Week 5 - Saturday Morning Class

First of all, I apologize for not posting sooner.  Thought I lost the camera, travel for work and nasty cold virus has made it an interesting 2 weeks.  We have completed the back of the guitar, joining, gluing and putting the bracing together.  We then fitted that onto the back of the guitar, cut the sides with a router to allow for the back bracing to come through.  We have now focused our attention to the front.  But before I go there, a couple of pictures of what we have completed.

Here's the inside of the guitar as it stands now.  Notice the mahogany kerfing on the bottom, spruce on top.  The center strip is a very thin piece of spruce, the cross bracing is mahogany also. 

Just a birds eye view.  We were very lucky with our wood.  It had extremely nice coloring to the Indian Rosewood.  We got our kit from Luthiers Mercentile Incorporated  (LMI).  I would highly recommend them, they have been a pleasure to deal with.

Here's a picture of the joined back.  The shape is cut roughly to size.  We will trim it to the guitar once we have our top completed.  The coloring is really magnificent.  I have not seen much rosewood with this amount and hue of reds.  I think once polished up it will look magnificant.  It is a feeling of joy to walk around the shop and watch everyones project start to look like a guitar.

And this is where we started this morning!  You will notice the white looking wood in front of Cian is actually the joined top of the guitar.  The top, like the back, came in two pieces.  We planed the sides until they matched exactly and then glued the together.  The first thing we need to do is install the Rosette.  The Rosette is the decorative trim around the sound hole of the guitar.  There are actually two 'accompaniments', perfing, which we will be two cirlces, one inside the rosetter and one outside.  In order to do this we use the measurements from the plans and plot out the center of the sound hole.  From this we draw a circle which forms the outline for the soundhole, then we measure and mark the rosette, and the accompanying rings.

We then drill a hole in the center and sink a post which will anchor our circle routing jig.  We then set the diameter to the diameter of the rosetter and off we go.  The outer rings we did in one pass with an 1/8 inch bit which was exactly the width of the perfing.  The rosette took three.  The last one we did was because the rosette could almost fit.  We probably should have tried working it in by running a steel ruler inside to compress the wood.  So ours actually was not a really tight fit, but it was snug.

Cutting into Spruce is very interesting.  It is a very soft and fibered wood, rather that a grain.  It tends to splinter and fuzz.  So after each route we needed to recompress the fibers or remove them so the channel is clear. 

Heres a close up.  You can see the pencil outline of the guitar to the sides.  Notice alos that the top of the Rosette is separated.  This allows some flexibility when fitting it in.  It won't matter because the fretboard from the neck will be on top of this when it is finished.

Here Cian is fitting in the outer ring.

Here it is with two rings placed around the rosette.  Now we need to glue them in place.  We simply took tight bond white glue and spead them in the routed channel, place wax paper over it and a block of wood on top.  Then it was placed in the go-bar apparatus to apply pressure while it dried.  I dried for thirty minutes and then it was removed.

We installed the rosette and rings just a "skosh" proud.  In other words a little above the top of the guitar.  Now using a cabinet scraper we scrapped the front until it was smooth and flush.  We will then run the top through the drum sander once all the glue is removed.

The final sept was cutting the soundhole which was really just routing another circle.  We made sure the router bit would pass through the entire top of the guitar.  Above is the result.

Here is where it stands presently :-)  Next week we will begin work on the bracing for the top.

Notice the inlaid tail piece...

Week 3 - Saturday Morning Class

This morning we retrieved our clamped guitar body and removed the clamps.  It was pointed out to us (by our teacher) that the kerfin was raised in about a 5-6 inch section.  When I asked him if he would leave it that way he replied "Not if it were my guitar".  We debated the risk in trying to repair it vs. possible back problems later on.  We decided since we were taking the class we needed to repair it.

So we began the process of replacing the section with new kerfing.  First step was to remove the kerfing from the section with a chisel.  This was not try and knock the kerfing down to a manageable size.  Gently the chisel is placed in the groove and struck with the other hand.  Eventurally Cian got very good at this and was able to get it down pretty close to the rosewood.

From there we took a scraper and scraped what was left of the kerging.  Then with 150 grit sandpaper we sanded down until the rosewood. 

This was rather nerve wracking as you can imagine and we escaped without doing too much harm to the body. New kerfing was applied, glued and clamped and looking much better.

OK, time to clean up any glue squeeze out.  We took a razor blade and ran it in the space where the kerfing meets the rosewood.  In some spots we sanded with 150 grit sandpaper until smooth.  Robbie is a real stickler for leaving everything spotless on the guitar.  It is a great motivator and the guitar is starting to take shape...

Time to add more tone to the sphincter.  We are going to add an end piece to the guitar.  First we cut out the tailpiece according to specifications then we trace it onto the back of the guitar.  We clamp a piece of wood parallel to the line and cut and repeat on the other side.  Once we have two cuts we then chisel the glued rosewood off of the Mahogany block.

