BEVELLING THE SIDES EDGES AND MAKING THE SOUNDBOARD REBATE

This has been a huge hurtle for me to conquer. It appears that most builders just leave the edge of the sides, to which the soundboard will be glued, flat. And, perhaps for good reason. But, while some argue that it is preferable to build in a little bit of tension into the soundboard, and mating a domed top to a flat gluing surface would definitely do that, I was determined to try and fit this the best I could and thus bevel the edge.

INITIAL CONSIDERATIONS
I started by drawing an elaborated version of Rik Middleton's string height diagram featured in his book. I found it a very helpful guide to visualize how different parameters, such top doming and neck angle, would impact the final setup of the guitar.

Initially, it was my intent to have a 25' radius dome in the soundboard that tapered off linearly above the lower transverse brace, forming a kind of tear drop shape, but from Middleton's diagram it became obvious that this wouldn't as easy to do as just that. I started to experiment with alternative scenarios such as having the lower transverse brace arched more to create a more elliptical shaped dome, another version had all the transverse braces flat, and so on and so forth.

Through a lengthy correspondence with two of my luthier buddies, Udi Vachternman and William Londree, I ended up deciding on a more traditional solution where basically everything below the soundhole will be domed to a 25' radius and everything above it will be flat.

With all this, I also settled on a neck angle where the nut is raised 1.5mm. This will give a string height of 3.4mm with a 3.0mm saddle sticking out of the bridge. These numbers are of course theoretical as some distortion is likely to take place once the strings are on and tuned up to pitch, but it should hopefully be in the right ballpark.

I had a friend from work help me out with calculating the right angle for the bevel in various places on the rim. Measured with the center of the dome at the saddleI, it came up somewhere in between 1.05º and 1.26º, changing with the undulating shape of the lower bout. As it was not practical for me to work closer than a 0.5º proximity, I decided to settle on 1.0º for all of the lower bout and tapering to flat between the lower transverse brace and the next one up.

THE JIG
To do this, I constructed a little fence jig to hold a spokeshave. It's a simple little thing that consists of a base that functions as a fence and a little tilting shelf that holds the tool. The shelf has a rare earth magnet that anchors the tool down and at the end a bolt replaces one of the tool handles and locks it in place. In future I might alter it a little by adding a slice of veneer over the magnet to protect the blade and rework the shelf part so the jig can be used both left and right - at the moment it only goes one way.

The spokeshave was set up to cut as fine shaving as possible, the right handle was screwed off and the spokeshave was fastened to the jig. I set my sliding bevel to 1º and transferred that angle to the jig and was ready to go.

CUTTING THE BEVEL
First the guitar was fastened to the bench by resting the body on the 15' dish the back rim was fitted to. A support for the neck was built up with some MDF and other scrap and the hole thing was secured with two clamps, one at the top of the neck and one at the end block.

Cutting the bevel was quite straight forward. The only thing I really had to concentrate on was to keep the fence flat up against the sides while working my way through the job. Once the kerfing got down close to the actual side, I lowered my work light so it was virtually level with the rim. This revealed all the areas where the kerfing wasn't cut down far enough by casting a little shadow on to the edge of the sides and allowed me to monitor quite closely where more shaving was needed and where it wasn't.

When I got to the endblock, I repositioned the clamp slightly off to one side, worked the endblock area down, moved the clamp back again and continued on the other half.

Once the whole rim was done this way, I reset the jig to 0.5º and worked the area from the lower transverse brace and up, trying to gradually work the shallower angle in. The same was done with jig set to a flat angle, though this taper was gradually added, starting halfway between the upper and lower transverse brace.

The last few inches near the heel I couldn't get to with the spokeshave was pared away with a chisel.

MAKING THE SOUNDBOARD REBATE ON THE HEEL
Since the neck will be set at an angle to the soundboard, I've also been debating whether to cut the rebate to compensate for this or just do it parallel to the neck. My first instinct was to compensate for the neck angle. However, I decided to compensate by angeling the fingerboard graft on the soundboard instead, once the soundboard is ready to go on.

