turntable

[full maxx]

 what is the smallest radius of track made...not flex track...something solid that will keep shape

[Michigan Railfan]

In HO gauge, that is easy to find -- 15" radius.

What does your question about curve radius have to do with a turntable?

I may have an idea how they relate......
Fullmax, are you planning on building your own turntable? I see it workin as you making a circle of 15" radius curves, and using let's say trucks from a frieght car for the ends of the deck. Am I right? Seems like it could work.

[Doneldon]

maxx-

Neither rail of 15" radius is 15" radius.  That's the centerline radius, so you'll end up with something just a little longer or shorter than 15"  Frankly, you may have a good idea percolating here if the other posters' hunches are accurate.  However, I'd urge you to cut the rim track in half and just use either inside or outside curves.  That will look much more prototypical.  Also, don't neglect the common turntable solution of building one on top of an Atlas turntable.  All of your indexing and electrical supply problems will be solved and you can have plenty of stalls with the new model which is indexed at 10^o or 15^o, I forget which.  Good luck!
                                                                                                                                                                                          -- D

[full maxx]

Blink you are correct...that is my intention...i have till March to get it done,however if 15 is the smallest then it would have to be out of sight ... dont need a 30 in bridge...biggest engine is close to 13 in total length...how does the atlas index system connect to the turntable as in how does it make it turn

[OldTimer]

Atlas uses something called a geneva movement to index their turntable.  It is a mechanical device used to change constant rotary movement into intermittent rotary movement.  That is to say that as rotary movent is input (you turn the crank or run the motor), intermittent movement results (the turntable starts and then stops at each stall in turn).  You can find an annimated example here:

http://kmoddl.library.cornell.edu/tutorials/10/

The problem with using a geneva movement is that you can NOT skip a stop.  The advantages are that it is inexpensive to produce and it will work reliably until it wears out--nothing to adjust or fiddle with.
OldTimer

[full maxx]

so I take it if it wont skip stops then the stops are not adjustable as far as the distance between stops

[richg]

so I take it if it wont skip stops then the stops are not adjustable as far as the distance between stops

That is correct. I would post some photos of the Atlas I have but Photo Bucket is just about at a standstill.
I posted some photos here sometime ago but I doubt a search would turn them up. The search engine is not very friendly.
You might try though. From what I recall, there are two different versions for indexing.

Obvious Man just told me to look at You Tube for a video about this turntable and below is what I found.

http://www.youtube.com/results?search_query=atlas+turntable&aq=f

Rich

[full maxx]

hey richg in the link you posted the third vid down it says atlas o turntable demo....is that also the speed at which it will turn in ho scale as well or can you slow it down

[richg]

hey richg in the link you posted the third vid down it says atlas o turntable demo....is that also the speed at which it will turn in ho scale as well or can you slow it down

You can operate the motor with a power pack like any locomotive. Vary the speed like any loco. Just don't try to run the turntable at 100 mph like a cheap loco.

Connect the orange and grey wires from a decoder and use a DCC controller to operate the motor.

Both will work. The motor is a common DC motor.

Rich

[full maxx]

ok the turntable is more or less a rotating bridge right and this bridge has two ends right ok so we will call them A n B ...so will A and B both line up with the same engine stalls for parking so you can drive it in or back it in depending on whether you keep rotating it or not

[jonathan]

FM,

The short answer is "Yes" you can.  The Atlas turntable, automatically switches polarity at one point in the turn.  In DC, you don't have to change direction on the throttle, whether you drive forward or turn around and back in.  Not sure I explained that well enough.

Can't speak for the other brands, as all I have are Atlas turntables.

Regards,

Jonathan

[jward]

the atlas turntable will rotate through 360 degrees.

here are some other specs you might find of interest.....

track spacing is 15 degrees (as opposed to bachmann turntable's 20 degrees. this gives a total of 21 track slots, with 3 other slots taken up by the geneva movement.

out of the box, it comes with a hand crank, with a motor concealed in a shed available as an add on.

length of the turntable "bridge" is 9" and due to the location of the geneva movement if you wish to build a pit type turntable using this as a base you probably won't be able to lengthen the bridge. bridge length is sufficient to turn small steamers with tenders, just about any tank type steamer, any 4 axle diesel, and 6 axle diesels up to and including a u30c or alco c630. sorry, you won't be able to turn a dda40x on this table.


the turntable has a slip ring inside which automatically reverses polarity as it turns. you don't need an autoreverse unit with this turntable. half the track slots are one polarity, the other half the opposite polarity. an a or b in the track slot tells you which way to wire that particular radial track.

last, the following link shows how to convert the atlas turntable into a pit type turntable.....

http://www.2guyzandsumtrains.com/Content/pid=11.html

[CNE Runner]

Check out these articles on Carl Arendt's excellent website. I started to construct one of the 'CD Turntables'; but never finished the project ('sound familiar?).

http://www.carendt.com/articles/index.html

Carl's website is full of clever ideas, so check it out.

Regards,
Ray

[full maxx]

instead of a cd how about a lp ... vinyl...anybody know the diameter of a standard record...after all it is a turntable right...

[OldTimer]

33 1/3 LP's were, as best as I can remember, about 12" diameter.
OldTimer