Guitar Thickness Measurement

[scamp]

Trying to put together tools to build a guitar from scratch.
Some of the fun in this is building your own tools/jigs etc.

As a result, I was looking at making my own thickness caliper for measuring wood thickness.
The simple solution is buying a cheap dial indicator and building a c clamp to hold it accurately out of plywood etc.
Another possibility which is taking it up a notch is to build a magic probe type electronic measurement device.

I have searched on line and found a way to build the basic instrument using a hall effect probe, usb interface and software from a company called Veriner and a round rare earth magnet from Lee Valley.
The basic design seems easy but it seems to me there is a problem with this.
The people who have built this seem to be assuming the magnetic field is linearly related to distance from the sensor. I don't believe this is the case. As a result, I don't think these designs are accurate.

I would still like to try and build something like this for fun but it needs to be accurate and I don't think the designs I have seen and available software are.
I was wondering if anyone out there has tried to do this and if they could provide any guidance.

Thanks

[phavriluk]

Here's one person's opinions:

OP: we can get lost while we're trying to reinvent wheels. Buy and us a digital caliper. If something else is needed, obtain that. I suspect that for most folks reading this, tools are things we need to build and maintain instruments, not ends in themselves. And our goal is to build instruments.

[Stray Feathers]

Here is one made by a friend, and passed on to me when he got out of instrument making. (Along with guitars he made at least one each mandolin and violin). He was a boat builder and I think it is teak. It's obviously patterned after the expensive commercial ones, and it works fine. I don't use it much, though; I have a thickness sander which is very accurate so I use a digital caliper at the edges. I have not graduated yet to thinning the edges of plates, or carving violins, so the digital is fine. I do use the dial caliper when carving necks, to check the thickness of the wood under the truss rod trench (don't want to see daylight there). I can see the CNC crowd (which doesn't include me) manufacturing these . . . Bruce W.

[tippie53]

not all digital calipers are accurate. I am old school I like the dial calipers but any one you use check its accuracy
from time to time

[MaineGeezer]

Being one who has frequently gone down the rathole of building a tool to build a tool to build a tool... I know the appeal of building something that any sane person would buy. And if the idea of building a Hall effect thickness gage appeals to you.....go for it, if you want to experiment. Why not?
If you're concerned about linearity of the output, you could probably calibrate it by measuring several known (i.e. measured with a micrometer) thicknesses.

[scamp]

As always, thanks for the feedback/opinions. After further investigation I think a simple thickness gauge using an analog gauge makes the most sense. I think I will focus on building one of these.

Also, while I understand the focus for many is the guitar not the tools, I find there are also many who build their own tools because they enjoy it ( vs just saving money). I find I am one of those people. I also am discovering that building using hand tools is also rewarding. Sometimes I guess it’s the journey that’s rewarding.

[Diane Kauffmds]

I'm also old school. I prefer analog measuring tools.

[BlindBo]

Our old friend Jimmie Hall also loved building his own jigs and tools. His shop was full of very creative set ups, jigs and equipment. He not on;y loved the challenge, he was damn good at it!
Rest in peace , my friend.

[Bob Gleason]

Some analog tools just make more sense than digital tools. For one, 90% of cheap digital tools eat batteries like crazy!

[JLT]

I bought a cheap Harbor Freight caliper that happened to be on sale:

https://www.harborfreight.com/6-in-digi ... liper+tool

and epoxied some extenders made of plastic to the jaws, with a little protrusion at the end of the extender. Of course, with the protrusion, the jaws won't close fully, but it doesn't matter since the caliper can be zeroed anywhere along its beam.

It works just fine.