US Wooden Trestle Bridge for New On30 Layout

[bertiedog]

As I can now use my hands and arms much better, after a long illness, I am assessing a whole railway room for the layouts, 009 and 00, but I also need a small layout for On30, mainly Bachmann Spectrum items and a couple of scratchbuilt boxcars.

 

Rather than building a full layout, an end to end run over a trestle is the plan, with an entirely scratchbuilt trestle bridge about 4 foot long and 2 foot depth. Each end can have a small halt and building, and one end could be readied for a further extension. Basically a shelf layout fitted to the wall for support.

 

I had built an H0 trestle a few years ago, about the same size, but it is too delicate in size to convert to O scale, with the decking and top of each trestle too narrow. The bents and cross members are therefore to small as well, so a complete new bridge will be needed.

 

Looks like a long session on the band saw to cut out the new timber parts. I have some old drawers that are suitable to cut up, not sure what timber it is, but not pine. The wood is old and dry, and should not warp, and will take stain to get overall matching of any other offcuts etc

 

I will make a quick jig to hold the parts as they are assembled into each trestle unit, complete with the cross bracing. They can be made the same size for the middle trestles, sawn to contour of the surface or inserted into the surface, with progressively smaller trestles as they reach each end.

 

The H0 bridge featured a steel girder centre span, but this one will be all wood construction, on a slight curve of about 10 foot radius to the track. I will add a waterfall behind it and the stream under the bridge. plus pine trees etc at each end of the board.

 

The width will be about a foot overall. I have to work out how many trestles are needed to suit O scale, also scale lumber sizes to suit. The construction will be with superglue and PVA combined in each joint, very quick and very strong. To strengthen overlapping joints, I will use brass lace pins in pre drilled holes, and also use these for bolt head patterns on visible outside surfaces.

 

The assembly will be be done upside down, the only way to really ensure a flat top for the track, although with a wood trestle the track can be pretty out of true in real life.

 

The track top will be lumber as well, with beams from each trestle to the next, topped with a decking of cross beams to tack the track, which can be slightly off set to allow a walkway over the bridge, complete with safety zones. Also a hut for Staff of the station to work at the bridge.

 

The buildings are already done from an older layout, so not much to do there.

 

The track will be code 100 with sleepers spaced to On30, and I have just bought 4 points from Ebay to suit requirements in code 100 kits from BK enterprises, these are just the preformed rails and blades, no sleepering, so can be done as On30 points. All that's needed to complete are some spikes to suit O scale, have to see what's available in the UK, or use more brass lace pins with the head filed away. Trouble with the pins is that they need pre-drilling, not needed with steel spikes.

 

The plain track could be the Peco On30. but I feel the sleepers are a bit short in length really for the scale, but it is a small point, and there is not much track to lay either way.

 

Any body know a UK supplier?

 

Stephen

[Mike Bellamy]

 

 

All that's needed to complete are some spikes to suit O scale, have to see what's available in the UK, or use more brass lace pins with the head filed away. Trouble with the pins is that they need pre-drilling, not needed with steel spikes.

 

Any body know a UK supplier?

 

 

 

 

Spikes by MicroEngineering are available from Paul Martin at EDM Models. Shown here

 

http://www.ngtrains.com/Pages/Track2/track2.html#ME-Spikes

 

Available in 3 lengths

 

If you are a member of the Narrow Gauge Railway Modelling Online Forum there was a recent discussion there. Sorry viewing is only to registered members

http://ngrm-online.com/forums/index.php?/topic/17826-rail-spikes-for-7mm-scale/?hl=spikes

 

.

[PaulRhB]

See Paul Martins page for everything track from pins to rtr track. This page covers all gauges

http://www.ngtrains.com/Pages/Track2/track2.html

 

Ah his trusty part time sidekick beat me to it, highly recommended and RicketRescue on here.

[bertiedog]

Outline of the basic size to fit the space available, works out to 4inch by 4inch, (15 x15 feet), which produces the dimensions overall of 3ft 6 inch by16 inch deep... best not to get too carried away on size, it could be expanded a bit in depth, with the trestles mounted on rubble stone basses in the water.

 

 

Nominal scale is 1:48 scale to work out lumber sizes, 304.8 mm in one foot, therefore 6.35 mm to the foot or about 1/4in stock equals a foot. Lumber up to 20 inch was common, about .4 inch, so all model lumber will be under 1/2 inch.

The sizes above are for US O gauge scale, not UK 7mm to the foot scale.

 

About 150 feet of wood stock of the various sizes will be needed to be sawn on the bandsaw to make the parts, and also sanded, but I now have a decent large bench sander to do the work on.

 

The top deck will be approx 4 inches wide overall, with the track spiked to the top via sleepers, open construction, no ballast.

 

I will have to see if the modern spikes will fit a very old Lindsay push spiker, which was said to take O scale and HO sizes, but of course the sizes may have been different in the 1940's, I suspect bigger than current sizes. It is not much worry as the total track length is so small at about 12 feet.

 

It is being fitted to above an old desk, with storage shelves each side, to be covered with a curtain to keep the dust off as much as possible. it will have another shelf above it which can have LED lighting strips placed on the underside to light the whole thing.

 

The back board and the sides, will be 5mm MDF, with thicker floor grade sealed 12mm chipboard for the base shelf. No complex joints, just butt and pocket screws with glue. The back board will provide the strength to keep the open front from sagging or flexing. Usual plaster and paint scenery, with some home made pine or redwood trees at each end, trying not to look like Christmas trees. I can operate it as an auto shuttle with two points at each end, giving an auto sequence for two locos.

 

Two of the Bachmann locos are DCC sound fitted so I may use that as well as a DC controller to cover any other models, as it can function as an 00 test track as well.

 

Stephen

 

Stephen

 

[bertiedog]

The Dimensions work out, but the 4 inch spacing is a bit wide, about 15foot, which is not far short of the max of about 16foot between uprights.

 

I may reduce the distance and include another bent in the design, leaving the overall length the same.

Most of the wood is about 6mm square, bracing 6x2.5mm, cross beams 6x6mm and the stringer beams under the track about 5x3. The track bed beams would be about 4.5x4.5.

 

The ex-drawer wood is a form of mahogany as far as I can tell, plus some oak panels. It needs tight grained wood really, making pine unsuitable.

 

There is some birch, but the grain is the same as pine in the stuff I have to hand. There are some deal floorboards, and they have a tighter grain than modern pine, and may be usable.

 

The band saw cuts tight grain better than open, which causes the blade to follow the grain. I could use a table saw,but it wastes more in each cut than the thin bandsaw.

 

All the wood will need staining before construction, as glue shows badly as it cannot take stain, and then needs painting out the marks.

 

The PVA glue I use is outdoor grade, more waterproof, and the superglue is the normal thin type from Poundland. Each joint is painted with PVA on one side, and superglue on the other, then pressed together. The PVA sets the superglue, and then dries very quickly to reasonable strength, full strength a few hours later. The PVA acts as a filler in the joint, and potentially such joints are as strong as the wood itself.

 

I suspect it will be best to get a brand new fine tooth blade for the bandsaw to minimise off course cutting etc., tearout is not a problem as each strip is put through the belt sander on all sides. With older wood there is a risk of nails hidden near the edges, they must be removed as although the blade cuts them, it dulls the edge and alters the set of the teeth to cut steel. The blade is then slow to cut and wanders around on the cut.

 

But the first thing is the frame base and backing board to cut out and fit in place, then start the trestles in a few days time.

 

Stephen