Pin depth.

[Overs Pianos]

Roger, David and list,

While we choose to file finish our bridge pins, we still drill them 
to a uniform depth when drilling. We use a custom depth stop which is 
attached to the drill flute with a small hex key set screw. The stop 
is turned from free machining brass and the end face which meets the 
bridge cap is chamfered to 20 degrees to match the angle of bridge 
pin inclination. The chamfer prevents the stop from damaging the 
bridge cap

If anyone would like to see a line drawing of our depth stop, please 
email me using the link below:

mailto:ron@overspianos.com.au?subject=bridge_pin_drill_stop

When we drill the pin holes, we attach a bubble gauge to the drill to 
ensure that the pin inclination is accurate for all pins.

The holes are drilled to a depth of 19 mm. Several years ago we 
repaired a Chapel grand with bridge pins which were inserted to a 
depth of only 16 mm. Although the bridge cap was made from European 
red beech, considerable movement was evident.

Prior to inserting the new pins, we grind a fine lead angle where the 
side of the pin meets the swaged point. There is often a small burr 
on the pin at this point which can damage the hole during insertion. 
It is most important that the pin is firm in the hole right to the 
top of the bridge cap - a burr on the pin would ruin any chance of 
achieving this.

Regards,

Ron O
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Website:  http://www.overspianos.com.au
Email:      mailto:ron@overspianos.com.au
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