Yet another trestle question: creating trackbed for a curved trestle

[PuttChoo]

An excellant source on trestle construction is:  www.rhyman.org

click on:  articles,  then on: building RGS bridle 45-B (a curved trestle)

               w/44 pages of text, "how-to", drawings and jigs.

see also:  trestles-RGS style

               w/text, "how-to", drawings and photos

see also:  bridge 44-B at Red Rock creek

               w/text, "how-to", drawings, photos and jigs

note:  this is a garden r.r. site @ 1.20.3 but the info is general and very well done.

[RR_Mel]

NP01

Alright, some progress made. I was able to make a 1/4 circle 30" radius piece of plywood. 2" wide. 

Then I formed two pieces 6x6, (24" long) pinewood along this curve using various pieces of wood glued to form a template. 

I then attached cross members and other stuff to make it stay. It's great so far!

 

Post some pictures as you progress. I for one would like to see how your project is coming along.

 

 

Mel

 

 

Modeling the SP in HO scale since 1951

 

My Model Railroad   

http://melvineperry.blogspot.com/

 

Bakersfield, California

[NP01]

Alright, some progress made. I was able to make a 1/4 circle 30" radius piece of plywood. 2" wide. 

Then I formed two pieces 6x6, (24" long) pinewood along this curve using various pieces of wood glued to form a template. 

I then attached cross members and other stuff to make it stay. It's great so far!

[carl425]

NP2626

Take a stick drill a hole...

I did this with a cheap aluminum yardstick.  I also use the holes to tack it down next to a piece of track I want perfectly straight.  Shove one rail against the edge as you secure it to the roadbed.  You can also use it to measure stuff and draw straight lines.  I love multi-taskers!

There are several choices on Amazon for under $10.

[NP2626]

NP01

One final question (I hope): what is the most effective way to draw a 30" radius arc that is 48" long?

You can use a string with a pencil tied to one end.  Tie the knot close to the lead in the pencil.  More accurate would be homemade trammel points.  Take a stick drill a hole that will fit a pencil or pen tightly and use a sharpened nail as the pivot on the other end the two holes should be 30 inches apart.  

Are you talking about the curve itself being 48 inches along it's curve; or, the cord (a straight line between two points) being 48 inches apart?

[NP01]

Thanks Rob and NP, I think I am ready. When I get a chance I will get some pinewood 6x6's and start. I also realized that I could do a cross-member that was 12" wide at each join. That will even out the spacing between stringers as well. 

One final question (I hope): what is the most effective way to draw a 30" radius arc that is 48" long?

[NP2626]

Rob has shown one way this cat was skinned.  There were other methods that were used.  The book is a great asset and shows the many different variations used: https://kalmbachhobbystore.com/products/books/12452

I would not have started my bridge/Trestle building projects without it, I think that highly of it.  

[wp8thsub]

NP01

I am still struggling with one thing: after I have my track curve drawn on a piece of plywood or paper, I lay down the stringers. Ok, when I start gluing them, how do I connect the ends to each other. I would need to cut the stringer ends at an angle, right? do I just do this by eyeballing it?

This is relatively simple if you can picture it the right way...

Imagine the roadbed arc being part of a full circle, like a wagon wheel, with evenly spaced spokes.  Each set of stringers connects one spoke to the next around the rim of the wheel.  The ones closer to the hub need to be shorter because the distance between spokes narrows.

Here's an illustration I found at http://www.railroad-line.com/discussion/topic.asp?TOPIC_ID=22854 , which also has some additional photos.  In the image, the lines marked "A" would be the spokes I referred to, while the groups of stringers are "B."  The precise angle of the joints between stringers can be figured using some trigonometry, or you can just make a diagram that's "close enough" and miter the pieces to fit.  Each joint rests atop the cap of a bent on the finished trestle.

