Contact
You can get me at:
matt (at) hairybrain (dot) co (dot) uk
All comments, questions etc., are welcome - some, of course, more welcome than others :-)
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Logs and Bowls
Bowl making: fun!
I've been having lots of fun making bowls recently so I thought a bit of a ramble about it was in order. Now, I've done buttloads of spindle turning (chess pieces, honey dippers, tamper handles, stuff like that), but bowls are different in several ways:
1. Bowl blanks generally have the grain running perpendicular to the lathe's axis instead of parallel. So it's extra important to have good cutting technique, or the grain will tear like crazy when the cut runs against it.
2. Bowls are bigger than spindles (how's that for a rampant generalisation?). So blanks are bloody expensive and it's often easier to murder your own wood instead of buying it.
3. Because bowls are wide, you use lower spindle speeds (unless you like being hit in the face/chest/groin by flying hunks of wood).
Now, my friend Pete recently came into a truly spectacular quantity of freshly felled tree chunks, and he was good enough to send several of them my way. Time for some bowlage!
Roughing the blank
.jpg) | | A not even slightly bowl-shaped hunk of woody goodness |
Here's a particularly chunky, lumpy bit of wood. It's a bit where several branches merge into a larger one, so there ought to be lots of exciting things happening in here - irregular grain, swirly bits, knots, perhaps even some spalting (fungal attack which causes awesome colours and patterns). But first it needs the pointiest corner bits taken off. A few passes on the bandsaw and it's a little less unruly.
.jpg) | | Still not exactly round... |
Now, this looks dangerous and awkward and impossible to turn, but it's really only dangerous and awkward. A little bit of trial and error gets the wood lined up so that its centre of mass is on the axis of the lathe, which means it can be spun surprisingly fast without causing any wobbliness. Notice the driving torque is coming from a Steb Centre - given the size of the blank and the rather poor state of the outer surface of the wood (it's been exposed to the weather for a while, see), this can be expected to strip out and freewheel uselessly several times before the blank is roughed into a more-or-less bowl-shaped lump.
Incidentally, my lathe is covered in white powder because I recently made a chess piece out of soapstone for a pal of mine. I don't recommend woodturning under the influence of cocaine.
.jpg) | | Getting there, after a lot of patient chipping away at the corners |
Eventually it gets to the point where a spigot can be turned on the blank for gripping in a chuck (visible at the tailstock end here). After this point things go faster, since with the chuck holding the spigot the lathe's full torque can be transferred to the workpiece. There's also less chance of it tearing free and killing me.
.jpg) | | Forming the outside profile of the bowl |
This piccy is really just so I can show off the lovely replaceable tip bowl gouge I got from Phil Irons. Here it is effortlessly scooping long curly shavings off the outside surface of the piece. The wood's moisture level is ideal - moist enough that it cuts very sweetly and with minimal tear-out, but not soaking wet like freshly cut wood (which would warp and split like crazy while drying after turning).
.jpg) | | Ready to hollow out the bowl now |
After turning the bowl's outside profile and giving it a sanding using drill-mounted neoprene backing pad and an 80 grit disc, it gets a coat of 50/50 mix of tung oil and turpentine. This is only a rough sanding and a light coat of finish, and will produce a matt surface. The bowl is then turned around and held in the chuck, ready for hollowing. The chuck is being used in expansion mode, i.e. the jaws expand into a recess in the base of the bowl. Thanks to the nice crisp dovetail shape on the jaws, if the recess is carefully cut the chuck can grip the bowl solidly without marking the wood.
.jpg) | | I really must get one of those curved toolrests |
There we go - ready for storing fruit! Things I've learned the hard way when hollowing bowls:
1. It's preposterously easy to get a nasty catch when entering the cut at the edge of the bowl. Go really slow.
2. Although long bevels work wonders for roughing and finishing the outside of a bowl, and for shallow hollowing, the deeper internal surfaces such as the bowl's inner corners and the base require a gouge with a short bevel.
3. Using a side-cutting scraper with the toolrest below the lathe's centre line is just asking for a nasty catch and a smashed-up bowl.
More sanding and more tung oil and turps, and we're...
Finished
.jpg) | | Who needs cocobolo eh? |
And there we have the finished bowl - and what remarkably pretty wood, considering how plain the original chunk looked! I have loads more of these logs, so check back soon to see what woody treasures they hide.
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