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L-girder layout





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#1 jabberwock

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Posted 13 September 2017 - 14:46

Hello

I am about to start construction of an OO guage layout in a second floor room.It is part of a good quality loft conversion not subject to damp at all and fairly well insulated but subject to temperature variation of course.

I have bought some plywood to use for the L-girder frame and legs but am not sure what to use for the track-bed or risers. Will 9mm birch plywood be OK. and if so any advice about how close the supporting risers will be. The width of the track-bed will vary of course some being wide enough for 2 way track and some being wider for 4 track and stations etc.

Regards

John



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#2 kevinlms

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Posted 13 September 2017 - 15:04

Hello

I am about to start construction of an OO guage layout in a second floor room.It is part of a good quality loft conversion not subject to damp at all and fairly well insulated but subject to temperature variation of course.

I have bought some plywood to use for the L-girder frame and legs but am not sure what to use for the track-bed or risers. Will 9mm birch plywood be OK. and if so any advice about how close the supporting risers will be. The width of the track-bed will vary of course some being wide enough for 2 way track and some being wider for 4 track and stations etc.

Regards

John

This book is excellent for L Girder layouts. There are a couple of editions around.

 

https://www.abebooks...-0890242895/plp



#3 Silver Sidelines

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Posted 13 September 2017 - 15:21

Hello John

 

I have constructed a number of layouts around the 'L' Girder idea.  There is a Post on my Blog which details my construction techniques and variations.

 

Early layouts used softwood framing and risers with chipboard track beds (very heavy and rough on the hands).  The latest incarnation uses MDF for the track beds.  It needs to be supported by risers at 12 inch centres or perhaps even more frequently for narrow widths (single track).  Plywood wil be more stable than softwood but you may need more woodworking skills.

 

I have a lot of pictures on Flickr that might help

 

Regards

 

Ray


Edited by Silver Sidelines, 13 September 2017 - 17:07 .


#4 Miss Prism

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Posted 13 September 2017 - 15:38

John - 9mm will be fine for risers and trackbed, but you might want to augment the top of the risers with 20mm (say) square section, to provide a good and flat screw-grab for the bed. For 9mm trackbed, I would say 10" max between risers. (Any longer will probably require additional bracing of some kind.)



#5 jabberwock

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Posted 13 September 2017 - 15:51

Hello

Thanks for the advice to date. Having looked at Ray's very impressive layout I am very tempted to follow his lead and use 12mm MDF. Apart from a small amount of condensation on the Velux windows in cold weather the room is very dry. I guess MDF does not mind reasonable temperature variation too much, just damp. And 12mm MDF is certainly a good deal cheaper than ply so a bit of wastage due mistakes would not be too serious.

John



#6 Silver Sidelines

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Posted 13 September 2017 - 17:22

Thanks John

And 12mm MDF is certainly a good deal cheaper than ply so a bit of wastage due mistakes would not be too serious.

 

From the dates on the pictures the MDF has been in use for ten years and has not required any remedial action.  You need to make sure that the sheets of MDF have not been subject to damp or have warped whilst in store at the supplier.  My railway is  not heated.  In retrospect I should have given more attention to the sourcing of the softwood for the framing as some of it has shown a tendancy to warp.  MDF is much easier to cut to shape than plywood.  I made a number of different sized circular cardboard templates to mark out the 8 x 4 foot sheets which I then cut up outside in the fresh air supporting them on upturned plastic crates.

 

Regards Ray



#7 DavidCBroad

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Posted 14 September 2017 - 03:43

The point about warping is important, I have been battling with warped timber this afternoon, timber bought "New" 30 odd years ago which has distorted quite noticeably and enough to create unwanted 1 in 100 gradients, Today 3 hours work lowered the summit by 1/4" and allowed a 9F to pull an additional 3 bogie bolsters up the grade, (or a total of 14 Mk 1 coaches).  

Somewhat fortunately the bit in question has trackbeds built on risers so so apart from the summit where the 5" trackbeds join a 30" wide baseboard I was able to adjust it by changing the thickness of the packing etc.  

My "Answer" to warping is to buy good dry second hand timber, I get mine from scrapped builders vans in a local scrap yard. Planed and sanded it is as good as new and won't twist like a dogs hind leg after a couple of years.

MDF sounds like a very good choice for trackbeds,  the problem I had is the trackbeds are double track width climbing at 1 in 50 around a 3ft radius curve and keeping the track level means quite a significant lateral twist has to be applied and the fibre board used fought me constantly as it didn't like the idea of not staying flat. I used Riser supports every 8 inches or less around the curves.

L girders or other riser based baseboard systems make realistic scenery much easier than trying to do something based on a flat monolithic slab, 


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#8 PaulRhB

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Posted 14 September 2017 - 07:12

If you need more than 12" between risers I added 1" strips of 6mm ply to the underside to make the trackbed into a T section, you can even cut or sand the vertical piece to convex or concave for a gradient change. Just glue and clamp the 6mm to the 9mm trackbed. My Swiss layout used this and had no problems despite living in a large damp ex chicken shed.
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#9 jabberwock

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Posted 14 September 2017 - 09:45

Hello

Yes I will have plenty of curved sections on a perhaps 1 in 60 gradient. I had no thought of this being a problem since it is my first layout since 1962!

John









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