Tortoise & Foam Sub-roadbed

[WHartman]

I am curious to learn how (if?) anyone has a great method of mounting tortoise switch machines beneath 1" or 2" foam sub roadbed? I am thinking about using the foam instead of plywood, with cork on top, and n-scale flextrack. Any good "lessons learned" out there?

[rrinker]

You could try moutning them on TOP - this is what I am goign to try on my layout I am now building. I found this link from doing a lot of searching that shows how to do this.
http://www.pbase.com/tracktime/norcalf

[jwmurrayjr]

I think that you could make plywood mounts and glue them to the bottom or the foam.

[robengland]

I have two installed and 6 more to go.

Screw them to a square of something. Masonite will do. I use cork tile - I find it is stiff enough and holds screws. I used it just because I can cut it quickly with a hobby knife with no dust. I use screws small enough to not protrude through.

Fit a lever wire to the Tortoise that reaches just clear of the foam, with a little right angle hook bent at the end back towards the Tortoise. I put the green fulcrum up close to the motor so the wire has the maximum swing.

I use a rotating wire up thru the foam. I think 2" is too far to use a swinging action. So I bend a crank 12mm long at the end of some 0.032" wire with a 2mm hook on the end to go into a hole in the throwbar. Cut about 100mm of wire from the angle of the crank. Push a length of brass tube 62mm long down thru the cork and foam: use the crank you bent to measure the distance from the throwbar to locate the hole for the brass rod. I find no drilling is required: I'm using fine brass tube just slightly larger than the .032" wire - it's pretty sharp.

Then I drop the crank wire down thru the brass tube, and hook the crank into the throw rod. Grab the bottom of the tube with pliers (it should protrude a few mmm from under 2" foam), and bend the wire at right angles so it is snug in the tube - cant move up and down, just pivots freely side to side. this bent bit should be about 30mm long. Bend a little horizontal loop in the end of it. We'll call this the crank-arm.

Swing the crank-arm as far as it goes each way and mark these points with a pen on the underside of the foam.

Put some double-sided tape on the base of your tortoise-mounting-plate. Centre the tortoise manually: ie move that little black pivot with your finger until it is half-way across it's travel. Now peel the backing off the tape, and get a comfortable position under the layout where you can see from below the crank-arm and those marks you made before.

Without sticking the plate to the foam, hook the tortoise lever wire into the loop on the crank-arm. Centre the crank-arm half-way between the two marks and line the tortoise up so its centre line is in line with the crank-arm and the brass tube. Move the tortoise along this line until the lever arm is just comforatbly in hooked into the loop without pulling on it. Now press the plate onto the foam.

Test the Tortoise. With the dimensions you gave you should get enough travel each way to move HO points firmly to each stock rail. I had to mess around some to get it right but now I think I am ready to mass-produce.

I will cover the little 10mm crank with a small box structure to make it look like a prototypical switch engine, or at least a hypothetical one.

Sorry about the metric measures. and sorry no pictures yet.

[bogp40]

I think that you could make plywood mounts and glue them to the bottom or the foam.


--------------------
Jim Murray
The San Juan Southern RR

If you decide to use plywood mounts find a quality 1/4" or 3/8" and try using ceramic tile mastic/adhesive applied w/ a notched trowel- brace overnight. A very strong bond beats liquid nails anyday. Mastic is also agreat adhesive to bond your foam.
Bob K.

[robengland]

Is rigidity of the tortoise mounting really critical? As i mentioned, I am using cork. I have not seen any movement in the tortoises, although admittedly they haven't been there long. Will I get maintenance problems? Do I need to move to something more solid?

[rrinker]

The tortoise mounting needs to be stable relative to the switch points it is controlling. That's all. Of course, if the whole thing shifts it could knock the rail joints out of alignment.. There is usually plenty of throw in the tortoise relative to how far the switch points actually move, so the alignment doesn't have to be micrometer precise. As long as tension is maintained to hold the points in position, it shouldn't be a problem. But if your mount loosens up and allows the tortoise to shift side to side, eventually it will read a point where the tortoise moves rather than the points, and that would be bad. [:D]

[robengland]

Think I'll stick with the cork base. There is plenty of "give" in the linkage I made, so there is not too much back-force on the Tortoise once it hits the end of the movement. As I say, no sign of movement in them yet....

[SP4449]

For maintenance: I had the occasion to open the box and found all inside is lubricated plastic. There should be little to zero maintenance, except to keep dirt, ballast and spiders out of the opening the actuator sticks out of (the yard is stored in an unheated garage). We have been using tortoise motors on our modular layout yard and started having turnouts that didn't move thinking that the gears inside needed lube. Turned out the motors were suffering low voltage. Wired with larger wire and higher capacity transformer, good to go. [:D]