I used the Helix calculator (borrowed) from our NMRA Division website to do my calculations (http://michiana-nmra.org/resources.html). After reading Jeff Johnston's MR article (and emailing him), I decided to build mine from 1/2 cabinet grade baltic birch plywood. I contacted a local wood working shop that had a CNC machine, and for $65 more than the material cost, they cut perfect 6" wide rings for me from 5'x5' pieces. It was well worth it! Now I'll just paint them with white sealer and start buiding the frame. I plan to secure my HO track with 5/8" PowerHead Screws, a super thin head screw with a drill end (http://www.fastcap.com/estore/pc/PowerHead-Screws-Metal-p13284.htm) in lieu of Jeff's recommended wood screws and washers.I hope my comments have some applicability to your project; have fun!
Thanks Everyone for the Information
here are a couple excel programs I made that should help you.
http://www.brickshelf.com/cgi-bin/gallery.cgi?f=565927
Steve
Dragoon 45I've never used a helix before, so was thinking for a first time builder using either KATO Unitrack or Atlas Snap Track for the helix.
Because of the extra height of the roadbed, Unitrack will require more elevation per turn for the same clearance. Flex track will entail fewer joints that can be slightly kinked, so may be smoother in the long run than any sectional track.
Good luck with your layout.
Byron
Layout Design GalleryLayout Design Special Interest Group
I built my own (mostly because of cost) using flex track and the construction wasn't all that difficult, but there are a lot of design issues to consider that the commercial builders can help with.
I can answer the part about a commercially made helix. While I've built all of my benchwork for my layout, I knew that a helix needs to be level and 99.999% perfect. I didn't want to mess around with rods, blocks, etc. I knew my capabilities with wood construction and the helix was not one of them. That being said, I had a custom helix made with a 2% grade, double track, and I had 2 tracks that went around the top of the helix so I could have constant running. I had it designed with a marking on it for the center of each track, so I knew where to lay the cork and track. Expensive? Yes. Worth the money? No question about it. I did have to tweak it a little as I built it. Good thing is that wood is very forgiving. When people see the trains run up and down the helix, they are amazed how great it runs, and when I tell them it's a kit, they really appreciate the what I put into it, meaning time and MONEY! Best thing I invested in for my layout next to DCC.
Neal
Thank you. I've never used a helix before, so was thinking for a first time builder using either KATO Unitrack or Atlas Snap Track for the helix. Both have 19" radius as the largest available. I know there are folks out there that commercially build helixes, but don't know if they are worth the cost.
Dragoon,
A 19" radius at a 2% grade would give you right around 2.5" of rise in your helix. I have an N scale double deck layout (was going to be three, but commen sense prevailed!). My single track helix has almost a 3% grade (because of space restrictions) and my trains have no problem with it. But, it isn't ideal. If I were you I would use as large a radius as you can (22"-23"?) Especially if your going to run long trains (25+ cars). With a 4'x4' space, you may want to consider a double track helix. Lots of guys on the forum can give you several reasons why that is a good idea. But if I were you, I would go with as large a radius as you have room for!
Good luck with your project!
Tim
In the planning stage for a small room size layout in N scale. Spare bedroom measures approximately 13 x15. My initial thoughts was to build a single level, around the walls on three sides. But the thought came to me about possibly using a helix and a second or third level. Something like a loop to loop, but with the main level built to allow continuous running.
That leads me to my question. Assuming a 4' x 4' square space, what would be the best radius for a single track helix? If I recall my geometry correctly, a 19" radius helix would be slightly less than a 2% grade. I assume the broadest radius possible is the best answer, but am not sure. So your thoughts. Thank You.