Notched straight edge

[Ze.]

I went for an ebay notched straight edge off ebay and i wish now i had sources a straight edge piece of aluminium and made my own that spanned from the wood fretboard before the first fret right down to the top of the bridge but something has me puzzled about the straight edge i did buy .It starts at the beginning of the sound hole end of the fret board and fits neatly over every fret (the other edge being different size ) but stops only going over the first fret not past it to rest on the fretboard of the first section before the first fret .

Looking online their are a few notched straight edges that do this and i'm thinking their must be something i don't know ....why is the first section of fret board not included in the check for straightness of fret board or relief as i can't think for the life of me why they would make some (not all ) notched straight edges one section of fret board shy ?

Please enlighten me

[bausin]

Doesn't the last flat section fit between the nut and first fret? Even if it doesn't fit, the notches look deep enough that they might fit over the nut.

[charles Tauber]

Opinions vary, but in more than three decades of making and repairing guitars, I see no purpose for a notched straight edge.

What really matters is what happens with the tops of the frets. If a fingerboard has something wrong with it that results in the frets not being "level", one can see that by sighting the length of the fingerboard. If one needs accurate measurements, an un-notched straight edge long enough to cover the entire fingerboard and extend to the saddle/bridge can be placed on top of the frets, or, if frets are not installed, on top of the fingerboard.

For measuring relief, most guitars come equipped with six straight edges that are usually adequate for most purposes. In cases where a string is not adequate to use as a straight edge, I'll use a metal straight edge, one thick enough to stand by itself on its edge.

[redir]

I never really understood the need for a notched straight edge either. Perhaps some one can explain why it's a good idea. In any case I would thing that you would most certainly want it to extend all the way to the nut.

[tdnate]

I bought an aluminum yard stick at a Home Depot. Made sure I had dead straight edges by running it along sandpaper places on my table saw, then marked and notched my own. One side for Martin D28 scale, the other for Martin 000 scale. I cut off what I didn’t need and just notched the appropriate amount off for the shorter scale. Seems to work fine.

[charles Tauber]

Originally Posted by tdnate

I bought an aluminum yard stick at a Home Depot. Made sure I had dead straight edges by running it along sandpaper places on my table saw, then marked and notched my own. One side for Martin D28 scale, the other for Martin 000 scale. I cut off what I didn’t need and just notched the appropriate amount off for the shorter scale. Seems to work fine.

This raises an interesting question. Manufacturers go to a lot of trouble to make "high-end" measuring devices that are very accurate - and the prices of those devices reflect that. For example, a square that is out-of-square by 1/2 a degree is pretty useless for accurate machine setup. Similarly a straight edge that is out of straight by 1/16" on a 36" length isn't much use in places where high accuracy is required.

So, just how accurate does a guitar straight edge need to be?

As an aside, part of my process for dressing fingerboards is to finish off the shaping of the fingerboard using a "straight" aluminum construction level to which sandpaper is glued. Rubbing something back and forth over a flat piece of sandpaper guarantees that the object will come out convex. I make use of that characteristic to slightly back-bow a neck/fingerboard prior to fretting.

How straight will an aluminum straight edge be that has been sanded straight on a piece of sandpaper affixed to a table saw table? How straight does it need to be for guitar-related work? What effect, if any, does cutting pieces out of the aluminum do to the straightness?

Mostly, just thinking out loud.

[Ze.]

Originally Posted by bausin

Doesn't the last flat section fit between the nut and first fret? Even if it doesn't fit, the notches look deep enough that they might fit over the nut.

My sentiment exactly why not cover the fret board to the or over the nut like some do .The question of why would anyone need one for me is in my immaturity setting up guitars it seems a reasonable starting point so as to say you rest assured begin with a flat surface for to then be able to reliably assess the condition of the frets .Its the first and last adjustment in the process for me ,one to know the board is made flat with truss adjustment if necessary and lastly to set if any relief 1 by the board and 2 by the strings .I find the finest adjustment is the last stage of setting prior to the manifestation of fret buzz .I'm as sure it straight under tension at the last thing i do ....i have found it the way i like it ,i want as little bow as is possible .

