Non Tapered Bridge Pin Holes

[John Arnold]

I would say the truth is that Martin uses a slightly smaller drill bit to drill though the top and bridgeplate.
When I make a bridge, I drill it the smallest size, and use the same drill when I drill through the top. The result is a straight hole that I then ream with a 5 degree reamer.
Instead of measuring the holes, I suggest measuring the bridgepins. Standard Martin plastic bridgepins have been close to 5 degrees since 1930.

[Victory Pete]

Originally Posted by John Arnold

I would say the truth is that Martin uses a slightly smaller drill bit to drill though the top and bridgeplate.
When I make a bridge, I drill it the smallest size, and use the same drill when I drill through the top. The result is a straight hole that I then ream with a 5 degree reamer.
Instead of measuring the holes, I suggest measuring the bridgepins. Standard Martin plastic bridgepins have been close to 5 degrees since 1930.

Yes, that would explain my belief that the holes had a taper. Thanks

..........

[Victory Pete]

Originally Posted by Todd Yates

From post#16.

Yes I see this, sorry but I tend to believe representatives from the company initially. If you could have provided some sort of an explanation it would have helped. In the end I ultimately have faith in myself, as I did indeed determine that they were not 5 degrees taper and I was fooled into believing it was a 3 degree taper due to the 2 different size measurement of the holes.

[murrmac123]

Mods, please close this thread .. it makes my brain hurt ...

[mirwa]

Originally Posted by Victory Pete

After many e-mails to Martin, they now say that they do not taper their holes.

Interesting, I am a Martin warranty repairer and was unaware of that info.

I just pulled out a brand new 12 string Martin in for repair (snapped headstock) and I can confirm the pin holes look pretty straight.

Steve

[Victory Pete]

Originally Posted by mirwa

Interesting, I am a Martin warranty repairer and was unaware of that info.

I just pulled out a brand new 12 string Martin in for repair (snapped headstock) and I can confirm the pin holes look pretty straight.

Steve

What info are you unaware of? That they said they are straight holes? Apparently the holes are straight but may be stepped, bridge hole itself is slightly larger than the top and bridge plate hole, which gave me the impression they were tapered.

[JonWint]

I measured the pin holes on a dozen new (never installed Martin bridges) I have. The holes are drilled completely through the E holes and partially drilled on the others.

All holes (parallel sides) vary from 0.185” to 0.195” diameter. Bridges include belly and pyramid; Richlite, rosewood, and ebony. When installed, I ream for 5 degree pins. I believe that a continuous taper results if you use the appropriate, smaller diameter bit through the top and plate.

[mirwa]

Originally Posted by Victory Pete

What info are you unaware of? That they said they are straight holes? Apparently the holes are straight but may be stepped, bridge hole itself is slightly larger than the top and bridge plate hole, which gave me the impression they were tapered.

I was unaware that Martin just drilled straight pin holes.

Having checked one of the New guitars here, that is correct.

There is also a small step in the pin hole to the bridgeplate and top.

Steve

[LouieAtienza]

Originally Posted by Victory Pete

After many e-mails to Martin, they now say that they do not taper their holes. The 3 degree taper I measured can be explained by the fact that the bridges are pre drilled before gluing to the top. A drill is then used to drill through the predrilled bridge and through the top and bridge plate. I have measured numerous times that the size of the bottom of the hole is less than the top. This is because even if the same size drill is used for both bridge and the top that slightly different size holes can appear. The bridge being ebony would tend to have a larger hole than the softer spruce and maple which may not be cut so cleanly, also the bridge hole has a drill go through it twice making its size slightly larger. The truth is all I am looking for here. So anyway I have modified my D-42 and HD-28 with the fish glue method and they both seem to sound better because they both now have 5 degree tapered holes and matching bone pins.

It's also possible that because their bridges are CNC cut, they may helix down (helical interpolation) with a smaller endmill that may also be used to slot the bridge, which could cause a variation when the bridge is glued down and holes drilled through the top.

[Victory Pete]

Okay, thanks for the helpful relies, now we are getting somewhere.

[Victory Pete]

I replaced the tiny Waverly tuners on my Western Classic with Grover Imperials and put on new strings. This guitar, which was always a bit too bassy is now absolutely perfect. It is well balanced with nice treble and midrange. Even with the old strings the mod proved itself, but now it is just an overwhelming improvement with the new strings.

[Victory Pete]

Doing the fish glue mod to my Martin D12-28. Because the bridge is so high and thick on this, I am not sure if the glue is needed. It is possible just reaming the stepped holes will provide the desired taper and tight fit for the bridge pins. But it seems too close to be sure so I think I will proceed.

[Victory Pete]

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