I started by marking the heel 3.5mm down from the edge with a scalpel all the way around. Ready to pare away. Cumpiano's method of making the rebate is similar to the way he cleans out waste inside the head slots - by first paring the waste down to the marking while leaving a peak in the middle and then slowly taking the peak down to a flat, a method I really like when I did my head slots.

But, this proved to be a real chore as the already attached sides got in the way big time. Instead I had to work my way through the task in a quite random manner, using both sides of the chisel, paring sideways from the center and out and from the end and in towards the side joint. It was a real pain in the neck to say the least. But down it went.

As I got closer to the marking, I started sanding the rebate a little allowing the scratches to show the peaks and then carefully chiseled these away and repeated the cycle until the sanding left a somewhat evenly scratched surface on the entire rebate. I finished the rebate off by scraping it lightly with the chisel, leaving it a little shallow on purpose to do the final fitting for when the soundboard goes on, being satisfied just to have a it fairly flat. Oh, well - next time.....

IN CONCLUSION
Since this is my first build and I have gone a little astray from tradition, I have to ask myself if this was the right thing to do, and to be honest I don't really know. I was surprised to see how little an angle was needed to fit the 25' soundboard dome and since I ended up rounding the correct bevel up to the nearest 0.5º it wasn't accurate anyway.

Another caveat was that it was difficult to monitor whether the rim ended up on a perfectly flat plane - that some parts of the sides ended up being cut deeper than others. For this I mainly had to rely on my hope that the side were flat already and all I had to do was to cut the kerfing down to match it. I don't know if this is easier to achieve by sanding the whole side on a flat sanding board prior to installing it, as it is normally done. To me, it seems that it might be just as difficult to sand a loose and floppy side evenly along it's length, but I don't know.

So the question remains whether this effort had any value at all or if I was just being another newbie trying to reinvent the wheel. One thing is for sure though, it made me go places and read up on things I would have if I had just followed instructions and as always it was fun to do the research and think it all through.

That and cut the heel rebate before the sides go on!!!

DOMING, NECK ANGLE, STRING HEIGHT DIAGRAM

EDGE BEVEL DIAGRAM

SPOKESHAVE JIG DISSEMBLED

SPOKESHAVE JIG ASSEMBLED WITH TOOL

SETTING THE BEVEL

SETTING THE SPOKESHAVE JIG

BEVELING EDGE OF THE SIDES

PARING KERFING NEAR HEEL

SPOKESHAVE SHAVINGS

THE LOWER BOUT SIDE BEVEL

MARKING THE HEEL

PARING THE REBATE ON THE HEEL

THE FINISHED REBATE

THE FINISHED RIM

NECK AND SIDE ASSEMBLY

Well, I think I've been stalling long enough with this and it's time to get a move on. A decision has been made and there is no turning back now; The sides are going on the neck first. It has taken me a long time to figure out a way to do this that made sense to me but more on that later.

FITTING IT ALL
The side and neck fitting was pretty straight forward. I started by setting the sliding bevel to the correct angle for the heel block. Then the distance between the bottom of the slots and the heel block was measured and transferred to the linings. As the linings were glued on 'by eye' and the sliding bevel was resting against them, I wasn't sure it was all that accurate and allowed a millimeter or two for inaccuracies and final fitting. Each side was done with separate measurements.

Once the linings were marked, I cut them with a dovetail saw a pared away the waste with a chisel. The two processes were a little cumbersome as it was difficult for me to clamp the work down properly. I ended up making a little caul with a slightly curved face that fitted in between the top and bottom linings and clamped the side down to the bench with a bar clamp. In retrospect I think it would have been better to use a vise. Maybe next time.

