Cookie Benchwork Question

[Casy jHOnes]

I just started attaching risers on a 8x 12 layout (ez track). I had this 3 level layout working on my floor and the grades were held at each track joint with piers, toy blocks, drinking cups etc. Anyway - I transfered all the track onto plywood and carefully traced to cut out 3" wide cookie cuts. (I also traced the actual pcs. of track so it would be easy to put back together)
Now that I am putting it back together it doesn't allways line up. Does tilting the plywood change the distances enough so it doesn't line up? Its not alot but with only 1/2" "play" on either side even a 1" difference puts the track off the plywood.

Is it just me? Is it slight variations in the EZ trk pcs? Does tracing it on the flat change a whole bunch in a 3" elevation over 8-10'? I guess I will be getting proficient at making 1" & 2" Atlas "corrections. No big deal I just wonder what I did wrong if anything. 

1 More?. I ran my 1 st level at top speed and it was amazing how well it worked even with a few really crappy joints and stuff. It seems like it might not be that hard to "tweak" the roadbed ply so that curves are "banked". Is that something you would normally do? Would you bend the plywood OR would you shim the ez trk pcs. Whats easiest/best? All my curves are 22' & 18' radius.

Thanks anyone for suggestions.

[hotrainlover]

Casey,
When I elevated my "Cookie Cutter" areas of track;  I built the plywood LEVEL.  I  then put shims every 6th tie to super elevate the curves.  That way, I could then space the shims farther apart, and gradually banked the track into the curves.   I then tacked the track down, after I was assured of great running track.
I hope this helps.

[Joe Satnik]

Hey, Casy.

Congrats on your progress so far.

I think what you are seeing is a "spiral" effect on your curves. 

Off the top of my head, I can't quantify it, nor tell you which pieces to use to correct it.

However, I can tell you how to demonstrate its effects.

Make a circle of track.  Split the track at one spot and attach 9" straights to the ends of the curves.  Raise the top straight 6".  If you want,  put 1.5", 3", 4.5" and 6" piers at 90 degrees apart around the spiral. 

Note that the straights (as viewed from above) are now no longer parallel with each other, that they have pulled apart from each other slightly,  and that they have a slight twist to them. 

You will have to fight the "pull apart" and non-parallel" effects more than the twist, I think. 

Does anyone else have any experience with sectional track and spirals?

How do the fancy CAD programs handle these change of elevation effects?

My guess is that most people end up using flex track for their spirals. 

Hope this helps.

Sincerely,

Joe Satnik   

[Casy jHOnes]

Joe - Thanks for illustrating with words what I was trying to think of! Spiral effect - of coarse.

I almost hastily glued a long straight section and at last 2nd decided I should wait 'til I wasn't as tired and try to understand what was going on.

Its so obvious now. Just take any half circle - the more you bring one end out of level with the other they get closer together. Duh...........

Thanks again. AND thanks other guy about track shimming - makes good sense.

[Yampa Bob]

If you bank the track on the spiral, there is another geometric principle, "cone effect". An easy way to demonstrate this is, cut a circle about 6" diameter from heavy paper or manila folder.  Cut one slit to the center.  Now pull the outside up into a cone, like a funnel. Notice the overlap required to form the cone.

(A neat trick if you need a disposable funnel in a pinch, cut the tip off the cone)

Anytime you try to bank a curve, the outside diameter is effectively made smaller. The only way to super bank a curve is to use flex track, with the movable rail inside the curve so the ties will converge. 

[grumpy]

II would suggest not using the cone unless you can obtain a sheet metal layout book so that you can put some dimensions to the cone
Don