What's your preferred method of installing a turntable? Is it shimmed up to the level of the roadbed, is there a ramp that partially reduces the height of the approach track with the TT still being shimmed, or is it mounted directly to the plywood with a ramp bringing the approach track to this level?
Or do you have some other way that I haven't thought of??
There's never time to do it right, but always time to do it over.....
I model in N scale, use Peco code 55 track on cork roadbed and have the Walther's built-up turntable. I laid cork right up to the edge of the hole and placed the turntable lip over the cork. The ties and lip of the turntable are at the same height, so the rail transitions from the tie to the turntable without any needed shims.
Scott
I agree with Scott, run the cork up to the cutout in the plywood and put the tt on top of the cork. Your rails shoud now line up with the track on the bridge of the tt as long as you use the same code track. I have the Walther's HO 130' tt and that is how mine will be installed (it is still in the box but has been tested and works great).
Bob
Life is what happens while you are making other plans!
You'll want to match the overall height of the ties and rails to what will be needed to meet at the railhead height on the bridge. So, do what you must to make that meet happen. It could be one or the other, or a mix of several adjustments.
In my case, I was using Atlas Code 100 and the entire yard system sat on a layer of commercial vinyl underlay about 1/8" thick...yellow stuff that a local carpet installer threw my way. I wanted the pit lip at or just higher than ground level, as it would likely be in a prototypical yard. So, once I had the lead started, I added a single layer of the same vinyl underlay as a lift layer under the pit lip, effectively raising the pit lip that thickness above the surrounding yard terrain. When I got to placing the bared rail ends of the lead atop the exposed lip (meaning minus one or two ties), I found the Code 100 rails were higher than the code on the bridge supplied by Walthers. I took my Dremel-like tool with a thin stone wheel on it and eroded two parallel grooves for the rails to be glued to. And that is how it went and how it works.
The reasons I raised the pit lip were two: The local Seneca Yard engineering section took direction from the railroad company manual and ensured that a loose engine couldn't roll onto the bridge, or worse, into the pit. The way to do that was to have engines climb on a 0.6% grade to get onto the bridge. However, a more compelling reason was that, mated to the model of the roundhouse I was using, I would have had to do major surgery to get the Code 100 I was using in the engine bays to meet effectively with the smaller code rails on the bridge...unless I elected to tilt the entire pit upward on the side toward the roundhouse...which I didn't want to do.
-Crandell
If you cut the hole in your plywood and drop the turn table in and secure it track placed right on the plywood is at the correct height and you will only need to remove the last couple of ties and attach them to the lip of the pit with some cyanoacrylate to keep the rails in gage, but you don't want to do this. The sound reverberation that comes form mounting track directly to plywood is horrendous (ask me how I know)
Lead in tracks and engine servicing facilities in general did not have typical ballasted roadbed as it wasn't required . Locomotives would never be moving more then maybe 5 mph so if you study a lot of photos of turntables and engine facilities track appears to be right on the ground with with ballasted which in many cases were cinders which were in plentiful supply.
I would put some sort of yard panel down on your plywood first I am no longer a big fan of cork but thats your decision. A lot of guys use it without any issues. In my o/p Homabed sheets would be the way to go some guys like to use extruded foam the choice is yours Regardless of what you choose the same still applies to laying your track and removing the last few ties.
I am a big fan of research material and if I may recommend MR has an excellent book out by Marty McGuirk, "Locomotive Servicing Terminals " an excellent source of information and he include a complete illustrated tutorial on how to install the Walthers turntable and roundhouse. I found a lot of information that I never even considered in his book such as inspection pits, water columns ash pit placement sand & drying houses and a lot more.
Good luck with your turntable and engine facility your really gonna enjoy it.
Note: If your using the Walthers T/T it's set up for use with code 83track if your modeling HO, I would not recommen using code 100 track as the transition between it and the code 83 on the bridge is just going to be a giant pain that you don't need.
Allegheny2-6-6-6I am a big fan of research material and if I may recommend MR has an excellent book out by Marty McGuirk, "Locomotive Servicing Terminals " an excellent source of information and he include a complete illustrated tutorial on how to install the Walthers turntable and roundhouse. I found a lot of information that I never even considered in his book such as inspection pits, water columns ash pit placement sand & drying houses and a lot more.
Thanks guys for the great information. It gives me some additional options that I hadn't thought of before. I am using Atlas Code 100 rail on cork roadbed but am going to transition to Code 83 before the TT. Getting from the height of the roadbed to the height of the TT was always a question but after reading your posts it helps with the issue. I have the book on order from Amazon and have found some pictures dated in the 1950's of an old engine servicing/TT facility near the area I am modeling. It's pretty rustic and very basic so the book will be great information. Thanks again!
Here's my way for my staging yard Fiddletown.I adjust the bridge track.
Wolfgang
Pueblo & Salt Lake RR
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