Cello Frog Series #4

Posted in Cello Frog, Cello frog making, Frog Making on September 18th, 2011 by Robert Morrow

The pearl slide has been fit.  This step begins with selecting the shell.  Most often I use Japanese abalone which is known as awabi.  As with all bow making materials finding the highest quality shell is a task in itself.  Once the maker has found a source for the awabi and purchases a quantity he or she must sort it out.  I would expect a yield of 20-30% on average of usable shell.  Shell is prone to many defects.  The maker will pick out a gorgeous piece only to find a tiny crack, blemish, chip, or hole from some tiny invasive predator.  It can be heart breaking really to have to pass up some otherwise lovely material.

Once the piece of shell has been selected I thin it out from approximately 1 mm in thickness to about .6 mm on a diamond stone.  Now it is thinned it is glued to a 1 mm thick piece of ebony.  After the glue has set it is filed to match the dovetails seen in Cello Frog Series #3.  The taper is filed to match the channel or coulisse and the slide is slowly fit.  When it reaches the back of the channel against the silver talon or heel plate it is filed to match.  The front of the slide is then cut off with a jeweler’s saw and the front is filed to match the ferrule or passant.

Returning to the top of the frog the coulisse for the silver underslide is created using chisels made specifically for frog making by local artisan Ed Louchard http://www.zephyrwerks.com/contact.asp.  One of these chisels can be seen to the right of the frog in the photo.  I made the handle from Bubinga wood and did a short silver wire wrap that is similar to a winding on a bow.  Ed has made some beautiful tools for me based on old French models provided by Charles Espey.  I will devote some time in future posts to the tools and French method.  The channel that you see in this photo was created entirely by hand with chisels and the base was finished with a fine file.  Early French bows were fit onto the stick as you see this one.  That is to say the silver under-slide wasn’t used until the early 19th century.  I have made several bows in this fashion.  You can see a photo of one at the following link, look for my 2006 gold medal winning cello bow.  Notice that there is no line of gold in between the frog and the stick.  http://www.robertmorrowbowmaker.com/bows/indexflash.html  It is possible that the under-slide has a dampening effect on sound quality.  The bows that I have made without under-slides have been well received.  The trade off is that the ebony is fragile and can easily be damaged by careless work while re-hairing.

The silver under-slide has been fit, glued in place, pinned with silver pins, and filed flat.  I make the under-slides on a steel form made by local machinist Wayne Meginnes.  The hole for the eyelet is drilled at this time as well.

In the next post we will move on to the stick.

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Cello Frog Series #3

Posted in Cello Frog, Cello frog making, Frog Making on September 10th, 2011 by Robert Morrow


In this photo the recesses for the pearl eyes are being created.  The tool that is being used is a bow drill or foret.  Just below the photo my right hand is operating the bow causing the foret to spin.  The drill bit or cutter that is making the recess is one that I made from a piece of round drill stock.  Bow makers usually make their own cutters so that they can create the exact dimensions for their own particular eyes.

The pearl eye is now in place and filed to the shape of the flank of the frog.  I will outline the process of making pearl eyes in another post when I have the photos.  To make the eye you first cut out a piece of shell with a jeweler’s saw roughly to size.  The piece is filed square and to the size of the recess.  Afterwards, the piece is made first octagonal, then 16 sided, then 32 sided, and finally round.  When Charles Espey first taught me this technique I found it very difficult and tedious.  I began to make eyes with a lathe.  While in France I didn’t have my lathe and noticed that my friend Yannick Le Canu was making them by hand.  When in France as the saying goes…  I now make all my pearl eyes by hand and enjoy the process.  Not only is it a joy but I’m sure that it is faster than using the lathe and less shell is wasted.  Working with hand tools really can be faster than machines once you hone your skills.

The channel (coulisse) for the pearl slide (recouvrement) and the heel plate (talon) have been created with files and specialized chisels.  You can see photos on my website of this work being done.

The last two photos show the frog with the talon fit and the mortise completely carved.  Ultimately the hair hank will fit into the back of the mortise and be secured with a wooden wedge.  It would be difficult to describe how to fit the talon.  Basically, cut out and bend a piece of silver that is the shape of the coulisse and heel of the frog.  It is just something that the maker learns to do.  The frog is now ready to have the pearl slide fit and that is where the next post will begin.

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Cello Frog Series #1

Posted in Frog Making on September 7th, 2011 by Robert Morrow

The first step is selecting ebony.  This block is Cambodian ebony which has been cured for nine years.  I have worked with this particular lot before and it will take a high lustrous polish with a rich black color.  Not all ebony will produce these results.  Ebony of this quality is extremely difficult to procure.  Look to future posts on bow making materials for further information on this topic.

Here we see the block roughed out.  Beginning dimensions have been established and the block is now trapezoidal and symmetrical.  The flanks have been hollowed just a bit.  A hole was drilled through and a channel has been made down to the hole with a handsaw.  This is the very beginning of the throat, an important stylistic point for the maker and connoisseur.  All of the work that you will see in this ongoing frog series is done with hand tools right on the bench.  An historic French maker, say Dominique Pecatte could sit down at my bench and make a bow with the tools at hand.

Now a shelf is established on the base of the frog.  This shelf is the same depth as the thickness of the bottom of the sterling silver ferrule or passant.  You can view photos of the tools and techniques used in this process at my website,  http://robertmorrowbowmaker.com.

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