welding brush leads

My hand drill stopped running today so I took out both brushes. Found they springs that push themn into the commutator where not soldered/welded on to the carbon brushes. Any ideas on how the attach the leads'springs to a carbon brush. I have seen copper plated carbon rods but I doubt I could weld/solder wires to a piece of carbon. Do motor brushes have any metal in them or are they really pure carbon like I always thought.
Bill D.
PS I have seen brushes with wire leads molded into the sintered brush block

Just go down to a well stocked hardware store. They usually hae little bins with assorted brush sizes. Chances are you will find something that will fit. If not find something a bit bigger and file to size with a bastard file or touch against the flat side of a grinding wheel.

Also most name brands of power equipment still have brushes available.

Go and get some larger power tool brushes and grind to size, bench grinder works great, file to finish.

A common way for the leads to be attached for larger brushes is to drill a hole bigger than the lead and pack in fine silver powder. High surface speed brushes are pure graphite, which comes in various hardness grades, some other brushes such as starter brushes and alternator slipring brushes contains varying amounts of copper.

Silver is excellent for conducting power into graphite, I used silver foil between the the copper clamp and a large plating anode, saved 50mV over straight copper on graphite.

The brushes I've had out all appeared to be cast/formed around a short copper braid conductor, capturing the spring between the graphite and a metal button.

ditto the HW store - the local well stocked True Value and the Sears HW store both have at least a small assortment.

Another option would be a motor repair shop.

Spring steel does not work well when its the only conductor between the power supply and the carbon brushes. Usually the resulting high resistance causes significant heating, which in turn causes the spring to loose its springiness and the brush to stop contacting the commutator.

Even my little Dremel tool has copper braid tack-welded onto its brushes.

I think I do have some brushes that fit I was just wondering how they attached the springs/wires to the carbon.
Bill D.
PS: this is a millwauke drill

Often, the wire leads go to the brush holder, not the brush. Brass brush holder makes contact with brush. also sometimes the lead goes to a tab that sits between the spring and the brush....Joe

The pig tails should be attached to the brass piece at the other end of the spring. I've only seen spot tacks at these points. If you don't have access to a spot welder, the next best thing would be to use silver solder. Low temp silver solder would probably work just fine. A jewelry supply shop will have have it in small quantities. Be sure to push and clamp the springs out of the way. Maybe wrap with a wet rag and cover with some sort of a heat shield. I believe the silver would conduct better than a spot tack. Use only enough heat (oxy-acet) to get the job done. Too much heat and the silver will start wicking along the copper braid. Good luck.

Bill D, I reread your original post. You were looking at the connection between the brush and the pigtail. If there is no hole where the pigtail has pulled out, then Joe D. is correct. The current passes from the brass brush sleeve to the brush.
If I had a brush with a pigtail pulled out, and absolutely could not find a replacement, I would glue it back into place with a homemade mixture of high temp epoxy and fine silver or copper filings. WWQ

If you're looking to replace the brushes (or other parts - drill stopping dead could be the trigger switch), try searching on:
ereplacementparts.com
or
toolpartsdirect.com

I'm not affiliated with either, but have always been able to find parts for power tools at places such as these.