I’m going to start this week on building a helix in my HVAC storage room. I’m using aluminum shelving attached to studs. Planning on using 1/2 inch particle board. Problem is, where the particle boards.
Some questions:
What type of wood or other material do you use for the helix; not the vertical part but the roadbed? Thinner is obviously better.
What do you use to connect the sections of roadbed together?
My helix will be a weird looking blob, not round, as it coils around the HVAC room. How do you determine the slope; just use the slope=rise over run formula or, do you test your heaviest train to see how it pulls up the steepest slope and then use that slope. In other words, do you set the slope first or do you find the steepest slope possible by testing your train first?
I believe this one assumes that the helix will be round, but you can still get some good info off of it.
Essentally, the grade is run over rise. If you have two 180 degree curves of the same radius connected by straights, then the run is the perimeter of a circle with the same radius plus twice the length of one straight run. If your helix looks like a hexagon with O72 curves in the corners, it would be (Pi * 72) + (6 * the length of one side).
As for materials, you might consider MDF or Homasote for the roadbed in the helix itself. It’s not like you’re going to scenic it, especially if it’s in your HVAC closet. Plus, you want to make everything as thin as it can be & still support your trains, since the mateiral thickness contributes to the rise & so affects the grade.
I mispoke; not planning on roadbed; just “structural support” as labeled in your link.
Problem with my helix is that it won’t be a particular shape; just a sort of blob as it winds thru the HVAC elements. Figuring it would be a nightmare; or rather a dream if you are into geometry.
The challenges for me will be accessibility and easy-to-remove helix, to get to the various HVAC elements if repairs ever become necessary. it definitely will be one of a kind.
I already layed a temporary lower shelf (to store all my trains on while I scenic the upper shelf). Thus, i have the distance down that the helix needs to coil; about 20 inches.
I’m just curious, for those of you who have helixes, how you arrived at the percent slope. Did you just pick a number, say 2% or, perhaps you calculated the depth from shelf to shelf and then how many coils were necessary.
One other question is how did you join the “structural supports” without appreciatively increasing the thickness? I’m thinking metal joiners instead of wood to join the sections. Am I on to something here?
Is that 20 inches the circumference, or the rise? If it’s the run, you’re going to have a very steep helix indeed!
Here’s a way to connect the structural supports, if they’re made of hardboard or wood: tongue & groove. Or half-lap. Both allow you to connect the pieces without adding a joiner plate. Half-lap would be easiest. Just use your table saw or router to remove half the thickness on two pieces & glue & screw & you’re done.
Half-lap will work for the lift-out sections too. You can use dowels as locking pins through holes drilled through the overlapping pieces. Just yank the dowels, then lift the section out. You might tie the dowels to the helix with fishign line to keep from losing them, though it would be easy enough to cut new pieces.
Regarding the slope, it’s just rise over run. Let’s work a theoretical here.
If you need the helix to rise a total of 20 inches, you want to do that with as gentle a slope as possible. You want to keep it in the 1%-2% range if you can. You have to go around all of your HVAC equipment; let’s say you can do that with an 8 foot diameter circle. I know you’ve got a “blob,” but let’s keep with workable numbers.
Now, an 8 ft circle has a perimeter of about 301.6 inches. Let’s say each coil of the helix has to rise 10 inches, in order to do th total 20 inch rise in 2 coils. That grade is then
10 / 301.6 = 3.32%.
If you do a 6 2/3 inch rise, you come out with 2.21%. This is much better, though you need to go around three times and you may be limited in your choice of rolling stock that can go through the helix.
Dave, I used plain O27-profile tubular track attached to the wall with corner braces–no shelf at all except in the corners–for an around-the-walls track. I spiral (inside) corners keep the track close to the walls.
Didn’t see you post. Actually, I priced out the braces and the aluminum vertical posts with holes AND the brackets that come with them at home depot, price well compared with the metal angles I saw there, and, since the vertical aluminum posts have many holes, I can simply use them for each ring of the helix.
