Tuesday, December 8, 2015

Phosphor Bronze Staples

If you've been following along for any reasonable length of time then you'll know that the main area that seems to trip me up building or designing model locomotives is getting the pickups to work properly. On the Clayton loco I think I've hit on a fairly good way of fitting the pickups where what looks like a staple of phosphor bronze strip is pushed through slots in the model from the inside with the ends then bent back at an angle against the outside of the body so that they rub on the rear of the metal wheels. The problem is accurately making the initial staple shape so that it fits perfectly as that helps with setting the tension of the pickups which if not right can affect the running of the model.

On the first prototype I folded up the staples by eye and while they were fairly good they weren't a perfect fit. With the addition of the keeper plate and retaining screws this is even more of an issue as I need to make sure the pickups are flat on the inside so they can't short against the screws. To help with this I designed an etched part to act as a forming tool (it actually has other uses so you'll see this part again).

The tool works well and as you can see the fitted pickup lays nice and flat against the inside of the body so it was well worth adding the tool to the etch. Hopefully it's other use will prove as successful but you'll have to wait a little to find out.


  1. Neat. I like the fact that the pick-ups are integrated into the design and not just an afterthought.

    1. When I was doing the initial design work I made quite sure to think about the pickups really early on to try and save causing myself problems later. With the wheels so prominent and outside the frames this is even more important as there is very little space to hide the pickups, hence the staple approach I arrived at. It seems to work well in practice, especially now I have a sensible way of forming the right shape before fitting them to the body. The proof will of course come when I try and wire everything up.