boring head and tools

[Clive FosterParticipant @clivefoster55965]

When it comes to assessing boring tool cutting tool angles and clearances I found it useful to spend a few minutes with the CAD program drawing a set of circular arcs of different radii with a boring tool shape having appropriate angles for cutting and clearance touching the inside.

Having always found visualisation of boring tool clearance angles a bit of a blind spot its really handy having a simple diagram to look at. For some reason I was never able to "get it" from a simple table of angles and minimum hole sizes although its exactly the same information in a different format.

For smaller holes the tool always seems to need a sharper clearance angle than I feel it ought to need.

Clive

[Howard LewisParticipant @howardlewis46836]

Running a Boring Head in reverse, I would expect it to unscrew from the arbor.

Looking vertically upwards, on the end of the spindle, a Vertical Mill running forward rotates in an anti clockwise direction.

Viewed from the toolpost or tailstock, a lathe runs forward in an anti clockwise direction.

So, in both cases, if the tool is mounted perpendicular to the body, (parallel to the axis ) of the Boring Head, it will cut normally if used on either machine.

When the tool is mounted perpendicular to the axis of the Boring Head, to bore a large diameter, the normal tools are not suitable.

For this disposition, it would seem that the solution is to make up a tool holder, with an angled bore for the toolbit, so that the cutting edge is beyond, and below, the end of the holder. Into this angled hole, is fixed a toolbit, probably round, ground to suitable angles to cut when rotated in the forward direction.

In this way when a n existing hole, at the normal maximum of the Boring head, needs to be enlarged, the task can be performed.

Howard

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