With all the waste gone, I fitted the sides into the slots and started trimming the linings with a little bullnose rabbet plane until they were seated fully into the slots. I had to hold the plane at a slight angle to compensate for the curvature of the sides and the fact that they don't enter the neck at an right angle. The plane did tear a little where the individual kerfed blocks got cut down to thin segments, even though the blade freshly sharpened and set to a fine cut. Thinking back, I wonder if I would have been better off using a small sanding stick instead. However, be it a sanding stick or a plane, using a tool that was able to rest against one of the lining while cutting the other, insured straight cuts that otherwise would have been difficult to achieve, had each lining been cut individually.

The bullnose plane is a wonderful little tool. It's made by Lee Valley and I must confess that I'm really impressed with their planes. The level of precision, thought and intelligence that have gone into their designs, makes them a joy to use. I cannot speak highly enough of them.

Once the sides were seated well into the neck, I started trimming the linings to allow for the end block. This was done the same way, apart form the marking, which was done with a machinist square instead of the bevel. Also, I did most of the final trimming with the chisel to avoid some of the tearing mentioned above, and saved the very final touches for the plane.

During the final dry fitting it became clear that the curvature of the end block needed to be increased slightly. This was done by rubbing it back and forth on a sanding board, Cumpiano style. The sides were also thinned slightly by sanding in order to enter the slots with ease.

I made a clamping caul out of 1/2" Baltic Birch plywood lined with 1/8" cork. Two kerfs were cut leaving about 2mm of solid wood, enabling the caul to be bent slightly and conform to the profile of the end block.

GLUING THE END BLOCK
Once everything was fitted it was time for the end block to be glued. It soon became clear that this all became a little bit of a challenge; It didn't make sense to clamp end block down in position on the solera, without adding glue to it first because the sides were already in place. And, I couldn't use the end block clamping caul without having to get rid of the support block on the solera that insured the sides were perfectly square in the first place. Confused?....

I ended up with a somewhat half arsed approach by mixing two schools of methods into a one, Cumpiano and Courtnall representing one and Sloan and Bogdanovich the other, but, the end block did get glued on.

First step was to place some wax paper on the support block and bottom of solera adjacent to the glue-up and then slip the whole assembly down into position on the solera. Then glue was added to the end block and pushed into place, up against the sides as hard as I could and clamped down in place, square to the solera, with a big Bessey bar clamp. Next the solera support block behind the heel block was removed, and replaced with the clamping caul. Once the support block was gone the end block went a little out of squareness and I had to adjust the position of the bottom of the bar clamp to get it square again. Finally the end block was clamped to the sides with four small bar clamps. A MDF caul was used on the end block itself.

The glue clean-up was a little unwieldy as all the clamps and cauls were in the way, but I managed to get most of it off with a chisel. I left it to dry over night and did the final cleaning the next day.

GLUING SIDES INTO NECK SLOTS - WHAT A PAIN IN THE NECK!!!
Gluing the sides into the neck slots was no less than a nightmare and it nearly ruined the whole build. I kind of expected it be a challenging process, but I didn't fully realize what trouble was lying ahead of me.

I started by carefully coating the slots with glue, using a little stick to rub it on with and placed the neck on my work bench fingerboard side down. I carefully pulled the side assembly apart and inserted the sides into their slot sideways. But, the glue started to grab before they were fully seated and I had to yank it all apart as quickly as I could without damage anything. I have never been a big adrenaline junkie and this episode was no exception. I did not like it.

I cleaned the whole thing up and tried my luck again a second time. Well, why not? There was still some wet glue in the slots I could use. Dare I say that I wasn't particularly successful the second time around either - I'll leave it at that!

Third time lucky! Now it became a matter of pride. I was determined to get the sucker to obey. The whole thing was cleaned up again. During the clean up I noticed some small saw marks in the slots and I began to wonder if that had been the source of the problem, or at least partly so. I carefully thinned the sides a little more, rounded their edges to ease the insertion, added glue sparsely and they finally went in, albeit with a little bit of play that hadn't been there before.

The whole assembly was then placed back in the solera. The neck was lined up with two bar clamps and the sides were held in place, suspended on the little soundboard shims, with spool clamps.

