So on earlier builds I am noticing some bowed necks, wood mainly maple with glued fretboard on top then secured inside the box with blocks.Lately I have been reinforcing the neck with material that runs the inside length of the box then extending about 2.5-3" and haven't seen any bowing problems
Besides appearance and a higher string height across lid,does this slight bowing affect anything else?
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Hi Brent, I may have misunderstood your opening comments.
You say you had bowing neck problems and fixed them. My earlier answer suggested looking for the problem to avoid it happening again, which it seams you had already done.
When you said "bowing neck" this normally conjures up a vision, to me, of the fretted area or fingerboard area bowing up. It appears to me now that you may have been referring to the "neck extension" into the body/box bowing. Is this the case?
I would normally consider the "neck" as the part that sticks out from the body, not what's inside as a support, as also used in some banjoes and resonator guitars.
To answer your question though, the height of the strings over the body - if not too low - will not have any detrimental effect. More important is the height of the stings over the frets, as that will effect playability, tuning etc. I cant imagine your strings being higher over the body than those on a violin, mandolin or even an acoustic guitar.........are they???
Most guitars would have a slight bow - relief - either built in or adjusted in by a truss rod, to help with buzz free fretting.
Taff
This build has no extension outside of the box for reinforcing, its all inside,my string height Is probably 1/2" at lid top, higher than anticipated, but the neck appears less stressed when strings relaxed
That 1/2" sounds good, that would be a minimum height over top for my instruments.
Taff
Maple is usually hard enough to handle the string pressure for a 3 string guitar as is several other types of wood even without a trussrod. I'm wondering about the construction of the guitar(how it's braced). What scale are you using? What tuning?
I have built over two hundred CBG's using every type and style of neckwood imaginable...and.... I have yet to have a neck bow on me. True that I only build three string CBG's and typically tune down to EBE.
is the neck actually bowed? or is the neck just tilting up under tension? how big a block did you use inside the CBG? as Tom T said thinner strings will definitely help with the tension.
I've found that string tensions of between 16 and 20 lbs are very playable with either slide or fingering. For D3-A3-D4 tuning strings with diameters of 0.027, 0.017 and 0.012 will give approximately 20 lbs of tension on a 25 inch scale guitar.
0.025, 0.016 and 0.011 will produce tension of approximately 17 lbs on a 25" scale.
These string tensions are significantly less than those currently installed"
0.042" = 50 lbs tension
0.034" = 70 lbs tension
0.025" = 70 lbs tension
These tensions may not be representative of what Brent actually has on his guitar since he may be tuned to something other than D3 A3 D4. Still, it should be noted that lighter string tensions are very playable and easy on the neck.
These days, I usually take my desired tuning and desired scale length to calculate what strings I need to give me the 16~20 lb range. I do this before I begin the build so I can order the specific strings I need. Several online sites sell individual strings and it may cost you a buck or two more for a custom set, but I think it's worth it.
I'll try it
Hi, all the above suggestions are a good way out of your problem. But I would be more proactive and look at the cause of the problem, why are my necks bowing with the light pull of only 3 strings.
i would hate to build a guitar for somebody and have to tell the customer they can only use certain gauge of strings and limited tunings.
I would look at the cause. Neck dimensions, stiffness and grain orientation.
Taff.
i think the main clue is this "then secured inside the box with blocks" i think the side of the box was twisting under tension because he then goes on to say "Lately I have been reinforcing the neck with material that runs the inside length of the box then extending about 2.5-3" and haven't seen any bowing problems"
i dont think the original blocks were big enough to support the neck tension with the large strings.
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