Saturday, 29 September 2018

A Bass Rider Fix, for Nelson

Hi everybody--it's been a while. Hope you all had a fine summer. Mine was great: plenty of time relaxing, holidaying, swimming in rivers, lakes and oceans (a major summer pastime with Julia and I), as well as a little time to finish up a new crop of instruments. I'll talk about those in a future post, but for today, I want to tell you about a small repair job I did back in early July.

The last week of June I attended the Lute Society of America's LuteFest in Cleveland. As always, the LuteFest was a lot of fun. It was nice to meet up with old friends again, and make some new ones--it's always great to see new people excited about the lute!

And, of course, it was great to be able to spend an afternoon wandering the galleries at the Cleveland Museum of Art. You never know what you might find there....

The Atrium, view from my table at lunch, the Cleveland Museum of Art

One old friend and client I met up with at the LuteFest was Nelson Amos. I've made him a couple of lutes over the years (and fixed one of them for him too), and our paths seem to continually cross in lots of interesting ways. Toward the end of the week, Nelson asked me if I could have a look at his 13 course lute, one that was not made by me but by a now-retired lute maker in the Pacific Northwest.

The problem: the bass rider had been knocked off. Dang!

This lute had been a topic of conversation and debate at Andy Rutherford's Lute Doctor repair shop during the week at the LuteFest. It was pretty obvious that the rider couldn't just be stuck back on with glue: this had been tried once already, prior to the LuteFest, and had failed. Part of the problem was the angle of the bass rider. As on the original Burkholtzer lute (Vienna KHM SAM 44, upon which this lute is based), it leans over the bass side of the pegbox at a pretty steep angle. The arrangement seems to work fine as long as the bass rider is whole and strong (and made from a stout piece of wood), but under string tension, the broken-and-glued bass rider didn't stand a chance, and toppled over.

Here are a couple of pictures showing the rather extreme angle of the bass rider on the original Burkholtzer lute. I have no idea what kind of magic spell is keeping it in place, but I doubt the museum keeps much tension on the strings these days...

Photo by Stephen Gottlieb, Courtesy Grant Tomlinson

Photo Robert Lundberg, JLSA XXXII, 1999, p.42

Various solutions to re-attach Nelson's bass rider were put forward: glue the rider on again, and reinforce it with pins inserted in holes drilled through the back of the peg box; build some kind of support attached to the treble side of the peg box; or replace the entire peg box and bass rider with something stronger and less leaning-over.

None of these suggestions seemed practical. It was hard to see how pins could be inserted to reinforce the joint--there's just not much material to drill into, and even if one could, it didn't seem likely that they would offer much support. Same problem with building a support from the treble side: where and how would it attach? What on earth would it look like? As for the third idea, replacing the pegbox and bass rider, that would work, but it would be very time-consuming and intrusive. It would eliminate a lot of nice work done by the original maker, and change the character of the lute completely.

At the end of LuteFest week I still had no solution, but we packed Nelson's lute, along with all our other lutes, into the van and headed back to the northern side of the border.

I was travelling that week with Wilma Van Berkel, a rising star in the lute making world who lives in London, Ontario, Canada. Wilma's been working with me periodically in my workshop in Vancouver for a number of years now as my protégé, and over the last few years we've developed the custom of working together on lute repairs at her workshop London in the week after the LuteFest. It's a good opportunity for her to gain experience doing lute repairs in a supported environment, and it's a good opportunity for both of us to to get a lot of lutes working again for players on the eastern side of the continent.

We took a couple of days to rest up, then got back to work. Wilma's first project was to re-attach a theorbo bridge that had flown off due to an impact.

Wilma, hard at work preparing the belly to re-glue the bridge

And mine was to get this bass rider back on. I still had no clear idea of what I was going to do to fix it, but I decided to go ahead and work carefully step-by-step, and trust that a solution would reveal itself as I went along.

The first step was to create two new good gluing surfaces, by planing away the broken sides of the joint--on the peg box cheek, and the bottom of the bass rider.

