Truss rod slot and spot facer question

Joe Desperado

Senior Member
Joined
Aug 18, 2009
Messages
148
Reaction score
107
Doing a 50s Gibson style build and had a couple of questions. For some reason when someone on this forum posts fractions, they display as weird characters with a hashtag etc. so I couldn’t decipher some sizes and depths.

For the 50s style straight (as opposed to curved) truss rod depths, how deep are you guys going at the nut and then at the tenon? I see Tom B’s post with a jig to accomplish this rake but couldn’t make out the dimensions.

For the truss rod cavity, I have seen two different size spot facers used. 5/8 (,5625) with no spacer under it when being drilled and 3/4 (.750j with an 1/8 spacer under it. It seems this comes to the same depth, but a slightly larger opening. What are you guys using? When repairing vintage 50s guitars of different manufacturer, I have seen both wide and narrow openings.

Recommendations on where to purchase the spot facer in the US?
 

pavel

Gold Supporting Member
Joined
Dec 17, 2009
Messages
70
Reaction score
38
Hello Joe,

I'll make sure this doesn't turn into fraction glyphs :). I'm not the definitive authority on vintage measurements, but I believe you want these measurements:

Straight neck channel: Nut 1 / 2 in, heel 5 / 8 in
Spotfacer 3 / 4 in

I got mine on yardstore.com.

You can make yourself an insert like stewmac in this kit to hold the spotfacer in place (the 1 / 8 " spacer): stewmac.com
- a strip of maple works well. You also need a 3 / 8 steel rod as a pilot.

I'm sure you have seen Gil's thread where did the bore a bit shallower to leave more material in the decapitation area.

I tried a couple spacers to achieve the same : 1 / 8" for a deeper bore and slightly taller for a shallower bore. I ended up going with the more vintage/deeper one in the end.

IMG_4685 Medium.jpeg
 
Last edited:

nuance97

Silver Supporting Member
Joined
Feb 25, 2009
Messages
2,846
Reaction score
2,469
This came up in a PM to me from @Roxy13, and it’s something that has been glossed over in pretty much every build thread around. It took some trial and error to get it right, but it works to perfection.

Cutting the truss rod access with a 3/4” counterbore with 3/16” pilot

Ok so here’s the jig. As you can see it’s 9” long (not critical) by about 1.25” or so (again not critical), and it’s just under 3/16” thick. Sized so that it’s easy to slip in the 3/16” slot and bottom out without binding ..

This is critical. You need to route a 3/16” slot so that there’s a .15” tongue to give you the proper depth on your access cavity

My pilot is 3.5” beyond the blade, and you can see in the first pic my slot is 4” or so (not critical so long as the slot is longer than the pilot).

It should leave you with a perfect cavity with just enough clearance to get a truss rod wrench on the nut and no more. Obviously the least amount of material you removed the better for strength...this is a known weak spot for Gibson guitars
View attachment 507144

StewMac sells what’s essentially the same setup for $122...no thanks (I’m pretty sure they stole the idea from this forum, but I couldn’t prove it)
See my above quote from the tricks/tutorials sticky thread
 

Joe Desperado

Senior Member
Joined
Aug 18, 2009
Messages
148
Reaction score
107
Thanks guys. This was just what I needed. I have a few other counter bores with 3/16 truss rod center bits I use for Fender style necks as well as for the output jack. In the past I used a 5/8 ball router bit to achieve this on slanted headstock. But wanted to try this Method with the straight channel.
 

Joe Desperado

Senior Member
Joined
Aug 18, 2009
Messages
148
Reaction score
107
Hello Joe,

I'll make sure this doesn't turn into fraction glyphs :). I'm not the definitive authority on vintage measurements, but I believe you want these measurements:

Straight neck channel: Nut 1 / 2 in, heel 5 / 8 in
Spotfacer 3 / 4 in

I got mine on yardstore.com.

You can make yourself an insert like stewmac in this kit to hold the spotfacer in place (the 1 / 8 " spacer): stewmac.com
- a strip of maple works well. You also need a 3 / 8 steel rod as a pilot.

I'm sure you have seen Gil's thread where did the bore a bit shallower to leave more material in the decapitation area.

I tried a couple spacers to achieve the same : 1 / 8" for a deeper bore and slightly taller for a shallower bore. I ended up going with the more vintage/deeper one in the end.

View attachment 552788
thanks for the link. Just ordered.
 


Latest Threads



Top