I purchased an 18" ross turntable which is great however I need to find an 18" roundhouse for it or a diagram and parts to build one. Anyone have any ideas or suggestions about this.

Roundhouse size and position is a trial and error, there are several veriables.
One piece of information that was always quite good was from Bowser when they were in the Turntable business. Bowser/Korber house

Critical mass is that the track has to come straight off the TT and through the center of each door. Where the track ends in the house can vary. In some instances it is recommended to use flex track in the house and curve it.

Note that in my Korber house the rails move to the outside of the two outside bays, almost paralleling the outside walls. 26" turntable with about 12" between the TT and the house. With an 18" TT you may have to extend the distance between the TT and house,(May be 15"), or curve the tracks inside the house.

This message has been edited. Last edited by: Mike CT,

Hi guys,

gbsson, to answer your question, almost any of the roundhouse kits on the market will work for you because you have chosen a small turntable. The smaller Korber kit is a nice piece and would probably be the best fit.

Roundhouse geometry can seem like black magic, but it's really quite simple once you know the variables. There are two things that determine the dimensions and location of a roundhouse.

1. How wide are the stalls, including door frames and surrounding walls.

2. Degrees of rotation between the stalls.

Let's say we want each stall for an O-gauge roundhouse to be 5 inches wide. That's fairly comfortable spacing to fit our engines through the doors. Now, let's say we're going to have a track come off the turntable every 22.5˚. We can draw that out with a 5 inch wide box centered over each track. For right now the length of the boxes doesn't matter, but in the drawings below they are 24 inch deep. We move the boxes in towards the center point of the turntable until the corners touch. That gives you the exact distance from the center that the roundhouse should be located. In this case 13.25 inches.



If we change either dimension the location of the roundhouse will change. If we make the stalls only 4 inches wide, but keep the 22.5˚ between each stall, the roundhouse will now sit only 10.25 inches from the center point.



If we keep the 5 inch stall width, but change to only 15˚ of rotational spacing the boxes move away from the center point. The roundhouse would now sit 19.5 inches from the center.



Unless you bend the tracks between the turntable and roundhouse, as Mike CT suggests, each roundhouse can ONLY sit one specific distance from the center point. Since the roundhouse is fixed the distance from the edge of the turntable to the doors of the roundhouse is determined by the size of the turntable. If we use the 5" stall width and 15˚ rotational spacing (a good choice since the Ross auto indexing TT works in 7.5˚ increments) an 18 inch turntable will leave 10.5 inches between the TT and roundhouse doors.



A 33 inch turntable will work with the same roundhouse, but there will only be 3 inches to the doors.

IIRC the Korber RHs are all 15 degree.

Excellent Thread!!!! Thanks so much.

Rob,

Is the stall width on the Korber Kit 5"?

Thanks!

Dave-
Great description and drawings.

Hi all,

I used RR-Track's accessory library to figure out dimensions for the four most popular roundhouse kits on the market. Here's the stats:

Atlas #6904

stall width - 6.5 inches
rotational spacing - 15˚
set back (center point of rotation to roundhouse doors) - 23.75 inches

Korber #304 and #320

stall width - 5 inches
rotational spcaing - 10˚
set back - 28.5 inches

Ross Roundhouse

stall width - 4 inches
rotational spacing - 7.5˚
set back - 31.25 inches

Hope that helps.

Correction. The Korber Roundhouse, either 304 or 320, have 10 degree stalls when assembled correctly.

Dave thanks for excellent info and diagrams. This one is definitely a saver. I've already printed a hard copy for my notebook binder.

If building one with a clerestory in the front top I find that 1/3rd for the front roof and 2/3rds for the back roof seems to feel right proportionally. So for a 21" roundhouse the front roof about 7" and the back roof about 14".... approximately. Happy Railroading!

If I'm not mistaken, Steve Brenneisen at Ross Custom Switches sells a large roundhouse that is laser cut, a beautiful piece. Pat Marinari has one on his layout that is quite stunning. It seems to be the perfect companion for the Ross turntable on Pat's fantastic layout.

HelpfulBear

If i had the 33" Ross TT and i had my auto indexing at 7.5 degree increments, what would be the distance between the TT and the roundhouse if the stall has a 5" width. I believe ths would give me 48 stalls. Are the Korber roundhouse stall 5" wide?

As stated in one of Dave Hikel's post above.

quote:

Korber #304 and #320

stall width - 5 inches
rotational spcaing - 10˚
set back - 28.5 inches

There is a diagram in the Bowser/ Korber information of my first post that shows a 32" TT and a spacing of 16.17" between the TT edge and the Korber roundhouse for a perfect circle RH.

I agree that this thread is definately a keeper!

As always, nice photos Mike!