Once that was done, I pretty much knew how the repair would go--I would need to build some sort of ledge, or cantilever, off the side of the peg box for the rider to sit on. Once I had decided that, all I needed to do was make sure a) that it would be strong enough to hold under pressure, and b) that it would preserve as much as possible the original look of the lute.

I decided to affix a pear wood plate to the top of the peg box cheek. It's pretty substantial--about 8mm thick. You can see here that I drilled holes with a jeweller's pin vise through the plate, partway down into the cheek (being careful not to drill all the way through.) You can see one pin, a piece of bamboo dowel, in the upper hole, and I put one in the lower hole too. These pins help align the piece during gluing, and also provide added strength to the glued joint.

I carefully masked the cheek and padded the back of the peg box, so that I wouldn't damage it during gluing.

Once the plate was in place, I used my pin vise and bamboo dowels to locate the bass rider in the same way.

Front view

Back view

Before gluing up, I did a couple of things--I strung some fishing line from the bridge down to the bass rider, to make sure that it was aligned properly; and, I rounded over the inner edge of the plate (I figured it would be much easier to do this before the bass rider was glued on.)

When the fit and alignment were great, I glued up, and got some good clamping pressure.

Action shot of your humble narrator gluing on the rider courtesy of Wilma Van Berkel

Next morning, I got to work carving the plate to match the look of the bass rider.

As you can see, I also carved a bit of relief on the underside of the plate, up near the top: I needed to make sure there was enough room for the strings of the 10th and 11th courses (which wind onto pegs outside the peg box) to travel freely from the nut to the pegs.

I finished off the piece, then blackened it to match the surrounding work. I first inked it with some permanent black ink, then brushed on a number of layers of very thin shellac mixed with lamp black. Here's a final look:

And a view from head-on:

As you can see, the angle of the bass rider is now much closer to parallel with the 12th and 13th course strings, so there's a lot less torque on the bass rider, and a lot less tendency to pull to the side. When I strung up the lute, I was prepared to see some deflection to the bass side under tension, but there was very little. It looked like the bass rider was secure.

As I said above, my other aim in this repair was to try to preserve as much as possible the original look of the lute. I think I did that. There is, of course, an extra chunk of wood on this lute now, and the bass rider no longer sits at its original daredevil angle; but that was the trade-off necessary to get a good lute working again, with minimal fuss, and minimal intrusion.

So, there was one more lute back in action--and for the time being, I felt satisfied. I bade farewell to Wilma, who had by this time moved on to an archlute repair, and flew to Montreal to join Julia for some holiday adventures. There were still some lutes back in my workshop in Vancouver, lutes so close to being finished that I could almost hear them crying out--but they would have to wait a few weeks longer for their first breaths. I will tell you all about them in my next post.

Saturday, 3 February 2018

Because You Asked: Body Frets

I recently received a request for a "how to" blog post from Mr Bill Good, and I'm going to do it.
This time out, I'm going to describe my procedure for installing body frets.

It's one of the very last things I do when I'm making a lute, or a group of lutes. Everything else is pretty much done--all the woody bits have been glued together, a nice, shiny finish has been slapped on, I've fitted a set of tuning pegs (now there's a finicky procedure), made a nut, tied on a set of gut frets, and strung up the lute. I've tuned those strings and played the first, quivering, barely in-tune notes, and an indescribable thrill has begun to form in my being as I realize, again, that I've created a living, breathing thing. The lute is alive!

The Lute Maker, in the Throes of Creation

In such a state of creative fervour--and after such a long time putting the lute together, weeks and months of sometimes very difficult, demanding work--the impulse can be to... well... get into a bit of a hurry at this late stage, cut corners a little, just tape down some toothpicks, nobody will notice, nobody ever uses the body frets anyway....

No! Don't you even think about it! Calm down--you've still got work to do. An hour's work, if you do it right, and have a procedure to follow. Here's mine.

Finding the Octave

The first thing to do is to tune that lute. And I mean tune it, pretty much constantly, for a couple of days at least. Regardless of the type of strings you've used, they'll be continuously stretching and going out of tune for most of that time. I find it useful to actually play the lute while I'm tuning--in addition to waking the lute up and helping it to find its voice, my playing works and stretches the strings so that they will fall into tune that much faster. Besides, I'm a lute maker, it's my job, and I have built this thing to make music--at this point, what else would I rather be doing?

