I have a JV models N scale tressle kit, which is just a drawing and the raw wood. Should I build an actual 11" long gently curved tressle? Or should I make a series of straight ones, with angles? If I go curved how do I make the curve? I intend to put Microengineering flex track on it, so I really dont want to do wood ties, if that matters.
Any help out there?
Real RR’s build their trestles as a series of short, straight sections, with angles on the ends. You should build yours the same way. Trying to curve the wood would not work out in the long run. You should also use so called “bridge track” (which I think Micro Engineering sells) for this, as it has the correctly sized and spaced “bridge ties”. You may want to install the “guard timbers” on the ends of the ties when you are done.
As per prototype practice, when you build the bridge, the rails should not extend out beyond the edge of the “stringers”, the timbers that support the ties and track. You should space them wide enough to keep the rails (more or less) centered on them, or at least in between them. On real trestles, these provide a lot of support, the ties really only serve to help keep the track in guage more than anything.
Brad
I’ve build a curved trestle. You can see my description with pictures at my site under curved trestle.
Wolfgang
The kit has no instructions? If not, or if the author(s) missed explaining how to do a curved trestle, the reply above that says the bents are placed in such a way that the stringers are parallel, but angled where they join on each bent might work for you. However, the prototype did a series of stringer angles on the deck such that the entire deck does actually curve…in a way. See the description in this site, about halfway down the page…at the title about curved decks. It is what I did, and it worked well once I figured out how to place it on a suitable surface and glue it all together.
http://members.cox.net/sn3nut/trestles%20part%202.htm
This is what it looks like from below.
Here is how I did mine:
1, I drew, full size, exactly what I wanted from a top view. This included the exact curve I wanted for the two curved stringers.
I cut some strip wood, 1/16 inch thick by 1/4inch high, about 10 of them so I would have extra. I am in HO so for N you may want smaller sized stringer, material.
I laid out the drawing on a soft wood board and pounded nails every inch at the exact out line of the inside curve of the outside stringer.
4, I glued up three stringers with lots of wood glue and bent them around the nails, leaving sever inches on each end.
I then put nails on the outside to hold everything in place and waited a day for it to dry.
I then repeated the proceedure foir the inside stringer.
I then marked to possission of each bent on the curved stringers
When done I had a perfect template to glue the bents to.
Here is the one picture I have of the two curved stringers, fasened to the template and having the stringers glued to them, Obviously the trestle is upside down for this process.
Trestles are really really really REALLY hard to do and should onlt be done by a professional!
That or some one who has too much time on there hands…
Or someone who ignores silly posts like this!
Though it looks hard don’t be fooled they are a lot of fun
Fergie
Quote from a civil engineering book I read sometime back in the age of the dinosaurs:
Curved bridges are actually a succession of short, straight bridges. Only the rails or roadway have an actual curve.
Prototype railroads build trestles with straight structural members. If the rails curve, the stringers sit on the bent caps at an angle to those in the next panel. If the curve is sharp enough, the bridge builders may widen the bents, lengthen the caps and install extra stringers to avoid having insufficient support under the rails halfway between bents. (The other alternative, placing bents closer together, is much more expensive.)
Chuck (modeling Central Japan in September, 1964 - with curved track on straight deck girders)
Its only a matter of time…LOOK OUT BELOW! And no gaurd rails to boot!
David B