Dave, your description and drawings are fantastic.

I'll be building my turntable over the Christmas holidays and was just considering adding a engine shed. Now, I definately will revisit and see if a roundhouse is possible!

Jim

Glad I revisited this.

Can't seem to recall things like I ought to...

10 degrees IS right for the Korber houses... I had to measure it to be sure.

Here is my issue, I have a 36" table and 2 Korber houses. Right now I have it setting at a 44.5" setback from the center of rotation. Note that my setback is increased due to the desire of having the outer rails meet at a point right at the TT pit wall (hopefully to be frogged someday...). Seems that the tracks are centered in the RH, but would appreciate a backcheck from you computer drawing guys before I set it "in stone".

Thanks.

26.5" back off the edge of the TT. That is some real estate My modular layout worked well at 15 1/8" of the edge of the TT, which has a 33 3/8" bridge rail length. The picture above is a Diamond Scale TT on my layout.

You may want to build a floor plan template, even if the computer drawings show it to work well, I did final placement of the stub rails with the floor template and a string line hooked to the far end of the TT center rail. Primary objective is center of each 5" front and for the stubs to be perfectly straight inline with the bridge centered on that bay. Each stub inside the house is an Atlas 40" piece plus a small cut piece to finish. Edge of TT to the back of the house.

To converge the rails and add a frog, I can see maybe 3" to 4" more inches, which would push out to 19" off the TT edge. Moving further back would push the rail ends inside the house to the center. Your template and stub rail placement should determing your final position.

Here are a couple of looks at my Modular TT.











One of the things I didn't do that I wish I had, (hind sight) was align the stub rails at 180 degrees. In all but one position the TT has to be moved to drive on and then off. That straight through shot would have been great. Again the position of the template on the layout is key to determining the 180's. Moving my house an inch one way or the other would have allowed for this. Next time.

Here is a picture of the floor template I used with the Diamond Scale TT on my layout.




Pushing the edge of the layout.


Eventually it starts to come together. You can note that the outside rail here is paralleling the edge of the building and not centered in the bay. But very workable for a small space.


The floor template is a piece of luan board cut using the Korber templates. I actually added an inch all around. TT height was determined based on the track sections being fastened to this template, which matched well with cork under the tracks to the TT outside the house area. Eventually a three layer floor build up was done to give the house a concrete floor look and also add a bit of structural and assembly work-ability.

Rob:
Best wishes on your project
Mike CT

Mike,

I'm getting ready to build my own turntable and if I may ask, how deep is your turntable pit and how thick is the ledge for the pit rail?

gbbson - I apologize for taking your thread slightly off-topic.

Jim

Thanks Mike CT!

I'll post pics on this... updating as I build. I like the template Idea and will use it... THANKS!

Rob

quote:

Originally posted by Mike CT:

quote:

Originally posted by jd-train:
Mike,

I'm getting ready to build my own turntable and if I may ask, how deep is your turntable pit Modular turntable pit is 2.5" deep. and how thick is the ledge for the pit rail? Pit rail ledge is .5".

gbbson - I apologize for taking your thread slightly off-topic.

Jim

Thank You!

Jim

Re-post of Scratch Built Turntable for those interested. Originally posted 2007. I changed my website slightly this summer, so the original post and one I did about a year ago probably is missing a few pictures. I cleaned it up this morning and re-posted it here. Original post was done on the scenery forum. There was about $1,200 in tools, sub-contract fabrication, and material for this project. Have fun on your projects.

I have to apologize to Eliot, I promised a detailed post on the Korber RH assembly and never got it done. Sorry Eliot, the sun still came up this morning and it's still on the list.

Subject: Turntable, detailed post.


I've been working on this project since the beginning of Summer and thought I would share it here. It's been a great project and so far turned out well.

I used Diamond Scale parts that were still available and incorporated some ideas that I have seen. The idea was to build a large 33"+ TT that could be hauled around to train shows and still work well.

A couple of picture of the TT close to finished.







The TT project is a copy of an existing Diamond Scale TT that I purchased, used, a few years ago. I rebuilt it for my layout.


The larger turntable starts with a 4'X 8" X 1/2" MDO Plywood. The TT module will be 48" X 48". First thing is to determine the TT center and insert the main drive shaft bushing.



I used a fabricated rolled aluminum ring as the pit wall. I also used 1/4" Aluminum as the structural side rails of the bridge.


The pit has to be a circle which required adjustment before finally setting the ring in place. 1/8" clearance from the end of the bridge was my goal.


Once the pit was a true circle I painted and preped the raise ring area for installing of the pit rail.


Installation of the pit rail was done with Atlas flex track (2)(40")pieces were used with part of one piece left over.


