Friday, February 26, 2021

Today’s Work

 


A new East Indian rosewood bridge for a “Brahms” eight string classical guitar and some of the tools needed to create it. 

Monday, February 8, 2021

Re-Thinking Card Scrapers

The curve or shape of the beveled cutting edge of the scraper is critical and deserves some thought...

Robert Lundberg, "Sharpening Scrapers", American Lutherie, No.36, 1993





Recently, I re-discovered an article in an old American Lutherie magazine that was written by the late Robert Lundberg, who was a well known lute maker (luthier translated from French is lute maker!). 


The article, "Sharpening Scrapers", which is about a "typical French method of making and sharpening violin scrapers, was very timely for me. There is a guitar in my shop with new bindings that need to be scraped flush with the guitar sides and I am tired of using a regular straight edge scraper. The new curved edge scraper I bought isn't the most efficient for the task either, it is too big and meant to scrape big wide surfaces.



Mr. Lundberg's article has templates for five shapes of the scrapers he used in lute making, I chose two shape to copy and marked them out on a Bahco brand scraper that has been floating around in one of my work bench drawers for several years. I ground and honed a 45 degree edge on both scrapers, then lightly turned a hook on the edge.



These small scrapers are great for one handed use, the size and the shape offer better visibility, I'm less apt to dig a corner of the scraper into the guitar's side, top or back when I scrape the bindings.



When I first started out in woodworking, I read several articles that stated a 45 degree angled edge on a scraper with a light hook would create the best smoothed surface on wood. It worked for me, then there were the articles that pooh-poohed this technique, those authors said it was best to sharpen a scraper in the manner of Tage Frid. That is the method I have used for the last 30 years and it does work, but Lundberg's article makes me realize that every now and again, I need to re-evaluate woodworking techniques I use.

Robert Lundberg's article is in the Big Red Book of American Lutherie, Volume Three, which, unfortunately, is out of print.




Wednesday, January 27, 2021

More Repair Work

retrofit  verb

ret·​ro·​fit | \ ˈre-trō-ˌfit  , ˌre-trō-ˈfit \

retrofitted or retrofit; retrofitting; retrofits

Definition of retrofit

transitive verb

1: to furnish (something, such as a computer, airplane, or building) with new or modified parts or equipment not available or considered necessary at the time of manufacture

2: to install (new or modified parts or equipment) in something previously manufactured or constructed

3: to adapt to a new purpose or need 


Routing the edges of the sound board in order to remove the top.

Three years ago, I made my first "Brahms" guitar. A "Brahms" guitar is a classical guitar that has an extra bass string, usually tuned to the second "B" below middle "C", and an extra treble string that is tuned to the "A" above middle "C", giving the guitar eight strings. These extra strings extend the musical range of a classical guitar.


Top removed.

The problem with adding those two extra strings is that they increased tension and torque to the guitar's top. This guitar started to collapse at the sound hole end of the fret board making the string action too high for easy playing. 

Shelf cut for neck extension.

The owner brought the guitar back into the shop for me to repair it and I realized I needed to add an extension to the neck to support the fret board. Another thing I decided to do was not use a traditionally placed sound hole in the top, which is located at the very end of the fret board. 

Neck extension support and veneer to support the sound holes in the upper bouts.

The second "Brahms"guitar I made, I placed the sound holes in the upper bouts on either side of the neck, and I will do the same on this guitar. I glued veneer to the bouts to support the sides when I cut the sound holes. 


The neck extension was glued and screwed to the neck block along with the bracket that supports it.



I kept the harmonic bar attached to the sides for as long as I could, it helps maintain the shape of the guitar.


I added a pice of maple veneer to the upper part of the sound board with the hope that it will help keep the cedar top from cracking.




If you look close you will see the "floating brace" that is near the position of the original harmonic bar. This will help keep the top from collapsing in front of the bridge and it can increase the tonal qualities of the guitar.



The top is glued on! 




Since the owner has ordered and bought three other classical guitars from me, and is a good friend, I decided to upgrade the bindings on the guitar. Originally they were cherry, to match the back and sides, but to honor what this guitar has been through I am using ebony. 


The ebony goes well with the cherry.

I still have to install the ebony bindings and black/white purflings on the top, I need to make and install a new fret board, a bridge, and basically French polish the entire guitar again. It's a lot of work for a prototype, it will be worth working out all the bugs to make future "Brahms" guitars better.



Thursday, January 7, 2021

Replacing a Classical Guitar Top, Part Two

 After installing the new redwood top and re-glueing the fret board extension on the 1991 Manuel Contreras guitar, it was time to make a new bridge.


I chose a nice piece of East Indian rosewood from my stock and ripped out a piece. I made the bridge to be a very close copy of the original Contreras bridge, a large tie block with a deep valley between the block and saddle slot, the owner wanted a piece of bone to top the tie block.


I prefer to install the bridge before I apply any finish to the top, it is easier for me to clean off any glue squeeze out, there is less damage to the finish if I do it that way.


Once the bridge is properly located, I made locating pins from a sliver of rosewood.


Making these pins is a fun task!


Several years ago, I purchased a vacuum pump and vacuum clamp for glueing the bridge, both items were well worth the money. No longer do I have to fuss with clamps and worry about the risk of a bad glue-up!


Once the bridge is glued on, I can shape the fret board to optimum geometry for a proper string action, which means the guitar will be easy to play. This is a fret barber, its purpose is to thin the tang of the fret wire that I install. If the tang is too wide for the fret and I hammer it into the slot, the extra width will eventually force the neck into a back bow.


