I'm going down the open top baseboard route, I've got 2 sections of curved trackbed I'm wanting to fit to the frames, the trackbed is 9mm ply. In the main scenic area the trackbed is on a proper frame that's in turn fixed to the main frames. The curved sections are what's bothering me, am I supposed to mount them on a proper frame before fixing them to the main frames, or are uprights screwed to the main frames acceptable? Does the trackbed need support or bracing between the uprights to prevent warping or sagging or will the uprights alone suffice?

Chris

Hi Chris,

I reckon it depends on the length of any unsupported sections. On 'Bletchford' I am using 9mm sundeala as the trackbed and this board is perfectly OK (the board is 3ft in length)
As you can see, the sundeala is supported at each end and roughly in the centre.......

http://www.ngaugeforum.co.uk/SMFN/index.php?topic=22084.msg232405#msg232405

Hope this helps in some way

It might be ok then, the unsupported length is about 12 inches, I might add a spine of 2x1 though, just to make sure. 

I used the "L girder" system championed by the legendary Linn Westcott in the USA. What you describe doesn't sound too different and should be fine. All the curved trackbed on my layout is 9mm ply glued and screwed to pine supports , and it's been fine for almost 30 years.

I wouldn't be using 9mm for the top, too heavy !   

But, whatever the thickness of the top, if you took a strip of 4mm ply, about 50 to 75mm wide, and glued it at right angles under the curved top piece, to form an extruded T-section, then the top won't sag along its length.    Depending on your workshop, choice of glue, etc, you might need the odd corner cube of 1cm wood here and there to assist with fixing. 


- Nigel

As a mod, I certainly don't want to start anything here,  but for some reason many years ago I swapped to 4mm ply on some very inaccessible storage yards.

The bending & warping that has occurred there is one of my major headaches.

I can only suggest that 9mm ply is not over-engineering. 

Quote from: Bealman on December 14, 2014, 09:25:20 AM
As a mod, I certainly don't want to start anything here,  but for some reason many years ago I swapped to 4mm ply on some very inaccessible storage yards.

The bending & warping that has occurred there is one of my major headaches.

I can only suggest that 9mm ply is not over-engineering. 

And did you make the 4mm ply into a T-section, as I advocated ?   I really don't think you'll bend a piece of T-section which is 50mm along each edge !

If you use any timber, including ply, in an unsupported manner it will sag. 

Point taken, but it depends on location as to if it  is possible to use the construction method suggested. I still believe that if somewhere is hard to get to, or maybe going to be moved, better to be on the safe side.

But as already observed, it does become heavy.

Quote from: Wingman mothergoose on December 13, 2014, 05:07:12 PM
I'm going down the open top baseboard route, I've got 2 sections of curved trackbed I'm wanting to fit to the frames, the trackbed is 9mm ply. In the main scenic area the trackbed is on a proper frame that's in turn fixed to the main frames. The curved sections are what's bothering me, am I supposed to mount them on a proper frame before fixing them to the main frames, or are uprights screwed to the main frames acceptable? Does the trackbed need support or bracing between the uprights to prevent warping or sagging or will the uprights alone suffice?

Chris

Not sure what exactly you mean.  Like this perhaps:
[smg id=19485 type=preview align=center caption="Barebones oNe trk corner"]
I use 12mm external grade ply for roadbed on open frame baseboards (frame depth is 75mm, made from same ply as the roadbed).  The roadbed sits up to 100mm above the frame top on risers screwed to frame cross pieces spaced at approximately 300mm centres.  Quite light.

CFJ

Quote from: Nigel Cliffe on December 14, 2014, 08:44:06 AM
I wouldn't be using 9mm for the top, too heavy !   

But, whatever the thickness of the top, if you took a strip of 4mm ply, about 50 to 75mm wide, and glued it at right angles under the curved top piece, to form an extruded T-section, then the top won't sag along its length.    Depending on your workshop, choice of glue, etc, you might need the odd corner cube of 1cm wood here and there to assist with fixing. 

I'm using 9mm ply as that's what I've got, I'm recycling my old baseboard tops to save money.
Doesn't look like I actually need to brace it, going on what people have said, but I think I probably will anyway. Wanted to see what other folk had done with theirs.
Thanks for the comments.

Chris

Quote from: Wingman mothergoose on December 14, 2014, 01:41:00 PM

I'm using 9mm ply as that's what I've got, I'm recycling my old baseboard tops to save money.

Exactly what I was doing, Chris. I seem to have a plethora of sundeala offcuts from previous layouts as I'm one of those 'it will come in handy someday' types