How easy/difficult enlarge 2.5mm pivot hole to 3mm hole

rpardz · **on:** November 30, 2020, 03:29:28 PM

Hi all,

I'm new here, I've been reading a lot on the forum about modifying SAKs. I want to try replacing the pivots on a 93mm alox with torx screws.
I was wondering how easy/difficult it is to enlarge the 2.5mm center spring hole to 3mm? I don't have a drill press, but I was planning on purchasing 3mm carbide/diamond bits. Is this the right strategy?

Many thanks,
Rob

ddogu · **Reply #1 on:** November 30, 2020, 08:52:02 PM

I humbly suggest using a step drill bit instead of a regular one.

Fuzzbucket · **Reply #2 on:** November 30, 2020, 10:20:18 PM

I find using those little diamond ball drill bits on a Dremel or Dremel like tool work best... and with the least amount of skill or concentration.

hiraethus · **Reply #3 on:** November 30, 2020, 11:07:36 PM

The SAK springs are hard and will work harden quickly and blunt your drill if you're over-cautious. TiN coated HSS drills will work in a drill press with plenty of coolant. Cobalt is good too. Carbide in a hand drill would be OK if you've got a steady hand, but you'll get a better finish with a pillar drlll/drill press. Carbide is brittle so be careful not to snap it.

Diamond or carbide in a Dremel is good too if you're not doing lots of drilling.

I've never seen a step drill with a minimum size of less than 4 mm, but I don't think that they would be a good choice for this op.