Boring vs Reaming

Bore it!

Turn up a go-no gauge as in the book and you'll be fine.

Made mine probably twenty+ years ago an it's one of the most used tools in the workshop, mainly for tapping.

The original GHT handle was not at all user friendly so I made up my own.

Forget the sensitive drilling attachment as more modern alternatives available now.

For tiny taps the original Eclipse chuck works well.

For bigger taps, an ER11 collet chuck which can pass through the arm with the nut removed.

For even bigger taps a Jacobs chuck with a bayonet to disconnect the handle so it will pass through the arm.

Nice work Peter, tapping is the main objective of my build. The ER11 route looks an interesting option.

Boring versus Reaming? They're not deadly enemies, surely both are valuable.

My take on reamers is they are the fastest way of finishing a hole to an accurate size. Step one, drill or bore an ordinary hole, close but not particularly accurate or straight. Step 2, apply reamer to finish hole accurately.

Boring can also produce accurate holes but it takes longer and needs more skill, especially measuring the bore and not overshooting. Peter mentions 'no-go' gauges, a good way of speeding up. A big advantage of boring is the hole can be of any size whatever - it's not limited to standard reamer sizes. And big reamers cost big money!

My old book on high-precision work using buttons and other tool-room techniques to make jigs, fixtures and gauges doesn't mention reamers at all. Straight holes with precise diameters positioned at exact X,Y locations are bored, not reamed. I guess a tool-maker would still use reamers and other ordinary methods for any part of the job not needing high-accuracy?. However, this book shows ultra-accuracy was done by boring very carefully and checking with calibrated measuring tools.

It's an interesting book, but I've never had occasion to use any of it's methods - they take more time, concentration and skill than I have, I don't need that level of accuracy, and I don't have any way of measuring the results. My tool-box can't realistically guarantee better than ±0.02mm. Unless I use a reamer!

Dave