Fret levelling neck bow

I've just levelled some frets and thought that giving the neck a slight backwards bow/convex curve would mean that when the strings are on and tension pulls the neck, it all levels out nicely.

Since then, I've stumbled across many sources saying you have to make the fretboard completely flat.

In fact, while typing this, I've realised that when the strings pull the neck flat, the nut end frets will be higher, meaning higher action towards the bridge frets.

While typing that, I have yet another question- wouldn't levelling with a flat neck have the same result? You'd have to add a slight backwards bow to counter act this and have low action right?

Should I re-level my frets with a completely flat neck?

Quote:

Should I re-level my frets with a completely flat neck?

The short answer is yes.

If you have a curve in the fretboard and you are using either a flat levelling bar or a flat (radiused) sanding block (IYKWIM) the bar or block is not going to make even contact with numerous frets simultaneously.

eg: if the neck is concave, only the ends of a flat bar/block will make contact at any one time - if the neck is convex the bar/block will only make contact in the middle of the bar/block (essentially teetering on the frets).

Remember that you need a notched straight edge in order to set the fretboard flat. If you don't have one, there are lots of how-to videos online about making one out of a long steel rule.

^ What McCreed said. I'll just add, that it's normal to have a little relief (bow) once it's strung and setup, but for the purpose of fret level and dress, yes, neck should be flat.

EDIT: Here's a recent write up I did on fret levelling/setup. Note - this is my personal preference for order of operations, like everything, there is more than one way to skin a cat:

It's a bit of personal preference IMO and I often find myself repeating the process a couple of times to sneak up on the best possible setup.

So I start with making sure the neck is straight with zero relief. I then check that all the frets are properly seated with a mallet.

Mark all the frets with a black Nikko and let it dry.

Then Radius block and around 600 or 800 grit wet and dry.

Ensuring the block is centered I sweep from the low frets up to the high frets checking after each pass. You are looking to see that there is even amounts removed from all the frets, the nikko helps you see any low points. Having a couple of low frets can mean removing a fair bit of material and introducing a very flat top to some of the higher frets. You want to try and remove as little as possible, but sometimes it's unavoidable that quite a bit has to come off.

At this stage I will often do a couple of extra sweeps of the higher frets past 12 to give a very slight fall away in fret height.

Next I re-do the nikko marker and make sure the frets are blacked out again.

Then I use my crowning file to carefully dress the frets. Again, the black nikko lets you see where hasn't been filed and guides the high and low points. You need to sweep across the entire fret paying attention to not flattening out the radius in the middle. I usually find that the ends towards the E strings need the most work.

Then I file the fret ends to make sure there are no sharp bits or overhang.

Now they are essential shaped I polish with steel wool and then some cutting compound and a dremel buffer.

Once that's done I string it up and set the string height and do an initial pass of the intonation. Now comes the fine tuning. At this stage I usually play it for a bit to establish any problem areas. I normally find the next day after initial setup some relief has crept into the neck after having string tension on it. So it's a good idea to check that. For a strat style neck I like to see about an office paper thickness of light in the middle of the fret board. Some guitars need a little more and some less, it's a matter of trying and seeing.

Once it's settled a bit I move onto the nut. This can be a bit tedious, filing, restringing, checking. I generally aim for about 0.5mm clearance between the first fret and the low E string and about 0.3 on the High E string. At the 12th fret I aim for 1.5mm on the low E and 1.25mm on the high E (Adjusting at the saddles) Again, some guitars just need a little more height in the action, but I personally think that is about as low as is practical without ending up with a lot of string clash when you are strumming. You can reduce that 'clashing' by running heavier strings, but that can make it more uncomfortable to do big bends.

At this stage it should be pretty good, I would normally go back over the intonation now as well. Again, play it and see if you can find any problem areas/buzzing. I normally put a dot on any problem frets with a nikko. Then you can go over those areas using a rocker to work out what is sitting too high. If you've done a good job of the initial level and dress, there is normally only very small amounts needing removal to stop buzzes/deadspots.

I might end up doing this whole process a couple of times to get it really really good, it depends a lot on the starting condition of the neck/frets. Sometimes you get lucky and they need hardly any work at all.

Thanks both of you for all the information.

It seems I did it all correct (atleast matching Sonic's method) except the neck relief. I do have a straight edge so i'll bring that out and re do it all...