Baseboard construction to support elevated track and scenery

[RichD1]

I want to build a OO roundy-round track layout with a double track mainline and a single track branchline. 

 

The mainline loop will be on the base level of the top but the branchline will gradually rise to an elevated terminus. The main line will go through a tunnel as it passes under the elevated branchline.

 

There will be a fixed L section along one wall and around into the alcove. From each end there will be removal sections to take the tracks back around with an operating well in the centre. These sections will carry most of the incline and the tunnel for the mainline plus the scenery. The boards are not for transport but just to allow the room to be used by our son when he comes, but probably only 4 or 5 times a year. 

 

I think the fixed sections will probably follow the usual 9mm or 12mm frames and 6mm top. But I'm unsure about the removal sections.

 

Trying to reduce weight to ease removal, I had thought that a 2 x 4mm ply sandwich with softwood spacers topped by 6mm would be OK, but now I'm not sure whether this would support the planned inclines and tunnel. The sections also need to provide stable aligned joints between each section where these higher level tracks and scenic sections pass over. This is my biggest concern. The use of the 4mm ply worries me too as recently I've found that it's not very flat. Would the softwood spacers hold it flat and square?

 

What do you think my best solution will be?

 

Richard

 

BTW; I can cope with most carpentry needs as I have a workshop full of machines and tools.    

[Harlequin]

Yep, so just to be clear, some of the joints must connect sections of the branch line while it is still on a gradient.

 

This is more difficult to engineer reliably than level joints but should be do-able if you make very stable structures with tight and accurate fixings between them.

 

You might consider open-frame all-ply or nearly-all-ply construction for these units. That method is lightweight, strong, and allows easy variations in height of trackbed.

 

The basic principle behind all-ply construction is to use ply pieces joined perpendicularly, usually glued, so that each one straightens and braces the other. You basically form L beams, I beams, T beams, H beams or in extremis box girders from the ply. This works well if you can cut clean dead straight pieces, and it sounds like you can. The straight edges naturally take out any warping in the pieces fixed to them.

 

The open frame means that you can a lattice of cross pieces, where you can fix flats for level track bed but also from which you can fix risers up to your inclined track bed. Imagine that your track bed has ply risers from the lattice below controlling the level or the gradient Then fix reinforcing pieces under the trackbed perpendicular to the risers so that if you look at the trackbed in section you see a T beam. That should be hugely strong, guaranteed not to droop, very stiff and yet relatively lightweight.

 

The choice of ply thickness is a trade off between weight, number of parts you have to make and the frequency at which you need to support your track bed. 4mm track bed would need a lot of support, whereas 12mm would need much less but would be heavier and more expensive.

6mm or 9mm is probably about the sweet spot.

 

Use alignment dowels at the baseboard joints to get precise, repeatable alignment. That's one place where you may need the extra thickness provided by some PSE timber to stiffen up the structure and provide depth for fixing the dowels.

 

 

Edited February 24, 2021 by Harlequin

[RichD1]

Thanks Harlequin for your response. Would a lattice be the best approach or just straightforward crossbeams. Most modules would be about 1 to 1.2 metres long so would have about 3 crossbeams plus the 2 ends. How would you construct a lattice?

 

I was also thinking that the ends of the module would be substantial thicker to provide the stability and alignment for the dowels and scenery above. Was thinking about 18mm but this is maybe an overkill.

 

So considering a module with a raised section I would make a piece that fits the top of the whole frame then mark where the incline track would be and then saw this out and put on top of the risers to form the trackbed?

 

I was thinking of using the Woodland Scenics incline set so the boards in this area would be flat and then when it gets to the top of the incline would then go with the ply risers round to the Terminus at the top. Alternatively I could use Woodlands riser sets all the way round. I am hoping to have at least 2 bridges/viaducts in it on its way round to the top so the Woodland foam risers might not suit.

 

I'll try and sketch out a track plan so you can see what I'm trying to achieve.

 

Richard

[RichD1]

I’ve attached a sketch of the latest design. The area is approx. 3.2m x 3.1m. The boards at the top and top left are fixed. The board at the top right is removable as are all the boards back round to the alcove/chimney breast. Hopefully you can make out the planned joins.

[Harlequin]

4 hours ago, RichD1 said:

Thanks Harlequin for your response. Would a lattice be the best approach or just straightforward crossbeams. Most modules would be about 1 to 1.2 metres long so would have about 3 crossbeams plus the 2 ends. How would you construct a lattice?

 

I was also thinking that the ends of the module would be substantial thicker to provide the stability and alignment for the dowels and scenery above. Was thinking about 18mm but this is maybe an overkill.

 

So considering a module with a raised section I would make a piece that fits the top of the whole frame then mark where the incline track would be and then saw this out and put on top of the risers to form the trackbed?

Yes, more or less.

 

4 hours ago, RichD1 said:

 

I was thinking of using the Woodland Scenics incline set so the boards in this area would be flat and then when it gets to the top of the incline would then go with the ply risers round to the Terminus at the top. Alternatively I could use Woodlands riser sets all the way round. I am hoping to have at least 2 bridges/viaducts in it on its way round to the top so the Woodland foam risers might not suit.