Each post can be slightly offset on the stud as well so the slope is just right.
I’ll be doing a lot of experimenting before putting it up and once it’s up I’ll test it a bunch of times with the longest and heaviest stuff I have.
Good thinking! I’m going then w/3/4-inch particle board so the overlaps are thicker as well. I’ve used the table saw to do things like you mentioned; but never thought of using it for the helix. The table saw was a great investment.
Also, your lift out idea could have other applications as well (as in a liftout section crossing a door)
Always wear goggles and am carefull around it too. I respect it a lot.
Nice photos, I’ve often admired your helix but these pictures really show the steps. Nice work!
How did you arrive at 4%. Did you test your trains on 4%? If you had to do your helix over again, would you do anything different?
It looks like double-track. Will there just be 2 exits from the helix (top and bottom?) or are you planning more than that? Also, can your helix be used as a return loop or once you enter the helix, you must go up or down? And if not, have you considered using the helix as a same-level return loop?
Sorry about all the questions. Just trying to pick brains for ideas.
BTW, using Tony’s idea of overlap 4" rather than total overlap; because it will facilitate removing sections for access to the HVAC.
Dave, the 4% was just an example. Mine is more like 2%. That is so shallow that I have to keep giving the cars a push just to get them down. I think it would be very helpful to try and keep the grade as constant as possible during the entire climb, so you aren’t having to constantly adjust the throttle and worry about the train stalling.
My helix is something like an octopus.
Two tracks start at the bottom, after 2.25 turns the outer track exits at the main level, and the inner track goes on.
At 2.625 turns there is a turnout for the inner track to exit on the main level, or continue.
At 4.0 turns, there is an entrance through another turnout. this is a hidden track that forms the continuous run of the mainline, and brings trains back from a different part of the main level.
At turn 5.625 there is a turnout allowing trains to go one direction on the upper level.
And finally at turn 6.0 the track swings out one track width to allow for the headspace on turn 5. The track crests the hill gradually, and gently moves off center and makes a final quarter turn to end on the upper level heading in the opposite direction.
This helix is the key to the entire operation.
The layout design does the looping parts on the levels of the layout. I suppose it could be done to have a reverse loop in a helix, but I’m not sure why you would want to, since the goal of the helix is to get up and down.
My helix, actually, will be at one end of an elongated layout, about 30 feet opposite of another return loop (but not a helix). Your helix appears to be in the middle. Thus, the thought of a return loop so that my train doesn’t have to go down to the next level and can simply cruise back to its return loop at the other end.
In this way, I could, if I wish, have a train topside and below, cruising independently back and forth; each on its own level, without going up or down.
The helix would be for variety; you know, sending some cars up for switching duty or something.
What I might do to facilitate the return loops inside the helix is make the helix all single tracked except for the return loops inside the helix.
Yes, that is the return loop. Now, imagine a track peeling off from either the loop or the stem, spiriling up or down the helix. The drawing would have to be in 3-D to show that.
Thanks.
Gotta run to eat but will be back to tell you how I plan to bust thru the wall.
OK, back from lunch. Ate lots of onions so pardon my bad breath.
Anyway, where was I? Oh, yes, I’ll be busting thru the drywall of the HVAC where the helix will be located. As the train exits thru the wall, it crosses a great chasm, which is my 7 ft wide hallway. Instead of a bridge, I’m building a removable extension of the layout that will be scenicked as desert.
I may design a portal on the wall where the train exits/enters. Actually, based on the above Elliot diagram, 2 portals thru the wall, because once inside the HVAC, there’s no room for the Wye split.
Thanks for all of your great suggestions. Sorry for the bad smell but it’s even worse when I put raw garlic on my sardines.
Dave you don’t need the wye near the helix if this is the top or bottom level. The wye can be a part of the main layout, like the first diagram. I suppose the “I don’t know” could be used for a middle level if you didn’t have room for the wye.
