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 -- _________________________ Website: http://www.overspianos.com.au Email: mailto:ron@overspianos.com.au _________________________
This PTG archive page provided courtesy of Moy Piano Service, LLC