Toolmakers buttons – type 2
These can be used rather like the traditional toolmakers buttons but can have advantages.
These buttons consist of small drill bushes. The key feature here is that the inside and outside are accurately made to size and carefully finished. They are fitted to a small arm. This arm has a slot in it so that the bush can be positioned accurately and then locked in position.
These button can be used just like the traditional toolmakers buttons. The first most obvious difference is that instead of making a hole and tapping it so the button can be fitted at a point, the hole is drilled and tapped somewhere near the point we want to make a hole. These buttons are position just like the traditional ones using height gauges, micrometers etc.
The traditional buttons can only be used on the lathe. These buttons can be used directly for drilling holes. With these buttons the inside surface actually defines the position of the hole. With toolmakers buttons the outside of the button defines the position of the hole.
With these buttons fitted to a workpiece they are more like a jig and can be used directly to drill the hole.
But what if the hole needs to be reamed?
This is exactly like using bushes in a jig for drilling and reaming.
An alternative is to use the bush to guide a transfer punch and punch a center. A hole is drilled using this center. The hole is then reamed using the bush as a guide.