Fretboard slitting

[lemic_ray]

Hi gang,

My first ShopBot question is about fretboard slitting.

A fretboard is the part on a guitar neck that the frets (wires up and down the neck) are attached to.

The slit that a fret wire is hammered in to is abou .020" wide. It is a simple kerf with a flat bottom.

They are spaced at decreasing intervals along the fretboard which typicaly measures about 18" long.

I am imagining I will need to make a dedicated spindle that mounts horizontaly on the Z axis.

but then I remembered I often over complicate things, especially when I'm unsure.

So I put it to you folks,
Is there a simple way to make these fine slits?
Are bits this fine redily available?

I've attached a picture of a typical fretboard.
common materials are: Rock Maple, Indian Rosewood and Macasar Ebony.
7417

[bob_s]

Raymond
That is really very simple to cut. Just do the layout in a cad or 2d vector program, and Z zero carefully on top of your material.
The bits are probably available from several places. I would try http://www.precisebits.com I have bought .031 1/32 bits from them with collars to help in setting depth, nice feature.

[lexluthier]

You could use a die grinder with a slitting saw blade and mount it to the z-axis.
Another way is to cut the slots on a table saw using a special blade available from Stewart MacDonald's guitar shop supply.
Look in Bob Benedetto's book "Making an Archtop Guitar" to see how he does it using a pre-slotted fingerboard.

[lemic_ray]

Bob,
That was THE link I was looking for!
This is going to be a lot simpler than I had imagined!

Thanks so much

Ray

[ed_lysne]

I do fret boards on my Benchtop Alpha. You can get bits from Precise Bits. It's easy to setup the cuts in Partworks.

[lemic_ray]

Hey Ed!

This is good info, If some one else can do it so can I.

Curious, do you slit the fretboard the make the radius? or do you radius the board first and slit after?

I had planned on slitting the board and mount the board to the neck and radius it then followup by cutting the depth with a fret saw after.

[richard_saylor]

I have yet to come up with an efficient method of cutting the radius/radii for a fretboard. The back of the neck is another story!

[ed_lysne]

I slot the fretboard while it is flat. Then I radius the board by hand and then go back through the slots with a fret saw to ensure they are all deep enough.

[lemic_ray]

thanks again Ed,
that is pretty much wow I percieved the process.

no different than I have done before except no miter box.

[widgetworks_unlimited]

I was thinking about cutting the radius on the fret boards while shoveling snow today...

I'll bet it would be pretty fast to do with a 4th axis. A simple jig could hold the piece between centers while machining.

Don't know how hard it is to do the rounding by hand or if you guys have a 4th axis, but it could be interesting to experiment.

This might also be helpful for rounding the backs of your necks.

[shoeshine]

Hey all, this is really a question for my own edifcation more than anything else.

Is my understanding correct that frets are a kind of wire hammered into slots? if so wouldn't you want the fret slot to be arched too?

[lemic_ray]

Was thinking I could profile the radius with a ball nose cutter.

Sanding is manditory any how so why not take the bulk off first.

I plan on the same for the neck profile. it's got to be easier than using a spokeshave on my last build

[adana]

Hi all,

Thanks for this thread... I'm about to try milling some fret slots and it was great to see the discussion of those who've gone before me.

I'm about to buy a couple of the little cutters from PreciseBits.com, and these depth setting rings sound helpful. How exactly would one use them with the collets supplied with Shopbot spindles? My understanding is that the collet pulls up as it tightens, so won't the distance change with different amounts of collet tightening?

If I don't use the depth setting ring, will the 0.023" bit break if I try to run the zzero program and touch off the aluminum zzero plate?

Thanks - hope the other projects have been proceeding well since the thread began!

Adan

[erik_f]

I would not try running a z zero routine with a tiny bit like that. Rather get the bit just above the surface...loosen the tool holder so the bit slides down and touches the top of the material...then tighten the tool holder and do a manual zero of the z.

[adana]

Erik,

Thanks so much for the reply. I'll give that a shot.

I sometimes use aluminum foil (touching the normal Zzero plate at one end) for a Zzero routine (when engraving on a portion of a curvy surface). Then I VA out the difference in thickness between the foil and the normal Zzero plate.

I'm wondering if it might be handy to tape a small flap of aluminum foil hanging "diving board" style about 0.100" beyond the edge of the Zzero plate. Then the tiny tool could touch off of that, which would not provide appreciable resistance.

Thanks again,

Adan

[feinddj]

Just a thought, I have been thinking about this in a different way.

Two rail sweep to curve the fret board and then project the toolpath to 3d?

I want to try this with handles for spear guns to add in checkered grips.

[mikeacg]

I did a radiused board for a violin using the 2 Rail Sweep tool in Aspire. I didn't need to worry about frets but I am confident it would work and will be trying it on my next mandolin. I should think we could use the "Project toolpath onto 3D model" to get even depths on the slits. Any thoughts?

Beat me to it, David!

[adana]

Now I'm feeling jealous... that "project toolpath onto model" is only an Aspire thing, isn't it? So my Partworks options won't include that. Bummer. I've been faking a lot of things that I probably wouldn't have to if I had such options.

On the other hand, the mention of the violin fretboard me may inspire me to make a fretless ukulele! I guess there's a first for everything, if not necessarily a market.

[rcnewcomb]

So my Partworks options won't include that
Adan,
You may be able to use a fluting toolpath to get a varying depth across the surface of the fretboard.

[adana]

Yes, the fluting toolpath gives a lot of options I didn't initially know about. That was a big relief when I realized I could do sloping surfaces using a fluting approach.

My current ukulele design has a one-piece neck and angled headstock and I've used fluting toolpaths to ramp out the headstock angle.

It's just frustrating that it's a bit of an approximation: I can give start and end points, and specify curved vs. straight, etc., but if I wanted an actual curve for some reason (like a more complex varying fretboard radius) it might not be exactly right. Still, it's pretty good.

Thanks for the suggestion,

Adan

[ccreddell]

I was just down at the A------n Guitar Works, and they CNC all their necks-including the fret slots. But they use some sort of 90 degree device that they put a 3" sawblade into and cut the fret slots that way. They also do it after radiusing the fretboard and the slot is cut equal depth across the radiused fretboard. It was pretty awesome to watch.