EQUIPMENT

Winding Machines:

The basic thing you'll need is a winding machine of some sort. A winding machine is something that will pull your wire around and make it coil up into a spring shape. What kind of winding machine you'll need depends on what size wire you'll be working with, and also, how many springs you want to make.

If you want to make more than about 50 springs of one kind, it'll probably be worth your while to have your springs made commercially. You can find out about how spring factories operate: the Addendum also has a list of spring shops that have a Web presence. You can also find spring shops in your area by consulting the phone book.

Light Wire:

For light wire (.003-.025") extension springs, you can use a hand drill mounted in a vise. A variable-speed drill is best: set it on the lowest speed you can.

For light wire torsion springs (up to about .125"), you can use a hand winder:

For light wire compression springs and for medium wire (.025-.187") springs of all types, you should have a lathe. For wire bigger than about .187", you'll need a lathe strong enough to pull the wire: for compression springs in all sizes of wire, your lathe should have a back gear and a working lead screw.

Your lathe doesn't have to be a precision machine. In fact, the heavier the wire you want to work with, the better it is if your lathe is a piece of junk. All it has to have is a working motor, a tool post (for compression and torsion springs), and a reliable back gear, and, also for compression springs, a variable-pitch lead screw.

Other than that, it can be as sloppy as you want.

Wood lathes, by the way, may work for light extension springs if the tooling can be made to fit.

Grinding Equipment

You'll need a grinding wheel for several purposes. The best kind is a double wheel, where you can have a grinding wheel in one side and a cutoff wheel on the other. Metal trades suppliers can sell you the wheels.

For all springs, you'll have to be able to cut away the waste wire from the ends of your springs. You can do this with wire cutters (for wire up to about .062"), with a cutoff wheel, or with an acetylene torch. (One note: an acetylene torch will not be effective on large-diameter stainless steel wire.)

For compression springs, you may want to have the ends ground square with respect to the body of the spring. You can do this with an abrasive wheel. For heavy compression springs, you may need a bigger grinder: a small grinder will take forever.

Also for compression springs, you may want to deburr the inside and outside of the ends after grinding. You can do this with a conical grinding stone mounted in a drill (for the inside) and a regular abrasive wheel (for the outside).

You'll also need a grinding wheel to make some of your tooling: most of the tooling you'll need can be made rough, and a grinding wheel will work just fine.

Finishing Equipment

After you've wound your springs and formed the ends, you'll need to get rid of the stress that bending the wire has caused. To do this, you need an oven. How hot your oven needs to go depends on what material you use for your spring:

Oil tempered wire, music wire, and 302 stainless	500 degrees
17-7 stainless and chrome silicon	650 degrees
Chrome vanadium	750 degrees
Most exotic materials	>850 degrees

It's probably best not to use your kitchen oven for oil tempered wire, chrome silicon, or chrome vanadium. The wire will come coated with oil, which will burn off in the oven. If your oven won't reach the temperature you need, find a potter who has a kiln you can use.

For stainless steel wire, you'll also need a passivating tank to remove the chemical coating on the wire. This is a tank made out of stainless steel (an old sink is fine) and filled with acid.

If you want your springs to be plated, send them out to a plating shop. Don't try to do your own plating unless you're already in the plating business.

Hand Tools

You'll need some basic hand tools:

• A vise (either floor- or bench-mounted)
• Wire cutters (6" diagonal)
• Needle-nose pliers
• Calipers (if dimensions are critical)
• Tape measure (if dimensions are rough)
• Crescent wrench
• Acetylene torch (if working with wire over about .250")
• Bolt cutters (for wire between .080-.250")
• Round nose pliers (for forming the ends of torsion springs)
• Chalk

Testing Equipment

Depending on what kind of machine your spring is going to work in, probably the best way to test a spring is to make one and see if it does the job. Other than that, here are a few ways to perform rough testing on springs.

To test extension springs, you can always hang the spring from the ceiling and load it up with weights on the other end.

For medium-sized compression springs, you can made the spring act as a limited-travel extension spring (see extension springs for how to do this) and test them the same way. This method will not work for light or heavy compression springs — just medium ones.

I don't know of a simple way to make a really accurate testing rig for torsion springs: best bet is to just plug it in and see if it works.

Tooling Stock:

To make the tooling you need, you should have some pieces of flat stock (mild steel) and some bar stock. You'll get the idea of what kind of stock you'll need for your tooling as you read the section on tooling. You can find this kind of stuff at your local scrap dealer or junkyard: they usually sell it by the pound.

You'll also need arbor stock (an arbor is the bar or pipe you use to wrap the wire around to make the spring). Once you know what size arbor you need, visit your local scrap yard: it doesn't have to be pretty, but remember, it does have to be long enough.

If you're working with heavy wire, you may need a welding rig to make your tooling safe.