Hi - Looking for a source of small copper compression springs. I need copper so I can solder a wire to the spring. For prototyping the spring could come from a ball point pen. Any help appreciated -

 

You can solder iron/steel also. But it could be that your springs are covered/plated with some alloy that need to be filed/grind down before you solder. It could be that your spring is nickel plated
Edit
On second thought. I am not sure steel can be soldered with electronic solder. But I know for sure iron can be soldered with electronic solder. A problem may be to transfer enough heat from the solder iron to the spring. To get a proper solder

 

You might inquire from this company:
http://www.leespring.com/materials.asp

A blurb from the lower part of the page:

Nickel Plated Music Wire and Silver Coated Beryllium Copper
Lee Spring manufactures its unique line of Battery Springs in a choice of nickel coated music wire or silver coated beryllium copper.

Since most alkaline batteries have nickel coated containers, a nickel coated contact is suitable. The use of similar materials removes the possibility of galvanic corrosion and aids in wear resistance. Nickel will also tend to wipe and aid in breaking down the oxide that can form on the battery contact surface. In addition, a nickel coating will provide general corrosion resistance and is a good conductor of electricity.

Beryllium copper is among the hardest, strongest, and most wear-resistant of copper alloys. Silver coating further enhances electrical and thermal conductivity. The electric conductivity is 65 to 70% that of copper, and the strength and fatigue resistance are comparable with higher beryllium alloys. The light silver-plating allows for easy soldering. Beryllium copper is corrosion resistant in various environments, and is both non-magnetic and non-sparking.

The silver coated beryllium copper will be the easiest to solder to, and you will lose little in the way of conductivity over pure copper. Pure copper is a poor material to make springs from, as it is too soft.

Springs made from other materials will have poor conductivity, resulting in power dissipation/power loss in the spring.

You may find that it's easier to simply use a steel spring that presses on a small circle of copper with a flexible stranded or braided wire soldered to it.

 

Great info thanks guys -

 

The springs used in small electric motors for the brushes may work for you. Most times they are made of brass and conduct electric well and can be soldered. You don't say where your from, but, if you have a hobby/RC car shop in your area, they will have replacement motor brush assemblies to chose from.

 

Note, beryllium copper is safe, but if machine the metal the beryllium part is highly toxic. The dust will do permanent damage to your lungs, and possibly worse.

 

Saw these last week...

http://www.goldmine-elec-products.com/prodinfo.asp?number=G18542

4/$1.00

 

The springs in better quality fuse holders are also an option.

 

Saw these last week...

http://www.goldmine-elec-products.com/prodinfo.asp?number=G18542

4/$1.00

I broke out with a big grin when I saw the image - it's painfully obvious that the surface metal is NOT copper! I have to wonder what genius called them "pure copper" springs?

 

They look like brass springs.

Note you can copper plate steel (copper can be done with something like copper sulfate and an acid, IIRC); then it's easier to solder to steel. Another way is to just use an acid core solder and make sure you clean off the flux thoroughly.

 

I broke out with a big grin when I saw the image - it's painfully obvious that the surface metal is NOT copper! I have to wonder what genius called them "pure copper" springs?

Just remembered seeing them, wouldn't think a pure copper spring would be too 'springy', and would tend to break easy. Personally, I'd scrounge something up around the house. Spring out of a retractable pen, probably. Depends on how many the OP is looking for, just figured this would be a potential source, if several are needed. I'm sort of looking for a springy solution for using cellphone/camera lithium batteries in other projects. Copper would be a poor choice, gold plated ideal. Sort of worked out an idea using pin headers, but didn't really line up well with the battery terminals, little longer would have been nice too. Did notice that the plastic spacer moves when heated, so might try again sometime.