The engine is an HO scale New England Rail Service New Haven class K-1b 2-6-0. The old coupler is a plastic KD clone with a mounting hole drilled in the shank. A .020 diameter pin goes through the shank & the holes in the cast-on scale coupler box. The new coupler is an all-metal KD #58 coupler with the trip pin cut off and the shank cut down.
The Problem: the old coupler is starting to fail - i.e. the coupler face spring has lost its, um, "springiness" so (too) often the couple uncouples unexpectedly.
The Solution: install a KD
The Second Problem: drilling a hole into that narrow, metal shank.
I started a guide hole using the point of a safety pin, so the drill bit wouldn't travel.
Yes, I'm drilling a hole. Or trying to.
I'll eventually need a .025" hole to clear the mounting pin. That's a #72 drill bit. No way can I start that "large" (too big for the guide hole), so I started with a #80 bit.
Yup - a .0135" diameter drill bit.
I used a pin vise at first, but didn't get very far before - yup, you guessed it - the bit broke.
I had another #80 bit, so I mounted that in my Dremel flex shaft and, using my variable speed foot pedal, I continued drilling.
I actually got the hole .005" deep before that bit broke. I'm actually pretty proud I got that far, considering I'm drilling metal with a microscopic drill bit. In a Dremel.
But I still have .045" to go.
And I don't have another #80 bit on-hand.
Ah,well. There's always tomorrow.
Yes, "Model Railroading is Fun" - or at least a lot more fun than bathroom remodeling or raking leaves. I'll take a couple broken drill bits over that any day.
(Btw, if any of you have any tips/suggestions for a better way of doing this, please let me know :^)