Cobalt iP digitals with approx. 10cm piano wire throw wire

I would try the 10cm wire first and check how firmly the switch rails are held against the running rails. The danger is that they are not held firmly and will move under a passing train to derail it.

If that is not reliable, you could use DCC concepts right angle adaptor
Cobalt Right-Angle Adapters w/Mounting Hardware (3 Pack)

This allows you to turn the motor on its side. It is intended for mounting under the baseboard to reduce the depth it needs. The reduced depth means the cavern you need to carve in the 40mm foam is shallower.

You will be able to use the alternative mounting holes to attach the motor to the top of the ply. You will have to reverse the wires on the angle adapter so that it points upwards away from the baseboard. As delivered the actuating wire is facing the mounting surface which is fine for an undermounted motor but you will be overmounting and need the opposite direction. As everything is secured by machine screws, alteration is not difficult.

David

Hi and welcome.
Reading through, I wonder quite how the original 9mm Ply came to warp. You mentioned that it was set on a wooden frame, which got me to wonder if it was the frame, rather than the Ply, which caused the warp.

That being as it may, the question you asked was about the length and flex in the length of the operating rod. Given the measurements of the various layers and the desired maximum of 7cm in length, it should be possible to let up into the 40mm foam board by 20-25mm and fix the motor mounting board there. You could cut even further, if you like, for a shorter operating rod.

Alternatively, you could cut a rectangular hole straight through the 40mm foam board, enough to allow for the iP Digital to drop through. Small, 5mm width x 6mm deep, shelves, might be cut either side at the top of the hole, to let in two ends of the motor mounting boards. That would give approximately 57mm length for the operating rod, so you could keep to the one in the pack.

Wiring sockets should hang clear of the underside of the foam board, to connect them.

Julian

A couple of baseboard ideas that may be of interest to you, if you haven't yet started them.

I have a 4ft shunting game made by by reinforcing 40mm foam, which when supported at either end and stood on, [10st 11lb], it moved 1mm and it can't warp. It's simply a sandwich with 3 Ply top and bottom. The ply doesn't have to cover the whole sheet of foam, just match some lengths above and below - in logical places. The foam then acts like millions of tiny struts between the ply lengths, like a girder bridge. I have a picture of the underside, to illustrate a channel for electrics and point motors etc.



Re. ply baseboards, they are commonly made of all ply structure, like the WWII Mosquito. Probably the most accurate way is to buy them in kit form, laser-cut, ready to glue, accurate and no waste. These are from Tim Horn, who was very good and can do CAD designs to suit your needs, there are quite a number of firms doing them now. Again they are warp proof, light and very tough. [6mm top & sides, with 3mm perforated, braces & importantly, no softwood to warp.] The shapes also give plenty of room / support for electrics, points etc.





Julian

Some great replies and ideas! Thank you dwb, Julian and Norman!

Re the plywood: No, it definitely isn't the frame. Being a bit new at this, I bought really overly thick wood to build the frame (3.5 x 9 cm cross section) and it is very straight and sturdy. The first 9mm ply I bought was already a bit warped, maybe arcing up 4 cm in the centre of one end, but I assumed that pinning/glueing it down would keep it flat*. It did at first, but a few months later there was a very noticable bulge at one end of my board. Worrying it would keep getting worse, I removed it. It's now sitting on my scrap heap outside, where that bulge is at least 10 or 15cm depending on the time of day. (In retrospect I wonder if sealing it only on the upper side constributed to the worsening bulge.) Anyway, I replaced it with another sheet of 9mm ply that I made sure was 100% flat down to perhaps a few mm distortion. I chose to screw it down this time (given how hard it had been to remove the last one), and not seal it at all, but again, a few months in, it began bulging up in the centre of one of the ends...

Maybe it's just that the quality of the ply is just bad. (I sourced it from the same place.) Or I've just been really unlucky. I really don't know. What I do know is that sourcing it and sizing it twice has been quite expensive. And that now, with the XPS everything is super flat, and as a very considerable bonus, is a tiny fraction of the original weight. In all, I'm pretty happy with the switch. So far!

(* Almost forgot the countless YouTube videos I sat through claiming that wetting ply on one side and letting it bake in the sun on the other would straighten it - it does, but only for a few hours. Once it's warped, there is certainly no way of straightening it that I know of that doesn't consist of adding so many cross-members that you might as well just pin it to a solid surface, defeating the whole point.)