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Catnip's (John K) Bench


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Ready to temporarily  glue the fingerboard to the neck.  The piece of paper is used to check the fit in the corners when the fingerboard is held in the middle.  Sometimes there is a high spot which can cause the fingerboard to pivot slightly. The clamp is used to hold the fingerboard in place about 2 mm behind the nut line while the studs are glued.  When the clamp is removed the fingerboard will make a tight fit when pushed up to the nut line.

 

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Next, the neck root geometry is laid out which is essentially: 8 mm line for the overstand, 4.5 mm for the top, 36 mm for the upper rib, a 4.5 mm line for the back and a 24.5 mm circle at the bottom. Both cheeks of the root can be easily cut using a dozuki saw.

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It is a good idea to protect the scroll with plastic while trimming the neck root and neck flush to the fingerboard because of ebony dust.  When finished the neck thickness is about 1 mm more than that of a violin... in the range 20 - 22 mm.  It is better to leave it a little bit thicker and trim it down later in the final setup.

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After glue sizing all the blocks the top is temporarily positioned using all my spool clamps.  The overhang is checked with a digital caliper using the same method as for the back and adjustments are made as necessary.  Three clamps are removed and the hide glue is applied using two spatulas: the thick one as a lever and a thin wide one to apply the glue.  Then two clamps are replaced and two more removed. This process is continued until the the entire top is glued.  The excess hide glue is removed with a brush using hot water. This minimizes the glue cleanup afterwards.

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After removing the clamps and some additional residual glue cleanup it is time to set the neck.  The inner divider dots established the initial cut line with reference to the bottom circle. The outer dots are there for reference afterwards. The measurements are taken from the neck root (minus a couple of millimeters) and are transferred to the ribs. The circle at the bottom is a guide for the button's width.

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The guide line can be cut with a knife but I find that it can be started with the veneer saw using the initial cut at the edge overhang as a guide. In any case it is a good idea to go over the cut line with a knife right up to the bottom plate.

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After both rib guidelines are cut the next step is to cut top just behind the purfling.  IMG_2696a.thumb.jpg.ada9ea74c5f17e49aacd9b4ce4185405.jpg

This is done with a knife in two stages. Remove half the edge with a chisel then deepen the cut with the knife again before removing the whole edge.

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After the mortise is cleaned out with a chisel the "flatness" can be checked with a straight edge as the neck is lowered into place.

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Once the proper geometry is established it is just a matter of widening the mortise until the neck is lowered into place.

 

 

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After many iterations the neck is finally lowered into the mortise. I use a simple C clamp with two corked cauls to test the fit before gluing.  The end grain of the neck heel should be glue sized ahead of time.   A white center line on the fingerboard and a bridge helps to check the alignment before the gluing.

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After the neck set it is time to trim the root.

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The first step is to trim the button parallel to the neck root.   This is done with a flat chisel.  It is wise to protect the neck with tape to avoid any accidental nicks.

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Next I draw a circle offset 6 mm from the purfling and start to trim the neck root.  Again tape is used to protect the neck from any accidental nicks.   The neck is still a bit heavy so any nicks will be trimmed away but it is better to be cautious.

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More progress on finishing the neck root.  Again the tape is there to protect the edge since I sometimes use the edge as a fulcrum for the knife. A straight chisel is used to profile the button's circle. 

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The right side is a bit easier to do than the left side.  I also use a half round rasp the contour the heel followed by round sanding dowels... etc

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The neck is then finished using a template as a check.

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Last step before the standard setup of endpin, pegs, nut,  bridge, string spacing and adjustments is the saddle.  The straight cut line once the saddle width is determined is just behind the purfling.  The removal of the spruce is done using the same method as with the cutting the top neck mortise... Straight cut with the knife to half-depth, remove half the ledge, finish the straight cut to the end block, remove the rest of the ledge, square the cut out ... etc

 

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I have decided to install a Rocca-Hill style saddle which gives more gluing surface for the saddle.  Here is the lower part glued.