We then apply back to the section and slide the Maple inlay into it getting a very tight seal, then clamp and let dry.  Unfortunately I didn't get a good picture of when it was finished.  Thats one thing that is difficulty, remembering to take pictures when you are involved in a step :-)
 

Now came time to prepare the back.  The first step was using the safety planer to bring the back down to a width of a little under 3mm.  The picture above is of Cian and Jim running it through the planer...

Class 3 Thursday Night (9/11)

The Agenda for the night was to finish radiusing the guitar's back. Attach Kerfing to the back, Radious the front to a 15 foot radius, and attach Kerfing. Then construct our side bracing and maybe even bracing for the top. We had quite a bit of planing and sanding left to do on the back. We made three mistakes. The first was we planed one side down to far. This meant we really had to reduce the heel and end block also. When we planed the Neck Block, we planed it straight across instead of at an angle, but this was corrected by planing on an angle. The third was I slipped while planing the block and cause a small crack at the side running with the grain. It was fairly small but if unattended the crack could run further. So a little super glue and accelerant and we good to continue sanding. We finally got to where we thought we needed to be and started the Kerfing.

Kerfing is used sort of like a shelf.  I runs along the sides of the guitar and will provide the support for where the top and bottom meet the sides.  Kerfing feels almost like balsa wood. Our back Kerfing was Mahogany and our front was Maple. Very thin and light weight. It is heavily scored so it is really flexible but very fragile. 1st order of business it to measure from Neck to Heel Block the amount of Kerfing we would need. To do this you have to run the Kerfing inside around the grooves from Block to Block which is what Cian is doing in the picture above. The first time we tried to do this we promptly snapped the Kerfing...

There is a trick, if you lightly clamp in on with clothespins,and let the clothespins do the bending for you it is possible to do without breaking it... Not easy but possible.

Once you have the right amount of Kerfing you are ready to glue it. You apply a thin layer of glue on the back. Not enough, it won't be strong, too much and you will get a lot of 'squeeze through' which is difficult to clean up after. Once you have glue on your Kerfing, using your high tech glue application device (finger), you gently squeeze the Kerfing to the side while applying a high tech force distribution device (clothspin with a rubber band wrapped around it) you work your way around the side. You are watching to ensure the Kerfing makes clean contact with the sides, clean the glue squeeze out and ensure the Kerfing is a 'scosh' above the side. We will be radiusing the kerfin to match the sides at some point.

Here is the back side, Kerfing glued and clamped.  It takes about 30 minutes to dry which we used to start our side bracking.  We found some nice scrap Maple and measured and cut those.  Sanded and Radiused the Front along with glueing the Kerfing and had to call it a night.

Class 2 (Thursday Night)

We had a lot of work to do on Thursday, especially since no class on Saturday for the upcoming Labor Day Weekend. The agenda was to attach the sides to the Heel and End Block, then radius the back of the guitar to a 30ft radius, the top to a 15 foot radius and attach the Kerfling used to support the back and front and create the insert for the end of the guitar. We had our heel blocks created and the sides bent from the last class, so our first task was to glue the blocks in place. We had to measure the sides and trim them to fit in the form and not overlap. We were able to do this quickly and set to glueing the blocks.



Cian had to use his "high-tech glue applicator" to apply the glue to the block. While glueing may in and of itself may seem simple enough, it is key to a great majority of the steps in building a guitar. Not enough and you risk jeopardizing the strength of the guitar, and too much you have a real clean-up issue on you hands.

We thought this was too much and ended up reducing the amount considerably, probably too much reduction because once glued there were areas that while I am sure they are secured, you could not see the glue on the edges. So as with everything in life it is a balance that is learned. Just not to be taken for granted.

Here is a photo where both the Heel (neck) and the End (bottom) of the guitar are in place and clamped for the glue to try.

Just a close up of the clamping process. Note that we have clamped it from the top and bottom and removed the sides from the form.

This picture just shows it from another angle.  Clamps on the bottom and top with cardboard protecting the wood of the sides.  You will notice that where the sides meet don't match up exactly.  While it is perfectly ok for them to match up precisely, it is not absolutely necessary as wood is removed to allow for the neck and end piece.  What was a little more critical would be that those sides are parallel and did not have an angle, since any angle at this point produces some 'twist' through the sides.  We had a little, but believe we can compensate with the planing of the guitar later in the process.  But a good lesson for future builds...

Now comes the arduos and "pucker producing" task of planing the guitar.  The two ends are not the same size so there is a general "sloping" that occurs from the end to the neck heel of the guitar.  Using a hand plane the sides width is reduced from around 110mm to around 100mm.  Together with the top and bottom attached the total width of the guitar should be about 105mm.  You need to be very careful that the plane does not grab the grain and create a crack in the sides.  We had two colleagues have this happen.  It can be fixed with application of super glue.

In this photo Cian is checking the radius using a radius dish with assistance from Jim.  These are dishes that have the appropriate radius to them.  You turn the guitar over, lay it in the dish and check for spaces.  The guitar should fit nice and flush and not allow any sunlight through.  This identifies high spots and where to plane.  We did run into an issue here where we had a high spot on one side but when we flipped it to plane that side gets reversed and we were re-planing the low spot instead of the high spot.  Another lesson learned, easy to get confused where your top and bottom, right and left are when you are flipping these around.  We believe it is a minor problem but will probably result in the neck area being slightly more shallow than the plans called for. 

