Pick-ups for P4 conversion of Bachmann 45xx

[mattots]

I'm a bit unsure how to proceed with making new pickups for my 45xx conversion.

As the photos show (and as I've explained on my blog), I've added new 'frame' overlays and made a new baseplate to replace the Bachmann one.

I had got as far as soldering phosphor-bronze strips to pieces of copper-clad attached and recessed into to the reverse of the base-plate, and bending these to engage with the back of the wheel rims- at least that was the plan, but on initial offering up it turned out the phosphor-bronze was too stiff (it was impeding the movement of the wheels where it was making contact), wasn't springy enough (it wasn't making contact on some wheels at all), and snapped after just a couple of adjustments.

So back to the drawing board. Maybe it's as simple as trying a different type of material for the pickups - any suggestions as to what might be better (ie. less stuff, springier, and less brittle)? Or maybe wire is preferable to strip - in which case,any suggestions on suitable wire/gauge?

Or is there another, easier method I've overlooked? (I've ruled out re-using the Bachmann baseplate/pickups).

[Tim V]

Here's mine, the originals bent out.

IMG_2132.JPG

The two wires in the middle are for attaching croc clips for programming/wheel cleaning.

[jls_s4]

I favour top pick-ups, especially with a tank loco where there is usually plenty of space above the wheels. Top pick-ups have the following advantages: they can generally be longer and therefore more forgiving: they press down on the tread helping to keep the wheels from lifting: they stay snug against the flange (flat strip is better than wire but either works) and you only have to clean the tread not the back of the wheels as well. If you put a slight indentation where the strip contacts the tread so that the protruding pip scrapes on the tread the point pressure is higher for good contact but it will wear quicker.

Good luck!

[Dave K]

Here's mine, the originals bent out.
The two wires in the middle are for attaching croc clips for programming/wheel cleaning.

Yes I've done the same as you Tim - bent out the originals on the 45xx and 8750.

By the way Tim how does your ' programming/wheel cleaning' arrangement work - look interesting.

[Tim V]

So as not to hijack the subject my reply to Dave K put elsewhere.

I am not the person to ask regarding wiper pickups, as such things belong to the old days, but it's a good idea to keep them reasonably long so they aren't too stiff. If you can't make them long enough, put a coil in the wire, so increasing its effective length.

[mattots]

The reason I've discounted using the original pick-ups and baseplate is that I've widened the chassis with plasticard overlays, as the photos show, to remove the unprototypical gaps behind the wheels. I've also cut the spring mouldings off each side of the baseplate so they can be repositioned wider apart. This means that (1) the pick-ups no longer line up with the gaps in the mouldings, and (2) I think it would be quite a job to successfully 'reconstruct' the baseplate/spring mouldings - it would require 2 'padding' strips glueing in either side between the central baseplate section (to which the pick-ups are attached) and the spring mouldings to join it all together again and I doubt it would be strong enough to withstand much handling.

One rather unconventional idea I've had is to use wire pickups bearing onto the tops of the wheel treads - not unconventional in itself, but due to the way the chassis and body are made and to avoid shorting out on the metal chassis they would have to be attached to the body (underside of the footplate and splashers) rather than the chassis, and the wires then somehow fed through to the motor. The body could then simply be lifted off along with the pickups. I can't see any particular reason why this shouldn't work - although I'd need to find a satisfactory way of fixing the pickup wires to the body (maybe drilling holes and then super-glueing into these?).It just seems 'wrong' not to have the chassis self-contained, but then I guess you take what you can with RTR conversions!!