In case my 16mm musings made folks fear I'd been loosing interest in the P4 I wanted to show you that I used the last few days to make some more uncouplers for Alex Jackson couplings. I thought I'd put some pictures on here to show what I'd been up to.
The uncoupling magnets are made from two 3D printed parts with a plastruct tube insert, that gives a freer sliding movement that just making the 3D printed 'plunger' fit directly in the hole. The printer is not particularly well tuned at the moment but good enough for government work.
The plastruct sleeve is stuck into the main part and a 6mm diameter x 2mm thick rare earth magnet is stuck on the top of the plunger. I usually put a second magnet on top to give extra oomph but this sticks under its own magnetism.
The servo arm is extended with a length of wire which goes through the hole in the plunger. The wire has a little bit of spring which helps.
The complete unit ready for installation.. The sleeve sticks up by just a bit less than the thickness of the baseboard plus the thickness of the cork underlay.
The plastruct tube is a force fit into an 8mm hole so I drilled a hole in the track bed between the sleepers. I start off with a 2mm drill and then step it up until I get to the required 8mm, a bit of sanding cleans up the hole underneath. The uncoupler can then be installed by just pushing into the hole. There are a couple of holes for mounting screws in the base but I can fit these later.
The plunger bit is on one corner of the part which means that it can be easily rotated to avoid other stuff like turnout operating mechanism, track feed droppers and baseboard bracing.
The unit is tested prior to making good the hole in the ballast. This Hornby Horse box has been fitted with the Lanarkshire models Jackson coupling dropper http://www.lanarkshiremodels.com/lanarkshiremodelsandsupplieswebsite_174.htm
When the servo moves the plunger to the 'up' position the top of the magnet can been seen which pulls down the soft iron loop on the coupling.
I stick a piece of grit paper over the hole and cover it with a thin layer of ballast, I've user ash ballast so I can see where the uncoupler is positioned. I'll weather it down so it is less obvious to the eye that isn't looking for it.
And it still works.....
If anyone wants the .STL file I'll stick it on Thingiverse.
I've now fitted 4 on one baseboard over the weekend, I'll try and make a video of shunting over the next few days.