You may notice that there is sand paper in the bowl.  You can take the guitar body and "twist" it in the bowl which will sand it.  We have learned that sanding is useful but only used when needed.  Sanding at this stage will wear out the sandpaper and put a considerable amount of dust in the air.

So that calls for more planing!  I have never used a plane before so I asked for a planing lesson.  The 'trick' is to approach the wood at an angle and when the blade catches continue on the angle keeping the back end of the plane off the wood.  If the rear of the plane rides on top of the wood your cut is very shallow if you get a cut at all...  As with everything practice is needed.

We were not able to get to the Kerfing but are very close.  Some more planing was needed to correct the mistake we had made earlier and we just started sanding.  So another 20-30 minutes and we will be ready to apply the Kerfing.

Here is a picture of one of the students and Robbie applying clamps to the Kerfing using a "high tech Kerfing clamp" (clothespin w/rubber bands wrapped around it).  The Kerfing is sort of like a wooden 90 degree shelf that lines the front and bottom of the guitar and is what is used to glue the top and bottom wood to.

Next week we will finish our planing, sanding and radiusing, apply the Kerfing and start to prepare our back side for mounting.  General feeling this week was excitement as we started to see the guitar take shape and of course some disappointment as lessons learned always carry a little pain with them.  But overall we are very pleased with our progress, have learned a tremendous amount in a short period of time.  We are always a little disappointed when the clean up bell comes.

Class 1 (Saturday Lab)

Saturday morning class is a combined class of the classical and steel guitar making courses. There were several TA's on hand which was nice. The objective today was to build the shell of the acoustic guitar. Our sides would be made out of Brazilian Rosewood and we were lucky enough to have very distinctive coloring in our sides. There was a very noticeable red streak running through the middle of ours which turned to a purple.

In order to build the sides we have to bend the sides into the traditional S shape that an acoustic guitar has. In order bend the sides we needed to attach them together to make the frame. We attach the sides what is called a block. There is one for the neck and one for heel (bottom). The dimensions are 70mm wide 32mm thick X around 90mm tall. I had purchased a 8x8x2 block of mahongany the day before so I set off to find a T.A. to get checked off on the band saw. Cian began the work of sanding down the sides. We had planed it on Thursday night (First night of class) in the Safety Planer. The planer simply reduces the width of the board but does not leave it very smooth. Also if you weren't quick enough in pulling the board through the planer it would start to burn so we had a couple of ring marks that we needed to sand off also. After planning it down to 2.4 mm the board was still rather stiff. There were technical difficulties with the sander but once operational, the side was sanded several times until the board was much flexible

Once the side was sanded we had to do two things before we could bend them. We had to locate the beginning and the end of the side and mark them. You can see the white marks toward the end of the board. We had to mark the center point as well. Know that we knew which side was going to be external facing and which end was going to the neck or the heel of the guitar, we needed to adjust for the curvature of the top of the guitar. We found out that the acoustic body actually tapers slightly as it approaches the neck. Funny after all these years of holding an acoustic I never really knew that. To accomondate for the tapering the sides had to have a radius to the side board as it moves toward the neck. You can plainly see the tapering of the board in the above photo.

Now we turned out attention to constructing the blocks. Once we had cut and sanded the blocks to their specified size, we needed to adjust the bottom heel to the curavature of the bottom of the guitar. This was done by drawing the radius on the block and using a planer shave the corners until it fit snugly against the bottom. The neck did not need this adjustment, but the external portion (facing the sound hole) was planed for cosmetic reasons. Next time you have an acoustic look in the sound hole and you can plainly see the block looking back at you. As we were told, the insides tell as much about your ability as a craftsman as does the inside.

Now that we knew which side was up it was time to bend the sides. Bending the sides is done using a press. The board is thoroughly wet down using a spray bottle then placed in between two metal sheets. A "warming" blanket is place on top. This blanket rapidly heats up to about 500 degress. As it increased in heat we slid down the guides to hold everything in place. There are three guides, one on the bottom, one on the waist (middle) and one at the neck.

In the photo above, Jim (T.A.) shows Cian how the mold is put together. Once the sides are bent, they are placed in the mold until a top and bottom are attached to the sides, several weeks from now...

There is a risk of breaking the sides during this process. If this does happen (and it does), then super glue could be used to repair the break. Fortunately no ones has broken yet.

Notice in this picture the top guide has already been pressed into the waist. I am rolling the bottom guide down to bend the bottom of the guitar. Cian will do the neck as soon as the bottom is complete.

That's one side, now we turn off the blanket which is at about 500 degrees. We let it cool to room temperature. Once it is cool it will be placed in the mold and attached to the neck and heel blocks making the outline complete. That will have to wait until next Thursday since we did not have time to complete it.