how much neck relief is acceptable?

It's difficult to give a general answer, since every bass is so different, but as a ballpark starting point, I usually set a bass with about 1/64" relief, then see how it plays, adjusting (rarely more, but sometimes less) until it feels right. YMMV, yada, yada, yada.

 

Standard setup is usually .015 to .025 or the thickness of a couple business cards Max.

 

Yes spacers will give you more thread space to tighten it further and get it where you want it. They move the nut back away from the beginning of the threads.

 

The neck radius will play a factor in how much relief to set. The lower the radius, the more neck relief it will need, and vice versa. For example, a neck with a 7.25" radius would need more relief than a neck with a 16" radius. That's just a general recommendation that I've gathered from some various setup guides that I've learned from.

.015" would actually be the max that I would set for myself. The two basses I own are a Mike Lull P bass and a Mike Lull jazz bass, both 4 string with a 12" neck radius. I keep the relief on both of them set at .012". I've played on basses before where the relief was set above .020", it was almost unplayable to me.

I learned to do my own setups a few years ago, using Fender's "Bass Guitar Setup Guide" as a reference. I found their recommended settings to be very close to my preferences. This is Fender's recommended neck relief settings, according to the radius of the neck:

Radius: 7.25" --- Relief: .014"
Radius: 9.5" to 12" --- Relief: .012"
Radius: 15" to 17" --- Relief: .010"

Granted, that's just a general recommendation, but it fits my preferences very well. Someone with different tastes and/or playing style may prefer different settings than that.

 

The .012-.014" reference is a great starting place irrespective of the radius.

Riis

 

Riis is right, we're talking two thousandths of an inch. Whoa! As for your original question, a neck needs adjustment whenever it needs adjustment. The same changes on two identical basses will yield two different results.

Adjusting a truss rod is not magic, it is a simple procedure that all players must know. I was talking to a kid the other day that is sending his Rickenbacker over 1500 miles for a truss adjustment by a specialist. LOL. I read the manual for old type Ric rods and can do it easily for him. I swear half the bass players in the world think a genie lives in there.

 

From what I've learned about these things (granted that may not be much and it certainly is never enough!), you do want some relief on your neck no matter what - be it fretless or fretted. I tend to use the 'business card gauge' and like to keep the relief within 2 cards worth; one card thickness is optimum. I supose I should just measure what that is (mm though), but since card stock varies, I haven't bothered. It was good to read about the Fender guide though - very helpful and confirms what I've been doing already. Thanks!

 

It may continue to "Flatten" out a bit depending on how high your bridge is. Can you get nice low action and make it playable with Bridge adjustment?

 

A satisfying intellectual belch that clears the mind if ever one was written.

 

Made my morning...

 

Sounds like a problem neck if truss rod is maxed and you cant get dead flat neck. I go for minimum relief myself and wouldnt own a basss whose truss rod doesnt allow any play room with minimum relief. Makes bass unaccepotable if heavier gauge or heavier tension strings where ever used. I use 45-105. This also creates real problem for playability if weather changes made adjustment for flatter needed.

 

EH, Those MIM P-basses play like a dream with a little extra relief. I'd play the %#$ out of that baby. Drop the saddles down and have at it.

 

http://www.fender.com/store/truss-rod-nuts/truss-rod-washers-vintage-guitarbass-204x367-brass-12

 

Some say that .012 is the "standard", but up to .03 (a credit cards thickness) is fine, and what I prefer. If you play on your lower frets a lot or if your fretwork is less than stellar - having a tad more relief can be helpful relative to fret buzz. In reality - it's just not much more, and won't change the playability.

 

Actually, it is two and a half times as much. That is a lot.

If the fretwork is less than stellar, fret dressing or replacement is the remedy.

 

If I had a neck with 0.030" relief I'd buy a quill of arrows and a bail of hay

IMHO... a player's preferred neck relief and action is a very personal choice. Set it up how you like it