Just got back from another expensive but most profitable visit to David Dyke down near the South coast. Came back with the boot loaded up with enough wood for the next cello and my first violin.
New load of wood for cello #3 and first violin
Spent this morning doing the design for the violin inside mold using the solvespace parametric drawing package again.
I have decided to do a blog of the violin making process like I did for the cello so that interested parties can follow the progress as well as providing me with a reminder of what I did!
I finally completed my second effort at cello making and delivered the finished instrument to George (who christened her “Beryl”) just in time to play the Stratford Symphony’s summer concert.
Here are a few recordings made at George’s Bank Cottage studio:
And a set of pictures of the finished instrument kindly taken by George .
A complete pictorial record of Beryl’s 6 month build process can also be found here.
Really exciting day – I just collected the wood from David Dyke down in Sussex to start on cello number 2.
Procuring the cello wood
A whole lot of wood!Rough cut neck to let it settle
Front and back plate preparation
And here are the belly and back book matched pairs getting glued up after spending hours getting a perfect joint – lovely flame on the maple back.
Back halves glued up
Managed to do the back without clamps but the spruce always seems to move a bit when heated up for gluing so I just needed a slight clamp pressure to get it tight.
Top all clamped upGluing the book matched top
The belly wood has a wonderful ring to it and great grain even and straight structure.
I also started to thin the maple ribs down to size on the drum sander but not to finished size so that I could scrape a finish on what will be the outside.
Top trued upBack trued up
The cello ribs
Ribs getting down to size
Will have to scrape them next because I don’t want to see any sanding marks on the finished instrument.
And here are the blocks cut ready to to glue into the form. The end blocks are in spruce, corner blocks in willow as it is more forgiving to carve.
Blocks cut ready to glue into formBlocks glued in and trued upBlocks being carvedGluing the ribstrimming the rib edges to match the formIn the middle of fitting the liningsLinings fitted to the ribs on the top side – just need trimming downGluing up using home-made peg clamps
Note I have added some removable sections to the central form at top and bottom to make removal easier after gluing the linings.
Merlin inspecting the ribs just removed from the form
Just need to carve the blocks to shape and chamfer the linings.
Carving the cello back plate
Top and back roughly cutout on bandsawGetting ready to carve the arch
I built a simple jig to use with my small router so that I could cut the edges to the right thickness (5.5mm all around, 5mm in the C-bouts and 6mm at corners) with the top firmly clamped down onto the workbench.
Simple router attachment for thicknessing the edges of the back and top
This is an enormous improvement to the approach used on my first cello and as well giving a really consistent edge thickness, it gave me something to aim at when rough chiselling the back profile.
Back rough carved
Edges cleaned up on the drum sander and slots for purfling marked up.
Outside of back profile finished ready to cut purfling slotsGetting ready to glue up the purfling laminatePurfling in, channels cut and profile rough scrapedThickness contours marked
I used my new pillar drill to good purpose to drill out depth guide holes across the whole back (the old drill didn’t have a wide enough throat to reach the centre of the instrument).
Thickness guide holes drilled
Now to start the long process of thumb planing the inside to give the correct thickness profile and plate tuning to get the right mode shapes and frequencies.
Back hollowed out roughly ready for plate tuning
Carving the cello front plate
Now to start on the spruce top. I got to this point in just a day.
Working on the profile of the top. Spruce is so much quicker to work than the maple!
Came across a resin inclusion when carving out the top. On scouring the internet this is apparently quite common in good tops (1 in 10 maybe) and no problem – just have to to shape a plug to fit the cleaned out hole.
Resin inclusion cleaned out ready for plugPlug shaped and ready to glue inPlug glued in
Then a final bout of scraping to get a perfect profile before marking out the purfling channels and deepening with a scalpel.
Top profile finished and purfling channel markedTop purfled
Next step is to cut the channel and fair everything in before hogging out the back side of the plate.