Once the strings are really well in tune, you need to find the octave, the point approximately halfway up the string where the 12th fret will be located. It's not exactly halfway as measured by a ruler--because of the physics of string stretchiness, the octave will always be somewhat less than half the distance between the nut and bridge. (Depending on a few different factors, the octave will be probably be approximately 1.5 to 2mm shorter than half the measured distance.)

How to find the octave? Allow me to demonstrate. This is a lute that I recently repaired--not one of mine, but one made in the early 1980s by a maker in British Columbia. Like many lutes of that vintage, the fingerboard had warped a bit over the years, and needed to be re-shaped in order for the lute to be playable. In order to do the re-shaping, I had to remove all the tied frets as well as the body frets that were on the lute. Now that the work on the fingerboard was finished, I needed to put a set of new body frets down. (By the way, the gut frets I've put on are placed provisionally, and will be adjusted when I find the octave and calculate all the fret positions.)

I have a small ebony body fret that I have shaped and keep just for the purpose of finding the octave (I'll talk about how to shape these body frets in a minute or two.) I put the fret down on the belly under the top string, and strike a note.

I move that fret up and down the string, making slight adjustments one way or the other, plucking notes until I've found the true octave. I use an electronic tuner to do this (because I am lazy), but if you're a purist you could probably do it by ear, comparing the fretted note with the natural harmonic produced at the 12th fret. Whichever way you do it, when you are convinced that you've got that fret and that octave in the right place, take a very sharp but not very hard pencil (HB works well), and make a crisp, light mark on the soundboard on each side of the fret. Move the fret away. Then, between those two marks, make another mark exactly in the middle. That is the precise position of the octave.

Next, get out your ruler, and underneath the top string, measure accurately the distance between the octave mark you've just made and the front edge of the nut. Now, double that number: this gives the lute's playing string length. Use it to calculate the position of all twelve frets, according to whatever system of temperament you are using (this lute, a 9 course, will be fretted in equal temperament.) Cut a piece of card stock about an inch wide and a bit longer than the length of your octave, and carefully mark out the fret positions on it. You'll use this card to lay out the positions of the body frets (there will be three on this lute), and to adjust the positions of the tied gut frets on the neck.

I also write down on this card the diameters of each of the tied frets, and when I'm done using it to lay out the body frets and adjust the tied frets, I put it in the lute case and keep it there. It's very handy to have when replacing worn out gut frets.

Making the frets

After erasing the marks I've made on the soundboard, I lay a strip of 1/2" masking tape down on the soundboard, so that the inside edge is more or less in line with the edge of the fingerboard (the strip of tape isn't quite parallel to the first course, but flares a little.) This tape will mark the location of one end of each of the body frets, so I lay my fret card down alongside it, and mark the locations of the body frets on the edge of the tape--like so:

I can then get out my ruler, and determine the length of each of the body frets.

I want this 12th fret to cover the first three courses (the 11th fret will cover 4 courses, and the 10th fret will cover 5), so I measure the distance between the edge of my masking tape and the mid-point between the 3rd and 4th course. (You can see my mark on the masking tape on the left side of the ruler; you can also see the length of this fret will be 33mm.)

On this lute only the 11th and 12th fret will be on the belly, and the 10th fret will be on the fingerboard. In order to determine the length of the 10th fret, I need to measure from the fingerboard edge to the mid-point between the 5th and 6th course. You can see the fingerboard edge clearly here: the length of this fret will be 51mm.

Once I have the length of the frets figured out (and written down someplace), I can decide on the thickness of frets that I want to use.

This can be a bit of a tricky calculation, and it deserves some thought. The thickness of the body frets you use will depend partially on the thickness of the tied frets on the neck, and partially on how much and how quickly the belly slopes down and away from the strings, once you get past the body-neck joint. The slope of the belly at this point depends on the amount and severity of the "belly scoop" that the luthier has planed into the edge rib of the lute: some makers like a deep belly scoop which slopes quickly away from the fingerboard, while others prefer a more gentle, gradual slope (that's generally the way I like to do it, and that's the way the maker of this lute decided to work.)

