Why "countersink" endpin holes?

[GardMan]

I was on the way back from the pet store (buying worms for one of my amphibians), and stopped into a guitar shop ("The Guitar Czar") here in SLC to look for a humidifier refill (unsuccessfully). Walked to the back to see what was on the acoustic wall... and was pleasantly surprised to see a new (Tacoma) D-55 and F-412 (along with an unknown GAD jumbo). I was in a rush, so I didn't ask to give them a spin...

Some of you may recall that when I got my '92 D-55 off eBay, the trim around the end pin hole had been reamed out a little... like it was countersunk. I thought this was due to some damage from the original owner, so I had a custom rosewood pin made to cover the gap between a normal endpin and the ivoroid trim. Imagine my surprise to see that both the new D-55 and F-412 had the same "countersunk" endpin holes . Does anyone know why? Would it be to keep bumps to the pin from cracking the ivoroid trim? or to keep the trim from chipping out if the endpin hole is drilled out for a jacK? Should I be concerned that my oversize rosewood pin might damage the trim?

 

[bluegrass jubilee]

The answer is two-fold really. First, most bridge pins have a little rim below their head that when countersunk, sits nicely into. But I believe it has more to do with getting the proper break angle of the string over the saddle. On some guitars, you'll even see little slots cut up at the front of the pin hole to help reduce binding and acheive the break angle.

 

[The Guilds of Grot]

I think he was refering to the "endpin" where you hook your strap on to the bottom of the guitar.

 

[GardMan]

Yes, it was the end-pin (strap pin) hole I was referring to ("to which I was referring?")... but I did notice that the bridge pin holes on the new Guilds were also "countersunk," or recessed. I can see how the latter might improve the break angle... much the same as notching a ramp in the bridge.

I still don't have a plausible reason for countersinking the end-pin hole... not very attractive, IMO.

 

[hideglue]

...or to keep the trim from chipping out if the endpin hole is drilled out.... ?

Hi GMan,
Bingo!

Well, the finish would chip out far quicker than the trim itself, but yes
this was (most probably still is) certainly the biggest reason. The size of the endpin hole was initially dictated by the size of the hanging hook used in Finish (spray booth, dry room, etc). Usually that hole needed to be enlarged, either due to finish build-up or hook size, to accomodate the endpin or jack.

 

[GardMan]

Thanks, Hideglue!

 

[bluegrass jubilee]

d'oh!

*has senior moment*