I hindsight I wonder if gluing the side into the slots is such a good idea after all. There seems to be to schools of thought on this one too. Cumpiano and Courtnall both make this joint without the use of glue, whereas Sloan and Bogdanovich do them with glue. I my case, the joint was definitely a tighter one when it was dry fitted; A very snug fit that went together with a firm, but gentle hand. Whether it would have been a stronger one, I'll never know.

SETTING THE HEEL BLOCK BEVEL

MARKING THE HEEL BLOCK BEVEL

MARKING FOR THE END BLOCK

MARKING FOR THE END BLOCK

CUTTING THE LINGS FOR THE END BLOCK

PARING THE LINING WASTE FOR THE END BLOCK

TRIMMING THE LINING WASTE FOR THE END BLOCK

FINAL TRIMMING OF THE LINING WASTE FOR THE END BLOCK

DRY FITTING THE SIDES TO NECK AND END BLOCK

FINAL PROFILE SANDING OF THE END BLOCK

END BLOCK CLAMPING CAUL

SECURING END BLOCK IS VERTICAL
GLUING END BLOCK TO SIDES

ADDING GLUE TO HEEL SLOTS

GLUING THE NECK AND SIDE ASSEMBLY

FINISHED ASSEMBLY

FINISHED ASSEMBLY

FINISHED ASSEMBLY

MY SHOP

Lately not much has happened on the building front. Most of my shop time has been occupied by building a Go-Bar clamp and some other smaller jigs and fixtures. Apart from that, we've had an excessive amount of children's birthday parties to attend, not to mention Halloween. But, in the spirit of documenting this build I decided to take some pictures of my workshop last night.

It's a two car garage that, like so many other garages here in Southern California, is not used for it's intended purpose, but more a place where you shove all the crap you've accumulated over the years and that you don't really have any use for anymore but somehow has gotten too attached to to get rid of, in.

However, the garage has a small attic were all the really useless stuff has ended up, leaving the a fair amount of room for some tools and workbenches, and viola - a little workshop is born.

Last summer I completed my main bench made from MDF and two Rockler Shop Stands. It has six drawers and a shelf underneath. My other bench is made from the 1½" thick maple butcher block sink cut-out leftover from our kitchen counter tops. Like the MDF bench it is supported by a Rockler shop stand. It is on wheels and can easily be moved around as needed. I drilled several holes into the top to accommodate Lee Valley's Bench and Wonder Pups Combos and the attachment of a Patternmaker's Vise.

I also build a small dust collection system that is hooked up to my bandsaw. It has a port for a vacuum hose that doubles for the drill press, a floorsweep and an 'expansion' port that I can use to hook up a variety of other tools to. At the moment 'the other tools' only consist of a drum sander but in the event that more tools enteres the shop, this is where these would go.

Unfortunately the floorsweep is not very useful as bigger shavings from handplanes and the like just clog up the whole system. The port where the vacuum hose goes does not have very much suction, which I hope is due to the drastic and likely improper installation of a 4" to 1½" reducer. I hope to be able to fix this by adding a small cyclone seperator to it instead. This could potentially also take care of the inadequacies of the floorsweep; All projects for a later date.

The shelves on the back wall are cheap IKEA shelves.

THE SHOP

ADDING LINING TO THE SIDES

I'm slowly beginning to realize that guitar building is a peculiar thing!

I was very nervous about bending the sides by hand on a hot pipe, but to my surprise it went quite smoothly. When it came to adding kerfed linings to the sides, I thought it was going to be a piece of cake. After all it's just gluing a little strip of wood onto another. How hard can that be? Wrong!!! It soon became apparent that they were next to impossible to manipulate without snapping them left, right and center even though I try to handle them very careful. Where did this come from?

