I wouldn't recommend MDF. It generally not used as a structural material. It is a filler material. You should be using plywood or hardboard.It's easy enough to cut 1/4" MDF into arcs of the desired width - 4 (or more) pieces per 360 degrees.
For supports you can use 1x2 (or something similar) and just cut notches to fit the 1/4" MDF (at the appropriate angle). You cut the the needed number of notches at the needed spacing to obtain the desired grade and clearance. Eight pairs of supports, at 45 degree intervals, works well.
I glued all of the MDF pieces together, using small strips of wood spanning the joints, into a "spiral".
Then, with the help of my wife, I fit the supports into place - it was a bit awkward lifting the MDF spiral into place, turn by turn, but it worked out fine.
Frederick
Does sound like that doesn't it. 2 o3 layers with the joints staggered does sound interesting.
I'm trying to contact that poster to see what he has to say in addition to his posting.
Also if dcc is your plan run a bus around the base level then run vertically to connect to your tracks you will save lots of wire, you may desire to have two or more vertical runs.
Neal M
Mine is a two track helix. Inside radius 29.75 outside radius 32.00. It has a 2% grade with a height of 12" This was the biggest I could have due to space restrictions. I'm sure a wider helix with a lesser degree of grade would be better. I've run 2 diesel engines, both 4 and 6 axle engines and anywhere from 20-28 cars with no issue. However, with my 89' auto racks, I usually have 2 6 axle engines with 12 auto racks. I don't see any type of drag or issue running them up the helix.
Missed this way back when it was posted. However I would not run a bus wire all around the base. Just 1/2 way around the base at most.I saw this posting and wanted to make note of it here so I rememberAlso if dcc is your plan run a bus around the base level then run vertically to connect to your tracks you will save lots of wire, you may desire to have to or more vertical runs.
That would be 34" and 36". Without going and measuring it, it is about an inch and a half to the screws. At this radius, there isn't much of anything that leans out over the outside edge of the tracks that much. And I don't know rail head to rail head, but from rail head to the plywood over it is 3.5" - tall enough for double stacks and fingers.What are your two radius(s) ?
And what distance between the center of the outer track and those all threads??
And just for info, what height railhead to railhead?
That would probably work, but compared to copper, steel is a horrible conductor. I wonder if brass threaded rods are strong enough? But then that would probably be way more expensive than the "free" scrap wire that was used here.With the "Threaded Rod Idea", why not use the threaded rods as wires going up the helix?
I can think of another consideration for that. To put the rod through the center, the distance between the two tracks would have to be greater than (in HO) 2". That means the inside track would have to be that much tighter. In this case, probably 33" rather than 34". If one is already pushing minimum radius on that inside track it could be an issue.I saw one helix that had the threaded rods come up thru the center of the roadbed for the double tracks (instead of threaded rods on both sides of the helix roadbed,...something to consider.