Restoring a Glue Pot

20151026_171723Traditional hide glue was prepared in Glue Pots.  Hide glue is used in making violins for a variety of reasons, don’t take your violin to anyone who doesn’t use traditional glues they could seriously damage your instrument.  Read more about hide glue here.

Before the 20th century and the advent of PV glue, glue pots used to be as common as frying pans.  I found this typical old glue pot and decided to fix it up.  At one point it may have been enameled, this prevented rust from coloring the glue.  I won’t use the glue pot for my own work, but I like to have a 100+ year old glue pot on the shelf to put things in perspective.

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The pot is cast iron, I removed the rust by soaking in vinegar (this will etch the surface and would cause visible damage if the surface were polished, but this pot won’t notice).  I then ‘seasoned’ it with olive oil like you would a cast iron pan.  You can see the final result at the top of the post.  It turned out quite nice I think.

09a0282v1Lee Valley now sells a small stainless steel pot replica which would work well if you like the traditional look and feel.  It can be used with a small electric hot plate or coffee cup warmer which they also sell.

 

Rib Thicknessing: Scraping Planes

One option for taking down the thickness of ribs prior to bending is a scraping plane.  I was taught to use a low angle block plane to reduce rib thickness and added a few passes with a Lee Valley Scraping plane for final finishing of ribs.  The is a perfectly valid method and works provided that the plane is super sharp and the cutting depth is kept very small.  The downside is that it’s a slow process if your ribs are thick, due to the need to keep the cutting depth small.  Two ways to improve the amount of material taken with each pass include using a toothed blade or increasing the blade bevel angle.  Another option is a Scraping Plane with a toothed blade set at 70 to 90 degrees, or a York/Pitch plane with a blade set at about 50 degrees.

I have been researching traditional Japanese planesDai Noshi and became aware of  Sole Flattening planes (Dai Naoshi) which are traditionally used to adjust the soles of wooden Japanese planes.  For the interested, the soles of Japanese wooden planes are not flat, but are relieved in front of the blade and behind the blade leaving three or four contact points.  Also worth noting is the use of tapered laminated steel blades and specially shaped chip breakers in Japanese planes. Traditional Japanese joinery is amazing, check out this video.  For our purposes, the Dai Naoshi form is a useful model for a scraping planes for rib thicknessing and is a tool easily in reach of the construction skills of a violin maker.

While I was pondering a new plane to speed up my rib thicknessing, I saw Davide Sora’s video on rib thicknessing.  He uses a toothing plane with a toothed blade set at about 90 degrees.  Check out his use of the plane here.  Given his success I decided to build one of my own.

Here is my version.  Using separate sides makes it a quick build.  In my design the wedge goes behind the blade, while a wedge is not usually included in Japanese Dai Naoshi because it has a wedge shaped blade, it is necessary here as my blade is flat.  The dimensions of my plane were roughly based on the recommendations of this post.

Scraping Plane

I’ll keep you posted on how well it works.

Jigs: Purfling Miters

20160214_132358This jig is handy for cutting purfling miters.  The jig is made from a maple block in the shape of a c-bout inserted at an angle into a plywood piece used for clamping the jig to a work bench.  This idea came from Olivia Pelling who taught me violin making while I built my first violin.

I use this along with a small very sharp chisel to set the purfling miter.  After bending the purfling to shape on the bending iron, I mark the beginning and end of the mitre with a pencil and then cut on the curved surface of the jig so that the bend of the purfling is supported.  From there it’s trial and error to adjust the miter cut to remove any gap.

20160213_222613A loop comes in handy to check the result.

 

‘The Strad’ Posters Index

The Strad posters are an invaluable source of pictures, outlines and dimensions for those looking to make instruments inspired by great historically relevant instruments or simply those made by the great violin makers.  The Strad has published 62 posters to date.  I’ve complied a list of the posters, they’re now listed here, in my Reference section.  Collecting them all is a feat, given that these are normally published with The Strad periodical, and while you can order them from The Strad’s poster website, most are out of print.  A pity.

