Helix,

[Anonymous]

How do you build a 30" helix 7 ' diameter?

[ChiefEagles]

Elliot [Big Boy] has built this one. Maybe he will give you some info.

[Big_Boy_4005]

Congrats on your first post, you've come to the right place.

Given the 7' diameter, you must be talking O gauge. Maybe the most important factor is the height gain per turn. You will need at least 6" of clearance between the top of the rail and the bottom of the subroadbed above. 7" would be even better, but as you increase the headspace, and hold the diameter constant, the grade increases.

There are a few basic construction styles, the easiest and least expensive of which is wood spacers. You basicly establish your grade as you build your first 360 degrees, then cut equal sized spacer blocks to support each level as you work up the helix.

What you end up with is something like this.

[Anonymous]

Thank you for your help. If a 1/4" per foot is a 4% grade than a inch per foot would be a 16% grade correct. Therefore would O gauge engines be able to make that kind of climb?

[otftch]

Remember you're not only using grade but most "O" guage engines bind a litle on curves so you have to take that into consideration.I try to use 1 inch in 3 ft as my optimum grade.You're engines will climb 1 inch per foot but you may strain them a lot more than you really want.
Ed

[Big_Boy_4005]

Ed, you are right about the curve making the grade SEEM steeper.

Louis, the rule of thumb for model trains is to try to keep grade to actual 4% or less.

7' diameter is about 264" circumfrence, with 7" height gain per turn, that's about 2.65% grade, with just over 4 turns to climb 30". Very doable.

The one in the photo is 10' diameter, and about 2% grade with 8" height gain per turn. One modern dual can motored diesel can easily take 30 modern cars up it.

[Anonymous]

Thank you all for your help