Moving Along...

After test fitting the parts of the helix I hauled it out to the garage and set it down on the peninsula under Tunnel Hill / Gallitzin. It survived the move (I moved it while still assembled) and everything checked out. Then I disassembled the whole thing to finish the machining. Seems I had forgotten to make some of the cuts. Took all the panels outside so I could perform the magic without filling the garage with sawdust.

The first thing to do was make sure all the panels were lined up correctly. This was pretty easy to do. Using some alignment marks I had made (like THE JOINTS GO HERE) I was able to get them stacked in the correct orientation. I then ran short dowels through a few of the pin holes to make sure everything lined up. The only panel that gave me trouble was a panel I had created for the upper approach. I had laid it aside from the rest way back when and never marked it. I had to spin the panel a couple of times, but I got those holes to line up with the rest. The holes were aligned so well that the pins can fall straight through all five panels at once...

"I then ran short dowels through a few of the pin holes"

With all the panels lined up I fastened them all together in a stack with drywall screws. All the panels would be cut at the same time...

"I fastened them all together in a stack with drywall screws"

I also ran the pivot bolt through the center of the base and upper approach panel, which were the upper two in the stack. I used the bolt as the pivot for my router base and set it for the outside cut...

"I used the bolt as the pivot ...and set it for the outside cut"

I've been using a router for cutting the helix. The router cuts well and when used with the proper base or template cuts a perfect circle. I already own one and have some practice with using the beast. All the work could also be done with my jig saw. It would require a different sort of base if you wanted to make perfect circles, but it could also be used freehand if the cuts are laid out ahead of time. If you use a base, make sure you drill all the holes first. The first cut should be the outermost with the innermost cut left until last. You want to leave the center of the panel intact so you can use the pivot for all cuts.

In my helix I had trouble laying the track in a perfect circle. The track developed "flat spots" where the curve radius got impossibly tight and caused derailments on my steamers. To overcome this I routed circular slots about one ply deep in the plywood panels. Each slot was a different radius that corresponded to the track radius. The slot served as a guide, but also helped hold the track to the desired curve. If you can lay track in a perfect circle, you don't need to go through the trouble.

Anyway...With a router, it's best if you cut in multiple passes. This makes it less likely that the router bit will burn up or break. I cut two panels, removed the scrap and then adjusted the router bit for a deeper cut. I repeated the process three times, until I cut all the panels. I left the inner cut to the last step so I could keep using the pivot in the center...

"I repeated the process three times, until I cut all the panels"

I had originally thought I would leave the base panel an uncut square. It occurred to me I might want to reach the inside of the helix from the bottom (there's supposed to be part of a mountain on top). I cut the base the same as all the rest. Access from the bottom will require moving some storage out of the way, but that's not a big problem (especially when everything is in Rubbermaid tubs). The base and the upper approach panels are identical in appearance...

"The base and the upper approach...are identical in appearance"

Another modification to the general design was the upper approach. Originally this was visualized as a semi-circle that connected to the roadbed at Tunnel Hill. I opted for a full circle this go around that will replace some of the roadbed. That way I can take advantage of the helix pins to support part of the roadbed and scenery at the top of The Hill.

"full circle...that will replace some of the roadbed"

Moving back to the peninsula I laid out a 4' x 4' sheet of 1/2" extruded styrofoam. I spread some glue on the bottom of the base and laid it down over the foam. Like all the roadbed on the All East, the plywood sits atop the foam. I placed eight heavy weights on the base and let the glue cure overnight.

"heavy weights on the base...let...glue cure overnight"

Stay tuned for our next adventure..."Spiral Assembly"

Regards,
Frank Musick
Chief Cook and Bottle Washer

Allegheny Eastern Railroad