One way would be to use EDM Chris….

Regards,

IanT

looks rather like the one that Maurice Fagg of SMEE used to exhibit, I know it was at Guildford for 2 years as I was also there and had to explain it to a couple of people in Maurice’s absence – works very well, will even ‘burn’ its way thru carbide – there might well be a write up in a SMEE journal

Anneal it?

So how did they do it back in the 18th century?

In toolmaking the dies for punching are wire eroded to size an a hole is spark eroded through to allow the cut wire to be threaded. They can cut through up to 6 inch of hardened steel where I worked. You should look for someone with that capacity to spark through it dosn't take long. Look for die and toolmaker.

David

Drilled then hardened simples.

That's what I was alluding to,

Anneal, drill and re-harden.

* Danny M *

Thank you ndiiy.

That was exactly my point.

I was not trying to be rude but just wondering how 18th century clockmakers made tiny holes and maybe CTT should do a bit more homework.

I, for one, would be most interested in the results.

* Danny M *

* Danny M *

carbide tipped, whatever you use

slow speed high torque

must be a stiff setup so a short drill bit

.

Another point still not mentioned, Chris, is what the job actually looks like.

MichaelG.

Edited By Michael Gilligan on 17/02/2020 14:14:30

Drilling a hard material needs a drill harder than the material being drilled.

In the 18th century, not much choice – either the very best carbon steel they could get find and lots of patience and resharpening, or maybe carborundum or diamond. The usual method was to dodge the problem by drilling any holes needed when the steel was still soft. Hardened steel is usually worked by grinding, not by cutting.

Softening spring steel, drilling, and re-hardening is an option but making springs is skilled work. I'd want plenty of successful practice behind me before risking an antique clock, or at least an alternative if I ruined the original part. (An old time clockmaker would keep a few apprentices busy making parts. If anything broke, they'd be beaten soundly and told to do it again. Cost a fortune, which is why later clockmakers increasingly used parts bought in from specialists.)

Today we have more drills suitable for hard drilling, not cheap though! Whatever type is used, lots of pressure and cutting oil are needed. TiN coated HSS or Cobalt drills stand a chance but no tears if a few get destroyed in the process. Solid tungsten drills are perhaps the most affordable approach, but hard means brittle: thus any operator error means an expensive breakage. (A Karnasch 4mm K-Drill Solid Carbide Drill for Hardened Steels is nearly £70 from Cutwel.) Never researched the cost of really high-end drills like Boron Nitride, I guess they're even more pricey.

Spark erosion works but equipment needed and deep holes are a challenge. Acids make untidy holes.

Dave