Let me explain how I decided on body fret thicknesses for this lute. My general method of fretting a lute (which I normally use unless a client asks for a different setup) is to begin with a thick fret for the first fret--say, 1.05mm for the first--and then gradually tie smaller frets all the way up the neck. So, for a 9-fret neck like this one, this is how the tied frets go:

1st: 1.05mm
3rd: 0.95
4th: 0.90
5th: 0.85
6th: 0.80
7th: 0.75
8th: 0.75
9th: 0.75

The 10th fret is my first wooden fret and it will be on the neck, so  I will make it 0.75 thick as well, to give some uniformity of "feel" with the last three tied frets. Then, because the next two frets are on the belly--which is gradually sloping away from the string, and creating a bit more clearance--I will grade the 11th and 12th slightly thicker--0.85 for the 11th, 0.95 for the 12th.

Now let's make some frets.

I make fret blanks out of ebony and english boxwood, two very hard woods that will withstand years of playing, and generally choose the light or dark wood depending on the overall look of the lute. (On this lute, the original body frets that I removed were ebony, so that's what I put back on.) I make my body fret blanks 1.4mm wide, and I'm able to thickness them quite precisely to various thicknesses, as you can see in the photo above. This is the tool I use to size them up, a pull-through scraper:

I have described this tool and its use in detail in a previous blog post from a few years back. You can visit that blog post here (you'll need to scroll to near the end of the post.) It's well worth a look--I use this unit to make sets of rib spacers, ebony edge bindings, strips for striped veneers, and much more. It's an incredibly handy tool in the lute maker's workshop.

I take the blank of desired thickness, and cut a segment 3 or 4mm longer than the final finished length. Then I dress the edges of the fret, using this jig, held in a benchtop vice.

It's just a piece of particle board with some arborite on top--I think it came from a piece of old kitchen countertop. The arborite edge is nice and sturdy for holding the fret. I have a thin piece of some kind of plastic sheet stuck down on top with 2-sided tape, forming a ledge that's as wide as the fret, where I can hold the fret securely while working it.

With a #2 flat file, I break the top edges on both sides of the fret. I file them at about a 45° angle, then round over the two new edges I've just created. I'm careful not to go over onto the top of the fret--I don't want to lower it, I just want to make those edges comfortable to press a string down onto.

Then I relieve the sharp edges at the end of the fret. I put the end of the fret at the edge of my jig, and with my #2 file, give a quick downward stroke to put a 45° angle on it. Then I relieve the edges on that angle by trailing the end of the fret across the file. I then cut the fret to its final length with a sharp chisel, and dress that end of the fret in the same way. Here's how the fret ends up:

Now that I've got all the frets made, i can finish laying them out.

Laying out the frets

I need full access to the end of the neck and top of the belly to lay out the frets, so I unstring the lute. I just loosen off all the strings without removing them from their pegs, and tie them away from the top of the soundboard.

I lay down the frets in their approximate positions, according to the marks I've put on my long piece of masking tape. I then stick down smaller pieces of tape at the other ends, and bring back my fret card to mark the fret positions on them. Then I move the frets away, and use my small ruler to draw a faint line on the wood of the belly from the mark on the treble side to the one on the bass side.

I then use a small, sharp, curved scraper to scrape away the lines I've just drawn. I'm not really scraping away very much wood--mostly just a thin layer of finish on the belly and neck so that the glue I use to stick the fret down will adhere to the wood below.

Gluing the frets

I use hide glue for this job, as I do for all the gluing jobs on a lute. You might be tempted to use yellow carpenter's glue for this, which would be fine, but I find that hide glue tacks faster and cleans up better--instead of waiting overnight for yellow glue to dry, you can use hide glue and be playing again in an hour.

I use a fairly thin glue for this job--you don't need a lot of glue to get these frets to stick. 

