Incorporating contours into baseboard construction and other plywood questions

[NittenDormer]

I am considering buidling plywood-based baseboards (8 open plan boards that link together to form a 2-board x 4-board layout approx 1 garage long. The epiphany moment came when I realised I could (would have to) get all the pieces pre cut, meaning lots less cutting for me and lots straighter edges for the wood.

 

1. Would 9mm plywood be overkill/underkill/just right?

 

2. Is it sensible to extend the plywood edge pieces and end pieces upwards to incorporate the planned scenic outline (hills etc)? Does this make the frame stronger or would the added load weaken the under-support structure? Since support for the hills would need to be added at some point anyway, it seems sensible to me to integrate it rather than rely on screws and glue?

 

3. What is the advantage of plywood over softwood? 9mm x 100mm cross section is effectively the same volume as 18mm x 50mm (well 44mm in reality) softwood, so where is the gain? Is plywood lighter? Denser? Stronger? Does a deep, narrow beam offer more support than a shallow, wider equivalent?

 

Thanks as always for your advice, experience and thoughts.

[peter220950]

I am considering buidling plywood-based baseboards (8 open plan boards that link together to form a 2-board x 4-board layout approx 1 garage long. The epiphany moment came when I realised I could (would have to) get all the pieces pre cut, meaning lots less cutting for me and lots straighter edges for the wood.

 

1. Would 9mm plywood be overkill/underkill/just right?

 

2. Is it sensible to extend the plywood edge pieces and end pieces upwards to incorporate the planned scenic outline (hills etc)? Does this make the frame stronger or would the added load weaken the under-support structure? Since support for the hills would need to be added at some point anyway, it seems sensible to me to integrate it rather than rely on screws and glue?

 

3. What is the advantage of plywood over softwood? 9mm x 100mm cross section is effectively the same volume as 18mm x 50mm (well 44mm in reality) softwood, so where is the gain? Is plywood lighter? Denser? Stronger? Does a deep, narrow beam offer more support than a shallow, wider equivalent?

 

Thanks as always for your advice, experience and thoughts.

 

 

Hi,

 

Given that it's going to be set up in a garage I would go with 9mm ply, it's more stable than softwood, which can still be growing when you buy it nowadays!, Lighter weight ply can be used, but unless it's an exhibition layout, to be moved about a lot, I would go for the solidity of the 9mm. Having said that my board ends are mdf, but ply would have been a better choice.

 

Ply is also better if you are considering a more interesting outer edge of the boards than straight lines, it alows curved fronts if required.

 

It's also worth considering the sandwiches made from thinner ply and timber spacers, making deep lightweight beams, you queried the depth/strength issue, deeper beams are stronger and have less deflection than similar cross sectional area conventional timbers - look at any structural beams, they are usually deeper than their width.

 

Whatever you use I would advocate a couple of coats of clear varnish as soon as possible after making the boards, to prevent moisture affecting the boards.

 

The general concensus here seems to be that good quality ply, purchased from a merchant, is better than that from the DIY outlets, though I haven't had any issues with the thicker ply's. Always go for the best you can afford, it's going to have to last a long time.

 

I would also advocate making the ends and any other meeting faces much higher than the finished levels, and cut them down to suit land profiles at a later date, I did this with my boards, and it gives a nice crisp joint that's less vulnerable to knocks than hard edges formed in plaster or similar.

 

 

Outer edges can be added more easily after the main ground levels have been established, but drilling and installing dowels into the ends before they are attached to the boards ensures that the finished boards fit together well, once trackbed is fixed the ends can be cut.

 

You don't mention how the layout will site within the garage, or its size but if I read your post correctly you will end up with a layout that's two boards deep, and therefore quite deep from front to back, just make sure you can reach the back to work on the layout.

 

Peter

[DCB]

Just a couple of points, big advantage to ply, less warping. Big disadvantage, woodworm love it.   Cable routing, it would probably pay dividends to drill or hole saw 25mm or so holes into and out of every box of the egg box construction to provide cable routes.   Marking it up and pre drilling maybe six at a time would be a fraction of the time needed to add holes at a later date.

I try to incorporate cable trunking in my layouts from the outset, quite often on the surface in hidden sidings or the back.

It is also worth making a hinged thin ply bottom to the baseboard to keep wires etc well hidden!

 

Side end and front pieces can usefully project above the layout surface.  like to have a "Lip" at least 12mm high where the side pieces project above the baseboard top simply to stop derailed stock hitting the floor.   It is much more satisfactory than pinning thin ply or Hardboard to the edge as the damn pins work out and snag your trousers.   That lip can also be a viaduct or bridge parapet if you shape the baseboard edge accordingly, no reason the strength beam has to have a cosmetic bridge added if it is cut accurately and brickpapered or finished with plastic arches.  Even with 44mmX22mm I have slotted the 44  to take 3mm ply for a very "Thin" board on a lift out section.