Helix question

What you are looking for is Dec 2004 Railroad Model Craftsman, Octagonal Helixs. Neat idea.

Peter

In article HLDqe.17819$ snipped-for-privacy@fe07.lga, Frank Rosenbaum at snipped-for-privacy@charter.net wrote on 6/11/05 11:51:

It wasn RMC, as I recall, within the past 18 months, if memory serves.

Dieter Zakas

Thanks, Dieter. December 04 thanks to Peter Gross.

I (vaguely) remember it - I think it was a BASIC program for calculating cutting sizes. That would make it somewhere around MR1984/85. The problem I saw with it was that the segments were quite small and therefore needed a lot of supporting structure, which seemed to negate the apparent advantage of minimal usage of ply. In the end I bought an extra sheet of ply and cut my track base as half and quarter circles.

Regards, Greg.P.

reg

If you bought twice the quantity of ply you needed, but in half the thickness, you can overlap each seqment 50% and not have to worry about splicing pieces. Another idea is a friend of mine who used 8: lengths - sorry, 200 mm, NZ is a metric country - of 20 mm x 20 mm and joins the boards with two of these, on top of the boards with the track running between them. Saves valuable space underneath the track bed.

Steve Newcastle NSW Aust

Dear Frank R.:

You can also use a piece of string and a pencil to draw a circle on brown wrapping paper, and use a protractor and a cardboard template the width of the board you want to use to estimate the angle for the ends. It's easy and low tech.

Cordially yours, Gerard P. President, The Sparta Railroad

See Railroad Model Craftsman, April 2005, "Curves from Straights".

HTH

Now why didn't you say that _before_ I cut and spliced all that ply!!!! ;-)

(it's ok, I'm bi-lingual dimension wise :-)

That's not a silly idea! Hmmmmm! Where my low end track leaves the helix I left out the vertical threaded rod spacers. As it's only two of sixteen around the circumference and trains don't cause any deflection I seem to have got away with it, but I did notice about

10mm deflection when the cat was testing the trackbed for me. He's a particularly big cat.

Regards, Greg.P.

I have a particularly large shot gun! :-)

Any reason you chose the threaded rod for support? Friend who I referred to before (a retired civil engineer) didn't use it for cost, and the fact that if you drill the holes through the roadbed when laying on top of each other, then space them, you find the holes shift and the rods are no longer vertical. His solution was easy and elegant. He made sure the bottom loop was exactly as he wanted it as far as grade. He then cut a pile of 50mm x 25 mm timber, and notched it about 100 mm apart (or whatever height spacing you wanted on the spiral) with a notch of 18 mm wide (thickness of ply) by about

12 mm deep. The trackbed fitted into this notch, and kept the spacing even all the way up the spiral - 4 turns in his case. The 2 x 1 was screwed to the trackbed (on inside and outside of the spiral). The outside surface of the uprights was what he screwed his masonite to, to enclose it.

I was impressed! If I ever need a helix (luckily for me, with a logging road, I can use a switchback to join the two decks) I will use this method.

Steve

Most definitely!!! I can saw a wood support to the nearest 3mm (1/8") but with threaded rod I can adjust height to the limit of my eyesight which is about 0.5mm (1/50")

It was about $1 per meter length at my local hardware shop. The nuts and washers required were about twice that again. For the speed and accuracy achieved I have no regrets at the outlay!

Well, we're only talking a 1:40 gradient (2:5% in US speak, I think) so the shift was well within my working tolerances (3mm :-)

I got into trouble because initially I used eight 3mm (1/8") threaded rods and the resulting structure was wobbly. I went out and bought eight 4mm (3/16") threaded rods - the existing holes were too close to the track to go any further. At that point I had the roadbed glued into one piece and washer/nut/locknut top and bottom on each rod/trackbed intersection. Each nut had to be wound up a vertical spacing at a time in sequence so I could get the rods out of the trackbed. I replaced the 3mm rod with 4mm and then used the 3mm in the intermediate spaces. After that I had to reassemble the nuts, washers and trackbed in the reverse of dismantling - it took me an entire weekend. The 4mm rod is far stronger than the 3mm, there is abosolutely no shake in the structure.

I'm certain I have an absolutely even gradient through the entire three and a half turns on both tracks and I even have three crossovers spaced through the track. I don't recommend anyone tries that unless they are absolutely certain of their track laying skills!

Regards, Greg.P.

That's a 3/4" square board. I'm afraid I don't follow how this works from your description. Can you elaborate?

Why 8: lengths?

Whoops. Mistype - damn keyboard!

Should be 8" (inch) lengths of 1 x 1, but the actual length is not critical. Each one is screwed to the top of the baseboard where the sections join each other, either side of the track and roadbed. The trains run beween them. This does away with a major headroom problem where you normally splice together baseboard sections with an offcut of ply etc underneath the baseboards. On a helix, headroom is critical. Even saving 1/2" on the height of each spiral makes for a much easier climb, or grade.

Hope that clears things up.

Steve Newcastle NSW Aust

So are you metric or Imperial down here. I have always just taken for granted that the rest of the civilized world outside of the USA is metric. I thought we were the last refuge for inches, feet, yards, ounces and pounds.

Froggy,

want to create a two track helix of 26" and 28" radius. I seem to remember reading an article/hint about cutting straight boards in such a way that they would create the spiral for a helix. My questions are: does anyone else remember it and where was it so I can look it up? I tried the MR index and the dates don't seem right. I thought it was in the last year or so.

Thanks

Frank Rosenbaum Pres/CEO/CC&BW FarSeas Connecting Railroad

```````` Frank,

That article was in RMC, as someone else pointed out, by Peoria, Illinois (USA) area resident Roger Kujawa. Here is the link to his layout's webpage:

His email addy is on the home page and you can contact him if you have any questions. When I was talking to him about the article when it first came out I believe he stated there was a small error in the angle cut that was printed in the article. He could easily give you the numbers you need for *your* specific radii, etc. as he's an engineer.

Even if you don't contact him, be sure to check out his webpage as his AGW layout is HUGE, still growing and is fun to operate. Roger is also a former RR employee, IIRC.

Hope this helps you.

"Paul - The CB&Q Guy" North Central, Illinois, USA (Modeling 1969 In HO.)

Thank you Paul. I looked at the site and am impressed. I also emailed him my question.

Yeah, I see now... make the splices on top of the helix instead of below with a board on each side -- cutting the structure depth below the tracks to a minimum.