I have 2 beautiful pieces of book matched maple to make up the back.
I started by getting my jack plane (from Axminster) into good working order. This had never worked particularly well and after closer inspection I realised why – the blade was slightly bowed and so the burr did not rub off properly. Well after an hour or so of flattening against my diamond sharpening (stone?) I managed to get it flat and properly sharp and then joy, – producing cigarette paper thin shavings and both halves flat and true in no time.
I used the heat gun to warm everything up, made a new batch of glue and tried a rubbed joint – worked first time and no clamps!
Next was levelling the underside – boy is that maple tough but after about 3 hrs with the jack plane and a few blisters got it done.
Then clamped the ribs to the flat surface to mark out the outline and used a washer to mark the overhang before cutting out on the bandsaw and finishing off with the vertical spindle sander.
Next marked up the thickness of the edge – 5.5mm except for the corners (6mm) and the c-bouts (5mm) before starting all that chiseling! Boy, is that maple hard work!
I built some thin plywood templates to help with the arching profile. There is a great article by Sergei Muratov that gives a good starting point for the arching curves. I adapted these slightly to give an arch height of 25mm on the back.
I used a power plane to get a rough arch height and then a gouge, small plane, and thumb plane.
Finally finished profiling the outside of the back – this is a long week! For anyone actually reading this blog you will by now have realised that my weeks are “virtual” this week started at the beginning of June and now July is nearly over! This is the result of actually having to “work to live” and in a job that has me trotting round the globe regularly so this virtual week is so far 7 regular weeks long and have still to shape the inside of the back!
Now for the purfling – I made up the purfling from a 1mm piece of sycamore sandwiched between two 0.5mm pieces of ebonised pear all glued up (hide glue of course) and clamped between 2 cauls. Then sliced it up on the band saw into 3mm strips and after a bit of cleaning up with a plane all ready to go.
I managed to find a tool for marking the purfling groove on ebay but had to grind the blades down a bit to get them 2mm apart (the width of my purfling) and ground down a very small chisel (I had in my toolbox) to be slightly under 2mm.
Glued in purfling using a syringe to fill the pre-heated channel with hot hide glue, tap down with a mallet onto kitchen roll to stop it spraying everywhere and clean up with hot damp towel.
After gluing all the pieces of bent purfling having taken care to try and get “bee sting” at the corners I dug out a channel over the purfling with a chisel and then faired the channel into the body with scrapers.
Now I turn the back over and marked out the desired thickness profile in pencil.
I built a simple rounded stop to put under the drillpress and then drilled holes (1mm over-thickness) all over the back to provide a guideline when hogging out. Then using a fearsome wood carving attachment to the angle grinder (from Axminster) which cuts through maple like butter, I rough hogged out the back to the bottom of the previously drilled holes.
Then it was back to the thumb plane and more blisters to take it down to final thickness prior plate tuning.