Outside finishedInside roughly carved ready for plate tuning
Cello plate tuning
Top plate mode 5
I thinned the plate until I got good clean mode 2 and 5 shapes but before going further on the top I have to cut the f-holes and fit the bass bar.
f holes carved out – just need to undercut them and do the V’sf-holes cut and bass bar glued in
Tuning the bass bar
Started with a bass bar 11mm wide and initial depths set according to the following table:
Proportion of length
0
1/8
1/4
3/8
1/2
Depth (mm)
9
15
21
27
29
Then progressively reduced the depth to get the changes of mode shapes shown in the gallery below.
Reducing the ends helped to close the ring-mode shape but also reduced the x-mode frequency which I was generally trying to maintain. Reducing the centre of the bar predominately reduces the ring-mode frequency but I also had to thin the edges of the top and the centre of the upper bout between corners to try and get the ring-mode down to an octave above the x-mode.
A final tap tuning allowed to identify and remove any thick or high stiffness spots both on the top and the bass bar.
The final bass bar ended up only 18 mm high in the centre with X-mode of 58.2 Hz and ring-mode of 121.5 Hz. I then thinned the back to match those frequencies – much easier – and got 59.2 Hz and 120 Hz.
Making the box
Started by gluing the sides onto the back after first re-enforcing the sides with strips of linen.
Back glued onAnd the all important label! You can also see the rib re-enforcement strips of linenGluing on the topNow what about that neck!
The Cello Neck
The neck blank I cut back in March had settled a bit so I squared it up with the plane and then marked up and cut it out on the band-saw.
Neck blank roughly cut to size on the band-sawScroll nearly finishedScroll detail underneath
Next step is fitting the neck to the body.
I did a drawing of the fingerboard profile to give an even break over the strings at the bridge of 21 degrees and then an action over the end of the fingerboard ranging from 4 mm at the A-string to 6.5 mm at the C-string. This showed I needed a 2.4 degree slope on the neck towards the bass side. I have heard of 1.8 degrees being used so ended up going for 2 which still looks quite a slant!
Marked up the heel with this 2 degree slant narrowing the heel down to 27 mm at the bottom with enough material to give me a 22 mm overstand on the A-string side.
Before fitting the neck I will cut and shape the fingerboard and stick it in place temporarily to aid in getting the set of the neck right.
Setting the neck angle before shaping the neck and heelNeck shaped and ready for gluing to the bodyCello completed in the white – now for a bit of a tan in the light box
Finishing the cello
I started by making up a varnish ground coat from a recipe I found on the internet in an article by Harris, Sheldon and Johnston.
This consisted of cooking up Boiled linseed oil and rosin at 180C for a few hours in the ratio of 1 part linseed oil to 1.5 parts rosin by weight until the mixture achieved a sticky toffee like consistency when cooled. I used my trusty mini fat fryer to do this safely in a double boiler arrangement using cooking oil instead of water. I then added turpentine so that the resultant cooled varnish had a golden syrup like consistency.
Then I ground in 10g of Kaolin (china clay) to 30ml varnish with 7ml of rabbit skin glue and added water until I had a nice creamy consistency that could easily be applied with the fingers and then ragged off to give an even finish.
Ground coat applied
Then into the UV cabinet for a day.
In the UV cabinet
I added a few coats of shellac to make sure it was all sealed properly, cut back with 600 grade wet and dry and then a final wiped on coat of shellac before applying the first colour coat and drying in the UV cabinet.
After 1st colour coatAfter 1st colour coat
.
Back after smearing in oil pigments by hand
Next I mixed up some oil pigments – 1 squirt of burnt umber, 1 squirt of burnt sienna and, a bit less than half a squirt of alizarin crimson and a little boiled linseed oil and then smeared on by hand until the colour was the right depth and fairly even and then back into the UV cabinet.
Wasn’t entirely happy with that – a bit streaky on close up – so rubbed most of it off with a turps soaked cloth and put it back on with several much thinner layers so as to leave no marks.
Result has a nice warm glow and enough variation to look interesting!
Nearly there on the colouring – think I might add a bit of blue next!
It will darken up a bit more after another 3 or so colour coats.
The back after next colour coat
Next colour coat appliedAfter 2nd colour coat – curing the old fashioned way under the sun!