[wickman]

The stringers  are actually  quite easy to make  although they can be  as difficult as  you want to allow them to be.  I found the best way was  with the mainline curve where the trestle will go get a  couple pieces of  construcion paper taped together to make  the length of the proposed  trestle curve and rough cut the  curve  out with the construction paper (  I taped  mine in place  firstfrom underneath ) now lay  the construction paper rough  template back on the rail and  start scribbling back and forth across  the rails to  get an imprint and now you  have your path for the stringers to  follow glued end to  end.  Once you glue the bridge rail  onto the stringers it will be  a much stronger unit  to  start building your  bents  off  of.

[selector]

They ends don't actually meet in all cases, but pass each other so that their ends lie on opposite sides of each cap.  Also, for curved trestles, the stringers are NOT parallel.  They lie at angles to each other so that they support the roadbed but along their whole length....IOW, none is shorter than the rest, nor does it need to be.  Instead, they are staggered along each other.

I will attempt to find a link to a diagramme (my reference that I used years ago has been taken down, so no link to it).  I may just draw a diagramme, scan it, and post it for you.  Give me some time.

Edit (added): I found this site still up from our late friend Wolfgang Dudeler. Partway down the page are three images with the right-most, if you click on it to englarge it, showing how to lay the stringers for a curved trestle deck.

http://www.westportterminal.de/trestle.html

[NP01]

I am still struggling with one thing: after I have my track curve drawn on a piece of plywood or paper, I lay down the stringers. Ok, when I start gluing them, how do I connect the ends to each other. I would need to cut the stringer ends at an angle, right?

do I just do this by eyeballing it?

[RogerThat]

I am a former rc modeler and I have a ton of balsa left over from that hobby. I scratch built a trestle from balsa and it is very sturdy. However it is also fairly small. Two resources I used was Lex Parker's YouTube channel and the Black Bear HO Scale Kits web site. You can see my construction photos using the link in my signature.

[NP2626]

I did not say don't use balsa, I only said: I wouldn't use balsa for the stringers.   Some balsa would work for the stringers as it is a very hard grade.  However, finding balsa in the many different grades it is available in, is a kin to finding rolling stock kits on the hobby shop floor, now-a-days!

[dehusman]

I would draw out the stringer pattern on a piece of paper.  Draw a couple arcs for the rails, then draw the bent locations.  Put the drawing on a piece of soft wood, ceiling tile, homasote, foam sheet, foamcore or in a pinch corrugated cardboard, then cover the drawing with waxed paper.  Put the stringers in place and hold them with straight pins.

Personally I would probably draw the trestle upside down, make the stringers, build each bent and attach it to the stringers.  As i added bents i would attach cross bracing and when I was done, I'd have the bridge built upside down on the work bench.  Turn it right side up, attach ties and track to the top and its ready to stain/paint and install.

[NP01]

Hi guys,

Thanks for the responses. Got it no Balsa! I have built two sheds from balsa already ... One was a guard shack with Grandt line window and door and one was an office/tower in an engine service facility.

I studied both Wickmans and NP2626's threads.

the question I still could not answer is for the segmented curved top of my trestle, how do I measure and cut the pinewood? Surely cutting at a known predefined angle would be better, but I don't know how one determine this angle. Or would you just place stringers on the drawing and shave off material to kind of make it work?

thanks again  

 

 

[RR_Mel]

I agree with the above on using Balsa, not good.  If you have access to Basswood strips that will work much better.  Basswood excepts stain much better then Balsa too.  Caution, use a glue that will except stain. 

Checkout my home page on my blog, the 36" long 12" high curved trestle with the 2-8-8-4 is 25 years old scratch built from HO scale Basswood from my local hobby shop.  I used an Oak stain also from my local hobby shop.

 

http://melvineperry.blogspot.com/

 

Midwest Products sells direct and has a good selection of scale lunmer.

