Lever caps as used on my No 98 and Norris styled mitre planes
No 98 lever cap part machined
When the castings come back from the foundry there is still a lot of work to be done before I can even think about polishing. This involves flattening, and determining a datum – usually the centre line of the thumb screw. Then everything is lightly over machined to remove some of the unwanted texture and draughting (this is a taper to aid release of the pattern during moulding).
Drilling and tapping for thumb screw (14 tpi square thread, the traditional Norris style).
Retaining recess for removable lever cap. This lever cap remains captive for more than 2 revolutions on the thumb screw before it can be extracted.
Lever cap showing its retaining recess complete.