Shims for packing up cutting tools

[BazyleParticipant @bazyle]

Posted by frank brown on 01/08/2014 19:42:10:

The height of the cutting edge must never be above the centre line,

The Boxford (originally South Bend) book "Know your lathe" actually recommends setting it above centre with good reason. Not applicable to watchmakeing perhaps but by setting it high it produces a component of force outwards or back along the tool that keeps the cross slide nut play taken up.

[frank brownParticipant @frankbrown22225]

I think that last statement needs a bit of clarification. Its top of page 20 and applies to an angled tool holder where the tool is pointing upwards by 20 degrees or so. The tool also needs more front clearance. This type of tool holder has the advantage that as the tool is re-ground, it can be slid forward before clamping in the holder to keep the cutting edge at the correct height – even if it is for only one diameter.

Beneath that bit is a long list of where the tool must be set at center height, so the above centre setting is less then versatile.

I think that there is a lot of mileage in those angled tool holders, because the amount of work to make them looks a lot less then with a "quick change tool holder", so they should be cheaper. The cutting edge can be reset to the correct height after tool re-sharpening. The only odd thing is that the tool AND holder must be used when sharpening tools so the angle of the holder can be compensated for. They are clearly impractical for things like boring bars. Very suitable for parting tools, if the angle of slope is the same as the top rake required (as G H Thomas designed?).

Frank

[Neil WyattModerator @neilwyatt]

A tangential tool holder and a quick change toolpost aren't mutually exclusive.

Neil

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