more help needed

Yes, if your drill press isn't making a mark on it, you could soften the steel by heating it past magnetic and then letting to cool slowly. It will still be harder than mild steel however even after annealing like that. You might also just need to sharpen your bit or buy a new one.

While it's hot, you could also punch a hole instead of drilling it.

You could use a carbide drill - one made to drill steel, not a "concrete drill". I drill holes in allhard hacksaw blades that way.

The ones to drill concrete will work if you sharpen them. Not as well, but will work.

Dan

You can try a cobalt drill bit. They are less likely to shatter than carbide drill bits.

Welding a leaf spring is really not recommended. If it is trapped inside the bundle, it might work.

You will need to double bevel the joint. That means a groove on both sides. Warm the ends up to the point where motor oil smokes if dripped on the steel (about 500 degF)

Weld with 7018 rod or MIG. Tack one side, weld the other side, then weld the tacked side. That should keep it kind of straight. Let the weld area cool slowly by burying it in sand, powdered lime or wrapping it in an old wool blanket. Then grind off the weld bead so the leaves will stack correctly.

Yes; sort of :-) I've resharpened them and used them to drill stuff when there was no alternative, but I wouldn't recommend them as ideal.

With a little reshaping of the carbide tip - easily done with a cheap diamond disk in a Dremel - they also make handy boring bars for use in a lathe or mill.

-- Peter Fairbrother

Diamond core drills come in two main types, ones which cost about $5 and ones which cost about $25. The difference is in how the diamonds are attached, in the cheap ones the diamonds are sort-of glued on, in the more expensive ones the diamonds are embedded in the metal.

The cheaper ones will most likely cut a leaf spring, though they have to be used carefully as the attached diamonds may break off in lumps, and they are pants for interrupted cuts; the more expensive ones definitely will cut a leaf spring.

Use in a drill press, high speed, lots of water to cool and lubricate. You can use a clay or putty dam for the water, but no water = bye-bye drill. It's more a grinding action than a cutting action.

Note I am talking about diamond core drills, not diamond-coated twist drills, which are different (the latter are used for cutting abrasive, but not necessarily hard, materials).

Ernirwe would know most about that, but maybe try and find an unbroken one in a scrappy rather than welding?

-- Peter Fairbrother

The carbide used in the locally available concrete drills has always seemed very soft (for carbide) to me and I've had good luck sharpening them on a normal bench grinder.