Soldering

Hi guys! I am trying to solder new brushes on for the starter. I have one brush all soldered up, but the second brush is REALLY giving me a hard time. No solder will stick to it.

I started just using resin cored solder which worked fine. After a while it looks like there is a lot of resin on the brush I am trying to solder. I then cleaned it with alcohol rubbed some flux onto the brush and tried using silver solder.........still no go.

Can anyone suggest another alternative?

 

Yes, you need more localized heat and plenty of flux (Non active variety) to get the little bugger to alloy correctly and flow out. What wattage iron are you using? For this application, you'll want a 40 watt at least. What size tip? You should have at least an 1/8" clad tip. Silver solder is not the way to go, tends to be cheap stuff unless you are dealing with true Silver Solder, in which case your dealing with 1,200F for correct temps, something a common soldering iron is never going to approach. Your best bet is the 63/37 eutectic solder (about $30 a spool, check out Kester), it has no plastic state. Clean the wire spotlessly, you don't want any contaminates to mess up the alloying process. Get the solder bridge established first and formost. Then, as the heat is maintained, flow on some more solder untill you can barely see the strands of the wires, then pull off. Tin the wire up before you try to attach it to the contact. Once the alloying has occured, it is much easier to get a smooth flow to happen when subsequently joining the two parts. Hope this is useful. Shout if you are still struggling.

 

For extremely difficult alloying cases I use a pinch of ground up aspirin (generic variety, no coating) to flux the stubborn surface. It stinks like witches breath but will bond solder to just about anything :-D

I'm with Robert on the 63/37, as it does not get brittle right before it solidifies.