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Defretted-Negative contour

L

lowregister

Feb 26, 2009
255
1
Madison, WI
#1
I recently purchased a Warwick Rockbass that had its frets removed and filled with wood putty and sealed it all with tung oil. He did a wonderful job, neat and tidy. However, the neck still doesn't know how to behave.

When I look down the neck and from the side, I can see that the neck is countoured negatively, meaning its arching away from the strings. I'm new to making neck adjustments mostly because all I've ever had to do was a quarter turn either way. When I take the tension off the strings to get at the truss rod and then make the adjustment, the neck starts concaving properly, giving me some good adjustment. However, once I retune, the tension brings the neck back to negative.

I've already done about 1.25 turns total on the truss rod--each time doing only 1 quarter of turn every day or so. I don't know what are the limits of necks and truss rods. Can I keep going until I finally achieve some proper contour?
 
#4
With a fretted bass, you want about .015 inch distance between the top of the fret at the middle of the neck, usually the 8th fret, and the bottom of the E string when the strings are in tune. this is known as "relief". (To get the correct measurement you must hold the E string down on the first and last frets at the same time, essentially making your E string a straight edge) I'm sure the same applies for a fretless bass, but the value may be different. The neck should always arch slightly away from the strings. Since your bass used to be fretted and is now fretless, it might take quite a few turns to get it adjusted properly for the proper relief. You may do well to have it professionally set-up which would be cheaper than replacing a broken or stripped truss rod. :bawl:

When I purchased my Epi second hand, the relief was way out of the ballpark, something like .060 inch, if I remember right. It took quite a bit of turning to get the proper relief of 015 inch. I took it slow and only an 1/8 turn at a time.
 
#5
Sounds good. My only question though, if it is what it is, what's the difference between me turning it 1/8 turn each day and the guitar tech doing it for a week?

Also, if this thing is so fussy, what happens when I get it to the proper relief while the strings are tuned and then I change my strings and the neck is left with no counter force?
 
#7
lowregister said:
I recently purchased a Warwick Rockbass that had its frets removed and filled with wood putty and sealed it all with tung oil. He did a wonderful job, neat and tidy. However, the neck still doesn't know how to behave.

When I look down the neck and from the side, I can see that the neck is countoured negatively, meaning its arching away from the strings. I'm new to making neck adjustments mostly because all I've ever had to do was a quarter turn either way. When I take the tension off the strings to get at the truss rod and then make the adjustment, the neck starts concaving properly, giving me some good adjustment. However, once I retune, the tension brings the neck back to negative.

I've already done about 1.25 turns total on the truss rod--each time doing only 1 quarter of turn every day or so. I don't know what are the limits of necks and truss rods. Can I keep going until I finally achieve some proper contour?
Click to expand...

It sounds like the wood putty slopped into the slots, is allowing the neck to have too much forward bow. Not filling the slots with something solid, like some plastic shim stock from a hobby store, is asking for this kind of problem.

I would back clamp this neck, with the strings on, too see if there's enough adjustment left on the trussrod.
 

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