Too much plywood

Hi All.  What a twit I have been? I have just been reading a thread about Baseboards. And it would seem that I have gone about this the wrong way. I used an 8' x 4' sheet of ply cut into four. This is okay for a busy yard with a lot of tracks, like a depot, but along the line through scenery it seems that one only requires a "Skeletal" base, just wide enough for the track. I must admit this would cut down the weight, but I'm not sure how rigid the frame would be and is there.a way to accomplish this job? i.e. A rigid lightweight baseboard for double o.   Kevin

You could frame up a sheet of Extruded Polystyrene, and run a ply track base over that.you only need thin ply round the sides of a extruded baseboard to protect the foam.
 The Extruded  polystyrene will replace a lot of the torsional ridgidity lot by not having a plysheet  base and give you something to build scenery on.

Hi Q                      Thank you for your reply, but now that means finding somewhere that stocks the polystyrene.                          all the best  Kevin

I would suggest Wickes, I use Celotex, it is not as messy cutting it as the white stuff. It has foil both sides. I use cork tile for the trackbed, pins don't work too well in foam!

http://www.wickes.co.uk/search?text=celotex

For a one off board I've used Celotex which is easily available at BQ or Wickes. once I get to mass producing boards I'll go over to using,

Dow corning floormate 300 which is better and doesn't rely on tin foil for stability. But you need to buy about £100 worth at a time.



The floormate is available from here http://www.insulationexpress.co.uk/Floor-Insulation/Dow-Floormate-300A-Styrofoam-Insulation-Boards.htm online or from your nearest Branch which I think will be SIG insulation in Barking.

Kevin,

I assume you have you already built your baseboards, in which case, you are now suffering from information overload!

What you have done is absolutely fine and will work extremely well. In fact, you're able to build anything you want on it and will be able to do so again in the future if you ever want to modify your track plan. Please don't be tempted to rip up what you have and spend yet more money on a different way of achieving what you already have!

My very best,

Bill

Hi Mike.  Thank you for your reply. There is a lot to think about? Do I put the horse before the cart? Meaning That the horse equals the foam or the wooden frame , and is that Plywood or Timber. Kevin

Hi Bill.    I'm all for not spending money on replacements  but it was the overall baseboard weight that I was worriedn about, and how I should have.built the baseboard at the first . And now the boards are made I will have to keep theseideas for any future plans     all the best. Kevin

[user=1801]Passed Driver[/user] wrote:

Hi Bill.    I'm all for not spending money on replacements  but it was the overall baseboard weight that I was worriedn about, and how I should have.built the baseboard at the first . And now the boards are made I will have to keep theseideas for any future plans     all the best. Kevin

Excellent!

:)

Hi Kevin,

Building a narrow "scenic" only module is no different to a full sized one. However you don't need the wood dimensions of the big ones. I have built modules in 6" and 12" widths using 3mm ply for the top and 6mm ply for the frame. Exactly the same principles apply (ends, sides, cross-bracing, top). If you can find some seasoned planks that works as well (alone or with a frame). The alternative is regular shelving (Ikea et al.) with a bracing longitudinal spline underneath. Gene built a small module in Balsa some years ago.

My experience with HD closed cell foam (blue, pink and green) is that a) it swells and shrinks with temperature changes and with time; b) it sags if it's 2" or less thick and greater than 2'-long and unsupported; c) it still needs a frame (ends, sides and bottom cross-bracing on 12" or 16" centers); d) it out-gasses styrene monomer for a year or so; e) calking adhesive specific for HD foam is the only way to attach it to the frame; f) water-based adhesives such as PVA don't stick unless the surface is roughed with sand paper; g) if you sand it everything is covered in a blue/pink/green dust; h) it can cause contact dermatitis (which happened to me). If you suffer from allergies best keep away from it. Professionals use masks and gloves when installing this material. We should probably do the same when working with it.

From all of the above you may detect a certain bias against using it as baseboard material. You'd be right. I still think it's excellent for hills/valleys etc., just use a hobby hot-wire not the bread knife or box-saw.

The only way to cut it accurately is with a hot-wire cutter (rather like a bench saw but using a hot-wire instead of the circular blade, that's how it's done at the factory). Cutting it with a long-bladed box-cutter ("Stanley" knife) almost always gives a less or more than 90° cut.

Just caught your comment about the yard cutting a sheet of 8 x 4 into 4 pieces. Presumably to give 2 x 4 module tops. The only way to get four 2 x 4 pieces from an 8 x 4 is to find a board  that's over-dimension by 1/4"-1/2". That allows for a squaring cut and  the blade kerf. Hopefully this is what happened. If not, read on.

8 x 4 pieces are rarely square and the dimensions are nominal, and can be out by up to 1/2". Always get them to square the board before starting the dimensional cuts. If they question this they don't know what they're doing, squaring is standard practice. If it's exactly 4 x 8 and now square you will not get four 2 x 4 pieces. At least 2 of the 4 pieces will be less than that because of the width of the saw-blade, which on a commercial circular saw can be 1/8" (the kerf). Which is fine if you got the frame ends and sides cut to these dimensions, if you got them cut to fit a 2 x 4 you're out of luck. That 1/8" difference will create problems and stick out like a sore thumb. That can be fixed however. If it wasn't squared it's a bigger problem, as the pieces may be trapezoid, not rectangular. If the 8 x 4 was over dimension to start with 2 of the pieces will also be over dimension and possibly trapezoid.