 

 

 

Mel

[NP2626]

The parts of a trestle that are directly below the railroad ties are called "Stringers".  They run from bent to bent and are generally made up of 3-4 timbers under each rail that are laminated (bolted) together.  They follow the curve of the track.  On my trestle, because I didn't care about being able to see through the ties as my trestle is fairly close to eye level.  I made the stringers from a piece of mahogany trim I had that was 1/4^th inch thick.  I made it just slightly larger than the outside gauge of the rails.  So my stringers are actually one piece.  I will say it would be better to use some wood harder than balsa for this application.  However if you can find a high density/hard balsa the right size, you should be o.k.  I used 1/8^th diameter round dowels for my pilings as here in Minnesota, this is what I saw most of the trestles made from, and not square timbers.  I have seen some fairly tall trestles made from round pilings, so I would say it’s an arguable point if round pilings or square timbers where used.  This is a personal choice.  I did use balsa for the Caps, Sills, Girts, Diagonals and Sway braces as these parts didn’t need to be quite so strong.

 

Here is wonderful website on Trestles from a modelers perspective: 

 

http://www.rhyman.org/articles/trestles-rgs-style

 

I discuss how I built my trestle at this site: 

http://cs.trains.com/mrr/f/11/t/202778.aspx?page=1

 

["JaBear"]

NP01

do you think I am crazy?

More than likely,  welcome to the scratch builders world.(Sometimes you just have to push yourself to expand your boundaries!) 

Not a big fan of balsa wood myself for the same reasons as doctorwayne,

Anyhow here’s a couple of links to a reasonably recent threads concerning wickmans curved trestle....

http://cs.trains.com/mrr/f/11/p/241283/2690271.aspx?page=1

http://cs.trains.com/mrr/f/11/t/230924.aspx?page=1

 see page 2.

Have Fun

Cheers, the Bear. 

[doctorwayne]

NP01

I am looking for fabrication techniques to make this "arc" ... once I have a stable arc, I can attach trestle bents and stringers between them.

Technically speaking, it would be a segmented arc, as the members supporting the track on a real trestle would be straight pieces of lumber stretching between the supporting bents.  You could build it as an arc, of course, but you'd need to pre-form your material - perhaps by steaming the wood.  The model airplane builders were pretty good at that sort of stuff and they used balsa, too, although that wouldn't be my choice.

Whether you used a pre-formed arc, or a segmented one built-up of shorter lengths of material, lay it out and/or assemble it on a full-size drawing.  If you're using this method, lay your track on it next, whether commercially available flextrack or handlaid, since it will be easier and better-supported than after you've attached the bents.

To attach the pre-built bents, flip the arc upside down, and cement them in place at appropriate intervals - these should match whatever scenery elevations you've created or plan to create in the gap which your trestle will span.

If you have little scratchbuilding experience, though, I would suggest that you start with a less ambitious project. 
While balsa is strong and light, it doesn't make the best representation of scale wood, and many modellers would choose basswood or pine, both of which are commercially available in sizes to suit most scales.  Personally, were I building it, I'd use styrene - it can be made to look more like real wood than any model wood and allows fast assembly and good strength, too.

Why not start with a simple shed, building one from balsa, one from basswood or pine, and one from styrene?  There's lots of info here and on similar forums, both on construction and finishing, and it will give you a sense of which material you prefer, and of which yields the most favourable results.  Equally important, it will give you an idea of your current skill level - most of us start out knowing far less than we think, and accumulate skills and knowledge as we stumble along.

 

Wayne

[NP01]

I am planning on a curved trestle on the rebuild of my layout. After reading several topics on the forum and browsing available products, I think I am going to scratchbuild from balsa stock. With very little experience doing scratchbuilding, do you think I am crazy?

The design is 30" radius, about 48" long curve. How do I build the "trackbed"? Ideally it will be two parallel lines (29.5"R and 30.5"R) with some cross bars to hold them in shape. The bents will attach to the bottom side where cross bars are. On top will be Atlas. This will allow one to look down between the rails and see the ground below ... cool!

I am looking for frabrication techniques to make this "arc" ... once I have a stable arc, I can attach trestle bents and stringers between them.

Any input would be appreciated!

NP