Sir Lamiel’s 777 Quest - A Scale7 Micro Layout Challenge

[magmouse]

This discussion of baseboards is interesting for me at the moment as I am currently drawing up a design for laser-cut construction:




This is the fiddle yard board for my 777 project, 400mm x 1000mm. Changes from the standard G&H design are a denser supporting structure, which is also full depth (100mm). I'm hoping this will bring the necessary stiffness. My lightening/access holes are larger, so weight shouldn't go up too much.

I will be changing the ends to a full double layer (6 + 6 = 12mm thick) to accommodate the pattern-maker's dowels. Joining bolt holes and handhold holes still to be drawn...

After that the more complicated main board:



The sky background will have rounded corners made with a thin ply insert, bringing the footprint nicely within the 7 sq ft rule!

Nick.

 

[adrian]

There are many ways of making it torsionally stiff. Bracing the lower edges of the sides (all round) and then somehow stoping one side moving relative to the other is key

and for another variation, instead of cross bracing I’m trying curved spars. These are short boards to test principles and joints for a test track. 2 boards at 2’ by 1’ each and in total weigh about 2.5kgs just over 5lbs for the pair joined together.

 

[daifly]

There has been a bit of a discussion here about bracing of baseboards. Whilst I want my boards to resist twisting, this is not a force/motion to which they will often be exposed. There will be a fully adjustable leg at each corner so, in use, there should be no twist anyway.

Sagging between cross-members is surely a greater consideration and needs to be minimised to avoid heavy locomotives riding a series of ridges and furrows as they cross a baseboard.

Or am I missing something?

Dave

 

[Dog Star]

Or am I missing something?

No.

 

[RichardG]

My main concern is, twisting can encourage chairs to pop up off sleepers. More likely in 7 mm scale than 4 mm because the rail is that bit stiffer.

 

[adrian]

Sagging between cross-members is surely a greater consideration and needs to be minimised to avoid heavy locomotives riding a series of ridges and furrows as they cross a baseboard.

This is some of what I was trying to test with the curved spar.

 

[simond]

A traditional “open box” baseboard is more prone to twisting than to bending. You can make the shoebox deep, and it won’t bend, but it’ll still twist!

your four supports are fine, of course, but you’ll need to level both ends. I guess that’ll be necessary whether torsionally stiff or not, but it’ll not be as obvious on a flexible baseboard, until, something breaks, or falls off…

 

[RichardG]

Sagging between cross-members is surely a greater consideration and needs to be minimised to avoid heavy locomotives riding a series of ridges and furrows as they cross a baseboard.

If ridges and furrows develop, they are most likely because the baseboard top is absorbing or losing moisture in an imbalanced way. For example, if there is bare board underneath and layers of PVA and scenics on the top. I primed the tops of my G&H boards on both sides - I used MDF sealer or diluted PVA, whatever was to hand - and they have stayed flat. Truly, I don't think the weight of a 7mm train will have any affect, not even something like a big mainline diesel.