I assume you have tried the obvious: double stick tape? That is what I use for radiusing, cutting fret slot, inlay, and profile (in that order usually). I admit that I have never taken the blank off the table and then tried to index it back for a second round of cutting. Is that what you are trying to do?

I've had good experiences with vacuum hold down and locator pins - one in each end of the fretboard blank.

With that scheme I've been able to radius, cut fret slots, inlays or position markers, and cut the taper down the sides, but I've been cutting the ends off by hand.

If your priority is to cut out the fretboard completely, including the ends, then perhaps tiny locator pins on the underside of the fretboard blank which don't go all the way through could work.

Our blanks are prepped with counter sunk holes on center at each end, boards are then fastened to the machine bed with aluminum or brass screws. Same holes are used to locate for contour and fret slot operations.

I use a vacuum holddown with three 1/8" brass index pins that align the rough boards to the jig. The fingerboard blank is flattened on the back side, three index holes drilled about 1/8" deep. These same index holes are used for alignment to the neck later on, but at this point they lock the blank onto the clamp. Since I don't have a tool changer, I'll run several boards through a given operation, then set the next operation up and run them all again. The index pins keep everything in line over multiple operations. I surface/arch the boards, slot them, cut inlay pockets and cut to final profile on the same vacuum setup. I just use a small continuous running Gast pump for vacuum.

Dave

I use vacuum as well and while I do have locating pins, I hardly ever use them as it takes too much time to cut them on the backs of the fretboards. Instead I use needle plates which keep them from squirming.

Full Disclosure - I also sell these needle plates on my website. I'm continually amazed because they are absolutely amazing to prevent vacuumed parts from squirming yet I've only sold a handful of them. I guess most people just don't understand

I've never had to use more than two plates on any part I've cut, be it fretboards or whatever. For fretboards I use the .5mm plates.

Here's a shot of my fixture





If you need the alignment pins anyway it doesn't save time but if you don't, it's a no brainer.


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I thought that using the CNC to cut the index holes might have been a bit of a time soak. I'd have thought that a jig with drill guide bushings and a drill press could get through a pile of boards faster than having to load the machine, run, and unload. But I guess it depends on machine speed.