Neck Resets 5: FIRST, We Measure
Oops. I ‘fess up and say that I have to take you back a couple of steps because I forgot to mention something. Sorry about this. It’s the drawback of not spending enough time plotting out these emails in advance.
Measure first is good advice in most things. It certainly would have been good advice for me to consider here.
I should have discussed some measurements earlier on. Apologies. I suspect that very few readers have been performing neck resets in real-time over the last month as my emails come in. Still, this was an oversight. Sorry.
On to measuring.
It’s entirely possible to reset a neck completely by eye, taking off a little, checking, taking off a little more. No problem. I’ve done it plenty and for less severe angle adjustments, it’s probably the best way to go anyway.
But… It can speed things a little if there’s a measurement you’re working towards. If you have an idea of how much the neck should be adjusted in order to achieve your optimum angle.
And that’s possible. Mathematics makes it possible.
Relax, it’s not complicated.
However, we do need to measure. And one of those measurements must be done before the neck is removed. Only an idiot would forget that. Sorry.
Before I continue, I must give credit where it’s due. I learned this super handy formula from Dan Erlewine’s Neck Resets video. That link will get you a new-fangled “D.V.D.” version but it was all VHS and mullets when I first saw this as a fresh-faced young man. As always, Dan deserves credit for putting me — and a whole heap of repairers — on the right track (about the guitar stuff, not the mullet).
So, back to school. We need three measurements before we start pulling necks from bodies.
- (A) The amount the neck is underset at the bridge (I’ll explain this in a minute.
- (B) The length of the heel (from the bottom of the fingerboard).
- (C) The distance from the neck/body join to the middle of the saddle (between the D and G strings).
Measurements B and C are pretty obvious and are illustrated above. Easy. Remember that B is the heel length from the bottom of the fingerboard to the end of the heel.
Measurement A deserves a little explanation.
If I hold a long straight edge along the tops of the frets, so the end butts against the bridge, this indicates how much the neck is underset. Remembering our perfect neck set angle, the straight edge should contact the bridge right at the top.
An underset neck will contact the bridge some distance below the top. This difference is what we want to measure for (A). It’s a little tricky to do this with only one pair of hands but it’s not too bad.
Once we have our three measurements (and this is one job that’s definitely easier in millimetres, by the way), you can plug them into this formula:
X = (A x B) / C
or if you prefer it more old-school and visual:
X is the amount of material to be removed from the bottom of the heel for our reset.
Remember that we’re removing a wedge-shaped portion from the heel in order to alter the neck angle. X is the amount that is removed at the bottom and that should taper to zero as you approach the fingerboard.
More on that next time, though.
P.S. Not sure why it took me so long to think of it but, only last year, I realised life could be easier by building this into a spreadsheet. I have a computer right here in the workshop so I made a very simple Reset Calculator in Google Sheets.
There’s a cell for each of the three measurements and then the answer is calculated for me. Easy. The formula is shown in the image but it’s the same as above, just substituting the correct cell values.
A round-up of this neck reset series
This article written by Gerry Hayes and first published at hazeguitars.com
The final touches. Everything’s back together and the reset is done. Just a few last considerations.