Back after 2nd colour coat – curing in the sun
One more colour coat and then a couple of clear coats before cutting back and polishing.
Curing outside in the sun on one of the few sunny weekend days this year! – Just like the old Cremona makers used to do.
It all looks a bit shiny at the moment but that will go once the finish it has been cut back – aim to get a nice satin sheen.
Clear coats next.
Applied 2 top coats and then cut the varnishing back with micromesh down to 4000 grit and then finished with rotten stone and linseed oil. The cello has a wonderfully rich chestnut sheen to it.
The finished back
Glued the neck on after removing the keeper, and then fitted the pegs, saddle and endpin.
Only things left now are oiling the neck, and fitting the nut and bridge
Just finished the instrument and delivered to a very happy customer (George) who christened it “Beryl” in time for our weekend concert with the Stratford Symphony Orchestra!
“Anna” right (with me – David) and “Beryl” left (with George) at rehearsals
I just got back from an exciting afternoon with my good friend George Shilling at his Bank Cottage recording studio in the Cotswolds. George kindly spent some time recording my new cello “Anna” (after a visit to the pub).
You can find the resulting pictures and recordings here.
Having completed the rather rewarding finishing process I can now set up the instrument ready for stringing.
Fitting the pegs
The first step was to build my own peg shaver as the cheap Chinese one I had bought together with a peg reamer and end-pin reamer was way too small for the pegs I have.
I found a piece of maple off-cut and cut it down to the length of a peg and drilled it slightly larger than the thin end of the peg reamer before reaming out a hole with the thick end matching the thick end of my pegs (about 14mm). Then I planed away one face until I had a nice parallel slot showing about 5mm wide. Then I glued another capping piece over the slot and re- reamed the hole. Finally I fitted the blade from my Chinese shaver together with a very simple fine adjusting mechanism.
The result is shown below.
Finished peg shaver
I also built a very simple jig from 2 pieces of hinged oak to sand a finish onto the pegs.
Jig for sanding the pegs after shaving
Then I reamed out the pre-drilled holes in the peg box (using a few reverse turns at the end) so that I had a little more than the target 21mm between the edge of the box and the decorative rim of the peg to allow for the wood to compress a bit.
I then set up a simple jig to hold the pegs while I cut them to length and drilled them. I marked the hole positions a few mm from the centre of the box towards the thicker end of the peg and drilled the holes using a 2mm bit and then chamfered the openings.
Fitting the soundpost
I rough cut a 13mm square sction from a piece of close and straight grained spruce taking care to ensure no runout and then planed it down to an 11mm square section. Then I carefully planed it down systematically to an octagon and so on till I had a perfect cylinder 11mm diameter.
Actually fitting it could be quite an adventure with the fitting tool and retriever I purchased!
Yes – quite an adventure but eventually got the knack – certainly got my money’s worth from the sound post retriever! The f-hole was only just wide enough to fit the post through though – must remember to make it a millimetre wider on the next one – took me 2 hrs of frustrated attempts! Phew.
Fitting the nut
I filed down the ebony nut blank to fit the fingerboard profile and also added a 2mm T-extension as some makers have suggested this improves the look and I needed it anyway to get back to the designed dimensions. I tack glued the nut to the end of the fingerboard with a few drops of Titebond.
Nut ended up proud of the fingerboard by 1mm at the A string to about 1.4mm at the C string.
String spacing was set with dividers at 8mm and slots cut with a fine saw and then nut files before lubricating the slots with graphite (pencil lead).
Nut glued onto end of fingerboard
Fitting the saddle
Filed down the ebony saddle blank to match the curve on the bottom of the cello and marked /cut the top with a sharp knife to fit. Glued in with hot hide glue
Saddle fitted
Fitting the bridge
I built myself a simple jig to hold the bridge during fitting:
Close up of the bridge holding jig showing the feet spreaderJig for holding the bridge during fitting
I used a piece of carbon paper to highlight the area on the feet to remove.
