Nevin Wilson I model HO and I am looking for something about 28 inch diameter.
Oops, BL is right, I misread that the first time. If you really mean diameter, that's a non-starter in HO. 28" radius works in HO for most equipment. Perhaps a little smaller radius in some cases for short trains of short cars in HO can be made to work, but nothing like 28" diameter.
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LION maked own helix. First comment of him is "28" in diameter" That might work in Z scale maybe in N scale but NOT in HO scale. 36" Diameter is the smallest (18" rqadius) cujrves can built, but you MUST TAKE INTO ACCOUNT that at the end of that curve you MUST HAVE A RISE of at least 2.5 inches. The smaller the diameter of your helix the greater your grade.
HELIX of LION is buiilt on a 5' wide table, but the track diameter is somewhat less. But then the LION has a four track helix.
As you can see below, I tried this without a helix, and it worked for my locomotives, but when I switched to subway equipment they could not make the grade, so that half turn was pulled out and a turn and a half put in. A two-track helix, whgich in turn was pulled out and replaced by this four track helix.
You can see below the clearances on my helix. It is OK for the subway trains, but a locomotive could never fit through this section of track. Remember that you must account for the height of your tallest equipment PLUS the thickness of the wood stock, PLUS the height of your roadbed, which as you can see, the LION does not use roadved, what with this being a model of a subway tunnel.
ROAR
The Route of the Broadway Lion The Largest Subway Layout in North Dakota.
Here there be cats. LIONS with CAMERAS
I have a helix kit developed by EasyHelix. I don't think they are around any more. it had plastic sections and threaded rods for spacing. Even though the plastic sections are fairly thick and heavy, they have managed to warp slightly over the years. It was also not all that easy to build.
If I had it all to do over, I would have just cut my own wood.
Regards,
Greg
Greg Shindledecker Modeling the =WM= Thomas Sub in the mid-70s
I had a helix made for me by a company in California. It was a two track helix with 29 3/4: inside and 32" outside. In addition, I had them make me 2 tracks to go around the top. Made out of wood. Took me about five months of nights and weekends. The company made me a video on how to assemble it. Came out great!
www.lloydslayouts.com and you can see the pics of my custom built helix he added in his HO gallery. It was not cheap. I am handy and built the rest of my layout solo. This was one area where I knew it had to be a close to perfect as possible. When we bought our snowbird home in FL, and I was given a small room, I had Lloyd build me the same type helix, just not with the top 2 tracks.
Disclaimer: No affiliation other than a satisfied customer.
Neal
One thing to check is that the dimensions match the stated grade. One company (I think now defunct) consistently understated the nominal grades in their helix kits. (This is before considering the added effective grade casued by the curve)
You may already know that the added friction of the curves adds to the nominal grade of the helix for a steeper effective grade. The rule-of-thumb for HO is 32/R, with R the radius of the curve. So for a 28” radius, 1.14% would be added to the nominal grade of the helix itself. You’ll want to take that into account when considering the effect on train length, etc.
Good luck with your layout.
Byron
I have come to the conclusion that adding a couple of helices tp my design would subtantially improve it. I am sure that I could build a helix but I would consider purchasing a kit. I've noticed that companies making helix kits seem to come and go.
Has anyone used a helix kit and were you satified with it? Was it worth the expense? Who did you use and are they still in business. I model HO and I am looking for something about 28 inch diameter. Thanks.