Making sprung pickups for 4mm kit locos

[Michael Delamar]

There has been plenty of threads on pickups for kit locos, but one area has me stuck...

 

its the actual winding of wire to make the pickup a spring, may seem simple but I struggle with it, ie what diameter to wind it round, thickness of the wire and when I do try it the wire tends to crawl up the bar and its hard to keep the windings close.

 

any pointers id be very greatful.

 

cheers

 

Mike

[asmay2002]

What winding?  All the springiness you need should be in the wire.

[Wizard of the Moor]

Mike,

 

There's a good discussion of coil pickups here http://www.scalefour.org/forum/viewtopic.php?p=21164#p21164

 

I'm sure that WillL will be happy to tell you all about it.

[Michael Delamar]

thanks James, the big difference I can see is that he is using .35mm wire, which I would like to try as the phospher bronze I have, Im not sure of the gauge but its really flimsy and I struggle with it.

[Torper]

I made sonme coil spring pick-ups for a tender, unashamedly copying Will's method in the Scalefour Soc forum thread mentioned above.  The only difference was that I used 31swg (o.295mm) PB wire, probably because that's what I happened to have to hand, and it worked fine.  Eileens stock a range of PB wire - the trouble is that it comes in coils and it's a bit of a pain straightening it!

 

DT

[Michael Delamar]

wondering what the preferred diameter is to coil them around?

 

I like the idea of attaching them to a thicker rod to get to awkward areas such as where gearboxes are.

 

and making them removable doesnt seem a bad idea too.

[Gordon A]

Eileens stock straight lengths of 0.35mm p b wire.

I coil the wire around a 2mm rod / axle.

 

Gordon A

Bristol

[PenrithBeacon]

I notice that the pickups don't incorporate any insulation. I can appreciate that they are insulated from the chassis by the PCB, but is it useful to put a sleeve over the pickup wire to prevent accidental shorting?

 

Regards

[kandc_au]

Agreed.

On the same site there is an article about building a GWR Steam Railmotor:

http://www.scalefour.org/forum/viewtopic.php?f=22&t=1415

In this item it shows insulation on the p/u wires.

 

Khris

[Torper]

I notice that the pickups don't incorporate any insulation. I can appreciate that they are insulated from the chassis by the PCB, but is it useful to put a sleeve over the pickup wire to prevent accidental shorting?

 

Regards

 

I haven't put any insulation on mine, and I haven't had any problems with shorting.  The pick-up wires are well clear of the uninsulated chassis.

 

DT

[Horsetan]

....good discussion of coil pickups here

..and another version here

[Michael Delamar]

thanks men, I made them as suggested, wrapped round a 2mm drill bit while held in a pin vice, easy to wrap round when the wire is held in the chuck, I like that idea

I made frame spacers to hold them with a hole drilled in and a captive nut soldered on, then soldered the spring to some copperclad which can be screwed in, making them removable helped alot as I had them too tight at first and the motor/gearbox didnt like it and they where off and on a few times, but coiling them means you can back them off but still have good pressure, it may be .35 wire, Im not sure but coiling it gives it more strength, hard to explain and it may not look pretty under there, but it works well  I only need them on one side as the other side is live.