This is real exciting to me because I’ve always wanted a helix but never had the room either in my N-scale or my O-scale because of the grade and clearance problems. I think I can do this width. From everything I read about and from my own calculations I was looking at close to an 8’ diameter helix for O scale.
That helix is noted as being double tracked using O54 on the outside and O42 on the inside. Looking at the video, you can see that the outside track is not right at the edge of the ‘deck’, so a good guess might be that the total outside diameter of the helix structure is about 60".
60" X Pi = about 188.5".
Assuming a 3.5% grade the total rise each time around the helix should be 188.5" X .035 = about 6.6".
Assuming 4 3/4" clearance with a 6.6" rise leaves a little more than 1 3/4" for framing and deck thickness.
Assuming I did these rough grade calculations correctly, this seems reasonable.
Don Baker has contact with a guy who has figured all this out. They displayed a working model of a Helix at the Cal Stewart meet in California. You may want to check with Don on any specifics.
I looked at the rest of his videos which was pretty impressive and he mentioned something about his polar express not being able to climb the inner track. I don’t know what the difference would be.
Anyway I think I’m going to try it. There is a section of my patio that I would like to keep a clear access to the back yard so this will work great.
I made one in high school wood shop class over 25 years ago. Not that hard to do. Gargraves bendable track is the best candidate for this. Decide the size of the circle. The spacing between levels and how many support arms for each full circle of the track. Say for example you have 6" spacing between the top of each level and you have 6 evenly spaced support arms going up around the circle. The bottom circle will start at:
ground level
1"
2"
3" (half way around circle)
4"
5"
6" (one full circle) And after that first circle all spacers are 6" minus the thickness of the plywood. Really not hard to build one. The only slightly goofey thing about it is the track and base twists a little bit as it climbs up the grade and plays with your mind a little bit. But that is normal. If you have 2 tracks in the helix use the outer track for climbing and the inner track for descending. I considered one for my bedroom layout but there is not enough room for it.
Thanks, but I have 5 pieces of Gargraves bendable track in my junk pile because I kinked them up so badly. After destroying 3 I looked for advice in the forums and was told to cut a piece of plywood to the curve needed and use a hammer to bend it around. Well after destroying two more pieces, I gave up completely. It was just getting too expensive.
The inner track is steeper than the outside track. There are also forces on the cars that you don’t get when it’s not on a curve, which makes it even harder to pull up the hill. Good traction tires on good pulling, speed controlled engines are probably going to be a must or you are going to have to babysit the throttle the whole time or build some voltage reducing/adding circuits throughout the layout. This isn’t a big deal, just takes more time. If you can do O-54 inner and O-72 outer, you will be happier.
Wes
“and was told to cut a piece of plywood to the curve needed and use a hammer to bend it around”
don’t use a hammer. Never heard of doing it that way. Two ways I have used. With plywood use your hands. Screw down one end and slowly work it around. Put screws in track every six inches or so Or once you get the hang of it use your belly if its big (small) enough to get a basic shape. As a note anything less then 054 then use sectional track.
I can’t remember exactly, but I think was trying to bend something between a 0-36 and a 0-40 diameter curve with a small opposite curve at the end. Kind of an “S” shape, but not completely. I was using the 102 3-Rail “Phantom” with Stainless outside rails.
Remember that when doing the calculations you need to measure clearance to include the thickness of the track and any supports required to support it. This means the grade will probably be steeper than the original calculations since you are computing from top of rail to top of rails.
Sorry so late on entering this post. I just happened to stumble on this today while looking for something else. If you haven’t started yours yet, here are a couple notes that might help you.
If you use Gargraves and you are going to be running postwar, make sure its the tin plate version, so that the magnitraction works.
