Official Luthiers Forum!

I recently developed this electronic thickness gauge.
The device will measure 0-600mil (15mm) and is especially useful for measuring fully assembled instruments of all kinds or the top and back plates while thickness sanding. The ball will ride over most braces and wll also transition from top to sides and back, see the video for more.
Response has been great so far.
If you have an interest, feel free to PM me.
Thanks
Liam

Hi Liam, & welcome. Been watching this thing develop over on mandocafe & I really think you're on to something. Your market will be those that find the traditionally marketed "hacklinger" gauge simple to use but ridiculously expensive, so the question (as was asked over there) is what is the price? Also, do you have a website yet with specs/details??
Congratulations on the development of hopefully the "better mousetrap".

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Dave
Milton, ON

great concept - what are the tolerances (accuracy) and is the probe padded or can it be for use on vintage instruments.

Tim

great concept - what are the tolerances (accuracy) and is the probe padded or can it be for use on vintage instruments.

Tim

Hi, Well I got slammed over there for telling price etc so pm me, its more than a hundred cheaper that hacklinger.
The resolution is 1mil over most of the range for the bigger ball, from about 400 mil it is probably 2-3mil.
It is very accurate, more that a human can be accurate at holding the probe square etc, but overall much better resolution and definitive benchmark that a popping gauge.
The tip is nylon or polyethelene, plastic, so should not scratch anything if you keep it clean, you can also polish it if that is a concern.
Thanks
Liam

I saw this thing in action at the Master Class a few weeks ago, and it was pretty impressive. Great work on this thing, Liam.

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Jason McGowan
M&S Guitars
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United States of America, looks like another silent night
As we're sung to sleep by philosophies that save the trees and kill the children....
Casting Crowns

Liam,

I'm not intersted in purchasing this for now, since I wouldn't use it enough to justify it, but I have to say this is a pretty nefty thing you got there. I sure hope you get the business part of the process running just as smoothly.

Good luck with that!

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Alain Moisan
Former full time builder of Acoustics, Classicals and Flamencos.
(Now building just for fun!)

Hi Liam.

Very nice work - I really like the separate digital readout (great clarity and resolution) and small, easy to guide measuring unit.

Seems you and another fellow here in Australia have been on somewhat of a similar wavelength in the basic concept.

http://instrumentool.com/

I think he has had this in development since mid last year or earlier. At least, it was featured on an Australian Inventors program in July last year.

Anyway, good luck with the development.

Jeremy.

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Jeremy.

J.F. Custom® Guitars

www.jfcustom.com.au

Thinking about this a bit more, I think you'll find a major drawback is the large FLAT probe end. I know you're trying to mandate that the probe stay square to the surface, but this cuts out a lot of your market. I'll go out on a limb & say that much & probably the majority of potential customers for this are makers of carved instruments - violins, archtops, mandolins. And the area they're most concerned with is the recurve. They fine tune the recurve after assembly, so want to know how they're doing, want to know what others have done etc. This requires that the probe end be convex, or tiny enough to get into a tight trough. Waist recurves of a violin can get down to about 3/8"R.
To my mind, a ball probe aligning with a ball inside would be self aligning, always taking the measurement through the shortest path (perpendicular to the surface). Anyway, the flat bottomed probe won't work much of the time.
For anyone interested & hasn't seen it, I did a tutorial on the tool I use a few years ago
viewtopic.php?f=10117&t=15923&hilit=hacklinger

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Dave
Milton, ON

Thanks Dave
Yes you are correct and I ran into this with the mandolin makers as well.
I will offer a narrower probe with a curved tip, and leave it up to the user to keep the probe perpendicular. You arecorrect about the ball self aligning except that if you tilt the probe at the same loction, you are not moving the ball but only moving the tip further from the ball.
But as long as the user knows this there should not be an issue.
Thanks
Liam

No problem Liam. I guess my point was that if the probe end was a BALL with the sensor at the center of the ball (don't know if that's possible re your design), the probe held at an angle wouldn't affect accuracy. (eg get rid of the plastic pad, make the probe end a polished steel hemishere - so it won't scratch - & you're covered.) (Maybe ............just thinking out loud)

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Dave
Milton, ON

The GAL has an up and coming article on the subject in their latest issue.

