@jimfitch what is your problem now? If you have finished with the radius analysis you can notice the title of the op, the gatorboard, it's properties, the way the helix is built etc. Maybe then you will feel better and stop thinking about balls.
Firstly, no negativity in my comments. I found very nice the OP. Secondly I can't reach the negativity masters here.
By the way you can build a larger radius helix.

The negativity masters don't agree with the video. They are fully invested in being the contrarian for this thread. 

HO - Western New York - 1987 era
"When your memories are greater than your dreams, joy will begin to fade."

Hi all,

Joey previously said 

I had seen only 1 traveling layout that had a working helix and that was the famous N Scale Clinchfield back in the day

Now for a travelling layout that is probably part of a retail stand, I'll bet that a retail stand is paying to attend and is charged by floor area. So not only has the layout got to be portable and fit into the transport, it has to maximise the "Wow" factor while minimising the floor area that what is effectively a non-retail space that doesn't hold stock that can be sold. So for a space of about 12' by 4' you get a self-contained layout that can display some of his wares in action.

Maybe some extra WOW can be got with a travelling helix-display-helix footprint that features not one but TWO helices?? 

I'm sure Joey has some tricks up his sleeve when it comes to adding scenery to this layout, but the underlying structure is proven as "fit-for-purpose".  

Pointing out that a 22 inch radius is not NORMALLY a good idea for a helix isn't negativity or contrarian. It's stating a fact. Again, the concept of compensated grade on a curve is as old as the hobby itself. The rest of it is ingenious, if you have a laser. Personally I'd rather use a jigsaw than labor to cut all that gator board with a knife but that's just me. I'm done here, please carry on gents.

it was interesting to see that a laser was used for cutting something other than straight lines. I always knew intuitively that it could it just seems that in model railroading it is so often used to cut combinations of rectangular forms. 

Anyway, I found the build quite interesting.

The point wasn't that stating that fact was bad. It was that restating it in 30 odd posts from various posters was Odious.

Michael, I don't think your posts were a problem. However, it became a matter of missing the forest for the trees.

Wow, amazed that people get bent out of shape by someone posting a video that showcases their own particular method of construction. This is one really neat idea and certainly works in many applications. And yes, we can carry on just fine here w/o some posters, thankfully. The negativity of some people just never stops, they want to quash practically any idea they don't agree with, no matter how sound it is for the OPs original creation. But that just isn't good enough for some, negative is negative and I guess that's how they roll.

Having watched the entire video (I like your videos, Joey!), it appears to me the 22" radius came more from the layout space constraints than anything. So he took that and showed how he built the helix support structure for it from Gatorboard. There was nothing magic about that radius in the general construction method he showed.

Could he have gone into the impact of radius on effective (known as "compensated") grade for curves on grades? Sure, but that wasn't the purpose of his video.

I did an analysis of various helix radii and generated a comparison chart as part of a clinic on helix design I gave at a few NMRA regional and even two national conventions a few years ago. Here's that chart, just for reference:

Joey, I liked your video. I thought your design of the risers was great.

With that said I think it could be done with plywood very easy as well. Your same methods will work very well as far as the design and it will work for lots of radius options.

A very good arc can be cut with a router and a circle cutting jig, the components will come out as nice as the items you made.

As to the limitations of 22 inch radius I bet the n scale guys would love it. It sure seems to work well enough for the shorter trains and cars he was using. Changing it to 30 or 42 inch radius does not look like it would be much more work other than dividing your circle into 16 sections instead of 8.

Very good ideas that can be used with lots of materials.

One more post just to say thanks for the chart Mark. Very interesting information. Looks like the greatest reductions in compensated grade come in six inch radius increments so an increase from say 22 to 24 doesn't necessarily yield that much positive benefit for the space. Of course everyone as with everything, YMMV.