The fret slots are .023" wide, the fret tangs are .035" wide, you can see how quickly that extra width will force the ebony to move, giving the neck a "back bow", or a crown in the middle of the fret board.


After the frets are hammered in I glued them in place with thin CA glue. 



Here is a photo of the guitar with a sealer coat of "ruby" shellac. 

I haven't put strings on the guitar yet, I want to complete the French polish on the top and finish cleaning and polishing the original lacquer on the back and sides. 

Stay tuned for the next post about this project!
















Sunday, December 13, 2020

Replacing a Classical Guitar Top, Part One

 Few realize the influence of the luthier on the life and career of the artist.

Andres Segovia, In Memoriam of Hermann Hauser, The Guitar Review, 1954


Recently, a classical guitar made by a well known, highly respected Spanish maker came into the shop for evaluation. The current owner had removed all the original lacquer finish from the top and sanded so much that areas of the top were less than 1mm thick.  The first day it was in the shop I spent over an hour scrubbing the top to remove remaining finish remover and other chemical crud that was leftover by “a home repair”. 


The top after a one hour scrub with NAPTHA...


The bridge with remnants of finish remover...

The next day I spent some time with the guitar to learn more about the damage with the hopes that all I needed to do was to re-finish the top. With the aid of an inspection mirror I found a repair completed at some point in the guitar’s life, a “floating brace” was installed to prevent the top from further collapse and an ugly repair done by the owner, a piece of teak veneer and lots of epoxy. I gently flexed areas of the top with my fingers, one section so thin that the wood immediately split. At that moment I knew I would need to replace the top. The neck, fretboard, sides and back were in great shape, those parts need only touch up of the finish.


A floating brace to prevent further collapse of the top. You can see the smeared epoxy to the left.



These two photos so how much wood was removed by sanding to remove the original finish...

I called the owner with what I discovered and we both concluded that the guitar deserved a new top. The owner stopped by the shop later that week, he selected a nice redwood top and a new rosette.

The biggest challenge with this guitar is the original binding had to remain to preserve of the guitar’s integrity. My typical procedure is to rout off the binding, cut off the top, replace top and re-bind with in-kind wood binding. After some research for different techniques I found a short photo essay on top removal by John Greven and a video by Fritz Damler, both master luthiers. I am very grateful that they shared their knowledge and techniques! 


This guitar has an armrest which is glued to the side and is part of the resonator, this is the first pass with a laminate trimmer.


At the leg rest I used my old Ibex brand purfling cutter. I later set up a variable speed Dremel on a Stewmac precision router base with edge guide, which proved to be very efficient.


The guitar with top removed.


A photo of the owner's patch and epoxy.

The original top with bracing.



I didn't try to match the original bracing, this bracing has worked well for me on other guitars that I made.



The new top fits like a glove...


The owner told me that I could put my label next to the original, I declined.

The new top glued on an ready for purfling.


The purfling channel was cut with a Dremel and router bit and lots of hand work. If you zoom in on the photo you can see the original binding, which is about one millimeter thick. The BWB purfling you see in the channel is part of the original purfling.


The purfling ended up as East Indian rosewood, which I scraped down to exactly 0.0430", so it would added up with the B/W/B/W popular and curly maple veneer and fill the channel. I glued all strips in with CA glue, I feared that any other glue would make the strips swell so much that they won't fit!


Everything worked!


 Close up of the original binding and new purfling. I am quite happy with the result!

To conclude Part One, I present some photos on how I glued the fret board extension back onto the top.






Again, my thanks to master luthiers John Greven and Fritz Damler for sharing information on their top removal techniques! 

In Part Two, I will cover installing the bridge and maybe a few other things!



Monday, November 23, 2020

Who Says Hand Tools Don't Make Dust?

A couple of months ago, I posted a photo on Instagram of my air cleaner's filter after I had ripped a piece of East Indian rosewood with a hand saw, the filter was nearly black from the sawdust and I ripped only two small pieces. After I posted it, someone commented on the photo and said something like "What!? I was told that hand tools don't make wood dust! I was lied to!"

Yes, hand tools do make dust!

Saws make, well, um, saw dust when the teeth cut the wood.



The iron of your hand plane, or spokeshave, makes dust as it cuts and lifts a shaving of wood, and you should see the amount of dusting and shavings that a sharp hand rasp can make!



Anytime I pull out a rasp to work on a guitar neck I don a respirator, when I rip saw by hand a guitar top or back and sides from a billet I do the same. Even with an air cleaner in my tiny 238 square foot studio space I think about protecting my lungs from dust.



Look closely at this photo and find all the wood dust on the handle of the spokeshave! These shavings are from carving a guitar neck.

Every week I clean the filter on the air cleaner, the only power tool I use in my shop is a laminate trimmer for cutting binding ledges and that happens only once a month!


This is what the filter looks like after I have planed some wood and sanded a guitar just a little bit. 

If you look through my blog you will see that photos of my experiences as a historic preservation carpenter. I have worked in several nice shops that were set up to reproduce any kind of sash rail, stile or muntin, along with being able to reproduce any kind of wooden door or other part for a historic house, so I know how much dust, shavings and noise professional woodworking machines can make.

Don’t lose yourself in the romanticism using of hand tools, sure they are not as loud as power tools, but they can bite, cut, tear and make your life a little bit miserable. 

The point of using tools is to make something beautiful...




Today’s Work

  A new East Indian rosewood bridge for a “Brahms” eight string classical guitar and some of the tools needed to create it.