“A Springless Magnetic Thickness Gauge by Mike Doolin
A sudden international collaboration brings us a compact and accurate magnetic thickness guage with no spring. That's right, it works entirely with magnets. Build it yourself with easily-available parts. Mike Doolin developed this ingenious design by using Alain Bieber's essential insight that a magnet could replace a spring. You saw it first in American Lutherie magazine!”

http://www.luth.org/backissues/al109-112/al109.html

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Michael Lloyd

“I was born to ignorance, yes, and lesser poverties ...
I was born to privilege that I did not see ... I didn’t know it, but my way was paved” – John Gorka

Great idea, but you forget the magnetic fields dont change when you tilt it and there is a sensor in there somewhere......hmmm maybe I should just put a spring in and let you listen for a click....

Actually, that's why I thought it would work. I assumed you're sensing magnetic strength & converting that to thickness, so if magnetic fields don't change when you tilt it, thickness should read same at any angle. No??

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Dave
Milton, ON

No,Imean the magetic field is vertical into the probe, it does not tilt when you tilt the probe, so then your ball outside does not have the same efect on the field because it is no longer in the center of the field.
I have an Idea for a DAVE probe, i am working on it now.

Ahhh.....I see....well, good luck. I'm pretty sure this is a dealbreaker for a huge chunk of your potential market. FWIW the Hacklinger needs to be vertical too, so even if you could only achieve that (with a ball-end), you'd be no worse off ... & cheaper. Idiot-proof it (see "tilt") & you're ahead for less $ and NOW you've got something.

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Dave
Milton, ON

Ok, The DAVE recurve probe is done. I went a different direction. Even if I mad a probe with a rounded tip, you could only measure the center of the recurve before the probe touched the side, an option was to make a 1" probe.
Here is my solution. The ball now attaches to the side of a 1/2' probe instead of the tip. It can use a 3/8" ball which means you can twist it and measure recurves less than 1".
Does that solve all issues?

I'm afraid not Liam. No recurve is a straight trough. There's nowhere that a long probe like that could be laid into a recurve (even an archtop, let alone a mando or violin). It must be point contact, like a hacklinger. No further ahead really, sorry. Maybe beg/borrow/steal a violin so you'll see the problem to think it through.

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Dave
Milton, ON

Yes sorry, i named it incorrectly, I was thinking ahead to the curved side portions that I see on violins and some mandolins.
The Recurve issue is easily solved, that will be a 1/2' ptobe just like above but with a rounded tip. No problem

Although I am the competition, there's an article I wrote explaining the need for minimization.

Liam you're absolutely welcome to implement this in developing your own tool and I imagine you'll find it very simple to do so.

Happy sawdust production!
Joel

Hi Joel & welcome. I like the look of your gauge & I think you guys are tracking this down. Totally agree with your "minimization" concept, which has been in the back of my mind since starting to think about this. I'd even go so far as to suggest it should be a "default" setting (since it is always true)............ eg for each measurement, push a "reset" button (rather than holding down a button which might accidentally cause you to dent soft wood), wooble the probe around 'till the minimum value registers, then push reset again & move to the next location.

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Dave
Milton, ON

That's an interesting point Dave. The reason I'd be a little reluctant to do that is that a thinner area of wood is likely to be encountered on the way to measuring the next point. If the tool is always in minimise mode unless reset this would mean that the reset button would still have to be pressed once getting to the new spot. Although... the tool tip could be held off the surface in between measurement spots - a good move anyway not to scratch anything.

Good idea though. I've had the impression so far that the force of pushing a button on this handle shape is easily opposed by the rest of the hand so I'd be more concerned about using a magnetic ball that's too big on thin spruce thus giving too strong an attraction force. As different balls can be selected it'd be worth going for the biggest magnetic ball that doesn't bruise a scrap piece of spruce that's as thin as you're ever likely to encounter on that particular instrument.

Just to weigh in here, there is not a strong enough force to bruise the wood. The 5/8 ball is easily separated with 2 fingers.
I run it over cedar veneer, spruce and i can hardly leave a dent on paper.

Well, easy enough to say "note the minimum value, move to new location and press the reset".
Worth thinking about IMO.

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Dave
Milton, ON

Ok, so this is now implemented. I did not see a any difference really when applied to the flat tip probe because it is already stable, but it is a good idea with the round tip probe, Thanks Joel.

I decided against a button on the probe to eliminate any possibility of pushing or denting, the button is on the control unit. Instead of a HOLD button, i think a Latching pushbutton is ok, so it leaves your hand free once you have pressed it.

So the option is - do your readings as normal.
or when stopped in an area, press button, the display will lock on that value or anything smaller which then becomes the locked value.
When youre ready, push the switch again and the display is as normal.
comments?