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I started a discussion specifically about the saddle cutout for a viola about a month ago.  You can find it here:

It was Manfio that helped me with the Rocca-Hill style viola saddle.  I found a very large diameter cardboard tube that allowed me to approximate the curvature of the lower bout which I used (with some fine sandpaper) to establish the curvature needed.

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  • 3 weeks later...

Still waiting for warmer weather to start the finishing process.  In the meantime I started working on a flat-sawn flamed birch violin that has a nice contour line pattern.

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I also had a double bass bridge adjustment to do so I made a double bass string height adjuster (lifter) based on a commercial metal version.

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  • 2 months later...

Having just finished some major repairs and with the weather improving I have started varnishing the viola and my latest violin.  After being in the sun for a couple of weeks I have applied a sealer, a ground  coat and two coats of golden brown.

 

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  • 3 weeks later...

Catching up on a "to do list" of odd jobs ... replace the worn-out drive belt on my mini metal lathe JH-90 (vintage 1986) Central Machinery mfg in Taiwan.  Luckily the old belt still had the size marking 170 XL 025 which is a common timing belt.  Interesting to note that these lathes  came with metal gears whereas today's models come with plastic gears with an option to buy a set of metal gears.   To replace the belt I had to remove all the front gears in order to remove the motor to get at the belt.

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  • 2 months later...

A friend of mine asked me if I could make a wooden scabbard for one of his antique curved swords (circa 19 th century). It will be covered in traditional leather afterwards. I did a bit of online research first but could not find any details on making a curved scabbard with varying blade width.  Most of the online resources were from sword collectors rather than experienced woodworkers. The main issues arose from using wood that was not aired dried and stable.

After a couple of trials the main issue was to get a snug fit.  The simplest approach was to use a three piece assembly: the bottom, the spacer and the top. This was accomplished by pulling the sword out slowly and seeing where the blade would cut the spacer.  Afterward I used some thin felt liner to fill the space.  The pictures explain the process.

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One last project: upgrading to LED lighting. 

        I bought two Koda 4 ft LEDs (4600 lumens) from Costco a few months ago.  When I installed them I found there was some interference with my WiFi network.  This light comes with a 5G WiFi remote and has a builtin 5G WiFi sensor with motion detection etc... After some research I found that some people were able to remove the WiFi antenna (by de-soldering it) but this newer model is all integrated. I decided the simplest solution was to encase the WiFi unit with aluminum tape.  But before I did this I made sure to set the motion and light sensor to off so that it behaves just like an ordinary manual light.  Note: setting the motion detection to off does not disable the 5G interference.  Aluminum foil does the trick ( kills any remote connections)  and also voids the warranty.

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Before starting my next violin I must decide what wood to use (maple, pear, ash, walnut etc...), what model, ... etc.  I have some nice quartered flamed one piece pear wood that is 202 mm wide.  Using my standard models this pear wood would require wings in the lower bout.  But I do have a earlier Strad model that has a narrower lower bout that could accommodate a width of 200 mm. 

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To help get an idea of what the back will look like I find it very useful to use a "negative" template that allows me to explore what might be the optimum position to enhance the best features. 

Lightly staining or varnishing the underside also helps to see what the final figure might look like especially if the flame does not stand out on its own.  I also find industrial grade hydrogen peroxide 30% plus sunlight can even out the some irregular natural wood stain.

I am examining some flamed Aspen backs, one is very wide grain with pronounced flame; the other has tighter grain with less pronounced flame.  Aspen has a density around 0.46 gg/cc so if I decided to use it I will definitely use a thicker graduation pattern.  I have never used Aspen for a violin and I am reluctantly curious to see how it turns out. 

Here are some of the backs I am considering:

Aspen wide grain

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Aspen tighter grain but less pronounced flame

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Under side of this Aspen stained

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Cherry

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Another Cherry

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