Step one is to remove at least one of the roll pins. Which are installed flush with the opening in the vent assembly. No way to grab onto the roll pins. Since roll pins are hollow, maybe thread something into the end of the pin and use that to pull the pin out? Nope. These pins are 1/16″ in diameter and I didn’t have anything small enough to thread into the tiny hole in the center of the pin.
If the pin wasn’t installed deeply enough into the vent body to bottom out in the hole it might be possible to drive it in far enough to clear the vent assembly wall. A few minutes of careful tapping with a pin punch and wiggling the vent body and it popped out.
The bad news is that this left so little of the pin sticking out that I couldn’t remove it from the vent body. After an hour or so of trying different things it became clear that the only way to do this was to drill the pin out.
This could be done on either the milling machine or the drill press. I have direct access to the drill press. Getting to the milling machine would require a round of Shop Tetris to gain access to the mill, removing the mill cover, and installing the needed tooling in the mill. Drill press it is!
Chuck a 1/16″ cobalt drill bit into the drill press. Clamp the vent body into the drill press vise. Carefully center the drill bit over the roll pin. Tighten the vise down so it can’t move. Start drilling.
The drill easily removed the roll pin. I noticed that the runout in the drill press is more noticeable than usual. Not a problem with the 1/4″ to 1/2″+ drill bits, but I need to be careful with this 1/16″ bit. The hole is almost deep enough… Carefully apply pressure to get the last bit of depth in the hole.
A quiet almost innocent sounding Ping.
Yup. Managed to break the drill bit. Pull the vent body out of the vise and examine the damage. Worst possible outcome: not only did the drill bit break, it broke off below the surface. No way to grab it and pull it out.
Recall that initial observation about broken bolts. This was much worse. Normally you can find a way to remove a bolt. Common approaches include welding a nut to the broken bolt, using a bolt extractor, or carefully drilling it out.
None of these will work here. Can’t weld a nut to it – the drill bit is only 1/16″ in diameter and broken well below the surface. No way to machine it out either – this cobalt drill bit is the hardest thing in the shop. The only things that could touch it are carbide or diamond, and I don’t have either.
This is where you scrap the part and get a replacement part or start over.
After examining many possible ways to deal with the problem it became clear that the best approach involved heavy drinking. The second best approach was to machine out the vent body around the broken drill bit until enough was exposed to grab and pull out.
This would cause a lot of damage to the vent body. But at this point there was nothing to lose.
To be continued…