Model Railroading > Helix Cutting Template?

Before I go free form I thought I should ask those who have gone down this road already.

When building a helix from overlapping 1/4 inch plywood it would seem to make sense to have a template to make all the sections identical.

It would also be sensical to have a plan to get the most from a 4x8 sheet of plywood, of course dependent on the radius and scale (HO in my case).

Any plans that I can borrow or examples to learn from? Any pitfalls to avoid? Any general suggestions? Thanks, Happy Holidays everybody.

Earlier this year on this site, there were several posts regarding your inquiry. It just so happens that I am considering a helix for my next layout so I saved those posts. I dont know if this site saves information back a year but if so, here are the dates the information appeared. The first posting took place on 02-05-02 and was titled "Building a Helix". The second post occured on 04-28-02 and was titled "Helix-Staging-Layout Update. I hope you can locate these posts as they contained a wealth of information that I think you will appreciate.

Jim

I found this helix calculator some time ago - doesn\'t help in building the helix, but I find it useful in the calculations

Hope this helps.

Doug

http://www.fortunecity.com/westwood/beautiful/819/HeliCal.htm

Seems like it would be simple to make a template your self. Use the old yardstick, pencil, nail combination & carefully draw a !/4 circle arc then put it on relatively thick cardboard or 1/4" plywood. With that template Just draw your helixes on 4x8 plywood. Draw the arcs nestled into each other like ((((((( & that should take up most of the plywood.

When I built mine I made a cardboard template that I could layout on a 4x8 sheet of plywood and draw around to get the most efficient use of the wood. My template was 1/8th a circle. I allowed 2-1/2" clearance on both sides of the track. Therfore for single track the width of this template was 5" and for double track it was 7.5"
(HO scale).
Therefore 8 of pieces of plywood make a circle but you\'ll need 16 per level because of overlaping. You can cut fewer like 4 pieces per circle but the more pieces per circle the more efficient the use of your plywood. However, in the same breath, the more pieces you cut out, the more cutting you\'ll do. (In any event, if you do a large helix be prepared to get out the saber saw and saw until you get sick of it.)

On the same cardboard template I drew my track center lines using another template and poked holes through the center lines.

Therfore, I had a 1/8th circle cardboard template that I laid out on the plywood and drew around with a small magic marker and also marked the track center line by poking the marker through the holes along the center line. I repeated this process over and over on the 4x8 untill I couldn\'t fit anymore. I also used the same centerline template to draw the centerline on the plywood following the "dots".

This track centerline will not only be used to lay your roadbed (I used Woodland Scenics foam ripped down the middle) but also used to align the overlaping pieces of plywood. (My foam was glued down with Liquid Nails for Projects. It give you enough time to work with the roadbed and get it where you want it.

Incidentally, before I glued my overlapping 1/4" plyood pieces together, I sealed them on all sides with Thompsons water sealer. It did not affect glue adhesion. You will have to lay the pieces out to dry, preferably outside or in your garage. It\'s not the most potent smell but from experience it will permiate the house if dryed indoors and mix with your gas dryer to make your clothes smell funny. (Don\'t ask me how I know.)I would also say it might not be safe to do it this way. It\'s fine once it\'s dry. I can post some photos of my templates here later if you wish.

The past posts have been tremendous, I\'ve printed out much of the info but now it\'s time to go build something.
If Mr Wabash can post a template it would be great. I\'m trying to figure out where to put the holes for the rods. The last post was right on target, again. The first try will be cardboard or kraft paper, much cheaper that way. I\'ll have plenty of space in the room, at least until this thing gets built. Wish me luck.

tcnr:

There are many ways to skin a cat but I\'ll provide info on how I did it. My helixes are very solid and smooth and derailment free. I lay my track after the helix is constructed! I\'ll post some more photos in addition to the template this evening.

As far as where to put the rods:
I just used my cordless drill and about a 5" drill bit the diameter of the rod holes. With my 2-1/2" allowance from the centerline of the track to the outside, I just drilled my holes far enough out as to not be too close to the outside.
You might want to mark this with a template too.

Some won\'t believe this, but I glued my 4-1/2 helix together as one piece before I drilled the holes for the rods or laid the track or roadbed. I temporarily laid pieces of 2x4\'s sandwiched btw the levels. You have the get the the bottom level in place on top of your frame work first and leveled with your risers screwed in the bottom of the subroadbed and held to your benchwork with C clamps. The 2x4\'s turned out to be exactly what I needed for the distance btw levels. (not all 2x4\'s are crated equal however.)

I drilled my holes by lifting the corresponding level high enough to get my drill in. If your glue is dry, the plywood assembly is very flexible with no harm. I used rods long enough to thread all the way through the assembly and made sure that I put my nuts and washers in as I went from bottom up. Pull the rod up to the next hole to be drilled and mark an drill. I know it sounds crazy but it worked fine for me. The rod was flexible enough in that if I had to bend it a little it didn\'t inhibit the nut or washers. YOu\'ll tighter the nut later to line everything up and remove your spacers.

Kalmbach\'s "Model Railroad Planning 1997" had an article titled "A primer on helix design" that had useful tips and told of things to avoid (it generally was not a construction article, though).

tcnr and anyone else interested: I will post photos of the templated etc tomorrow. I loaned out one of the templates to a friend and will photograph it tomorrow.

Thanks to everybody and Happy Holidays.

Here is the photo I promised. The top template is for double track (HO). The inside radius is 30" and the outside 32-1/2". The width of the template is 7-1/2" on the ends allowing 2-1/2" track centerline and 2-1/2 in each side. This more than enough for the threaded rods because you need less side clearance (no trains on the sides.)

Notice the punched holes along the track centerlines. As I mentioned before, these are used to mark the centerlines after you have traced out the piece. Then, using the template in the lower half of the photo, the track centerlines are drawn by "following the dots". These lines not only help in centering your roadbed but are used to line up the overlapping pieces. I hope this helps. Notice that one end of this template is tore off. I had a situation where I needed a shim the thickness of the template and it was the only thing handy. Ooopps.

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Victor,

Sounds like an excellant topic for one of the future NMRA clinic. As always your work is great.

Mark Gaeth
Decatur, IN

Mark:

Yes, I\'m supposed to help Carl build one, and I thought I\'d photograph the steps as we go along. He wants a staging yard along the front of his layout and this one will be a two-turn helix.

But I think my next clinic will be train scheduling. Though my layout is not complete yet, I have the sidings and stations mapped out on the track plan and just made a schematic. With that done, I am graphing things out "fast time", 15:1, ala Bruce Chubb\'s "Operating Your Model Railroad". Thanks for the compliments.