Official Luthiers Forum!

Hello friends
i have a laser cutting machine nearby my locality
yesterday i went and checked whether it can cut wood or not and it does very fine job
so im planning to cut the fret slots of 0.55 mm wide and 2.5 mm deep
is it advisable to cut the slot with laser machine?
what are its advantages and disadvantages?

Never heard of anyone doing that. But, give it a try and let us know how it goes!

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Pat

funny you mention this. I always mark the position of the frets with a laser cutter. Actually I did 3 fretboards earlier today.
I don't actually cut the slots itself (at least not until now). Probably it can be done if you want to invest the time to find the optimal settings in laser power and traveling speed of the laser.
But even then, I find that even relatively light differences in the colour of the ebony I'm using can result in quite a big difference in the depth of the cut.
Anyway, feel free to experiment...

We have a laser cutter in the tech shop of my school. When cutting hard wood it usually leaves a burnt edge, this might affect how well the fret barbs hold. In addition it will cut deeper in the less dense wood than it will on the hard grain lines. I think you might see slots of inconsistent depth.

corrected
Martin is using lasers but not in this process
this is done with endmills

_________________
John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

I'm curious since I have no experience with lasers and wood working what stops the beam from cutting all the way through the board? Also is the beam a beam or a pulse and regardless what's being attenuated to control depth of cut or is it a duration thing?

Inquiring minds wanna know please?

Thanks

it is amazing what it can do and yes depth control is part of the design.
I edited original post
end mills ( upcuts ) are used.

_________________
John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

In the hands of a professional, I'm sure it would work just fine.



Alex

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"Indecision is the key to flexibility" .... Bumper sticker

I have a laser cutter & I'd say no way unless you were cutting some sort of perfectly homogeneous material.

The power or the beam is constant so the properties of what you are cutting must be constant too if you are trying to cut to a particular depth. Cutting all the way through is a much easier matter.

Different woods & materials behave differently & not as you'd expect. As an example, it's easier to cut Bocote than Koa although Koa is much softer & less dense.

Kevin Looker

_________________
I'm not a luthier.
I'm just a guy who builds guitars in his basement.
It's better than playing golf.

Maybe Martin is cutting those dark matter fretboards with it.

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Pat

I tried this a couple of years ago, but gave up in favor of using a CNC with a 23mil bit in it.
Kevin has is right IMO - the depth of the cut is too dependent on the consistency of the material being cut.
Even on the same piece of wood (ebony), I found laser-cut fret slot depth to vary too much (aimed for 75mil deep, got 30 to 100mil approx).
Maybe on more uniform density/grained woods it might work, but I found the CNC to be a much better solution.

FWIW, I also use my laser to make Ryan-style A4 kerfed linings (under license). Mahogany seems to be fairly predictable as far as laser depth-of-cut is concerned, but I still do test cuts to get the speed/power right before committing to a new batch of wood.

Dave F.

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Cambrian Guitars

"There goes Mister Tic-Tac out the back with some bric-brac from the knick-knack rack"

John, in a post on the UMGF on 09/26/14 you stated (in reference to the Martin fret slotting process)


Are you now saying that the entire production of the Martin fret slots is done by laser? I find that very hard to believe . . .

I run a laser cutter at my work and I know how it works.
In the time it would take to set in all up to cut at the right depth and the time you wait for the machine to do it you could already have cut 2 boards by hand if you have a jig set up.
Laser cutters are great for making templates and jigs. for example I made a nut slot guide where all the increments are off-set by 0.1mm. It's fantastic for headstock templates or bracing layout guides etc.
You could spend your time better making a jig to accurately and consistently cut fret boards by hand.
Martin may do it (I allso find it hard to believe unless the finger boards are some type of acrylic) but they would have a super-duper laser cutter that small businesses can't afford and they are doing production lines.

_________________
We are all in the gutter but some of us are looking at guitars.

I tried this several years ago. Before I figured out a good method of cutting multi-scale frets slots.
The results were very poor. Not only was the cut uneven because of the different color in the ebony, but by the time it got deep enough to render a good slot, the top of the slot was "V" shaped. After one finger board was ruined by this, we experimented with different settings and simply could not get a deep, narrow, homogeneous cut. I think blades/bits are the only way to do it well.

I wonder if the laser is used to cut their Richlite fingerboards? that seems more consistent than ebony or rosewood.

My experience with lasers cutting organic material (surgical) is that depth of cut is a constant concern. I can't imagine a laser being more efficient, unless you have a "smart laser" that monitors the depth of cut real-time. But now yer talking BIG bucks! (as in LASIK technology, applied to lutherie)

Martin changes this more often than you may think when something is available that works . I do stand corrected . End mills ( up cuts ) are still being used. They changed from a through slot to pockets slots a few years ago

_________________
John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

What if you mounted the board on-edge? It would take longer, but should work, right?

Martin uses lasers to print everything on the neck block. Fretboards are cut in a CNC process (not sure if they want to have that information disclosed it not, so I'll take the cautious route.)

Lasers are unpredictable, damaging, and slow when cutting wood. I wouldn't use them on a fretboard for anything beyond scribing lines to mark fret positions.

Martin does use the laser cnc to cut and profile the sides. It is faster that with conventional methods and there is no sawdust . They have a few laser machines as stated above one for the neck block and sound holes cutouts and they also use them for the back cross grained support and the bridge plates.
Not sure but I think they are using them for the backs also.

_________________
John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

The video I saw showed Martin using the laser to cut the fretslots. Even leaving a bit of wood uncut at the ends to actually bind the fb.


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As John mentioned Martin uses CNC routers/milling machines to cut slots for their now standard "faux" bound finger-boards. As indicated above a standard .023" bottom cutting end mill will produce more consistent slots. Lasers are great for profiling since the depth is not an issue. I believe there is also a concern for the draft angle that is made by the laser (the sides of the slot would have very slight taper) I've had plenty of the new Martin finger-boards here in the shop there is no indication that the slots were burned in. Also laser cutting hardwood produces an awful odor and plenty of nasty fumes.

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Ken Cierp

http://www.kennethmichaelguitars.com/

Have you got a link to this video ?

Here's info about C F Martin slotting process from the actual tool manufacturer and Martin Engineers

http://www.sme.org/MEMagazine/Article.aspx?id=20187

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Ken Cierp

http://www.kennethmichaelguitars.com/

No.

The beam has a limited depth of focus - imagine it like an hourglass shape with the lens at the top of the hourglass and the focus point at the waist. A longer lens will give you a taller & wider waist and taller overall height. The depth of focus is nowhere close to the 2" you'd need to cut a fret slot from the side.

Kevin Looker

_________________
I'm not a luthier.
I'm just a guy who builds guitars in his basement.
It's better than playing golf.

Murrmac the video was in a thread on this site. Sorry I don't remember which one. It was about safety?


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