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Making a double bass


Roger Hargrave
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Hi Roger:

 

In the 3rd photo above, the bottom rib seems to be proud of the c bout corner by about 1 mm.  Is that a stylistic choice or would that be trimmed back flush with the c rib in due course?

 

Best regards,

 

E

Already trimmed back. I leave them proud on fiddles as well in case the get damaged in the making process. As for your suggestion Ed, I doubt that it will be finished by June. I have several orders to complete as well as this fun job. By the way we will be wearing this bass in imitation of an Amati. Watch this space. 

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This is an interesting question. A truly hand made bass; from materials that would effectively have made at least six seriously fine violins; three years worth of violin and viola ribs; more than a dozen violin necks and scrolls, and any number of fingerboards. How do you assess its value in materials alone? As for the work, not to mention the travelling between workshops, my wife is pulling her hair out. It is almost as bad as writing on this web site and contributing to the Strad magazine.

Ok, so your holding out for gold and silver, I understand. :D

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I can certainly see why you fell in love with this wood; it's remarkable!

 

I didn't quite understand your comment about angling the scraper the same direction as the flame in the maple; do you mean the length of the scraper is held parallel to the angle of the flame with respect to the grain of the wood?

 

This is a wonderful thread and a real treat to see a master's approach to this work; thanks for taking the time to share this.

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Hey Ben that is a really nice video you posted, thanks.

 

I can certainly see why you fell in love with this wood; it's remarkable!

 

I didn't quite understand your comment about angling the scraper the same direction as the flame in the maple; do you mean the length of the scraper is held parallel to the angle of the flame with respect to the grain of the wood?

 

This is a wonderful thread and a real treat to see a master's approach to this work; thanks for taking the time to share this.

Bill, yes, since I will be varnishing this bass as I do most of my fiddles, ie. wearing the varnish, I wanted to make the flames more pronounced. So I did indeed run the scrapper parallel to the angle of the flame.   

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OK here we go again. I am sorry if this is all a bit disjointed. Maybe I will eventually do it on my web site in the correct chronological order.

 

While I was busy preparing purfling and cutting the head, over in Holland, as well as making the mould and ribs, Rene had thicknessed the two back panels, and completed the back and belly joints. First he prepared the belly with a planning machine, a luxury that I have never been able to afford. The planning machine flattened and then planed right angles on the two belly wedges. From the planner he then finished the joints by hand in the normal way using a low angle jointing plane similar to the one picture earlier. The belly was then glued and clamped with Record sash cramps. Like me Rene uses a waterproof Tight-bond type adhesive. Unlike animal glues these adhesives are unlikely to come apart when wet. 


In the 1970’s I saw a Guarneri violin that had been in a flood. It had fallen apart completely. All the new edges and the bass bar had dropped off, and even a large central bell patch had fallen out. But, although the belly center joint was barely 1 mm thick where the patch had been, it was still intact. The back joint, and the rib to corner block joints and end pin block joint, were also intact. As my 1980’s Strad article, suggested I believe that the Cremonese makers used casein glue for these jobs. Probably, as far as they were concerned, these joints do not need to be reversible. I believe that they also used casein for fixing the neck. Casein is waterproof when made with quick lime. It can be used cold for several hours allowing joints to be adjusted. This is not to mention the many disadvantages that animal glue had at a time when an open fire was necessary for its preparation and its use in hot summers, and in winter to prevent it from gelling in a cold room. Casein also has one added advantage over most modern  glues. It is possible to use animal glue to repair an open casein joint.


I used casein for center joints throughout the 1980’s and 90’s. Unfortunately casein as a (just add water adhesive) has not been available for several years, however an American company that makes fine casein  paints is experimenting with casein glues again. If anyone want to try, this is the address:

www.spectrafix.com or www.msnatural.com.

I have not yet had time to try these so if you do don't blame me.

As can be seen from the photographs the belly wedges were not quite wide enough. So, in the age old Cremonese tradition after sawing out the belly Rene fitted wings.


The thinner back plates were jointed using a shooting board and a low angled plane. There is just one point to make here. When the two pieces are being planed square, one of them is reversed before gluing. This cancels any slight angle differences between the shooting board and the plane blade. When jointing thin flat pieces in this way it is also necessary to keep them pressed down while the joint is being clamped. I will try and include some pictures from Rene’s next flat joint. 

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The diagram (The batteries in my camera are down so I will add this later) shows the various stages, beginning with the outline. The outlines of both the back and the belly were taken from the finished ribs. The flat back was simply clamped to the ribs and the outline of the rib and the overhang were taken using a scriber and a ring of the required thickness. (Sorry only photo of rings being used on a viola) Almost forty years ago I made a set of 10 rings, but this was the first time that I would ever have to use the (two) largest sizes. I was extremely excited. Unfortunately Rene had already used his own rings. So mine are back in the cupboard again. The overhangs were 5.5 mm in the center bouts and 5 mm in the upper and lower bouts. 