My helix is 6 inches top of rail to top of rail. That consists of the Lionel 0-27 profile 0-54 track, a thin carpet for noise reduction, 1/2 inch plywood for roadbed, and another 1/2 inch plywood for splices. The splices were screwed and glued. This resulted in an approximately 4 3/4 inch clearance, which is about 1/8 inch too little for my double decker passenger cars. Additional clearance could possibly be obtained without adding more grade by using metal plates for the splices, or possibly joining the pieces with wood biscuits,
If using 1/2 inch plywood, make sure to use 4 ply. 3 Ply is not as rigid in one direction as the other, so you will get more flexing (like in mine)
I don’t see how you are getting 4 3/4-inch clearance. The plywood alone takes up a full inch, or, more likely 15/16 inch if it is actually 15/32-inch thick, leaving only 5/16 inch for the carpet and track. The track alone is 7/16 inch.
I have no plans (nor room!) to build a helix; but it seems to me that an armature of thin plates, perhaps 1/8-inch-thick steel, radiating from a central vertical threaded rod and supported at the outer end by a circular array of vertical threaded rods, could support O27-profile track adequately, passing under the rails and between the ties. This would drastically reduce the track-and-roadbed thickness, to the height of the track alone, to allow significantly less-steep grades, or greater clearance, or both.
My notion is that the radial “roadbed” plates would be about 1 x 1/8 inch in cross section, with a hole through each end clamped between two nuts on the vertical threaded rods. I think that the combination of dozens of these would keep everything pretty much in alignment. Of course, each one of these plates would be completely flat and so would not quite match the slope of the rails that it supports; but the error would be only about 1/32 inch from one edge of each plate to the other edge. There will have to be a (thin) layer of insulation between plate and rails, which may be resilient enough to take up the difference. In any case, I think that there is no harm in supporting the rails entirely with the downhill edge of each plate.
A possible variation on this idea is to put the circle of vertical rods on the inside of the curve, with the plates cantilevered radially to support the track. This would allow unhindered access to the train from the outside of the helix. On the other hand, it would allow the train to fall off the track to whatever’s below.
Thanks Rick B. I gave up on the idea because it just took up too much space, so I moved the whole layout to the other side of the room and made it simpler design.
Several years ago I had seen an HO layout with what they called a double helix. They used 1/4" masonite with threaded rods on the inside and outside of the board, then used locking nuts with washers to support the masonite. Thing stood nearly 3’ and got me to thinking about building one for my trains.
One way to increase clearance height or decrease grade is to use sectional tubular track without roadbed or sound deadener. Then instead of a continueos (sp?) hard surface below the track as it spirals around, use strips of either metal or plastic going side to side and place them between the ties in order to reduce overall height. If you use metal strips either wrap them with electrical tape or dip them in that plasti-dip stuff sold at hardware stores (read the label of that stuff as its full of chemicals) so they don’t ground out the track. Larger “L” brackets would do this well. Or you could do this with gargraves but remove ties at the spots where the supports are.
As to making curves with gargraves, use a large round object to press against like a steel trash can full of something heavy. Or take some plywood and cut out pieces in varying radious’s and then stack them like a dagwood sandwhich with the largest curves on the bottom. They typically flex back a little bit. Its really not that hard. And to the guy who started this thread, save the ties from the gargraves sections you put in the junk pile as they can come in handy.
Bob, Using steel threaded rods is an interesting idea.
I have room for a 54"+ diameter helix in my future train room, though I never contemplated needing a double helix.
Regarding the two versions of your ‘notion’: I’m not sure I’m visualizing the difference. I see a rod on bothe the inside and outside of where each track section joins. I don’t know how many sections of 031 tubular it takes to make a circle, but it seems like there will be a lot of steel rods and a lot of 1/8 " x 1" steel flat stock to drill and cut. Would this be stainless? If not, galvanized? Or painted plain carbon? And I wonder about the cost? Still, it’s an intreging idea, and possibly the best alternative. But it would need a safety net or retaining wall feature for how high I contemplate by helix going: table height to overhead.
I was thinking of having only one circle of vertical rods, with the other end of the plates all going to a single central rod. So the difference between the two approaches is which side of the track the circle of rods is on. If on the outside, it supports the end of the plates; if on the inside, it supports the plates several inches from their outside ends, with the plate cantilevered out under the track.