Thread: fingerboard geometry - more neck questions

Ray, are you talking about width across the fretboard or thickness of the board?

If your width is greater at the nut then at the 22nd fret then something is out of kilter. Can you post up a pic and give us width of the fretboard at last fret, 12th or 14th fret and at the (front of) nut.

Here are calipered widths (in mm)from my last steel string, a 650mm scale dreadnaught with 14th fret body/neck join. In brackets are figures for the Dreadnaught in Jim Williams' guitar making book:

21st Fret: 60.5 (63)
14th fret: 57 (60)
12th fret: 56 (57)
Front of nut: 45 (45)

Before I start building an instrument I make up cardboard patterns of the body and I also make a cardboard template of the neck which runs from the nut to the saddle. I measure out all dimensions on the template including inner to outer string distance and compensated saddle position. The templates are useful for making up the neck and marking out the top. Its also useful when I thickness the top as vary thickness over my tops (eg a bit thicker around bridge etc). Note: dont use the template to mark out frets....measure fret slot position directly onto the fretboard using a ruler and scalpel.

Hope this helps.

The way I read it, Ray means the thickness of the outer edge of the f/board.
Tapering the board definitely changes it's visual appearance from thicker at the nut end to a thinner edge at your 22nd.
That's just basic geometry as you mentioned.

You can modify that by re-radiusing the fretboard and taking out extra at the nut end , but in doing that, you'll have to recheck the depth of your fret slots and it'll change your neck angle requirements a tad.
A can of worms, but it'll fix your visual issues.

Is this what you mean Ray?

http://www.buildyourguitar.com/resou...s/fbradius.htm

I'll have to check my old strat to see if I can see the difference.

I'm sorry I can't help.

Haven't done a neck yet.

Hey Ray, I had the same problem the first time I did a finger board. I stuffed around with the radiusing doing a bit at one end and then a bit at the other. I was using radius blocks about 8 inches long. It is very easy for the body to use slightly different pressure along a sanding stroke and when you multiply this small error by 300 strokes you get cumulative errors.
A longer sanding block was very helpful but more so was getting my form right. I used to make surfboards and the foam blanks are very sensitive to different pressures, it was easy to get out of shape unless you learned to control your bodies movement and pressure while working.
You can always mark it out and carefully sand down to the line on each side at at each end.
I have my fingerboard stuck onto a 2x6x20 inch block with double side tape. I can then clamp it in the vice higher at the back for good access and stand centered and use both hands on the sanding block and get very even pressure.
But knowing that the tendency is to take more off the bridge end of the fingerboard and do a few more strokes on the nut end for every 10 on the whole thing might be a way to maintain fluidity and get the results you want. I don't have any problems with fingerboards anymore.
The real trick is to learn how to think like one.
Dom

yes



a can of worms is what it is.

there must be a way around it without having to re radius the board.
if i can just figure a way to cut a binding chanel

godamn i just got 3 more straight radius boards from stemac too

Don't sweat it Ray.
I bought a squire strat back in the mid eighties which has the same taper/thickness . That's the neck in the pic.[

ATTACH]52878[/ATTACH]

Originally Posted by oz tradie

The way I read it, Ray means the thickness of the outer edge of the f/board.
Tapering the board definitely changes it's visual appearance from thicker at the nut end to a thinner edge at your 22nd.
That's just basic geometry as you mentioned.

You can modify that by re-radiusing the fretboard and taking out extra at the nut end , but in doing that, you'll have to recheck the depth of your fret slots and it'll change your neck angle requirements a tad.
A can of worms, but it'll fix your visual issues.

Okay Im with you now. A 0.6mm difference in thickness isnt going to be that noticeable unless you go looking for it.

Ray has gone for a 12' radius curve over his entire fretboard so I now see why there's the difference in thickness. I generally do a half a***ed compound radius (generally 16' - 12' - 9') on my steel string acoustics using three different sized radiusing blocks. The tightest radius I go to depends on width of the fretboard at nut end.

As you say the solution is to run the radius block over the nut end of the fretboard to bring the thickness at sides down a bit. Not a big problem the way I see it.

thanks
i gotta have a think about this for a day or so b4 i take any action
its a stewmac board - i just bought in 3 new flat 12" radius boards this week - dang it
they have compound boards for sale now which would have obviated this issue
by the time i get through them i planned to be makin my own
trying to figure out how to cut a compound radius with jig and router

Are you able to remove the fretboard? The only way I can think to fix it at the moment would be to remove the board, and use a belt or drum sander to thin it down from the underside. Second option would be to use the radius blocks working from the top, and then re-saw the fret slots.

The problem I can see after that though is the neck angle - making the side of the board the same height all the way along will mean the nut end will be thinner in the centre than the body end, and will result in less of a neck angle. So long as you haven't done too much work yet on creating the right angle for the neck, you might not have a problem.

actually if i use the same radius it would increase the neck angle
what i was thinking is use a smaller radius which means the sides would decrease but the centre of the board would stay the same [at the nut end]

i measured up a warmoth board last night and find even with a compound radius there is .5mm difference in depth of the board at the nut to the depth at #22

when i look at it it is slightly more rounded on the edge at the nut end sort of disguising the effect a little

i am thinking i am gonna leave it as is

Originally Posted by AwDeOh

Are you able to remove the fretboard? The only way I can think to fix it at the moment would be to remove the board, and use a belt or drum sander to thin it down from the underside. Second option would be to use the radius blocks working from the top, and then re-saw the fret slots.

Don't work the underside of the fretboard...this should be level.

After a fret board has been radiused you often have to deepen some of the fret slots...its not a big job and takes about 15 minutes max. The way I see it there are only two options:

1. Leave it as is....I suspect the thickness difference will only be visible to the person who built the guitar. My preferred option.

2. Do a bit of extra work with the radius blocks.

Originally Posted by old_picker

i am thinking i am gonna leave it as is

That would be my course of action. If youre really worried about the visibility of the thickness difference hand the neck to a guitarist and ask them if they can see anything "wrong" with the neck.

its gonna be a player for me anyhow so yeah leave it
what i am wondering though is when i go to bind it i am not sure quite how to go about it to avoid this effect. looking at the way benedetto binds the board in his book you would end up with the same result. maybe not quite so evident as he is using a 1 3/4" nut

I am not real keen on fiddling about with the radius on a perfectly level board. i can see as soon as i start trying to dummy it i will end up with a less than ideal result. I worked out that with the geometry of the board using a spreadsheet i downloaded, i would need a 6" radius at the nut to get that board hieght dead even.....although in reality yiou wouldnt need to go that far