Plywood is usually cut vertically, and unless the piece is supported at both ends the last few cuts will be on a diagonal. Minimum width that can be cut accurately is around 12" unless you can persuade the operator to support and clamp the piece while it's being cut.

Nigel

Hi Q.   I was thinking? The foam in question is that anything like ceiling tiles? Or something completely different.     Kevin

Hi Nigel.  Thank you for your reply. Every modeller has their own preferences, and I am singing from the same "Hymn Sheet" as you are. On this forum( and others?) I have heard good and bad opinions of all baseboard materials.But I thought that a complete "approximate" 8' x 4' sheet cut in to four tops would give rigidity but of course I didn't take the weight into consideration . Unless of course one is an experienced carpenter, who isn't trying to knock out baseboards on the quick! all the best. Kevin

Instant base boards.


Wicks flush doors. At 6'x6" by 30" light, strong, will not warp and, for what you get, very cheap.


Allan

Hi Allan.  Thank you for your reply, but I'm not sure if a 30" wide door would work with OO gauge, and if it is an "Egg Box" door it could have other implications?  Kevin

IMHO, the various foams have their place as a sub roadbed but do need support.  A simple timber batten on edge would do.  It could be ply set on edge or some softwood.  Ply, on edge, has the advantage that it won't sag whilst softwood, after some time, will.

Having ply, or whatever, as the roadbed just where you need the track, is called an "open topped" baseboard Kevin.  It's usually "raised" above the main framework by a few inches - say 3" to 4", and is great "out in the country" where you only have a single or double track.  In urban layouts, a "closed top" board is far more practical because of track density.

Apart from the savings in timber, and therefore, weight, another big advantage of "open topped" boards is that one can easily model scenery both above and below track level - underbridges and embankments etc.

Hi Petermac.  Thank you for your reply . that's where I went wrong I tried 3" x 1" timber for both edging and cross members coupled with 12 mm ply. That was definitely overengineered  For my next "mistake " I chose 2"x 1" timber.Experience is a great thing? Now as I understand it, there are various grades/types of plywood and of course there is a lot of advice to be gleaned on the forum. This is a clear case of putting the cart before the horse. Kevin

Hi Kevin
I'm coming in a bit late to the discussion but was wondering why weight is an issue. Is this an exhibition layout?
Andrew

Hi Andrew.  Thank you for your reply, no I don't have any ideas about exhibitions. I live in a rented house and I didn't want to screw anything to the wall. And I have been thinking about moving, and I have been looking to purchase a house and I am still looking, all suitable properties that include a "Man Cave" are snapped up, before I get there.If I do manage to finalise a purchase I will be very busy.   all the best. Kevin

 EXTRUDED Foam is nothing like Ceiling tiles.

When you cut Expanded polystyrene (used for ceiling tiles) you get a blizzard of white bubbles. When you cut Celotex or EXTRUDED polystyrene you get a dust which is very fine.
EXTRUDED, you can cut with a very sharp knife, I use one of those break off disposibles, from a pound shop or a fine tooth tenon or hand saw or a hot wire.

I  always wear a face mask if sawing and since I would be gluing up shortly after I'll be wearing disposable rubber gloves, I can get glue anywhere.

I always use at least 2 inch thickness EXTRUDED polystyrene, it has to be framed round the sides with thin ply (4-5mm), saving some cost on plywood. Due to the landscape being glued / built on the the 2 inch thick Board, ultimately the thickness of my boards will be up to 100mm in places, but at the track be level normally 50mm. If you wish to glue on a thin ply trackbed than that too will reinforce the boards.
Yes you do need  the thick glue supplied in tubes, like this http://www.screwfix.com/p/no-nonsense-11665502-grab-adhesive-solvent-free-white-310ml/87451 it has to be solvent free or you'll melt any type of polystyrene.

If you buy Celotex  it comes in 2400mm X 1200MM or 1200mm X 450mm sizes, so they are a little short of 8ft by 4ft or 4ft by 18 inches so you do have to adjust your chosen sizes slightly.
 
I have not had any problems so far with sagging with the 1200mm X 450mm X 50mm boards unsupported underneath, but have glued on 4mm ply sides, and a small piece of wood inset in the corners to allow screwing of sides to front and back. That's to allow the long length ply to take the strain of connecting boards, not the glued ends on their own. 

There have been reports of  shrinking EXTRUDED polystyrene, however there are also reports of it being used for many years without problems. "Pempoul" is I believe an example of this, https://www.youtube.com/watch?v=UEuTB6Iuje8

 Out gassing I've not had a problem with. but I do have a very large shed and it's taking a considerable time to build boards due to a lack of time.

Hi Q.  My mention of ceiling tiles was due to the use of the word  "Foam" just to get things clear to me and anyone who was new to Foam. Personally if I was to buy any Foam until I am confident in its use? It would be for scenery only. I don't want to sound naegative, but I now have a better understanding with the use of plywood fo baseboards.all the best. Kevin