Update: As of Feb 2016, The Strad no longer publishes posters twice a year with its periodical.  They are still available on their website when in stock.

Bending Iron: Redux

Commercially available bending irons are acceptable but leave plenty of room for improvement.  After having the heating element fail in my unit, I decided to give the whole unit an upgrade to produce more consistent bending with less chances of burning ribs.

I kept the aluminum ‘iron’ and discarded the rest.  I rebuilt the base from maple in a similar fashion to the original.  The cartridge heater was replaced with a 250 Watt unit.   A PID controller and thermocouple replaced the old-fashioned stove element controller.  This allows for accurate temperature setting, with a clear digital display.  The PID controller keeps the temperature on target.

The aluminum ‘iron’ was hollow, meaning that the outer surface of the ‘iron’ would cool if it was bending wood, particularly when using a wet cloth for steam.  By filling the head with lead free solder, the amount of heat held by the head increased significantly.  The temperature stability improves but the initial time to heat-up to bending temperature is increased.

I’ve very happy with the performance of the rebuilt bending iron.  I’ve found bending temperatures of 160ºC (320ºF) to 170ºC (340ºF) sufficient.

Resources Section Expanded

Resources Section Expanded

Hi all, I’ve expanded the list of books in my Resources Section.  For the most part these are standard references for those interested in violin history and violin making.  Many of these are available from local libraries either through local collections or inter-library loans.  WorldCat is a website that has bibliographical information on almost every book out there.  The great thing about WorldCat is that it also has access to the catalogs of many libraries, so by entering the book information and your postal/zip code you can find out if it’s in a library near you.  I’ve included the WorldCat links for each book.

Chladni and the his infamous patterns

Chladni patterns are visual representations of the nodes of vibrations setup in the a surface while it is subject to a specific frequency.  This and more on modern acoustics is found in Chapter 5 of Erik Jansson’s publication “Acoustics for Violin and Guitar Makers” here.  A good overall description of Chladni patterns can be found on the New South Whales University website here.

Ernst Florens Friedrich Chladni has been around a while and published a book on the patterns seen in vibrating plates in 1787.  His original publication is on Google Books here, however, a knowledge of old German and a Ph.D. in physics are prerequisite.  It’s reported that his interests in the patterns were inspired by George Christoph Lichtengberg’s earlier experiments on electrical figures[1].  Interest in this visual representation of sound waves was such that Chladni demonstrated it for Nepolean in 1809[2].  A plate of the image of Chladni is seen below [2].


[1]
Brain, Robert Michael, Robert S. Cohen Ole Knudsen, Hans Christian Orsted and
the romantic legacy in science: Ideas, disciplines, practices, Boston Studies
in the Philosphy of Science (Springer: 2007) p238

[2]
Stockmann, Hans-Jurgen, Quantum chaos: an introduction (Cambridge Univeristy
Press, 1999) p15

The cradle jig

A cradle jig comes in handy during hollowing and base-bar fitting.  I managed without one up until now, but decided it was time.  I based this one on pictures from Courtnall.  Its made to accommodate deep (high) arching, adjustable length (up to large violas), and interchangeable blocks.  The wood is poplar, the adjustment knob is an old piece of ebony, all unfinished at this point.

One jar of spool clamps please…

These are some spool clamps I made on  my lathe early on in violin making.  These are maple and roughly follow the specifications laid out in Courtnall.  I made 32 of them.  I modified the design to include a raised area so that the stainless steel threaded rod does not come in contact with the edge of the plates.  The rod is fixed on one end to ease installation.  They are lined with cork with a diameter of about 25mm and have a capacity of 47mm.  The finish is two coats of tung oil.  This jar exactly fits the 32 of them, so that’s where I keep them.  They work well!