Tuesday 16 January 2024

The Return of the Betterizer

 Hi. I recently experienced a tiny brainwave in my workshop, and I'd like to share it with you.

I've got a couple of lute backs here, and both are for a 5 course late medieval plectrum lute. The one nearest is made of curly ash; the one behind is of curly sycamore.

In the foreground is a contraption that I have described in a previous post, a locking turntable and block that are screwed up to the underside of the lute mold, and then held in a large ratchet clamp in my bench vise. The setup looks a little ungainly but it works great, since it allows me to hold the mold in practically any orientation. It's very useful when I'm building the back, fitting and gluing ribs, and working side-to-side (that is, working alternately on bass- and treble-side ribs), since I can simply loosen the knurled nuts under the turntable to spin the mold around. It's even more useful when I'm carving a lute mold, because that's an operation where it's helpful to see and carve the developing shape from as many angles and perspectives as possible.

So here's my brainwave. I decided to try attaching this universal-joint contraption to the lute back after it's been taken off the mold, to see if I could use it for scraping the back, resolving the rib lines, and giving the back a beautiful shape.

Now, I always do some initial filing of rib joints and scraping of ribs while the back is still on the mold; it's necessary, for instance, to get a shape that's pretty close to perfect at least on the bottom end of the body, in preparation for fitting and gluing the capping strip. 

But once the capping strip is glued on, I'm usually happy to get the back off the mold and reinforce it from the inside: glue paper strips on all the rib joints (and sometimes across the ribs too), glue in the counter cap, fit the false belly, and so on. Generally I don't work with the shape of the back again until later in the construction process, when I'm finishing out the whole lute in preparation for varnish.

The trouble with leaving rib/ body work till that late stage is that by then I'm working with an almost fully assembled lute, and there's no way to hold it completely steadily. The best way to hold it securely is in my lap, against the padded edge of my workbench. And as you can see, that puts me in the middle of a lot of wood dust (which I'm becoming more and more sensitive to every day.)

So, in an effort to separate me a bit from that cloud of dust, I thought I might try doing some of this work earlier in the process, by holding the back steadily in the vise.

Here's what I came up with. The false belly--the closely-fitted piece of panel board that temporarily maintains the shape of the body during the construction process--has been spot-glued into the completed back. I then pre-drilled four screw holes.

I screwed the block/ turntable assembly to the false belly, with a coupe of #10-2" screws. 

I then mounted the thing in the clamp in my bench vise. My only question at this point was whether the whole thing would be tight and sturdy enough to withstand the pressures of being worked on with files and scrapers (or whether, for instance, the spot-glues on the false belly might not hold.) The answer is: yes, it is strong and steady. I feel I need to be a little careful in handling the back when re-positioning it, but otherwise the assembly is very stable. 

That's my brainwave. It doesn't seem like a big deal, does it? And yet in a way, it is. It gives me a little more flexibility in assembling lutes, because it allows me to change up the sequence of construction. So, instead of waiting to the very end of the building process to resolve and tighten up all the rib lines, I can do it earlier on, and with more control. Or, I can do it later. It doesn't matter. The important thing is, I now have the choice. And the best part is, it didn't cost me a dime!

As some of you may know, I love betterizing: taking a contraption and adding to it or modifying it to extend its life or usefulness. I encourage you to betterize in your own workshop, and share the news with the world.

Here's a short video I made of the contraption in action. Enjoy.

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