Friday, June 20, 2014

Trimming the excess off the top and back

 I use a combination of rasps to clean up the excess material off the top and back.
 Here are different views.....

...the back...
 ...the top...
I start shaving the back then work on the top. First, mask off the sides so any slips aren't as painful as they could be with out masking tape.
 Masked off and trimmed...
 Tape removed and ready to cut the sound hole.
I used a circle cutter for the sound hole.

Next up..... Glue frets to fret board and glue fret board to neck.

Friday, June 13, 2014

Attaching back to "box up" the tenor guitar

 Just a refresher on the kerfing....

Once the bottom kerfing is measured and dry fit....
 ... it is glued and clamped.
 I notched out a section in the kerfing so the bracing stretches and touches the sides.
 The top kerfing is clamped with clothes pins....

 ... and other small clamps.
 Once the glue dries, I level the kerfing with the sides.
 A long "flat" sanding block helps keep the sanding even across the width and provides leverage on each side.
 Here's a shot of the kerfing level with the top of the sides.

Note: With the taper of the sides there was a divot at both ends of the tenor guitar, so I had to pay extra attention to leveling these sections so it blended evenly with the rest of the side profile.
 Once the kerfing was leveled, the back was dry fit and instead of notching the kerfing where the back braces met the sides, I just cut the braces.
 A small amount of glue around the top....
 ...clamped with spool clamps....
 ... and a handy tool for glue squeeze out is a straw....

... this makes trimming the over hang of the top and back much easier.

Next up... trim the top and back overhang and cut the sound hole.....

Monday, June 2, 2014

Kerfing/Tentalones for Tenor Guitar

Kerf Linings aka: "kerfing" vs Tentalones

The use of words kerfing and tentalones are commonly used interchangeably when in fact they are technically different that serve the same purpose.

Kerf linings have a thin strip that connects the thicker material used to reinforce the side-top attachment.

Tentalones are individual pieces of material glued to reinforce the sides to the sound board.

I am use the term tentalones since I purchased them from Hana Lima 'Ia, but technically, they are kerf linings, aka: kerfing. Once I meet a few more builders, I'll figure out the preferred nomenclature.

Back to the build.........

I pull all the spool clamps off and notice that a section of the left side did not glue securely......
To progress forward, I sanding underneath the section that wasn't glued, then re-glued and clamped.

At the same time, I measured and added my tentalones/kerfing.
Here is a picture of both tenor guitars in their different states of development.

One has the kerfing clamped in and the second has the top attached to the neck and sides bent.

Next up............I will add the top kerfing, then proceed to "box up" this build by attachig the back to the sides......

Attaching the sides to soundboard

 Once the sound board is mounted to the neck, I added a tail block at the bottom of the sound board the same width as the thickness of the sides away from the template line.

 Dry fit the sides and clamp in place........

INSERT expletive (here).......

Notice the gap between the bottom of the heel and the height of the sides....'s a little much, so I made a heel extension :-)
 Shaped to match......
 ......and then continued where I left off.
 Once everything was lined up and dry fit with spool clamps, I glued the sides down.
Another view....

Next up.......Kerfing/tentalones

Tuesday, May 27, 2014

Attach the top to neck

 Before I attach the sound board to the neck, I pre-shape the heel so I don't have to worry about damaging the sides or sound board once everything is assembled.

Once the heel is shaped, I cut the top portion of the sound board that will meet the neck.

To ensure alignment, I draw a center line down both the neck and sound board, the dry fit the two together and tac two small nails to mark my position.
 The two nails prevent the sound board from shifting out of alignment when I glue the pieces together.
 Clamp it up......
 Make sure I am centered..... Done.
 Next, I glue the tail block to the sound baord. 

Here's a pic of the tenor 'ukulele in progress as well, note the similarities :-)

Next up..... Attach the sides to the sound board and neck......

Tenor Guitar Fret Board

 This tenor guitar has a 23" scale length.

To determine the spacing between the frets and from the nut to each fret bar you have to do some math.

Who doesn't love a good math equation =)

The magic number to figure this out was derived from the Greek Philosopher/Mathematician Pythagoras and refined over the years to 17.817.

A good article to read about calculating fret positions can be found here. If you want to totally geek out, click here.

To find the fret spacing on any stringed instrument, you divide your scale length by this magic number to get your first fret position from the nut.

Next, subtract your first fret position from the nut from the total scale length, then divide by the magic number, 17.817.

Repeat until you reach the total number of frets you plan to cut. I used Excel to create this sheet and a conversion chart of decimal inches to find the closest fractional inch.

The first fret should be 1-9/32" from the base of the nut slot, the 12th fret should be at 11-1/2", and the 14th fret should be at 12-3/4".....

Side note: When I checked where the neck meets the body I noticed my drawing was 3/8" off, so I'll have to redraw my plans for my next tenor guitar build.

Once I drew all the lines with a straight edge and 90° square, I made a few photo copies at a local drafting shop and cut out my fret board template.

Prefab 23" fret board templates can be found at Stew Mac or LMII, but I chose to do it from scratch so I could, theoretically, reproduce any scale length going forward.

I cut out a little over 2" wide plexiglass and taped my template over the top and used scarp pieces of wood on the top and bottom so I could clamp to my work surface.
I notched the plexiglass with a hack saw and another small scrap piece to line up with my fret line. I tried to line up the saw blade with the middle of my line as close as possible.

Note: I had to re-cut this template because I cut the middle of the nut line at the top of the fret board instead of using the inner most width of nut line as the end point.

If I didn't re-cut the nut line to make a new template, I would have been 1/64th off at the 1st fret, then it would've thrown out the spacing and, most likely, the intonation across my entire fret board :(

Using a cross cut jig with a razor blade as my marker, I methodically slotted a couple fret boards using the Stew Mac fret table saw blade.
Next up..... attach top and neck...