 

 Apparently, Stradivari used a small square block with a pin for this job. This may be the reason why the overhangs increase slightly in the corners and in the C bouts. Where he was scribing around an outer (convex) curve the pin was as close to the rib as the square block could get. But against an inner (concave) curve the square bridged the line of the rib moving the pin further away. 


After marking I finalizing the back and belly outlines with the same hand-made rasps that I use for violins and cellos. (Talked about on the topic 'Rasps' on this site). With violins and violas I clamp a substantial plywood board to the underside of my bench sticking out about 12 inches. I then sit on a stool and simply hold the flat side of the back or belly plate against the underside of the board, by jamming it with my knee. I can then move the plate easily while rasping the edge at right angles. Keeping it close to the board edge eliminates chatter.

 

With the bass belly I clamped it to the underside of a table. This worked perfectly. The back is flat so holing and rasping at right angles this was not a problem.   

 

The belly was rough arched almost down to the final edge thickness. At this point I would normally mark the final edge thickness with a cutting gauge and simply gouge and then rasp to the line. To save time Rene used a router to thickness the edge. Routers scare the pants off me so I was willing to let him do this job.


From this narrow platform we then completed the already almost finished rough arching of the belly. This term ‘rough arching’ can be a little deceiving. Normally on all my instruments I like to begin forming the arching with the first stroke of the gouge. I do not like to see platforms and steps on arching’s even during these initial stages. I like to see the arching almost creating itself. Also I like to get very close to the next stage before I change tools. I may move on to a (large) flatter gouge to remove the furrows of the roughing-out-gouge. I may even use a smaller curved gouge around the edge-work, but I always try and use the biggest tool for the job. Consequently I do not expect to make many serious changes to the arching with either the thumb planes or the scrapers. Thumb planes are simply used to remove the gouge marks and scrappers to remove the (usually toothed-iron) marks of the thumb planes. I find that the more experienced I become, the closer I am able to work each stage. I had little difficulty transferring this technique from violins, violas and cellos to the bass. The biggest problem was seeing the overall picture. At home I black out my workshop and use angled lights.  Rene’s ultra modern workshop has large windows that are ideal most of the time, but if you need a back out, you have to wait for sundown. 

 

On these last pictures it is possible to see that the purfling has not yet been inserted, but that I have used a tight gouge to lower and open the channel slightly. In effect this leaves a square box looking edge. When building a baroque violin the arching would be completely finished at this stage but the edge would still be a flat platform. In addition the whole instrument would be glued together. However, because this is not a baroque instrument (in the strict sense) I allowed myself the privilege of finishing the arching and fluting in one operation before inserting the purfling. I did have however chose a similar method of applying the purfling and finishing the edge, as I believe the Cremonese did. I did this way because this system is fundamental to the appearance of Cremonese arching. This way did save me time by not having to finish the arching twice.

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Having finished the provisional back outline the purfling channels of the back were cut and the purfling was inserted as described earlier. I should point out here that the upper portion of the back outline and purfling channel was not completed at this stage because we needed to fit the neck and attach the back, before these details could be finalized.  

 

Although the bass belly was done in much the same way that I would approach the purfling and edge-work and arching on a violin, the purfling the flat back involved a slightly different process to the arched belly. On the back there is no fluting. This meant that the channel had to be cut perfectly. This is simply because whenever a fluting is cut after the purfling has been inserted, the channel has usually swelled around the purfling creating a better fit. In addition any chipping to the purfling channel edges are cut away when the fluting is finalized. Fortunately, because of the nature of the materials it is easier to cut a clean channel in maple than it is in spruce. 

 

Cutting good miters is not easy, especially to the extra depth required for a bass. It requires a narrow, sharp and non-flexible blade. Many years ago I tried using disposable medical scalpel blades for this job, but they proved too flexible. The blade tip was prone to bend off line resulting in a distorted miter. The problem with less flexible blades is that a fine tip can easily snap off, especially if it encounters a hard reed line. A useful tip is to use a little dry soap on the blade in the immediate miter area. This is not recommended elsewhere in the channel since it can cause problems with the gluing process, especially if the method of gluing that I have described here is being used. For the maple miters, after making the initial marking cut, I pick up a tiny half droplet of plain water on the knife tip. This helps the blade to slice the wood rather than to press through the fibers.

 

If, in spite of your careful efforts the miters are not good when the fluting is cut down, this is not a disaster. This frequently happened to Strad, and if it could happen to him… He simply reshaped the miter with a fine knife and filled the area with what Sacconi called black mastic filler. However, I strongly suspect that this was simply a pore filler mixed with varnish. It looks black in depth. I remember repairing a violin at hills in the 1970,s. It had whalebone purfling. I only had some greenish transparent whalebone (before the ban). I ask Arthur Jefferies how I might stain it. He told me that I did not need to. So taking his advice I just laid it in like a wood shaving and from the end it looked absolutely jet black. This is the same effect as looking into the edge of a sheet of transparent glass. 

 

This final picture shows an almost finished corner of the back. As can be seen it is worn slightly in anticipation of my final copy work. Later I will explain how the back and belly edge-work was finished.

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