Holding the bridge in position while fittingFeet just about fitted
Then marked the bridge height using a marked up stick on the fingerboard to give 4mm action clearance over fingerboard for the A, up to 6.5mm for the C string and cut the bridge profile on the band saw giving it a few millimetres extra to allow for final adjustments.
Next I used a small plane to get the thickness profile right before hand carving with a sharp knife to get the bridge to target dimensions. Finally hand sanded to get rid of any tool marks and marked the string positions with dividers (15.8mm string centre to centre) and cut the slots with fine saw and then nut files. Ordered some parchment to protect the A and D slots.
Stringing up
Finally got to the exciting bit of fitting the strings and seeing what the result of 9 months labour sounds like!
Held the bridge in place with the bridge holding jig I made earlier while I fitted the tailpiece and started stringing it all up with a set of Larsen strings. Everything seems to work ok – need to do a bit more on the pegs to get a more even grab between the two ends and the bridge needs a bit of tweaking to bring the action down to target and also a coat of linseed oil and the parchment protectors for the A and D strings – but it sounds wonderful! Very responsive, lovely sweet tone, good depth and well balanced across the strings and right to the top of the fingerboard. Quite a strong wolf note on F but a 7g eliminator on the G string sorted that out.
Finished at last! 9 months of hard work but sounds wonderful
Will be taking it to our cello-nite on Saturday night to try out on the felli celli!
Cant wait to see how the sound develops as it gets played in.
Finished instrument
I have decided to call her ‘Anna’ – I think she deserves a name after all that work!
Link to all the specifications for the finished instrument are here.
Link to some better pictures and recordings made with it by my good friend George Shilling.
After much reading on the Internet I decided to go for the following approach:
Finish the surface after raising the grain with water
Colour the wood in a UV light box
Deepen the colour by fuming with ammonia
Shellac sealer/ground coats
Coloured oil varnish coat
Artists colour rubbed in with fingers
3 more coats of coloured oil varnish
Clear oil varnish (2 coats)
Cutting back and polishing
I found an excellent supplier of ready made varnishes and varnish ingredients in Germany at Hammerl and ordered the oil varnish and a few extra ingredients.
UV Lightbox
I then set about designing a UV light box for both giving the white cello an initial suntan and for drying the oil varnish coats.
I settled on a design that I could assemble and disassemble easily for flat storage when not in use.
The base is 1/2″ ply 610mm x 400mm into which I routed some 6mm grooves to take the hardboard sides, front and back. The sides are braced with vertical triangular cross section struts at the edges and onto which are mounting UV fluorescent fittings (4 off 18W 600mm UVA fittings on each side).
The box is 1500mm high and a top piece of similarly grooved 1/2″ ply and with a small USB fan to extract heat/varnish fumes holds it all together.
All the inside surfaces are coated with aluminium foil.
In the UV light box before I put the cover on
I lightly glued a piece of scrap on the neck to hold it straight and clean during tanning/varnishing. Then the cello got a final wipe down with water and a final scraping all over before going into the light box for a week or two depending on how fast it darkens up.
Here is the result after 10 days.
After 2 weeks of tanning
I then tried fuming using household ammonia (only about 9% but seems to work quite well). Here is the result after 10hrs.
After 10hrs fuming with ammonia
Next I sealed it all with a few coats of a 1lb cut of shellac.
1st coat of shellac sealerSealed with shellac ready for 1st coat of varnish
And then the 1st coat of coloured varnish. This is incredibly thin and only a tiny amount was enough for the whole cello.
Just put on the 1st coat of coloured varnish
Then back into the light box to dry.
Once dry (I left it 2 days) I rubbed down with wet 2400 grade micro-mesh and then used a mixture of burnt umber and burnt sienna artist colours rubbed in with my fingers and wiped off with a kitchen towel until the colouring was even.
After rubbing in and then rubbing off some artist oils (Burnt sienna and burnt umber)
Another 2 coloured coats but still looking too light so had another go smutzing with artists colours.
After rubbing some more artists oils
Next step is a final coloured coat and then 2 clear coats.
