Adventures in Slotting, or Fretty's Back

[Jim Adwell]

So I'm getting a bit tired of cutting fret slots by hand, I don't have an extra table saw to dedicate for that task (I'm sure I'd hate changing the blade every time I felt the urge to make a fingerboard), and no room for more than the one I have anyway, too cheap to pay for custom fingerboards, and bored enough for a new challenge.


So I got the latest Harbor Freight catalog in the mail the other day, and they have the Mighty Mite 4 inch table saw on sale for $36. I have to have this, so I bought one from the local HF store. Here it is:





It comes with a HS steel blade and a diamond blade for dry-cutting tile (which works really well, BTW, who knew?), and an adjustable height table, with two miter slots. And it's solidly built of thick heavy cast iron (no wimpy plastic here, you betcha). And the motor is a crazed demon running at 14000 rpm. Perfect. All I need now is an .023" blade.


Turns out there's such a thing as a "jewellers slotting blade", which comes in a bewildering variety of diameters and thicknesses and arbor holes, including a 3" diameter .023" thick blade with a 1/2" arbor. Also perfect. The blades have a ridiculous number of teeth on them, two hundred and thirty to be exact. I order two from globalindustrial.com. They cost $9.50 each, plus $11.81 shipping (ouch on the shipping).


So now I need a sliding table for this tiny monster. I made this odd contraption from leftover hardwood and thin pieces of bald cypress. And some metal thingies for balance and whatnot, and two small strips of red oak that fit perfectly in the miter slots, just a hair thicker than the slots are deep. If I were to do it all over again, it would look better, but I'm not going to do that. Probably. The pattern (the stick with lines on it held down with metal thingies) is a quick and dirty job copied from another pattern and is not, repeat, not accurate. This is a test pattern (heh), because at this point I don't even know if the machine will work well enough to continue.





I glue it all up, paste wax the living daylights out of it and the table, and wait for the blade to arrive, which is 3 days after I placed the order (yay, UPS). Here's what I got:





Another pic, from which you should be able get the idea of how to use it. You line up the end of the fretboard blank with a mark on the pattern stick, hold it down, and cut. Repeat until done. Not too difficult.





So I try the the thing out. I've taken to calling the contraption "Fretty" (Nightmare on Elm Street, duh). Fretty's first victim is a left-over walnut blank for a tenor ukulele that I'd fortunately cut well over-sized (more on that in a moment). Here's the result:





You'll notice a slot or two is in the wrong place. I did say this was a test run, right? You'll also notice that the ends of the each cut are wider than the rest of the cut. This is from moving the table back and forth while cutting. Don't do this - cut in one direction and lift the work off the table before bringing the cradle back. Very important. Fortunately I've made this particular blank too wide, so I can cut off the crummy parts of the slot.


Here's a cut in the end of a Gaboon ebony blank (with a crack, sigh), done properly. There's a ~1 mm oopsy at the end of the slot (at the top). I can live with this. Also, I need to cut slowly; the motor slows down as the cut progresses and more of the saw blade is rubbing the sides of the slot (no set on the teeth, not hollow-ground). Not ridiculously slow, just slower.





So was it worth the $60 and 3 or 4 hours I spent making Fretty? You bet it was. No more hand sawing frets for me. I can make a custom pattern for each scale length I need and cut fingerboards until my ears bleed (always wear ear protection, kids, even though the saw really isn't all that loud). And I can let my big table saw do what it does best: cut big pieces of wood into smaller ones.


Should you make one for your own use? I dunno, that's up to you.


Cheers, Jim

[Mark Gunter]

Jim, interesting post. I've been putting a lot of thought into slot cutting lately, your experiment with an economical setup comes just in time, thanks.

[Grommet]

Nice project Jim!
I have made a few sliding tables for my contractors saw, and like you I tend to use wood rails to slide in the table slots. You mention using red oak just a bit taller than the depth of the slots. I always shave mine just a bit shallower than the slot depth to ensure the bottom of the sled in laying flat on the table while cutting. Just curious why you go a little taller. Less resistance?

Scott

[Jim Adwell]

Nice project Jim!
I have made a few sliding tables for my contractors saw, and like you I tend to use wood rails to slide in the table slots. You mention using red oak just a bit taller than the depth of the slots. I always shave mine just a bit shallower than the slot depth to ensure the bottom of the sled in laying flat on the table while cutting. Just curious why you go a little taller. Less resistance?

Scott

I left the rails slightly higher so I could put them in the slots and glue them to the sliding table there, insuring a perfect fit. Otherwise I would have to measure, which is iffy considering my eyesight isn't all that good anymore. I suppose I could sand the bottoms of the rails to make the whole thing flush with the saw table, but it doesn't seem necessary.

[murrmac]

I left the rails slightly higher so I could put them in the slots and glue them to the sliding table there, insuring a perfect fit.

That's how I make cross-cut sleds as well, but I make the rails marginally lower than the slot height, and shim them up with washers while gluing and pinning.

[Jim Adwell]

That's how I make cross-cut sleds as well, but I make the rails marginally lower than the slot height, and shim them up with washers while gluing and pinning.

I would have done that if I'd thought of it. Thanks, murrmac.