I cleaned up my garage last week and found my wood shop. So I am starting to build again. This time, I am trying to improve my accuracy and overall quality of my builds and that starts with using quality maple hardwood for the necks. As such wood is very expensive, I don't want to mess it up and waste it. The build I am working on now is for a short scale bass, similar to the U-bass. This will be my second build of this type. Because of the wider neck (1.75” at the nut) and headstocks (blank is 3” wide) I made this scarf jig somewhat wider (equates to taller) than would be required by typical CBGs.
Something I have struggled with in the past is making the scarf cuts for the neck and headstocks. I have been using a jig for my table saw I made a few years ago out of scrap but it had two issues. First, the plywood I used for the base of the sled was 3/4 inch thick and with my 10inch table saw, it would only cut to a depth of 2 1/4 inches. This is fine for my necks, but I need a bit more depth (at least 2 3/4 inches) for the 3 inch wide headstock blanks that I am using. The second problem was holding the wood securely to the sled base. In my previous jig, I just used a piece of scrap for the fence and would hold it on there with some clamps. The problem was that near the end of the jig where the blade meets the wood, there was not enough room to clamp it without it hitting the blade, so sometimes the piece that I was cutting would ride up the saw a bit and the cut would not be square. The last issue was the orientation of the jig to the saw blade. On my old jig, I pushed the work piece into the blade whereas my new jig pulls it. I think this makes for a better cut.
So, first things first, I set out to build a new jig for the table saw. First, I found a piece of scrap laminate flooring that was about 8 inches wide and about 1/4 inch thick to use for the sled base. I scavenged the runner piece (mounts to bottom of sled and rides in the track on the table saw) from my previous jig as It was the right size and made of hardwood. I attached this to my sled piece and ran it through the saw to get the blade side edge parallel to the track. I measured my 15 degrees off of here and marked a line for my cutting fence. I attached the fence with screws from the bottom side of the sled and countersunk the heads. I wanted to be able to accommodate the headstock blanks which are 3 inches wide, so I made the cutting fence 3 ¼ inches tall.
Next, I made a parallel fence (clamping fence) 1 1/2 inches from the cutting fence) and fitted it with some "T" nuts such that I can use some long 1/4 inch thumbscrews through the clamping fence to hold the work piece horizontally. Next I cut some small blocks of plywood to that attach between the fences and fitted with T-nuts such that I can use long thumbscrews to hold the work piece vertically to the sled base.
In addition to the new jig, I recently replaced my table saw blade with a much better one. The old one was a 50 tooth combination blade from home depot. The new one is a Diablo 10 in. x 80-Tooth Ultra Finish Saw Blade. The difference in cutting cannot be understated. My table saw cuts so smooth now compared to the old blade. Not cheap, but well worth the price in my opinion. Pics to follow...
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This is the results of new jig. Pretty much a perfect cut with little cleanup needed.
May be a dumb question,but is your table or blade tiltable?
yes the blade on the saw tilts to 45 degrees. That does not help me cut scarf joints though. It would only help if I could build a completely different type of jig that held the work piece perpendicular to the table surface (i.e. stand the board up on it's end).
New Scarf Jig 2
New Scarf Jig - Ready to cut
New Scarf Jig 1
Old Scarf Jig