After final colour coat
Next I cut it back with 3200 grade micro-mesh and water and then pumice and linseed oil on a felt pad. Still left some corduroy grain on the top. Finally polished to a nice matt sheen with rotten-stone and linseed oil.
Then popped off the keeper on the neck before gluing back the fingerboard.
The big moment has finally arrived and time to glue on the back.
I modified the form so I could dismantle the ends to allow me to keep the form in place while the back was glued on.
Gluing on the backThe back glued on – inside viewThe back glued on
Before fitting the belly I reamed out the end pin making sure the pin stayed centrally aligned inside the body and leaving 1mm gap between the pin body and the ribs.
Then I fitted steel pins to the belly where it meets the end blocks to make sure everything stayed aligned during gluing.
Heated everything up with my paint stripper air gun and then some weak hide glue and all came together nicely.
Gluing on the belly
One seam had a small gap so popped it and re-glued.
Box all glued up
Then I used a knife to round the edges and finished off with 400 grit sandpaper.
Edges rounded
Fitting the neck
I marked the side of the neck where it should meet the top (280mm from the nut) and with an upstand of about 17mm on the bass side and 19mm on the treble side (due to the 1.5 degree cant on the fingerboard).
Then marked the mortice position with a knife and carefully sawed out the sides of the mortice and chiselled out the waste. When I got close moved to a file and chalk to get a snug fit with the fingerboard centred over the body and projecting a height of 85mm at the bridge position. This was definitely one of the trickier operations but I kept moving slowly with lots of trial fits and got there in the end.
Before I did anything I roughly cut out the neck profile to give the wood a few months to settle.
Rough cut the neck to allow the wood to settle
Now with the plates nearly done I levelled the top and squared the sides (they had actually moved appreciably in the intervening 4 months) before cutting the profile more accurately on the bandsaw. I then filed/scraped the outer scroll outline and drilling the peg holes on the drill press before sawing the scroll sections and then started carving.
Just starting to carve the scroll
After much filing, carving and scraping I got here:
Basic scroll and pegbox carved
Next I rough carved the fluting with chisels
Fluting rough cut on the scrollFluting rough carved
Fingerboard
I bought a pre-shaped blank which reduced the amount of shaping required substantially. First back to the drawing board to get the profile right. I started with the string profile over the end of the fingerboard with a 20 degree break between strings and string heights over the fingerboard from 4mm (A string) to 6.5mm (C string) as I am going to use Larsen steel strings on this.
Fingerboard length will be 5/6 of string length = 580mm but added a few millimetres for luck.
1st job was to plane the edges straight and take the twist out of the blank.
Then made a template for the fingerboard profile at the end and started planing away with the jack plane to get a rough shape. It is quite hard to check for flatness using a straight edge so I just laid it on a flat surface with a light behind and looked underneath for the dark spots.
Once the rough shape was there I used a scraper to fine tune and get the 1/2 string diameter scoop measured with feelers.
Ended up with 8mm sides with a slight scoop on the edges to keep the wall height in the middle.
Fingerboard ready for finishing and gluing to neck
After cutting the outline of the neck root ready for fitting to the body I tacked on the fingerboard with a few dabs of weak glue – just hope I will be able to break the joint later!
Gluing the fingerboard to the neck
After fitting to the body I carved and filed the final neck profile and finished off the chamfers on the scroll. Note the chalk on the neck joint from fitting to the body.
The back is still a little high compared to the top but I will come back to that once I have cut the f-holes and fitted and tuned the bass bar.
Fitting the bass bar with chalk
Having cut the f-holes and glued the bass bar I then re tuned the top to bring the bass bar into balance.
Both Modes #2 and #5 had gone up with the bass bar fitted.
This is how the mode #5 shapes developed as I cut down the bass bar:
Mode #5
I must admit I wasn’t sure at first that this was actually #5 as it looked pretty weird!
Mode #5Mode #5Mode #5Mode #5Mode #5
And the mode #2 looked like this:
Mode #2
At this stage I had got the mode 5’s on back and front equal at 130Hz and the mode #2s to 60Hz on the front and 64Hz on the back so a little more to do still.
