Using Xtrackcad, I layed these helix pieces out on a sheet of plywood, exported it as a .dxf, emailed it to the local custom engraving guy that has a CNC router and he cut me out 4 sheets worth.
He charged me $40/sheet - kinda steep but way better than spending 2 days with a jigsaw. Kinda cool too.
Carl,
I don’t need a helix, but that’s a great idea. Not dissing your jigsaw skills, but if they’re anything like mine, that’s going to be a much neater project for doing so. And precision matters with a helix, unlike many of my wood skills required projects, which just adds to the reasons why this is a smart way to come up with a helix.
carl425:
Those look great.
I have designed helix parts using 3rdPlanIt but doing the actual cutting is a daunting task which I was not really looking forward to.
If I can be a real niusance and ask a bunch of questions:
Did you supply the plywood or was it included in the $40.00 per sheet?
What plywood did you use?
What is the radius, slope and clearance?
How many sections did you get per sheet?
How are you planning on joining the sections together?
What will you use for risers and how will they be attached?
Sorry to interogate you. I’m planning on building two single track HO scale helices with 26" radii and 3.75" between levels. They will rise somewhere around 24" at 2.25% grade. I have studied a couple of articles in MR but I would really like to see how others are doing it.
Thanks
Dave
I supplied the plywood.
It’s 1/4" (really .2") birch. ($20/sheet)
The track radius is 24", but by skimping on the clearance and using thinner material I have the grade down to 2.09%. When you add in the effect of the curve of an additional 1.33% I end up with roughly the same effective grade as a 30" helix with 3/4" material.
Clearance above the rail is only 2.585" but the tallest equipment I’ll be running is 2.04".
I got 9 pieces per sheet. Each is just over 1/3 of a circle.
Two layers of the plywood will be laminated together with the joints staggered giving me a .4" thick sub-roadbed.
Risers will be blocks cut from 1X2’s. I’m think 8 on the inside and 10 on the outside. Screws from the top, glue top and bottom. The 4" width leaves me room to put the blocks on each edge and have 2.5" clearance between them.
Hey Carl425.
Thanks for the detailed answers!
Your numbers pretty much confirm what I had calculated with the exception of the clearance between levels. Based on your calculations I should be able to lower the grade to about 1.9% from 2.3% with about 2.5" clearance which is just enough for my cabeese.
I am planning on doing the same method of laminating the curves with the joints offset, and using the same system for risers.
I hope you plan on posting your progress with the helix, including any issues you encounter. I’ll look forward to watching it develop.
Thanks again for sharing your information.
All the best.
Dave
Helix of LION
ROAR
That’s a lion of a helix!
[swg]
Dave
If you want to see The Mother of All Helices, put “helix” and “Brunton” in the search box.
My own helix is based on trapezoidal sections, not curves. It’s also steel. Steel stud material, to be specific. Thanks to the JNR’s standard 4.7 meter catenary height, I, too, can get away with 2.5 inches between railhead and overhead. Vertical spacing is handled with threaded rods, nuts and washers, assisted by a couple of standard risers which also support the flat for the five-tiered pagoda which will eventually be erected in that corner.
Chuck (Modeling Central Japan in September, 1964)
I have no plans to build a helix, but I like this idea very much. Thanks for posting
What type of equipment will you be operating, and how long will be the trains? As posted before on this forum, some experienced modelers have found that HO helixes of this radius caused problems with stringlining with some combinations of equipment.
Others just found that the hidden steep grade of a 24" R helix was a problem for operations. Joe Fugate, in particular, tore out his 24" radius helix and replaced it with a 40" radius helix. (As described in Layout Design Journal #14, Spring 1996, published by the Layout Design SIG)
If you’ve mocked this up and found that it works with your desired equipment and train length (with the full train pulling on the grade), then of course you already know the answer. And it may be moot since you’ve already cut the wood, but others may benefit from past experience.
Good luck with your layout.
I knew this was going to come up as soon as answered Dave’s request for details. I just wanted to share my fascination with CNC cut subroadbed. Oh well.
First let me say this: These are only the choices I have made for my layout and a little explaination of how I made them. I do not offer any of this as advice as how anyone else should build a helix.
My longest trains will be 18-20 cars pulled by either 2 X 6-axle or 3 X 4-axle Athearn, Atlas or Intermountain diesels manufactured this century.
I am also using 3/4" less than the usual “1X4” as my spacer between the levels. I had rolling stock boxes piled up and track on my desk about a week ago measuring the height of most everything I own. I have nothing taller than 2.2" including the track (I’m not using roadbed) so I expect the 2-3/4" spacers to be fine.
