Howdy, Robert.
I have one helix in an equalateral dodecagon, same shape as yours but fabricated from steel stud material. I expect to use the same system for some other hidden curves, but haven't worked out the precise geometry yet.
The stud, positioned like a rain gutter, is cut at right angles, leaving the outer 'wall' uncut. The 'floor' overlaps, and is screwed together to hold the angle. The inner 'wall' is cut free of the 'floor,' bent out 30 degrees, then screwed to the 'wall' of the next segment. A couple of risers were screwed to the 'walls' and continue upward to support the covering landform. Others hit the bottom of the 'floor' and were screwed up from below, taking care to keep the screws where they wouldn't interfere with passing rolling stock. The risers are also steel stud material, and the screws are those little things meant for steel stud assembly.
The whole purpose of using steel studs was to hold the grade to a minimum, on a hairy 350mm (sub-14 inch) radius curve! The route is operated with very short 1:80 scale cars and locomotives, and embargoed to anything long that isn't also super-flexible. Total thickness, railhead to bottom of 'floor,' is about a quarter inch.
Chuck (Modeling Central Japan in September, 1964)
Somebody did an article about an octagonal helix about ten years ago or so, don't remember which magazine it was in.
Disclaimer: This post may contain humor, sarcasm, and/or flatulence.
Michael Mornard
Bringing the North Woods to South Dakota!
hon30critter Interesting design! Almost no waste! Easily adapted to HO scale too. How are you going to attach the pieces together? Glue? Dave
Interesting design! Almost no waste! Easily adapted to HO scale too.
How are you going to attach the pieces together? Glue?
Dave
Hey Dave-
Well, you know . . . Saturday afternoon, nothing else to do, so why not take a sheet of 1/4" plywood and rip it into a bunch of 3-1/2" strips?
Yeah, glue. Smear a thin layer onto the 8"x3-1/2" connectors (shown as dashed lines in the drawing) and clamp them to the bottom of the angled joints of the slats. When dry, the yellow glue becomes just as strong as the plywood itself. The effective thickness of the ramp is 1/2", leaving 3" clearance (in this case) between levels. 1x4 dimension lumber could be used and joined with biscuits as described in a previous post, but that would decrease the clearance and then the pitch and grade would need to be adjusted.
Hex nuts are placed just under the glue boards along the 1/2" diameter all-thread vertical columns, and they allow very minor adjustments to smooth out the grade.
The 28.25" radius is pretty generous for N-scale, and that was used because I have a shoebox full of Kato Unitrak.
Robert
LINK to SNSR Blog
Robert:
Your photo posted just fine.
I'm just a dude with a bad back having a lot of fun with model trains, and finally building a layout!
Steve:
Thanks for the link to Inkscape.
Here is a detail for a dodecagon (12-sided) helix. It is N-scale and single track, but the dimensions can be changed to accomodate multiple tracks or different scales. It is not as complicated as you might think. A table saw and a chop saw are needed, but those are pretty common shop tools. All components are exactly the same size, so setting up some sort of jig would speed up production.
The slats are 3-1/2" across and are cut from 1/4" plywood. You can cut 14 8-foot long by 3-1/2" wide strips from a single sheet, and get 6 slats per strip or 84 slats all totaled. The glue-reinforcement pieces are 8" long and you can get 12 pieces from each 8-foot strip. For this particular helix you need 12 slats per level times 3.5 levels or 42 slats all totaled. Plus an equal amount of the 8" corner reinforcement pieces. Notice that you can use dimension lumber, but my plan is to use 1/4" plywood to keep the thickness of the helix ramp to 1/2" to accomodate the vertical clearance. The little holes on the inside vertices are for 1/2" all-thread rods to support the ramp. There are 12 holes, but I might only use 6 (every other one). Yeah, I haven't actually built this thing, but theoretically it should work.
My first photo attachment. I read Steve's instructions, but even so I'm not sure how it will come out.
hon30critterCan you explain a little bit more about what is involved in creating a DXF file and what program(s) would be needed?
