Fixing back bow in necks

PeteC

Quick update on the back bow problem which was causing some fret buzz high up on the b and e strings and stopping me from getting the action nice and low. 

In case it helps anyone else with this problem....

i had tried levelling the frets using the traditional approach with a beam but this wasnt working   I then tried putting a VERY small amount of back bow in the neck before levelling again to take off any high spots in the middle of the neck - but still no joy after restringing.    

So this last time i used the “strings on” method used by Sam Deeks which he calls the “banana”.  Its basically using a dial action truss rod with 400 grit as a sanding beam - matched exactly to the curve of the neck with some relief already dialled in.    After levelling this way and polishing the frets up to 10k micromesh all the buzz has gone and the action is really fast and low.  

I think the problem was being caused by some neck rise once the neck was under string compression.   The neck is 5 lams of maple and mahogany strips

i like this method and will try it on one of my juniors to get the action a little lower 

another useful lesson learned. 

Danielsguitars

What action did you go with, I've found going too low just doesn't sound good even with no choking etc

PeteC

Relief now measures c. 9 thousandths at the eighth fret, 0.3mm at the nut , and I have 1.6mm action at the last fret on the low E and about 1.3mm at the last fret on the high E.   I wouldn’t want it any lower !  I will use this levelling method again. 

It’s been very interesting trying to resolve the problems on this one. I took a lot more care when pressing the frets thinking I would have a perfectly playing neck and was gutted when it didn’t turn out that way initially.  Luckily the Jescar 55090 has enough depth that I could lightly level them twice and still have plenty of fret for crowning nicely. 

In future I am going to follow yours and @WezV advice to make sure I build in some slight upbow at the build stage when gluing the fretboard on.  I’m making a neck relief gauge at the moment so that I can dial in some relief when doing the gluing up.   I’ve been watching the Dan Erlewhine videos on this. 

I have another carved top build in progress where the mahogany and panga panga neck was made back in November using the same methods, so I will be measuring it very carefully and tweaking the board before final assembly to avoid similar fretting issues with this next one. 

Cheers all, and thanks for advice from everyone. 

Danielsguitars

I usually just make sure I pull the neck down before flatting it and fretting, I don't really measure it or relief, I like as straight a neck as I can get 

I've got a nice LP build I've just started

WezV

I have one of those stew mac neck relief things.... found it I a drawer the other day.   Think I have used it twice.  

 It's useful when you really need an accurate relief measurement, but I probably spent too many years doing it by feel before i got it

PeteC

Danielsguitars said:

I usually just make sure I pull the neck down before flatting it and fretting, I don't really measure it or relief, I like as straight a neck as I can get 

I've got a nice LP build I've just started

keen to see that.....:) 

Jazzthat

It's good to hear ,that is all sorted out .

Btw I too have a neck relief tool ( made one myself as usual )  , which I will use again . Great tool !