I wrap a little two-sided tape around the end of a small dowel, and just press that down onto top of the fret so I can lift it and hold it over the glue pot while I brush some glue on (the more dextrous among you could probably just as easily use tweezers for this job.) I just dip the brush in the glue, sweep upward onto the fret, then sweep back down to brush off excess. Then I stick the fret down quickly in position--locate one end of the fret close to its mark, then bring the other end down. It should be good--if not, adjust. Hold the fret down for about 30 seconds, until the glue begins to set. 

Then bring in the small metal ruler, and use it to press the fret down until the glue is well set (a minute or two of pressure should be good.)

Then move on to the next fret, and go through the same procedure, then the next. By the time you've got all three frets stuck down, the glue will have set well enough on the first one that you can go back to it and clean up the squeeze out. Just brush a little cold water on each side of the fret, give it a minute for the glue to soften, and clean up with a sharpened spruce stick. For a last measure, give each fret a quick wipe with a damp bit of paper towel, to remove any glue residue that might be lurking on the top of the fret.

And that, my friends, is that. Remove the masking tape bits, and start the process of tuning the strings. By the time the lute's back in tune, the body frets will be firmed up, and you're ready to play again.

So that's my procedure. It took a long time (and a lot of photos) to describe a fairly simple operation. Still, some might object that I go too far--that all this rounding and filing and fiddling is simply paying too much attention to a feature on the lute that isn't, after all, that important. To which I would reply: there is no detail on a lute that is too small to pay attention to. And in the case of these body frets, a lot rides on their position and shape. If they're not in the right place, the intonation will be wrong. If they're left square-edged, the note will sound thin, but more to the point (ahem), they will feel unfriendly to the fingertips. I've tried many lutes that had body frets with edges left square, and I've always had the uncomfortable feeling that I was stubbing my fingertips on them. Why would I want to leave something unfinished on the lute that I felt was impeding my playing?

When players and makers think of "playability", they're mainly thinking of big things like string spacings, action (string height above the fingerboard), fingerboard arching, and neck shape. But I would argue that apparently "small" things like body frets can make a significant contribution to playability too. There are a few other small details of finishing a lute that make similar contributions; perhaps I'll make them subjects of future posts.

Sunday, 17 December 2017

Here's a Thing That I Made, or, How to Hold A Lute Mold, or, The Return of the Betterizer

I have a question for all the lute makers out there: how do you hold a lute mold?

I've looked around at a lot of makers' websites and visited a few of their workshops, and I've seen a few different contraptions. Some are simple, elegant and useful, while others seem awkward and difficult. Here's a selection:

A plain stick of wood fitted in the underside of the mold, and held in a bench vice. This is the method used by Robert Lundberg, illustrated in his book Historical Lute Construction. Here is a photo of his protegé, Prof. Günter Mark, using the same method:

(Courtesy Liuto Forte)
I once used this method, for the second lute mold I ever made, and found it pretty inadequate. The mold can be tilted forward and back in the bench vice, but that's it. (I guess in a pinch you could turn it 90° in the vice, and tilt it side to side, if you really wanted to.) Not very convenient when you're carving a mold, and want to tilt it a little to scrape a rib facet, or slightly change the angle of light from your shop window or bench lamp. I'm sure this way of holding the mold worked fine for Lundberg (and does so for Prof. Mark), but my eye needs more angles, more ways of seeing. I want a way of holding a mold that allows a full range of motion, so I can set the mold in any position.

Here's a good example of a jig that I imagine works really well: two locking hinges. I've seen quite a few makers using this type of holder; here's a shot of Malcolm Prior with his. (Malcolm thinks this method might have originated with the renowned English maker Stephen Gottlieb.)

I once tried to make one of these jigs out of stacked layers of plywood (again, early on in my lute making career), but lacked the skill or resources to do a good job. Malcolm's version looks very well made and useful--note the tightening levers on the bolts through both hinges. The mold (and lute back in progress) is held very securely, but is fully adjustable, tilting forward and back, as well as side to side, and rotating 360° where it sits in the bench vice (you can't see that part in this photo). I can't comment on its ease of use, never having used one, but it does allow a full range of motion and orientation in any position.