Anyway why produce such a piece of kit that is shy ? there must be a reason mustn't there .It is as if to say either the first part will be true or it isnt important for to measure the truthiness of the first section .I even wrote and asked them and they didn't know they wanted to replace it for another haha i said i think you'll find they are all like that .Honestly it's like they buy a container full of suff for to sell over about which they know absolutely nothing .Come back the good old shop ASSISTANT with the emphasis on assist jeez

Not sure if this is the exact one i got but here you can just see it doesn't cover the first section after the nut .

https://www.ebay.co.uk/i/183331823832?chn=ps

[bausin]

>> Not sure if this is the exact one i got but here you can just see it doesn't cover the first section after the nut .

Those pictures could have been taken by a salesperson who knew nothing about how to use the product.

That's why I asked if it could be moved over a fret and still fit.

[brianhejh]

If you look at the Stew Mac website it demonstrates this item and shows that it butts up against the first fret. It does not measure the first fret, the one I purchased does the same. Re your point, No, I dont believe/think it needs to measure the first fret.

[John Arnold]

So, just how accurate does a guitar straight edge need to be?

The inexpensive stainless steel rulers I use (12" and 18") are straight enough for me. I can check relief on a guitar with the 12" one, flip it over, and the measurement is essentially the same.
I also see very little need for a notched one. If the frets have been dressed straight on a neck that is bowed, you can determine that by measuring fret heights. If frets have been dressed too low, they will need to be replaced. In that case, neck straightness can be checked with a common straightedge once the frets are pulled.

[charles Tauber]

Originally Posted by John Arnold

The inexpensive stainless steel rulers I use (12" and 18") are straight enough for me. I can check relief on a guitar with the 12" one, flip it over, and the measurement is essentially the same.

Thanks for your insights, John.

[redir]

IMHO I like to start off with very accurate straight edge tools. I'm not talking about aero space grade ones but having a good reliable starting point only degrades from there. I bought a precision 36in and 24 inch straight edge 25 years ago and while they were pricey they have lasted and will last even further after I am gone. Sometimes expensive tools are actually cheaper, in the long run... And again, within reason.

[mirwa]

Notched rulers are just a troubleshooting device.

Lets say you have buzz happening, you visually assess the top of the frets for straightness or use a straight edge.

When you have noted vee the straight edge that the frets are not level, for those that are curious if its the board itself, you can use the notched ruler and measure the gap under each location, this will tell you how much out of level it is, if the board is straight and level, then you have a mismatch of fret heights fitted or loose frets causing the issue.

PS I do not have one, but have used one in another persons shop, I commented on the fact its a cute wall hangar and then we mucked around with it until we came up with a valid use for it.

Steve

[murrmac123]

Originally Posted by charles Tauber

Rubbing something back and forth over a flat piece of sandpaper guarantees that the object will come out convex.

I think that statement needs some qualification, Charles. It largely depends on the length of the workpiece which is being being manipulated, and also the "stroke length". The pressure exerted by the operative is also a factor.

I have made and sold many hundreds of aluminium sanding beams and straight edges, and none of them have ever exhibited the remotest degree of convexity. I do have the advantage of having a 5' long granite surface plate to work on ... using the full length on every stroke, with high quality PSA abrasive attached to the surface plate ensures absolute straightness and flatness.

[charles Tauber]

Originally Posted by murrmac123

I think that statement needs some qualification... I have made and sold many hundreds of aluminium sanding beams and straight edges, and ... ensures absolute straightness and flatness.

"Absolute straightness and flatness" is marketing, not a manufacturing reality.

How do you measure straightness and flatness? What values for straightness and flatness do you achieve? With that many made/sold, do you use some means of statistical quality/process control, or do you measure/inspect each one for being within tolerance? Do you have a guaranteed tolerance that your sanding beams and straight edges achieve, such as .xxx per unit length?