The drive system requires a 7/16" drive shaft with a 1" X 9" metal plate. A wooden block is then attached to the plate.
Shaft and drive plate are shown in this picture.


The bridge sits down over this drive block.


The bronze drive gear will bolt up to the shaft under the table.


Assembly of the drive box is done with 3/8" medium density particle board.



I install (2) brass washers on the drive bar for increase electrical conductivity. This shaft and bushing assemble will supply power to the center rail of the bridge.


Wires attached to the drive bar will be attached to the center rail.


Drive box attached to the underside of the TT.






Since the turntable dolly trucks were not available I had to fabricate them.




Dolly installed on the bridge rail.








The module eventually becomes a sandwich with two layers. The second layer is adjust so that the bottom on the Atlas track will be flush with the top of the pit wall.





Detailing the bridge.
Brass rivet detail








Installation of the Bowser 7902 deck detail kit.


A little more rivet detail with styrene sheet.


Crow River electric winch kit.


Ladder and conduit on the electrical bridge.


Lower level detail.


Upper level detail.


Control booth area. Note the Kaplar lumber used to extend support for the deck.


Even the Atlas ties are painted Railroad Tie Brown to match the Kaplar lumber used.


Additional electrical conduit detail.


Deck and handrails installed. I had to order an additional 20 handrail stantions to complete this part of the project.








Project with an additional 48" X 48" module for a round house.


A big turntable.


A lot of work yet to do, but the TT is functional, we have had it at two shows. I was surprised that the small Diamond Scale drive seems to hold up well. We have turned it on and let it run for hours at a time with no problems.

Parts List from Diamond Scale. I e-mailed Diamond Scale a few weeks ago with a simalar list to see if these parts were still available. I got no response to my e-mail. Diamond Scale is under new ownership since I bought my parts in May 2007.
MK-111 turntable drive kit (1)
DT-09 turntable dolly trucks, (1) pair (not available)
CB-30 turntable control cab (1) may not be required if using the Bowser 7902 bridge detail kit.
AK-104 Turntable Arch Kit Angled (1) (not available).
WG-9 Worm and Drive Gear (Boston Gear 1049G) 7/16" bore. (1)reqired.
WS-87 3/16" X 6" Worm gear shaft (1)required.
B-187 3/16" ID Bronze Bushings (2) required.
SC-187 3/16" ID Shaft Collar (2) required.
B-437 7/16" ID Bronze Bushings (2) required
SC-437 7/16" ID Shaft Collar (2) required.
US-1 3/16" X 1/8" universal drive. (1)

Parts List from Bowser Trains
#7902 O Gauge Bridge detail kit.
#79417 handrail post. An Additional (20) were required.

Parts Kaplar Lumber.
KP1186-OP24 Scale 10" X 12" .208" X .250" match up to Atlas railroad ties.
KP1126-OP24 Scale 2" X 10" .042" X .208" addition deck material

Parts Plastruct.
#90423 ABS Ladder

Parts Evergreen Scale Models.
#146 .040" x .125" Styrene Strips.
#9077 .015" Clear Styrene sheet
#9040 .040" White Styrene sheet

K&S Engineering.
#91066 1/8" brass angle X .022" X 36"
#92098 3/16" brass bar X 12"

Crow River Products.
#O-56 Scale Electric Winch Kit. (2) required

Atlas.
#6056 40" flex track curved pit rail.
#6058 40" rigid track Bridge rails
#6094 Track Screws.

MSC Industrial Supply/ J&L Industrial Supply.
#607Z Bearing 7 X 19 X 6 mm bearing. (4) required.

Micro Fasteners.
RMB0212 2-56 X 3/4" brass round head screws.

Krylon paint.
#2323 River Rock spray paint
#1602 Ultra Flat Black spray paint

MinWax stain.
#224 Special Walnut. deck stain

Sherwin Williams primer/sealer.
#141-1699 Preprite ProBlock Alkyd Primer/Sealer in spray cans.

Floquil/Polyscale acrylic paint.
#F414137 Grimy Black
#F414329 Railroad Tie Brown
#F404076 Coach Green

Mike,

Thanks for posting the additional pictures!

One last question (at least for now - ) is what thickness of flat aluminum did you use for the pit wall and the sides of the TT bridge. I'm guessing either 1/8" or 1/4"?

Thanks,

Jim

[QUOTE]Originally posted by jd-train:
Mike,

Thanks for posting the additional pictures!

One last question (at least for now - ) is what thickness of flat aluminum did you use for the pit wall and the sides of the TT bridge. I'm guessing either 1/8" or 1/4"?1/4" Aluminum. I had this piece fabricated at a local fab shop who does a lot of heavy industrial duct work.

My website

Most of the large TT pictures are in the Fort Pitt High Railer file.
Have fun with your project.
Mike CT