You don't even have to use a full-blown CAD program. A vector drawing program like Inkscape can output in DXF format that should be able to be read by the CAM software. Inkscape should be a lot quicker to learn than a CAD app. You can download it for free at...
https://inkscape.org/en/
Steve S
Hi Markie,
To get back to your original question, that is how I made mine. 28" radius, 5 loops and I just used pieces about 6" long glued and screwed underneith the joints.
It has been there for about 4 years now and has worked well.
I was a little intimindated when I started but, it went together easily and not with the extensive engineering that I had read was necessary.
Go for it.... It certainly is the economical way to go.
Johnboy out...................................
from Saskatchewan, in the Great White North..
We have met the enemy, and he is us............ (Pogo)
Hi again Carl:
I need you to help me out a bit please. I thought that I had bookmarked the woodworking shop that had the equipment to do the cutting of the helix parts, but alas it has disappeared from my favourites list. Can you post a link to the thread where you talked about getting the helix parts cut so I have a better idea of what to search for?
No need. I found the company.
Thanks
Hi Carl:
Actually, it was your post that spurred me to find a local company who could do the same thing, and I did find one that is about 25 minutes away.
Can you explain a little bit more about what is involved in creating a DXF file and what program(s) would be needed?
hon30critterThanks to recent developments in CAM woodworking (Computer Aided Manufacturing) there are now companies that can cut semi-circular pieces out of plywood sheet very quickly and easily, and at a reasonable price.
That's how I did my helix parts. I dropped off 3 sheets of 1/8" birch and a DXF file and picked up these a few days later.
I have the right to remain silent. By posting here I have given up that right and accept that anything I say can and will be used as evidence to critique me.
Thanks to recent developments in CAM woodworking (Computer Aided Manufacturing) there are now companies that can cut semi-circular pieces out of plywood sheet very quickly and easily, and at a reasonable price. I did the math for a 60" dia. helix and I could get 12 - 90 degree curves 5 7/8" wide from a 4 x 8 sheet of plywood.
To do a 27" high x 60" dia. circular helix with 4" between layers you would need 6 3/4 turns (@ approx. 2% grade). That equals 28 pieces if you are biscuit joining them, or 56 pieces if you were laminating them.
To do an octagonal 27" helix you would need 56 pieces if you are biscuit joining them or 112 pieces if you were laminating them.
I hope my math is correct.
Both solutions will work.
I see no pitfalls whatsoever. My current layout has three such helixes. I assembled all the sections using a biscuit joiner, which makes for solid joints without needing splice plates.
Rob Spangler
My experience: I built a double helix with staging rising 27" total. The helix has been in place roughly 8 years now and works flawlessly.
The biggest drawback is the extra time it takes to glue eight pieces of wood together for each rotation. I used a design that cut the circle into quarters and that was tedious enough. There are those that overlap the layers, essentially doubling the number of pieces. I didn't find the overall strength of the stack to be enough of an issue to warant the extra effort.
I my helix design I wanted tracks to pass each other very tightly going around the helix. The curves gave me a tighter fit than sharp octagonal angles would have, thus allowing me to use less space for the helix area.
My two cents,
Guy
see stuff at: the Willoughby Line Site
presumably this is easier and less wasteful because it can be formed from straight pieces of wood with appropriately angled ends.
you could make it with two layers. If the layers are offset, the joints wouldn't overlap.
how wide do the pieces need to be?
greg - Philadelphia & Reading / Reading
I suppose it depends on how you do your joints. One advantage to using curving sections is that you can use two layers of plywood (each one being half the thickness that you want the final roadbed to be) and stagger the joints, making for a strong, continuous spiral. Doing that with straight sections isn't going to work that well because there will be a lot of areas where the two layers aren't overlapping each other.
If you plan to do a single layer of plywood by butt-jointing the ends and using another small piece of ply under the joint, then it wouldn't really matter. The disadvantage to this is that the extra piece of ply is going to add to the thickness, thus reducing clearance.
Hi;
Anyone with helix experience. I am thinking this would have some advantages over a circular helix. Easier to cut and less plywood wasted. What would the pitfalls be?
Thank you in advance.
Mark