# Engine House & Turn Table Geometry



## Cab1 (Jul 26, 2009)

I'm building an HO scale engine house from plans of a Detail Associates 3 stall branch line round house kit 7001 that I snagged from pictures on the internet. The templates are not exactly to scale because they were blown up to what I figured was close enough to scale and printed out. However, I do have the finished scale footprint (65' x 80'), I'm using scale wood and an HO scale reference rule to match everything up to. It should come out true to scale overall when I'm done - even if I make a few adjustments here and there to make it my own. Of course I don't have any doors, windows or other accessories that would normally come with a kit. So my first question is where's the best place to buy them? My second question has to do with turn table geometry. It's a round house so it will of course have a turn table. The problem is how do I get the turn table track to line up exactly with the track in each stall of the engine house? If the timing is off, even just a bit, the tracks are not going to line up right. How do I deal with this?


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## rkenney (Aug 10, 2013)

Consider your turntable as the center hub of a wheel. Each roundhouse 'stall' is centered on a 'spoke' of that wheel.

Simply draw radius lines from the exact center of your turntable. Some distance from the outer edge of the turntable will coincide with the curve of the roundhouse model.

Since your not building the roundhouse from scratch you'll have to build it, then mock-up your layout and measure.

The picture I have in my mind is to have enough room (open air) between the stall and the table to hold an engine and tender. i.e. 80 ft turntable, 80 ft open track, 80 ft stall.


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## Hutch (Dec 19, 2012)

Cab1 said:


> The problem is how do I get the turn table track to line up exactly with the track in each stall of the engine house? If the timing is off, even just a bit, the tracks are not going to line up right. How do I deal with this?


Seems like you would need some sort of sprung ball bearing and holes for them to click into as you spin it. Then add your track to these positions while they are locked in.


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## DonR (Oct 18, 2012)

Another point to keep in mind when building your turntable. You'll need
to make electrical arrangements so you can control the polarity
of your stall tracks and turntable track. A turntable is essentially
a 'reverse loop'. If you are DCC a reverse loop controller will
take care of it for you.

Don


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## Big Ed (Jun 16, 2009)

The first place I clicked in a search, check it out.

http://www.debenllc.com/servlet/the-Grandt-Line-Products/Categories


Some windows. (there are more)








I agree if you have the space about leaving " open air space" in between the roundhouse and turntable. It looks better, if you have the room.

Are you planning on buying a turntable or building one yourself?


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## Big Ed (Jun 16, 2009)

A bunch of windows and doors here too, I picked the roundhouse door page,
http://www.oakridgehobbies.com/catalogsearch/result/?cat=&q=roundhouse+door


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## golfermd (Apr 19, 2013)

One thing to note if you are using with a photocopy. It likely isn't an exact 1:1 copy. There are small variations in scale. We in the sticks and strings (model wooden ships) hobby are all too aware of this. If you want a perfect 1:1 (or any ratio) you have to take it to a professional copier business who specialize in rendering blueprints and architectural drawings. In your case that may not make much of a difference.


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## Cab1 (Jul 26, 2009)

Thanks for all the help. Right now I'm at the kick around stage. This round house kit was on ebay. When I saw what was inside (and the crazy money they were asking for it) I figured, hey, I could stick build this thing myself for a lot less bucks. The only real cost is in the windows and doors. Besides, I wouldn't buy a kit that was opened. There's too big a chance something might fall out unnoticed and you find parts are missing after you buy it. The seller was "kind enough" to show pictures of all the construction plans and templates too. All you need is a few overall dimensions and a good HO scale reference rule. That's the plan anyway. As far as the turntable? I'll most likely buy one from Walthers.


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