Here's the slickest of all the lute mold holders that I've seen. It belongs to Grant Tomlinson, and he tells me he bought it years ago from a supplier in Vancouver who's no longer in business; it was called a "universal carver's vice."

There's a big steel ball (like a trailer hitch) that bolts into a plate screwed to the underside of the mold. The ball is sandwiched between two half-inch steel plates, one of which is sunk into a big block of hardwood, which is held in the bench vice. A couple of heavy bolts cinch the plates around the ball; one of the bolts may be loosened (note the nut with lever attached in the view below), and the mold may be moved freely, and then secured in any position.

There's the owner of the mold (and mold holder) himself, Grant Tomlinson. As you can see, he's just getting ready to fit up and carve a new top block for this mold. In fact, he's getting ready to make top blocks (and bodies) for a new group of lutes. Here are the other three molds in the group:

Each is fitted with its own steel plate, so it's a fairly small matter to remove the current mold from the holder, and set up another. In this way, Grant can fit and glue a rib on one back, and while that's drying, set up the next mold, and fit and glue another. I doubt that Grant will be working on all four backs at once, but he might work on two at a time--most probably they'll be made of the same material (for instance, yew wood), so that he can set up his planes and other tools a certain way, and not have to change for a harder or softer material.

I got a chance to use this mold holder, and Grant's molds, when I worked with him in 2008-2009 (once again, my thanks to the Canada Council for the Arts for the grant that financed this residency.) One of Grant's instructions about using this piece of equipment is that it's essential to hold onto the work securely when loosening the nut and releasing the vice--if you don't, the mold will just fall over, and the consequences to it, and the back in-progress, could be devastating. (And no, in case you're wondering, I never let the mold slip!) If you've got a good hold of it, everything's fine: just re-position it, tighten the nut, and you're ready to go. 

(By the way, I've looked online for a mold holder like Grant's, and while I have found carving vices that kind of look like it, I've never found one that looked heavy-duty enough to withstand the weight of a mold and the wear and tear of using it pretty constantly for years, as Grant has done with his. If anyone has found a good version, please leave a comment and link at the end of the post--I'd love to have a look.)

What I used for years was a setup that Grant showed me a long time ago--the rig he used before finding that space-age carver's vice that he has now. A block of hardwood is screwed to the underside of the mold, and a large ratchet clamp grips the ends of that block. The bar of the clamp is encased in a built-up block of plywood, and that plywood block is held in the bench vice. It's low-tech, but effective--just the kind of thing I like. Have a look.

Everything's very secure. You can see that I've drilled through the hardwood handle of the clamp and inserted a 3/8" bolt, which gives plenty of leverage when tightening up against the hardwood block. 

Here's a look at the plywood block that holds the clamp, and sits in the vice--it's an essential part of the rig. It's built up of layers of ply, and as you can see, some thicknesses of card to ensure the clamp's held tightly. 

The setup has some drawbacks, but a few things work really well. Once you've clamped up the block a few times, there gets to be a kind of recess pressed into both ends, where the jaws almost automatically fit whenever you clamp up. Also, the clamping pressure is so good that you can tilt the mold by simply pulling it toward you or pushing it away (as shown in the photo above), without having to loosen the clamp. I've found it very handy to have this small amount of flexibility available, when carving the mold or fitting a rib. It allows a quick glimpse at the work from a slightly different angle, which can be a great help in the middle of the process.

Now the drawbacks. The mold tilts away or toward you, or forward and back in the bench vice, but it doesn't rotate, which means it's always facing in the same direction--unless you release it from the clamp or the vice, lift it up, turn it about in your hands, and then clamp or vice it again. (That's what you have to do if, for instance, you've fitted and glued a rib on one side of the body, and want to do the same on the other.) It's a royal pain--I did it for years, and while it's a good workout for your biceps, it's also pretty awkward, and potentially hazardous to the ongoing back assembly.

The main problem, though, is that like the Lundberg/ Mark setup, there's no way to alter the orientation if you want a slightly different view when carving a mold--to see how light and shadow fall upon the complex shape, or to follow a rib facet as it comes up in a long, graceful curve from the neck joint toward the abrupt transition at bottom end. I find mold carving to be a very demanding and difficult process, and as I said above, I need as many different angles and ways of seeing as possible in order to do a decent job of it.