 

I'll try and sketch out a track plan so you can see what I'm trying to achieve.

 

Richard

 

"Lattice" / "crossbeams" - pretty much the same things. I only call it a "lattice" because it's all ply and an integral part of the baseboard unit.

 

You could use the woodland scenic risers but in my mind they wouldn't quite fit with a modular open frame baseboard system because:

• One of the advantages of the open frame is that you don't need to cover the baseboards with a ply surface and the woodland risers would need a surface under them as well as a surface on top. (You need the surface on top at least at the joints to hold the track securely.)
• Since you have baseboard joints with solid risers quite regularly spaced, change to the woodland risers in between seems overcomplicated - may as well just use the same type of risers everywhere.

In your plan, I notice you have a river flowing under the main line, which is great. The main line around the point would be on risers above that particular baseboard frame and if only that baseboard is lower then the rest the joints might be more tricky. So to allow for that you might think about effectively lowering all the baseboard frames so they join together easily all round and have the entire main line (and the station area) on risers all the way round. That's not as mad as it sounds - it allows you to drop the scenery away from the track wherever you want, getting away from the billiard table effect.

[Happy Hippo]

Have you thought of using closed cell foam as a structural materiel?

 

  You just use ply to protect the edges.

[Harlequin]

2 minutes ago, Happy Hippo said:

Have you thought of using closed cell foam as a structural materiel?

 

  You just use ply to protect the edges.

Would that allow the joints between boards to be accurate and rigid enough to align tracks that are curving, angled in XY and on a gradient (i.e. angled in Z) where they cross the join?

 

[Happy Hippo]

2 hours ago, Harlequin said:

Would that allow the joints between boards to be accurate and rigid enough to align tracks that are curving, angled in XY and on a gradient (i.e. angled in Z) where they cross the join?

 

If you are doing this in timber, you'd  still require a modicum of good workmanship. Since one is still using 9-12 mm ply as end boards the same as normal construction, so I'd suggest that the foam would be equally as good as an all timber edifice, but being a lot lighter.  All the foam does is get rid of the heavier conventional baseboard tops. 

[RichD1]

The board with the river on I was planning on making that one about 50mm deeper than the rest. The tops would then be all at the same level and I would have a 50mm dropped area just where the bridges are shown to make a river and embankments.

 

Just trying to work out a materials list and have found a great optimiser website.  https://cutlistoptimizer.com

 

Also checked out birch ply pricing and its quite expensive now! 4mm @ £44, 6mm@ £47, 9mm @ £54 and 12mm @ £61 per sheet. So just for the tops in 6mm the Optimiser tells me I need 4 sheets and for the 4mm frame work I need 2 sheets. That makes a total of £276 just for the ply. I'm not sure if birch is worth the extra as when I went to look at it on the racks the sheets were still not that flat/straight but I guess better than Far East stuff.

 

Do you think I would have a problem using cheaper ply if say I use 18mm ply ends and the sandwich construction of 4mm ply spaced with softwood blocks for sides and crossbeams. Would everything hold square bearing in mind I do have a large mitre saw to cut ends very square.

 

Richard 

[Happy Hippo]

If you want to use good ply then you need to go to a reputable timber merchant and ask for Baltic birch ply.

 

However, it is expensive.

 

The stuff on the racks in the DiY sheds is just a form of compressed firewood.

 

 

 

  You just use ply to protect the edges.

[Harlequin]

1 hour ago, RichD1 said:

The board with the river on I was planning on making that one about 50mm deeper than the rest. The tops would then be all at the same level and I would have a 50mm dropped area just where the bridges are shown to make a river and embankments.

 

Just trying to work out a materials list and have found a great optimiser website.  https://cutlistoptimizer.com

 

Also checked out birch ply pricing and its quite expensive now! 4mm @ £44, 6mm@ £47, 9mm @ £54 and 12mm @ £61 per sheet. So just for the tops in 6mm the Optimiser tells me I need 4 sheets and for the 4mm frame work I need 2 sheets. That makes a total of £276 just for the ply. I'm not sure if birch is worth the extra as when I went to look at it on the racks the sheets were still not that flat/straight but I guess better than Far East stuff.

 

Do you think I would have a problem using cheaper ply if say I use 18mm ply ends and the sandwich construction of 4mm ply spaced with softwood blocks for sides and crossbeams. Would everything hold square bearing in mind I do have a large mitre saw to cut ends very square.

 

Richard 

I've used Builder's Merchants "hardwood" ply a lot and it's been fine for me. E.g. Travis Perkins, Jewsons, etc. Your mileage may vary.

 

(Check the sustainability of whatever material you use, though... That becomes ever more important!)

 

Here's a blog entry from when I was making open frame boards a while ago: https://www.rmweb.co.uk/community/index.php?/blogs/entry/20645-test-track-baseboard-construction-pt2/

 

 

 

[RichD1]

Thanks Harlequin for the link. I can now understanding fully what you've been saying. Did you use birch? Looks like you've used 12mm. When you put the tops on, any idea on the weight?

 

Looking at your workshop tools looks very similar to mine, mitre saw, router table, drill press, planer/thicknesser, bandsaw and table saw.

 

Richard