Being at a loss of what to do I read through my books on guitar building, "Build Your Own Acoustic Guitar" by Jonathan Kinkade being one of them. In the section about kerfed linings he mentions that "the kerfing strips are easier to manage when they are cut into 6" strips". This little sentence suddenly got a whole new meaning. I also consulted several fellow builders just to find that they too had been caught off guard the first time they had a go.

Something had to be done and off I went:

BENDING:
Through a lot of research it became clear that the best way to avoid breaking the linings were to pre-bend them in some way. Some people suggested wetting them and clamping them on the outside of the sides and leaving them over night. Others suggested steaming them with wetted paper towel and a hot household iron. I experimented with a little jig to hold the linings in while heating them with a heat gun. In then end I resorted to bending them like the side, on my bending iron.

At this point the linings were already in a somewhat bad shape: One had broken in two places, one had a fracture while the last two were still intact.

I started by bending the 'three piece' lining since it was the most damaged. What the heck, why not break it a little more if it would come to that. It went quite well though, and stayed in three pieces after all. Second came the fractured lining. This proved to be a little more troublesome than the first one, as it was still in one long piece and therefor had to be handled with much more care. Despite this, I managed to turn that into a 'three piece' affair too. Now, two of the linings were broken in three pieces; At least there was some sort of consistency (I'm keeping a positive mind).

Learning from my mistakes I managed to bend the last two linings without breaking either of them, though I did have a few close calls.

I aimed at bending them into a C-shape with each bout slightly overbent to avoid having the yet-to-be-clamped part of the linings smearing glue on the sides. I did not worry too much about bending the waist area for the same reason.

INSTALLATION:
I decided to use the damaged linings against the soundboard, where the fractures would not be immediately visible, whereas the two intact ones would be used for the back where they could been seen through the soundhole.

I clamped the side into the lining jig and started with a dry run with the three-piece linings to see if some unforeseen issued would pop up, but to my surprise it went pretty smoothly. It seemed as if all my struggles disappeared once the linings had been pre-bent. I started clamping the linings on at the waist and moved my way outwards along the upper and lower bouts respectively.

I took the lining off again and applied a modest film of glue to it by dapping it on with a finger and glued it on the side with 3/4" plastic spring clamps, about 1mm proud of the edge. I butted the broken segments up against each other the best I could to disguise the fractures. Some ended up being barely noticeable while others sported a little gap. Oh well!

In retrospect I think the clamps, though they are very nice and have a good squeeze, were a little too wide for the job. As a result there are a couple of spots where the linings are not sitting tight against the sides. I tried to shave a couple of the swiveling clamp tips down but to little effect as the area where the jaws connect has a big 'knuckle' that prevents the clamps on closer together. Alternatively I could have made two long bent cauls to go on either side of the glue-up to even out the clamping pressure.

I did experiment by applying the glue on the first strip with a newly acquired roller - the kind you use for lino printing - but even though it did leave a thinner, more even translucent film of glue on the work that produced virtually no squeeze out, it wasn't a particularly well suited tool for the fragile linings. However, I think I'll be trying it out again later on other processes. It might have worked very well if the linings had not been pre-bent and could have been laid down flat of a bench for support.

As this build is progressing I'm slowly becoming aware of how little glue is actually needed when you want two pieces of wood to stick together. When I started out, I was pouring it on with a thick coat that left me a huge mess of squeezed out glue to clean up afterwards.

After about twenty minutes I cleaned up the excess glue with a sharp chisel. In Bogdanovich' book he recommends waiting only 8 minutes before doing this, but I find it to wet to work with. Maybe he works in a dryer and warmer environment, but for me fifteen to twenty minutes seems to work better.

The back linings were installed in a similar fashion, including a dry run before the real deal. I worried it would be difficult to have the linings follow the undulating edge of the side made to accommodate the domed back plate. This did not prove to be a big problem, as it was relatively easy to manipulate the linings to follow the edge as they went around the bouts. The back linings were also installed 1mm proud.

