Fret levelling using radius sanding blocks?

Sarge

As the title says, is there any reason I can't level them with the correct radius block?
I've been using the 19" technofret alloybeam with great results for years now, but I just wondered if a radiused block would be more accurate?

WezV

I don't like doing it this way. you need to remember that the radius at the top of the frets will be different to the board due to the height of the frets. Only slightly so, but enough that you need to remove more metal than necessary to get them all level

Sarge

OK thanks, I'm not sure why the fret radius would be different though, would the fret wire not just follow the radius of the board?

Nomad

The radius will increase at the tops of the frets because they're higher than the fingerboard - they're further away from the imaginary centre. The bottom of the fret follows the radius of the board, and is the same radius.

Sarge

Ohhhhh, ok that makes sense, thanks for clearing that up for me.
so in theory, once they have been radius levelled they should be near perfect, assuming I've crowned them correctly?

streethawk

You'd think a radius block would work but a lot of people claim that you have to use a level beam. However, I read a discussion where folk went down the mathematical rabbit hole and couldn't deny that a radius block should indeed work really well.

I've used them on boards but never fret tops. 

Nomad

That said, the difference is very small...

Assume a fingerboard radius of 300mm, fret height of 1.5mm, and board width of 44mm. The radius of the top of the fret is 301.5mm. If you work it with a 300mm radius block, then the ends of the frets will be slightly lower than the middle with respect to the fingerboard because you're applying the smaller radius block to the larger radius fret-top.

In this example, assuming everything is held perfectly, the ends of the frets will be 0.004mm (4 microns) lower than the middle. That's about 0.27% of the 1.5mm fret height. Although that's tiny, the width of the resulting flat area could be proportionately quite large, depending on the radius of the fret wire - wider at the ends compared to the centre by something around 0.1 to 0.2mm is possible.

Maynehead

I also like to take away as little material as possible, and I imagine a radius block would take away a lot of material from a lot of frets. Good for getting the job done quick but I wouldn't use it on valuable guitars.

Instead I test each fret with a rocker and mark any sections that needs taking down, then do it by hand with sand paper. Quite a laborious process, although it often saves you from recrowning as the softness of the flesh on your fingertips gives it a natural crown.

Sometimes if it's really bad near the heel end I use a short diamond file to level, then recrown with a crowning file.

melvynhiscock

It will not be good. Use the old oilstone methof along and across the board. It has been used for years and works.

Sarge

Thanks for the replies guys.
I have my method pretty much nailed, though it's a common documented routine, marker pen (red), levelling beam, Crown file, micromesh.
I was just wondering if my levelling process could be improved.
Or... I could just be looking for a first use for my radius sanding blocks which I've had over a year now!

melvynhiscock

I have been fixing guitars for over forty years and have never had a radius block. In my view they are unnecessary. A nice idea that doesn't actually work.  They are too short to do anything about lumps and bumps along a board, you need something longer and straight to take out lumps, and they are not that good for radius as when you push them along, your hand does not go in a straight line, that is just basic anatomy. I have always used something long enough, after intitial planing, to level the board along it's length and then used it across the board to make the the profile, like stoning frets but on wood. It works.

On frets I use a good stone and then crown.

I wrote about this 30 years ago and still use the same method. Recently I have had two guitars in that have been Plek'd several times. They now play properly. Experience counts

octatonic

I tried to get this working. I made a jig for bolt on necks that allows you to put the neck in it that gives you a fixed edge to run along, which keeps the radius block straight.

In the end it proved more trouble than it was worth and took up to 20 mins to set up properly. 

I went back to using my old method using the flat metal beam from Stewmac.

JohnB

Sarge said:

Or... I could just be looking for a first use for my radius sanding blocks which I've had over a year now!

Make your own fingerboards mate - it isnt that difficult and very satisfying to do

Sarge

JohnB;746099" said:

Make your own fingerboards mate - it isnt that difficult and very satisfying to do

This could happen, but not until I've a 2nd shed built, I'm currently working in a shed shared with all manner of garden shit, mowers, strimmers, the kids old bikes.... One step at a time methinks

Andyjr1515

For what it's worth (and that's probably not much), my take on it is:

Yes, you COULD use a radius block, but it will not optimise the two things you generally want to do with frets.  That is:

-  Levelling the whole fret train from 1st to 21/24th.  For this, a beam does it better because you get absolutely straight runs from nut to last fret

and/or

-  Taking off high spots along an individual fret length.  Usually it isn't the whole fret that is high.  Particularly for a new fretboard, often it is high spots in random places on an individual fret.  Here, you want to get rid of the high spot but not lose too much fret material in the process.

 
Why is this different to using a radius block to create a fretless board (which I've just done this weekend) ?

Because for a fretless, you are doing both, but in the process removing a lot of material...which generally is not critical for a fretless.  But with frets, taking the tops off and re-shaping them wholesale can remove a lot of metal, and the impact of the thinning and widening of the fret is proportionately much higher.

So, yes you can, but the other ways are probably better...if that make any sense 

Sarge

Yes that does make total sense, my primary concern was using the shorter block, I think mine are 9", I am an absolute believer in using a long beam and have misgivings about the shorter not getting straight runs as you said @Andyjr1515, although I'm sure the more skilled will get great results with said short beam, Crimson guitars make and sell em and people seem to rate them so I won't poopoo them entirely, just not for me.

Thanks for all your input chaps.