Locating pins for bridge plate

[Dave M]

I didn't feel that the steel pins were very secure in just the 2 to 3 mm of the top material when gluing the bridge plate down so made some space in the dished workboard for the pins to sit properly through the top.
I did feel much happier with this arrangement.

[kiwigeo]

Dave, I always drill the holes through into the dish. I draw a line through the holes and that becomes a reference to allow correct lining up of the top in the dish.

[Trevor Gore]

A couple of points:

I draw a line through the holes and that becomes a reference to allow correct lining up of the top in the dish.

If it's a spherical dish, it doesn't matter where the top is on it, for most applications.

I didn't feel that the steel pins were very secure in just the 2 to 3 mm of the top material when gluing the bridge plate down so made some space in the dished workboard for the pins to sit properly through the top.

Things can get real secure, real quick (well, once the epoxy has set...)

I always put a double layer of waxed paper (yes, one layer isn't enough) under the soundboard where the holes are, so the soundboard doesn't get glued to the dish if any epoxy leaks through (which it can do). With the pins in (clearance) holes in the dish, it's hard to get that safety, because they'd punch through the paper, running the risk of gluing the pins in the dish (clearance) holes and the soundboard to the dish. Also, I only drill 4 holes. A couple of reasons for that. Two less holes to leak/get pins stuck in etc.. Also, when it comes time to locating the bridge, if you have some minor adjustments to make (I'm talking 0.5mm type adjustments here) you can get the bridge exactly where you want it, clamp it, and drill the outer two holes. They can then be used for doweling the bridge when you glue it down. The other holes get "straightened out" when you ream for bridge pins.

[kiwigeo]

If it's a spherical dish, it doesn't matter where the top is on it, for most applications.

True....but when youre anal like me it just has to sit in the same place every time...because it just has to

[Dave M]

Ah Ha. That very point has been puzzling me - why only four holes. Thanks for clearing that up. The ability to do an adjustment would take some of the tension of that whole measuring/layout thing for the bridge.

I did use waxed paper, making only small holes in it so the pins were a tight fit, but I do accept that the risk is there.

[kiwigeo]

I always put a double layer of waxed paper (yes, one layer isn't enough) under the soundboard where the holes are, so the soundboard doesn't get glued to the dish if any epoxy leaks through (which it can do). With the pins in (clearance) holes in the dish, it's hard to get that safety, because they'd punch through the paper, running the risk of gluing the pins in the dish (clearance) holes and the soundboard to the dish. Also, I only drill 4 holes. A couple of reasons for that. Two less holes to leak/get pins stuck in etc.. Also, when it comes time to locating the bridge, if you have some minor adjustments to make (I'm talking 0.5mm type adjustments here) you can get the bridge exactly where you want it, clamp it, and drill the outer two holes. They can then be used for doweling the bridge when you glue it down. The other holes get "straightened out" when you ream for bridge pins.

A coat of paste wax on the pins helps too.....Im pretty sure this is mentioned in The Books.