LAST THOUGHT:
I have come to believe that installing regular kerfing and reverse kerfing must be two quite different beasts. When installing reverse kerfing you have to bend the strips 'the other' way, making the bouts the tricky parts as the kerfing is opened up, making the thinner segments, the ones that have slightly deeper cuts, prone to breaking as they will take more of the bend than the thicker, less deep and stiffer cuts, while the waist, where the thinner sections only can bend so much before the 'kerf blocks' are butting against one another thus limiting how much each segment can bend, is a piece of cake. With normal kerfing I imagine the problem is quite the opposite and that the waist is where the breakage is likely to occur. And if it does, it is no big deal as the fracture will have little effect on the stiffness and cosmetically it is virtually hidden.

I also believe there is a great distinction in the properties of regular and reverse kerfing (and solid linings for that matter). Apart from looks, reverse kerfing will inherently create stiffer and stronger construction than regular kerfing due to the fact that the uncut, solid part is on the 'outside' and not glued to the side itself. Whether this is something desirable, something that will make the guitar hold up longer and make it sound better is another matter. But, if stiffness is what you are after, then it is not desirable to have the reverse kerfed lining broken or cut into sections. Whereas it is likely it would ease the process of installing them, it would also defeats the purpose of having them reversed in the first place.

BENDING LININGS

BROKEN LININGS SEGMENTS

DRY FITTING TOP LININGS

APPLYING GLUE

GLUE CLEAN-UP

SOUNDBOARD LININGS GLUED AND CLAMPED

THE SIDES WITH BACK LININGS INSTALLED

INTERIOR VIEW OF THE LOWER BOUT

FINISHED SIDES WITH LININGS

FINISHED SIDES WITH LININGS

FINISHED SIDES DETAIL

TRIMMING SIDES FOR BACK DOMING

My doubts about whether or not to add the sides to the neck first continues. However, yesterday I took yet another step towards doing just that by trimming the sides for the domed back, ready for the kerfed linings to be glued on.

Earlier I had fabricated some small shims that was to function as spacers to raise the sides equal to the thickness of the soundboard, about 2.2mm around the neck area, and attached them to the solera with double sided stickytape. Well, actually they were a little more than that including the stickytape, but when I squeezed my calipers a little they went down to 2.20mm. Then I put the sides back in the solera and marked the sides at the neck to 78.5mm, measuring from the bottom of the solera, roughly 2mm less than the final height, allowing for the thickness of the back. The same was done at the tail, though here to 84mm, roughly 1.5mm less than the final height. The reason for this was that the soundboard is about 0.5mm thinner around the lower bout than at the neck and the shims were at consistent thickness.

Next, the 15' radius disc was laid upon the whole assemble. In order to have the disc resting at an equal height above the marks at the neck and tail, two shims were added, one to each side around the bottom of the lower bout. I made a little 'marking device' from some scrap walnut by drilling a hole 21mm down from the top, matching the distance from the bottom of the radius disc to the marks on the sides.

I butted the little marker device up against the radiused disc, stuck a white pencil through the hole and traced a line all around the sides creating an undulating line following the radiused dome of the disc. Unfortunately the support blocks on the solera were so high that they got in the way, interrupting the line whenever I bumped into one. However, once the initial marking was done I took the sides out of the solera and finished the segmented line by using a piece of card as a ruler.

A couple of weeks ago I also made a clamping jig for the sides as an aid for gluing on the kerfed linings. This jig proved to be a very handy asset when it came to trimming the sides to final height. I first tried to plane them without clamping them to anything but it was virtually impossible to control, the jig however, provided a very nice and sturdy support. The sides were planed with my block plane using long even strokes, mostly starting from the waist area, the peak of the dome, and outwards following the bends of the bouts in order to plane with the grain. The plane was first set to a coarse setting but gradually adjusted to fine setting as I got closer to the marked line.

SOUNDBOARD SHIMS

MARKING SIDES FOR BACK DOME

MARKING THE MISSING LINES

TRIMMING SIDES

SIDE CLAMPING JIG

THE TRIMMED SIDES