What style of turn table do

What style of turn table do you have in mind?  A wooden gallows turntable using the armstrong method for propulsion? A big honking modern (relatively speaking) with a concrete pit and compressed air drive?  Something in between?

Cheers,

Charlie

Here is one I know of...

I can't vouch for how good it is or anything, but here is the link.  Turntable Mechanism

I used to know of another turntable tutorial that was more detailed.  It used a Geneva Mechanisim as the heart of the drive system.

Here is a Geneva Drive discussion from another forum.

Here is the one I was looking for, Geneva Drive Turntable

Scratch building a turn table

Bruce      Try googling Build a model train turn table and you will find quite a bit and step by step articles

                on building a turn table. Hope this helps.               ron netti

Hi Charlie Mine will be sort

Hi Charlie

Mine will be sort of a backwoodsy, set in the early 40's, branchline terminal type turntable, definitely nothing fancy. I model the Appalachian region of Virginia based loosely on the Interstate Railroad. In one of my Interstate books a pic exists of one of their turntables that is pretty basic. My main use for the turntable will be to purely turn locos - it will have 2 exits only, one to the engine house (single stall) and one to a track beside the house. Trains interchange at my town and the engines will need servicing and turning before heading back to whence they came.

Cheers

Bruce

Thanks ron & 14869, That

Thanks ron & 14869,

That mech looks beyond my construction abilities but it *is* nice! I am still deciding on the drive mech - manual or powered. I have an old stepper motor from one of those air conditioner like coolers (they use water & a fan - can't remember what they are called!) so have been thinking of doing something with that.

I'll jump on Google and see what I can find...

Cheers

Bruce

Turntable links

pages.sbcglobal.net/sgratke/sgrr/trains/matt/index.htm

http://www.housatonicrr.com/DIY_Turntable.htm

http://www.2guyz.info/Content/pid=15.html

cs.trains.com/TRCCS/forums/p/157709/1739483.aspx

modelrailroading.wordpress.com/2009/06/22/atlas-turntable-kitbash-from-wooden-wonder-to-sp-common-standard/

Rich

Agreed!

Yes the Geneva Drive System is an engineering wonder.

I have always liked the turntable mod below.

As an inexpensive, fairly easy alternative to scratchbuilding a turntable, what about customizing an Atlas Turntable like this one from the 2Guys how-To's?

Atlas Turntable Makeover

For my H0n3 turntable I want

For my H0n3 turntable I want a manual device for a manual driven turntable.

For power I've made a PC board plate, and wipers at the bridge.

Wolfgang

I just looked at Jim Marksberry's turntable tutorial.

Great idea for using an inexpensive Atlas as the basis for a kit bash with a pit.  I would add one more idea to his plan.  If you check out a craft or sewing store, you can find perfectly round wooden embroidery hoops that will make nice round pit walls if you get one of the correct size.

Jim Marksberry's Tutorial

I always thought so too.  I was surprised by how great the humble Atlas turntable could be made to look without too much difficulty.  I have also heard that while inexpensive, the Atlas turntable indexes very well.

The embroidery hoops sound like a good idea too.  Making a note...thanks.

Thanks for all the info guys,

Thanks for all the info guys, very helpful. Will take me a while to digest it all but good never the less.

I mught start a blog on the building of this RR too to go along with the TT 

Cheers

Bruce

building a turntable

Thanks for the mention about building a turntable guys, it is very much appreciated. If anyone needs any info on my tutorial I will be glad to help.

Jim Marksberry

Atlas lurching?

Didn't see any comments on the Atlas drawback:  turning more than one of the broad increments results in interrupted rotation, stopping every 15 degrees.

I have one of the Heljan 14" (100 ft  -  just long enough for a Bachmann USRA 2-6-6-2) kits partially assembled.  A stepper motor and associated cogged belt from a dead inkjet printer are the planned drive  -  it has a pretty small step, and the belt fits tightly in the V-groove on the under pit rotation mechanism intended for manual string drive, so it should be accurate enough, and a stepper motor control circuit allowing slow speed and nudging should make manual indexing work.  After all, manual is how the railroads do (did) it.  