My subroadbed will only be .4" thick.
Here are the calculations I did comparing my plan to the “straw man” 30" helix that most folks suggest will usually work.
Radius |
30 |
|---|
Because that’s where many people make mistakes that compromise the rest of their layouts.
Best of luck with your helix – pardon the interruption, I won’t trouble you again about it.
Carl425:
I followed your example and went looking for a CNC company who would do the job and I found one right in my backyard. Well, OK its about 35 km but that’s close enough. Their machine has a 5’ x 10’ vacuum table so a 4 x 8 sheet will be a breeze. They do tons of custom work. I haven’t contacted them yet to get a price.
I was kind of shocked when I did the calculations for how much track I will need! I’m looking at about 200’ to do two helices with 6 turns each, not including the leads.
Thank you as well for posting the effective grade formula. It works out to about 3.1%.
Regards
Dave
Sorry, no offence intended - just making a friendly joke. (as I tried to indicate with the smiley)
You asked questions about my plans. Because I respect your opinion, I explained my design and goals. If you have an opinion of my logic, I’m always interested in hearing it.
It’s not your logic, it’s the physics.
I understand that folks who post here are often already invested in their ideas, and in this case it extends to wood having been expensively cut. So I offer these thoughts with apprehension. If you’ve tested with all your potential equipment and are satisfied, then these points are moot.
In working with clients, I usually start with a clean sheet of paper, and so my concern is designing something for someone else to construct that will be bullet-proof even if not precisely built. So I do err on the side of caution and conservatism, for sure. But on a couple of occasions I’ve worked with folks who already had HO layouts under construction with helixes in the 24” range who could not make them work reliably with all of their equipment – and so we worked on a new plan to either allow a broader helix or to eliminate it.
One of these was built with laminated half-circles of 1/8” material (1/4” deck total thickness), so even though the clearance was a little greater than yours (as I recall), the grade was not that much higher. (This is a great way to build a helix, by the way, for other folks reading).
In both of these cases, the issue wasn’t the grade alone, but a tendency to stringline across the center of the helix (derailments to the inside of the curve). This didn’t happen every time, but was worse with mixed-length cars in the train and happened most often when the full train was all the way around the helix partway up and pulling. Running the trains slowly and looking closely, one could see different trucks trying to lift at different points as they rolled around the helix as oblique forces built up through the couplers. At some point, with some co
Byron:
Thanks for adding your expertise to the discussion. I had been planning on using a 26" radius for my helices but based on your explanation of the physics and your personal experience I have redone them at 30". I had to steal some more space from the garage but that is a small price to pay for reliable trackwork. The larger surface for the main layout is a bonus too.
Regards
Dave
Thanks for the extra info, Byron. As you point out, I am indeed heavily invested in this project, but then the value it brings in scenery options (my original plan was a narrow intermediate nolix level) makes it worth a try. I do hope it works and am taking every step I can to make it work, but I’ve made expensive mistakes before so if I fail, I’ll go back to the nolix.
This is semi-encouraging. I’ll be running nothing but 40-50’ cars. Mostly 70 or 100-ton hoppers. Maybe I’ll get some benefit from the lower center of gravity of the shorter cars.
Do you know anything about the weight of this clients cars? NMRA? More/Less? Consistent? I’d weight is a catch-22 - heavier cars will resist stringlining better but they also increase the drag that causes it.
I’ve been thinking a lot about this issue too. I’ll have a completely removable fascia and I’m planning to include some type of “hill holder” device to keep the rest of the train from running away. Also, if I can figure out how to do it. I may make some of the outer spacer blocks removable.
I think that will be a safer alternative since you have the space and will better accommodate any variations in equipment and construction.
Both layouts are now gone, but I imagine that the car weights varied a little more than one would wish. It was hard to tell if it was the weight (which might be addressable to some degree) or simply the differences in length. The one layout that had a lot of open-top hoppers was downhill on the loaded leg.
One layout had some brass freight cars which, while heavy, rolled poorly. These seemed to always be involved in any derailment (for one reason or the other) and were removed from service early-on. That diminished, but didn’t eliminate, derailments.
Unless the hill holder is somehow only deployed at the exact moment of a derailment (not sure how that could work), it seems like it might be just another variable inducing drag. But it might be worth some experimentation.
I’m not sure how the spacer blocks could be removable and still do their job, but there might be a way I’m just not clever enough to figure out.
It sounds like you are doing all you can to mitigate the issues, let’s hope it’s enough and you happily write me off as a worry wart!
You call those helixes, look at this one (i saw it in person to)