So, a little while ago, I put the betterizer part of my brain to work, and came up with a solution that performs very well. I've talked about "betterizing" before in this workshop diary--I define it as a specific kind of improvement one makes to a tool or a jig in response to a displeasure one has felt building up, almost unconsciously, over many years, toward a certain shortcoming in the tool. It's like a burr under the saddle or a stone in your shoe, an irritation that can be ignored or withstood for a long time, but once decisive action is taken... there is only the freedom and sheer joy of having a tool that performs exactly as you want it to.

Here's what I came up with--a turntable that allows the mold to rotate 360°, and can be locked firmly in any position. As you see, it fits in between the mold and the hardwood block.

Here's a look at it separate from the mold.

There are two knurled nuts, on two bolts, one on each side of the hardwood block. Remove those nuts, and the top plate (along with the hardwood block) can be lifted off, to show the inner workings.  

The turntable base is made up of two thicknesses of 1/2" birch plywood, with one extra thickness of 1/8" ply on the bottom. The upper layer of 1/2" material, as you see here, is cut in two pieces in the bandsaw--an inner circle and an outer ring--to leave a channel about 1/2" wide, wide enough for the shanks of a couple of carriage bolts to travel freely around it. The lower 1/2" layer is cut in two pieces in the same way, but the space between the outer ring and the inner circle is a little more than 1" wide--wide enough to allow the head of the carriage bolt to travel freely. If you flip the base over, this is what you see: the outer 1/8" plywood layer. All of these wood screws are what hold the layers and pieces of the base plate together.

One other crucial feature of the turntable is the length of 1/2" maple dowel which centres all the layers, connecting the top plate and base plate together. It's the axis upon which the turntable turns. This is the underside of the top plate, showing the centre hole into which the dowel fits; the #12 screws that attach the top plate to the hardwood block; and the two holes through which the carriage bolts will fit up when the two plates are put together.

Here are the carriage bolt, spacer disc (made of 3/8" ply), and knurled nut.

Just a word about the knurled nut: it's simply a hexagonal-head nut which I embed within a couple of layers of ply (you can see the threads of the nut winking in the photo below.) I "knurl" the outer edge of the disc in the band saw, and then relieve the rough corners with a file. I could use wing nuts for this purpose, I suppose, but I prefer these shop made nuts because they are secure and easy to twist, which you end up doing a lot with this rig. I think wing nuts would be harder on the fingers, after a long day at the workbench carving a mold.

And here's what it's like, with the plates fitted together, waiting to be fixed to the underside of the mold--

Which I do with a couple of stout #12 wood screws on each side of the turntable (so there are four screws altogether holding it to the mold.)

Once it's fixed to the underside of the mold, just clamp the hardwood block into the big orange ratchet clamp and get to work. To turn the mold around, just back off the nuts about a half-turn, rotate the mold to the desired position, and tighten the nuts back up again. It really is that simple.

I remember the day I first made one of these things and tried it out: I was so thrilled, I must have spent an hour just loosening the nuts, repositioning the mold, tightening the nuts again. The turntable, and the mold, could be spun effortlessly, but there was no danger of anything falling over or falling apart; and when I tightened up the nuts, with only moderate finger pressure, the mold would stay very securely in its position. I could tell I had made a good jig, one that worked and would be safe and durable to use, whether I was carving a mold, or fitting and gluing a rib, or as I'm doing here, carving a top block for a new lute back.

It's like a miracle--I can position this mold in any direction I want, except, perhaps, upside down (but I will work on that.)

So there it is, another troublesome operation in the shop all betterized. It really is not an exaggeration to say that this invention has made my work with molds and backs much easier and more satisfying in so many ways. It's like a toothache is suddenly gone. I can't believe I made lutes before I started using this rig.

If anyone reading wants to make one of these things for him or herself, please be my guest. If you need any further hints on how it's done, just leave a comment here. And if you make any improvements to this rig, please let me know.

Go forth and betterize!