The Heljan bridge bogies are pretty crappy, plastic on plastic rotating in plastic, rolling on plastic.  I have some little 1/4" ball bearing rollers salvaged from some old 5 1/4" hard disk drives (supported the head drive mechanism) that may fit with some cobbling.  I don't like the lack of a pit rail, but it does look like a code 55 rail could be Barge cemented in place after being pre-curved.  This would then require raising the bridge mount by .055 or perhaps .060 (accounting for larger rollers as well as rail height), and likewise building up the pit rim the same amount.  Spackle could transform the European looking masonry pit floor to a concrete look. 

All in all, if Walthers had a more reasonable intermediate size between the 90 footer and 130 footer  (18 inches!!!) full auto indexed RTR tables, I'd probably bite  -  but 90 ft is too short,  and I don't have room for an 18" diameter table  -  so it looks like I'm stuck with this project.

Atlas Makeover/2guyzandsumtrains GONE :-(

Just checked out the link you posted and it seems the site is for lease .... too bad. That was a good site at one time.

Steve

Drawback of Atlas....

Is that it stops at every indexed stop. Takes forever to make a revolution to turn an engine. Unless someone has figured out a way to overcome that. I have seen some really nice conversions appearance wise and always wondered about the indexing thing. There is a thread here somewhere where MC Fujiwara built a manual turntable in N scale. It's nicely done and uses a 1/4" phone plug as the center mechanism it turns on which also gives an easy way to transfer power to the rails.

Michael

All the ideas are really good, how would you ...

How would you make the Atlas tt look like a stationary concrete pit?

Lovev some ideas on that.

Mine built from

an article in MR several years ago. I don't remember the month or year but I'm guessing you can search their website. It uses inexpensive wood and commercial parts. I little ingenuity is required to make it work but well worth the time spent to build the project. One thing I did was use wipers on the ends of the bridge instead of bogies (wheels) as described in the article. Wipers are more forgiving if you don't have a perfect pit rail circle.

Maybe someone on here will remember that article.

John

Tyebrable

As was said, centering the bridge in the pit is probably the biggest challenge. The speed of the Atlas is not an issue. There is no hurry. Time the Atlas TT as compared to a prototype TT for a comparison.

I just did a Google search for, Modified atlas turntable. There is a lot of info available that might help.

The MR article about using a 1/4 inch phone jack is in the Feb 1987 issue

Rich

Speed is not an issue

But the Atlas turntable stopping every few degrees is irritating to me. I don't know if there is a way to do such a thing but I've always wondered if something could be mechanically modified in the drive train to make it rotate past unused "stall points" and only stop at the desired ones.

Michael

MR article

Atlas Mechanism

I read once that Atlas uses a Geneva mechanism inside their turntable.  The link below explains how this mechanism works.  I've never dismantled one of their turntables, so can't vouch how similar it is to this, but if it follows this motion, I can't think of a practical way to "override" it.

http://en.wikipedia.org/wiki/Geneva_drive

-Jack

...

It is indeed a Geneva mechanism, whereas there is an arc on the underside of the turntable.  As you turn the crank, the notch in the gear wheel slides in this mechanism, effectively turning the table for the full distance of that one arc - 15 degrees, or so.

In otherwords, tear one apart and you'll understand why it stops at each stall.  There is no "re-engineering" this table without completely throwing out a lot of it.

That being said, it's dang near bulletproof, and with a lot of creativity, it has a number of great uses as a turntable. 

Scratch built turntable pit

Hi Bruce,

Years ago I turned a turntable on a wood lathe. I had a piece of high density foam board kicking around and chucked it into the lathe. It only took a few minutes to turn. It came out looking pretty good. I didn't have any prototype info so just made it up as I went along. Its been kicking around for years mostly outside in an open shed. Stood up well to the weather.

Rob Teed

I have one or two of the

I have one or two of the Atlas tables and have given numerous hours of research to its use.

Someone mentioned the time for rotation and the delay at stop points. Question can the motor voltage be increased for faster rotation. A few volts can make a difference.

Also build the turntable up high enough to clear the motor, remove the plastic building covering the motor and you have a 90 to 120+ turntable with exacting indexing.

http://modelrailroading.wordpress.com/2009/07/03/sp-common-standard-turntable-from-atlas-tpt2/