[Cartierusm]

Hey, what's the easiest way to cut frets to match the fingerboard radius. I have artcam and Rhino, but I'm not very adept at Rhino yet and I can't figure out how to draw 3D in artcam. All I guess I would need would be one 12" radius Line going up and down the Z axis .090" high and then I could cut and paste and place them in the correct fret positions. Any suggestions. Thanks.

[jabguit]

Are you talking fret slots?

[ger21]

G18 or G19 arcs.

[turmite]

G18 or G19 arcs.

Or G1 moves in an interpolated curve!

What help with Rhino do you need to get this going? That might be a better way to go at this?

Mike

[RandK]

Model exactly the fretboard surface that you want. Cylindrical ? Conical ? Project the lines indicating the fret positions onto the curved fretboard surface. Move those curved lines down to indicate where you want the bottom of your slots. I'm assuming your cutter diameter will match your fret slot width. Use a 3d cut path in CAM.

[Cartierusm]

HAAA...Honestly I really appreciate all the help, but I don't know how to do any of things all of you describe....HEE HEE. For those of us with cro-magnum brows how about dummin' it down. Thanks.

I'll check out what the G commands you descibe as far as Rhino I come from a graphic design background and CAD confuses the hell outta me. For instance I was able to import the arc (12" radius) line from Adobe Illustrator into Rhino but when I went to rotate it from flat to standing up so it looks like I want it asks for points of reference. To me I want to be able to exactly, with numbers, rotate it. Why can't I just say this piece here roate about the Z axis 90 degrees. Anyway, these are the hurdles I'm facing when trying to learn CAD. I'm used to using a window with number to draw specific lines and number to specifically place objects exactly where I want them.

[fatal-exception]

Fret slots don't need to follow the radius of the fingerboard. As long as they are the correct depth on the ends of the frets, having the middle deeper dosen't matter, unless you are just looking for additional work that might jeopardize the accuracy of your slots....


Paul

[BobF]

I don't think most fingerboards are radiused (2 piece finger board) on the bottom, and unless cut with a CNC very few have radiused slots. Its far more important to get the scale right.

[RandK]

Fret slots are normally radiused when cut with a CNC because the expensive cutters are tiny .023-.025 and the cutting length is only .070 for the Micro100 bits and .090 for the Precisebits (IMO a much better bit). There isn't enough CL to go straight across, especially on a Fender radius. Radius the board then cut the slots of course.

Cartierusm: I don't have time for a picture show right now but here's a small model with a few sparse notes. The Rhino level 1 and 2 tutorials on the disc are very good try them. Like I said before, make a simple surface. Make a set of lines representing the slots from something like fcalc and then project the lines onto the surface and move those lines down to your depth. Yea, in a cylindrial FB the slots match the same radius but if you go compound or build in some relief you'll need to project them. You'll have the surface to machine the radius and the 3d profiles for the slot.

[Cartierusm]

Thanks guys.

[NB70]

I have written a ruby script for conical tapered fingerboards (with curved fret-slots) for Google's free 3D design program Sketchup. I haven't tested it on a CNC machine yet. You can alter most of the parameters to your needs.

To use the plugin you should download it to your Sketchup plugins folder. If you have installed Sketchup on the C: drive then this folder will be at C:\program files\google\google sketchup 6\plugins. After copying this file you should now a menu options in the Sketchup Draw menu to draw a fingerboard. I had to alter the file extension from *.RB (Ruby) to *.TXT (Text) to allow me to attach it here. You should change it back to *.RB if you download it.

The script's webpage is here. I am hoping to update it soon to make it more useful. At the moment it produces a 3D mesh of the fingerboard, I think single lines defining the fret slot cuts would be more useful for CAM.



This is off topic but I have been pondering about this. The design of the guitar fret, with it's barbed tang, is a consequence of sawn fret slots which have been used for centuries. Since we now have CNC machines that can mill fret slots why not just use a ball nosed end mill to mill a round bottomed fret slot and use conventional round wire with a matching radius (glued in) for frets.

[dbassva]

fret tops are not perfect cylinders for one thing....and you would still need something for them to grab onto to keep them in place when the wood moves....there is one company that actually has a pattent on something similar....they are something similar to diamond shape like a 5 sided gem shape if you know what i mean....im sketchy on the details, its been awhile since i looked at them...but i do remember they claimed they did it by hand with a router and a jig....

