Thinking of a helix?

[signalmaintainer]

You might want to consider this method of construction: https://appalachianrailroadmodeling.com/double-pinwheel-helix/?utm_source=feedburner&utm_medium=email&utm_campaign=Feed%3A+AppalachianRailroadModeling+%28Appalachian+Railroad+Modeling%29

[MDW]

Well thought out engineering, but man, that’s a lot of plywood & cutting.

[ednadolski]

Well thought out engineering, but man, that’s a lot of plywood & cutting.

It looks like that could be cut with a table saw and mitre saw, which should be pretty accurate.  The thing is to get the angles right, because if they are off then any errors could be cumulative.

When I built my helix I cut the plywood as curved sections, and it resulted in a fair amount of waste.

Ed

[mu26aeh]

Not much different than the method I used for my helix on the Hanover Sub.  Except I just used the octagon route.  If you get the right size material and the helix is a certain size, material waste is very minimal. 

[Dave V]

NO HELIX!!!

 

[CRL]

Looks to me that waste would be minimal using this method, and if 3/16” ply used, the ending 3/8” thickness would be fine for n-scale.

[conrail98]

Looks to me that waste would be minimal using this method, and if 3/16” ply used, the ending 3/8” thickness would be fine for n-scale.

That's my take on it too. Definitely a very intriguing idea and the riser placements add more stability than what I've seen from straight octagonal designs,

Phil

[ednadolski]

Looks to me that waste would be minimal using this method

The scraps might be less perhaps.  It would be interesting to compute and compare the actual area used for this method versus circular cuts, but I'm too lazy to bother.

Ed

[CRL]

I started having flashbacks to high school trigonometry looking at his calculations. I’m guessing if one wanted a 36” diameter rather than a 48” diameter helix, you might be able to reduce the long side length of the pieces by 3.5” then make 45 degree cuts on each end and call it close enough. Just eyeballing it... didn’t do the math.

Anyone bored enough to do the proofs for a 36” (n-scale) helix? Or if you’re really bored, an excel spreadsheet for various variables for different radius?

[mu26aeh]

I used the excel file here when constructing my helix

https://brickshelf.com/cgi-bin/gallery.cgi?f=567010

[Kentuckian]

The scraps might be less perhaps.  It would be interesting to compute and compare the actual area used for this method versus circular cuts, but I'm too lazy to bother.

Ed

IDK how the area compares, either. But it appears to me that since the design uses 45 degree cuts and straight, as opposed to curved pieces, there is no waste. That is, all of the plywood area could be used to form the helix.

[ednadolski]

IDK how the area compares, either. But it appears to me that since the design uses 45 degree cuts and straight, as opposed to curved pieces, there is no waste. That is, all of the plywood area could be used to form the helix.

Yes, but an octagon is actually an approximation of a circle.  You don't really need that extra material to be part of the helix, just the circular portion.

In some sense, one could say that there is 'no waste' wrt how much of the plywood ends up on the shop floor.   OTOH it could be said that the waste simply remains as part of the helix.

It's not a terribly important distinction, unless if perhaps for some reason ( ) you wanted to make the helix as light as possible.  Then the extra material is just dead weight.

Ed

[MDW]

Why would you not want to make the helix as light as possible..... says the guy with 3 plywood-less, unitrack helicies?!
But if I was ever going to build a plywood helix, something along the lines of this discussion would be the way to go.

Michel

[ednadolski]

Why would you not want to make the helix as light as possible.....

Perhaps if you would want to make it moveable, I would think.  But the words 'portable' and 'helix' don't usually go together in the same sentence.

Ed

[Lemosteam]

Theoretically one need not make this from plywood at all. Zero waste, just alternate the miter cuts on a 1x4 or 1x6.  Use a biscuit joiner on each end for alignment and only the ends of each board would be the waste.

Yes I know ply is more stable but its really not that critical when the spiral is "endless" and supported by riser blocks.  Unitrak should have no issue with that.  If one wanted thinner material, you could resort to pine batten molding of various widths.  Some are even available in PVC.