine had the opportunity to punch holes in the card. I know this because 40 years ago I started repairing these machines for IBM.
A geneva drive is an EXECELANT method of locking the rotation of a shaft in a given position. The Atlas turntable uses that method to turn the table.
Hope this helps ------ John T. in the drying cow pasture
That is some pretty impressive work!
What is the repeatable accuracy on that?
What do you expect the wear characteristics on that material to be like?
loathar wrote:Sorry to sound ignorant. What is a Geneva Drive and what are they used for? I'm assuming they weren't originally made for model train turn tables.
check out: http://en.wikipedia.org/wiki/Geneva_mechanism
Philip,
The material is polycarbonate and I think that the wear will be miminal. The Geneva Wheel is positioned on the main shaft with a set screw, therefore if a segment should show wear it can be repositioned. If you had 36 tracks then this would be rotating 360 degrees. I only will have a six stall roundhouse.I will only be using about one third of the drive positions.
At the present time the drive is locked solid in position. When I have time and build a large bridge I will check the end with my indicator. This will be the acid test as to the accuracy of the unit.
pcarrell wrote: That is some pretty impressive work!
I am gonna second this notion.... awesome craftsmanship!!!
*jots down screen name for future reference ;) *
Dave Loman
My site: The Rusty Spike
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