The machine is more than fast enough for heat treated spring steel even at that diameter. You might want some suds but not oil as spring steel is prone to glazing, a form of work hardening the surface.

How does a person guess the load? A kilo?

In one of the Machinists Bedside Readers Guy Lautard has an article on a drilling system for hard materials that uses low speeds with standard drills but high pressure. If I get a moment I could try to find it. There was a US made tool looking like a large gee clamp, with a mandrel that had an acme screw to force it down on the workpiece. The chuck was driven by a socket from a portable drill or even manually. So maybe an alternative worth trying is to use low speed and high pressure? You would want the minimum amount of drill protruding from the chuck to minimise the risk of breakage, and use hss rather than carbide.

Not tried either of these methods myself yet but they may be worth bearing in mind for some situations.

Downloaded an old book on gunsmithing recently that is my coffee break 'browse' currently. I'm not interested in gunsmithing per-se but some of the machinists methods used are of interest to me. One thing I spotted was a method to drill into hardened parts (rifle barrels) by locally annealing the spot to be drilled. He used a small diameter carbon rod with an arc welder – and just touched the spot where he wanted the hole. Apparently the intense local heat generated anneals the area enough for it to be drilled with "normal" drills. Don't see why it wouldn't work with thinner hard materials too.

Alternatively (and I cannot find the reference) I also recall reading a method of drilling thin spring material (for loco springs) by punching it with a centre punch to form a small 'pip' which was then filed (or perhaps ground?) off – leaving a small hole which can then be opened out using normal dills. I think the usual caveats about drilling thin materials would still apply so rather than just drill it (which might work OK) I might be tempted to further (progressively) deform & grind the hole out to size with larger punches/dies. Must admit I don't relish drilling thin materials at the best of times.

Regards,

IanT

Agreed Capstan – but I think this idea is that only a small area is effected..

IanT

Most of the ones that broke did so at the transition of flutes to shank so not really sharpenable. I put the improved performance down to reduced work hardening because each edge was cutting at a different point.

With two identical cutting edges more pressure is needed to ensure that both edges keep cutting before the opposite edge comes round and skids over it. With unequally ground edges not only is it a full revolution before an edge comes up against the surface it has cut, that cut surface has changed! so it just keeps on cutting. I feel a patent coming on! (Oh dear, I've just told everybody)

Ian P

I have only ever dealt with spring steel in rod form. Is it harder to drill than stainless generally?

I have used a diamond coated point (from a cheap set) mounted in my Dremel at max rpm to make small holes in springs for model D-T timers. One good source for small sharp cutters and grinding tools is your friendly local dentist; – very good quality and they throw them away.

* Danny M *