Thread: First go at Arbortech carving a bowl

I'd like to share my experience at carving a bowl and welcome any advice that will help me improve the next attempt.

The Shape
The River Red Gum Eucalyptus camaldulensis burl bowl – 11kgs finished; av. 550mm O/D 135mm high gave me a problem because of the thin and uneven edges of the blank, so I decided to give power assisted carving a go using an Arbortech wheel in an angle grinder. Because of the thin outer edge I would use the radius of this wheel to produce a curved channel round the uneven outer top (to rest fruit or nut shells on). To avoid a thin outer edge, which would be weak and sharp, I filed a 6mm wide flat on the surface of the perimeter. The inner/deeper section of the bowl would be ground out to produce a relatively even slope angle but to reduce wall thickness as best possible without chomping through a mal-formed hole or resin pocket.
It took a fair time to produce a smooth controlled action (I think it is what Arbortech call their MK1 model, cutting wheel) but I got there in the end by using my elbow as a pivot to get a smooth curve on the channel. Plenty of PPE got used and it had to be carved outdoors and the cutting wheel filed sharp 3 times. When I was happy with the shape I took a rest from my eldest son’s engagement pressie and got stuck into the Bonneville for a bit.
The Texturing
The break was good and I had worked out that a textured contrast was the call and had decided to get the channel as smooth as possible and the inner section scored from the bottom middle up to meet the inner edge of the channel, like a volcano rim. I tried a variety of methods – Scotch-Brite paint remover mounted on an arbour for electric drill (relatively slow and finish was too fine), Josco abrasive nylon brush also on an arbour (much too slow and flexible for the required pressure); Josco - Brumby strip-it disc on an angle grinder (worked well but wore down too quickly) and finally a Josco - Brumby heavy twist knot wire wheel (worked quickly, did not wear and gave just the line textured finish that I had envisaged).
The Finish
Having dealt with the inner bowl as described above I made up curved sanding block just smaller than the channel radius and worked through from 60 grit to 400 which, on reflection, was a bit OTT but I wanted that contrasting texture! NOTE as the dust got finer I was glad that I opted for 3M -9312 surgeon type material mask with an exhaust valve. These fit well and I felt were doing their job far better than the standard shaped paper types (Available from Blackwoods). I sanded the channel and perimeter flat then set about the underside – knocking off anything loose, wedged seeds and texturing the cut parts with a wire brush as well as removing the oxidised outer layer. I used a planer on the base, sanded and finished off with 3 thin coats of the Feast Watson’s a then, when dry applied 3 large flat felt pads.
Aesthetic enhancement & Protection
I asked the forum for some advice on a finish earlier this year but although read by 90 curious woodies I received no replies at all so had to go by my own gut feeling….
Wanting a degree of bug free cleanliness I had regularly used compressed air to blow dust, seeds, dead critters & the like out holes then sealed all orifices, from both sides of the bowl, using turps based Feast Watson’s.
Due to the high density of the timber I decided on waxing and set about simple alchemy by melting & mixing some beeswax, decent furniture polish and a little turps for easy application & slow evaporation/hardening. As it happens I didn’t need the turps part in the end, as you will note.
Whilst the brew was molten I roughly brushed (using a pot washing-up brush) on sections of about 150 mm square then used a hair drier (the good lady was out on retail therapy classes) to melt and observe all of the uneven surface and holes etc were covered. When the wax was fairly hardened I used a stiff brush to spread and smooth it and finally a soft shoe brush to bring up the finish finally buffing cloth by hand to remove any excess – paying particular attention to the smooth channel and lip.
My son and the daughter-in-law says I have to hang on to it for a while until they buys a house – I can handle that as it has become an item I can’t go passed without stroking or feeling.