[RobSm]

Model exactly the fretboard surface that you want. Cylindrical ? Conical ? Project the lines indicating the fret positions onto the curved fretboard surface. Move those curved lines down to indicate where you want the bottom of your slots. I'm assuming your cutter diameter will match your fret slot width. Use a 3d cut path in CAM.

UnbeF*****glieveable. it WORKED!!

Thank you Thank you

But how does one indicate to the software Rhino or aspire that these 'lines' are fine dados or slots? Or does the spindle just follow the lines on centre to a depth?

Thanks,
Rob.

[RobSm]

I apologise for sort of crashing this discussion - but it's very unusual for things to go so smoothly and I got excited - & well another glitch.

I have the projected fret slots bot on the surface and at a depth of .075" in Rhino, but Aspire doesn't see them at all. I guess this links to my last question.

How do i signify that these lines are slots .023 wide and .075 deep?

Thanks,
Rob.

[RandK]

I haven't used Aspire but it's supposed to be really nice stuff. You won't be using the surface(s) for this operation, only the 3d curves, and you may need to hide the surfaces. In many CAM packages they call that kind of toolpath a 3d engrave. You want the one that makes the tip of the bit follow the curve in 3d. It is best if you have each slot cut in the same direction (R-L or whatever) rather than alternating each slot. Hopefully it also allows you to specify a cut depth so that you can take 2 passes to get to the the full .075 slot depth. If it doesn't have this functionality, just make 2 sets of 3d curves, one for each depth pass. Make sure your stock matches the curves ie. board profiled before trying to cut the slots etc. Always a good idea to do a test cut in air before the real thing. Chip packing is a problem with cutting these small slots, a big air blast helps, or even stop between passes and clean them out with an x-acto knife. The chips can deflect the tiny cutters and cause wander or bit break.

[ger21]

Aspire is not going to work with 3D curves. If you're using Aspire, I think what you want to do is draw the fret slots as stright lines, then model the fretboard with a 2 rail sweep, and cut the slots with a profile toolpath, with the toolpath projected to the 3D surface. I don't have Aspire on this PC to check, though, as I'm in a hotel right now.

[Larken]

Some guitar makers don't cut the slot right to the edge for appearance. They file the rib away on each end of the fret back about .060"
You should be able to just run from the 3d dxf from rhino instead of needing a cam program.

But how does one indicate to the software Rhino or aspire that these 'lines' are fine dados or slots? Or does the spindle just follow the lines on centre to a depth?

Just do a center line cut. otherwise you will move the fret. And use the right width cutter.

[louieatienza]

I cut slots routinely using .024, .025, or .026 end mill depending on the fretwire I am using and hardness of the fretboard. On ebony I can get away with 5 or so passes. I find rosewood has more a tendancy to clog the endmills and I go easier and blow the slots out as I go.

The bits themselves are not that expensive; I buy them from Kodiak Cutting Tools. Thankfully in NY, so it's next day shipped for me. The ZrN coating does help a little. But basically as above, I draw the centerlines of the frets and project them to my fretboard model. I am lucky that my CAM supports variable Z cut chain.

It is believed that cutting the fret slots following the surface of the fretboard surface leads to a stiffer neck, and possibly more sustain because of it. Straight slots never hurt Fender, Gibson, or Martin though, who use gang saws to cut their slots.

Another note: I actually demonstrated on the MIMF a few years ago that the "conical section" compound radius fretboard is something of a myth. This situation can only occur with the right end radius given the nut radius and taper profile of the fretboard. You CAN make ruled surfaces with any two radii, but there's no guarantee they will produce a conical section.

[Larken]

I learned a lesson about fret height a few months ago.
I have an old 1970 Regent Les paul custom copy that i played for years but the frets got badly worn from bending strings. So i decided to sand down the frets with 20" of sandpaper glued to a straight piece of aluminum. I guess i took all the frets down close to 0.010" to get all the low spots out.

But playing it it seemed different.. my fingers would slip over the strings when doing bends and vibrato.

Now i realize that you need higher frets on a blues or rock guitar or the strings slip under your fingers.

Larry K

[RobSm]

Some guitar makers don't cut the slot right to the edge for appearance. They file the rib away on each end of the fret back about .060"
You should be able to just run from the 3d dxf from rhino instead of needing a cam program.


Just do a center line cut. otherwise you will move the fret. And use the right width cutter.

Sorry to be a bit thick - but how do i set up a 'centreline cut' in a modelling or toolpathing programme. That's what I'd do intuitively - but i don't know how to tell the software!

Thanks, Rob.