2022 Archives - Alabaster Handcrafted Instruments

This is a repeat of a first very successful commissioned instrument. It is small with a body length of only 390mm (15.4″) that is based on an 1830 Guadagnini and the record of that first build can be found here.

I visited Steffen Nowak again in Bristol to select the wood. His selection was a little limited due to Covid but still had some lovely figured sets to choose from. What I ended up with choosing was some well seasoned Bosnian maple from 2011 for the back sides and neck and some Alpine spruce from 1992 for the front.

I am keeping the design the same and the build process for #2 is recorded below:

Wood from Steffen Nowak. 30 year old spruce and 12 year old maple.
Neck blank rough cut out to give it a chance to settle before final shaping.
Spruce blank sawn through
rib blanks
Ribs thicknessed to 1.1mm
Maple back blank resawn before bookmatch jointing
Rubbed joint on back
Ready to glue in the willow blocks
Spruce front rubbed joint
Willow blocks glued into the form
Blocks marked for carving
Blocks carved ready to take ribs
Inside of the back flattened
Front flattened
Front rough thicknessed to 18mm
Back rough thicknessed to 16.5mm
Ribs cut to length and grain patterns oriented
Glueing in the C bout ribs
Gluing in the lower bout ribs
Gluing on the remaining ribs
Marking out the back profile around the ribs using a washer to give the 2.8mm overhang.
Back marked up ready to cut out on the bandsaw
Front profile marked ready for cutting out
Gluing in C-bout linings on the back
Linings fitted to back and levelled off flush with top of ribs.
Back cutout on bandsaw
Front cutout on bandsaw
Rough carving the back with chisels
Carving the back using thumb plane
It’s a long process and the maple is really hard!
Back profile finally finished after days of chiselling, planing and scraping
Started to chisel out belly outside profile – so much easier than the maple on the back
Nearly finished with thumb planes on the outside profile – scrapers next
Temporarily tacking the back and belly to ribs in order to set the edge overhang before marking and cutting purfling grooves.
Standoffs taped to file for finishing the edge overhang
Edges all trued up ready for marking purfling slots
Veneer cut ready for gluing up the purfling sandwich
Gluing the purfling sandwich
Started purfling slots
Purfling slots cut on the top
Purfling sliced up on bandsaw
Purfling slots cut on the back
Purfling dry fitted to back
Purfling levelled off on back before cutting the purflng channel
Finished cutting and fairing in the channels on the back
Finished cutting and fairing in the channels on the top
Carving out the back with gouges
Carving out the inside of the back with thumb planes
Mode 5 309hz – early stage in plate tuning process
Mode 2 – early stage in plate tuning process
Roughing out inside of top with gouges and thumb planes
Mode 2 @ 130.8Hz on belly
Mode 5 @ 260.9Hz on belly
Final contours on back
Mode 2 @ 126.8Hz on back
Mode 5 @ 263.2Hz on back
Marking out f holes
f holes cut
Gluing in bass bar after chalk fitting
Initial mode 2 @ 133Hz after fitting bass bar
Initial mode 5 @ 282 after fitting bass bar
Mode 2 @ 127.1Hz on back
Mode 5 @ 262Hz on back
Mode 5 @ 255.9Hz on belly after bass bar tuned
Mode 2 @ 127.8Hz on belly after bass bar tuned
Blocks carved back ready for glueing on the back
Gluing on the back
Adding the linings on the front after removing the form
Measuring mode 5 frequency (dropped to 227Hz) on the attached back
Blocks carved back and cleaned up ready to glue on the top
Gluing on the top
Box closed up
Neck blank trued up and marked up ready for carving.
Just needto add flutings now
The finished scroll
Fingerboard shaped
neck joint cut
Finished neck and fingerboard ready to glue onto body.
Gluing on the neck
After a couple of coats of Vernice bianca
Finished instrument after 2 coats of Vernice Bianca, 1 coat of shellac and 10 coats of oil varnish.

Here are some pictures of the finished instrument which weighs in at 522g (without chinrest):

Design

I decided to have a go at another cello because I enjoy building them so much! Of course I also wanted to improve on the cellos built so far by making a few judicious design changes and tweaking the build process based on experience with the earlier builds.

The key design changes were:

Sight changes to the archings (25mm belly and 23mm back)
Reduce f/b side thickness to 7.5mm from 8mm
Change break angles over the strings to improve playability (19.5 degrees ADG and 24 degrees DGC)
Changed f/b profile to match change in bridge profile
Increase over-stand by a few mm to 22mm
Attempt to increase Mode2 and Mode 5 plate frequencies to around 65Hz and 130Hz
Colouring the instrument a richer chestnut brown

The resultant design drawings done using solvespace are below.

cello template da2 top

cello #4 back profile

cello #4 belly profile

fingerboard profile #4

cello #4 side view

cello #4 neck

I also decided to make use of my CNC router to build new 6mm MDF templates based on these drawings.

Build process

As usual, not everything went perfectly to plan but most of the desired changes seemed to work. The one area I had real difficulty with this time was tuning the plates especially as i was trying to hit higher resonant frequencies this time around. As I was trying to tune the top I was having real difficulty getting mode 2 and 5 and octave apart – the ring mode just didn’t want to drop. Then I happened to wash the outside of the top to get rid of some surface bruising (from when the top was drilled out) and the following morning it suddenly started to behave properly! My assumption is there must have been some latent stresses in the spruce and the wetting allowed them to settle out – a bit like annealing. Anyway I ended up with Mode 2 and 5 exactly an octave apart and matching on back and top at 60Hz and 120Hz respectively.

The finished instrument is a beautiful chestnut colour and has wonderful a rich singing tone using a set of Larsen Magnacores. I have christened her “Doris” and she weighs in at 3.01kg.

I am delighted with her – a definite keeper!