Home > Lutherie, Woodworking > So you want to be Luthier?

So you want to be Luthier?

Two Shop-made Tools

Why yes, rhetorical question, that is the reason I started woodworking in the first place. I think I’ve got a mental block with regards to instrument building. I’ve reached the point where I’m ready to overcome it. I just have to get started and I have a plan…. no really I do!

Radius Sanding Block – Band Saw Method

While surfing the InterTube, I came across yet another interesting idea for making one’s own fretboard (radius) sanding block/caul. Lovely examples of these tools can be commercially purchase, for a price. An 18″ aluminum version runs $136, and it comes in 7 radii. Wow almost $1,000 if you wanted one of each. A 5-piece set of 4″ maple blocks is much more affordable at $44 but really if these were to be used for cauls, you’d need several sets to do the job. This is the sort of tool that cries out for a shop-made solution and many have been developed. I wanted to try out one that utilized a bandsaw as published by “Dave Mac’s Window on the World“.


The methodology is actually quite simple although it took a couple of moments to get my head around it. Essentially a 3″ or 4″ board is pinned the correct distance for your radius (in this case 12″) and is rotated through the blade for the cut. But wait, that leaves the end of the board with a convex cut so what gives? Of course we are interested in keeping the off cut with the concave radius. So by dividing the board into equidistant  sections and drilling a pivot hole at each location, you can slice off as many cauls as you need then glue them together into a block.

Simple jig to band saw 12" radius cauls.

Simple jig to band saw 12″ radius cauls.


The holes in the board are equidistant which results in off cuts being the same size. It is the pin hole in the clamped board which is set to the desired distance from the blade. In this case it is 12″.

This was my first attempt at this and my impression was very favorable. I did notice some very minor blade flux when I entered the cut but I kept the work piece flat and used a steady cut rate and the results were very consistent.

Off cuts (cauls) cut to 12" radius.

Off cuts (cauls) cut to 12″ radius. My goal was to cut 24 to make an 18″ sanding beam.

All went very smoothly until it became time for the glue up. The devil is in the details as they say. I decided that it would be hopeful to glue up all 24 (actually I only had enough board for 23 and the first cut is always a different shape because the end is not rounded).  To help get things lined up I glued 2 sets of 11 to make reduce the complexity. After being frustrated using F-clamps on the first attempt, I opted for weights on the second. I think it was easier to get things aligned with the latter method but neither turned up perfect.

Two ways to clamp the stack.

Two ways to clamp the stack. The F-clamps proved tricky without a jig.

Oops, I forgot to glue up one of the pieces. Actually I was using the convex end of that piece to help align the stack but it only proved partially successful.

Out of clamps and a level sanding.

Out of the clamps and to the bench vise for sanding and clean up.

Once the stacks were out of clamps I took them over the bench for some sanding and clean up. Some parts were aligned quite well and other bits were not. I used that caul again with some sand paper to sand everything flush. The jury is out. I feel that these will make very suitable clamping cauls when gluing a fretboard to the neck or when pressing frets but I’m not sure it is precise enough for the initial radiusing of the board. It might be especially if the inner surface is covered in cork first.

To finish off this project, I’ll cut tops flush and then put a nice round over on for better gripping. In theory the cauls should have been of identical size but I was obviously not as careful as I should have been with this. Had I been more consistent, alignment would have been easier I’m sure. And a final observation, Dave from whom I borrowed this technique mentioned he had no trouble with alignment by turning them concave side down on the bench. I too realized that was the only common alignment point but didn’t find the narrow edges perfectly consistent at least not enough to rely on for alignment.

Conclusion, it worked well but I’ll need to rethink my methods for glue up.

Fret Bevel File

So this tool was basically following the DIY Fret Bevel File from Derek at Big D Guitars. Derek has a wonderful YouTube channel which I enjoy immensely, thanks Big D!

Essentially this a piece of wood with a kerf cut down the center wide enough to epoxy a file in to it. One side of the wood is beveled to 35º for filing the fret edges on the edge of the fretboard.

Shop made fret filing bevel tool.

Fret bevel ready to epoxy in the file.

The only thing tricky here was shimming the skinny end of the file to prop it up. Derek recommended exposing about 1/4″ of the file above the block. I decided to mess around with the wood burning iron for a little customization before adding a coat of Tung Oil finish.

Messing with the wood burner freehand.

Messing with the wood burner freehand.

Did you notice the plaid duct tape? I was wondering if this would provide a frictionless surface while using the tool. It also served to keep the oil finish off this area as I might want to try some UHMW frictionless tape on these surfaces. Might be overkill but it would also be no-marring I should think.

Tune in next time for a Turtlecove fail project… at least failed on the first attempt


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