A Bowl on a Pole Lathe
Well, I managed to obtain some small success in my second bowl turning attempt. The first try was one of those 'learning experiences" one hears about. One learns from one's mistakes, eh?
Ed in Oakville dropped off a chunk of recently cut maple for me to practice on, and I roughed out a couple of bowl blanks from this rapidly drying maple, slathered them with wax emulsion, and put them in a plastic bag to keep them wet enough to work. Time passed, my summer holidays approached, and the bowl blanks grew mouldiy and ugly.
When I finally got to the cottage (where my pole lathe lives) the weather was not conducive to spending a lot of time outside at an activity like operating a pole lathe. Sitting on the beach drinking cold beverages was a more proper occupation when the temp ran over 35 C. So I set up the lathe in the "basement" (more correctly termed a crawspace in this instance, but tall enough for a short guy like me) and mounted the Bodger's Muddle in the rafters above. The basement was a bit cooler than the Great Outdoors, so I could actually work on the lathe without expiring from heat exhaustion.
I used the mandrel I made in July (scavenged birch from the firewood pile). A 1 inch hole bored in the face of the bowl blank would accept the end of the mandrel. Note the interesting "stuff" growing on my bowl blank...
I rounded the outside of the bowl first, using a roughing gouge and a Sorby bowl gouge. I dunno if the Old Guys used anything like a bowl gouge, but it worked great on the pole lathe for me. Now that the outside was round, it was time to start hollowing.
And here's the fun part: you can't get too close to the centre because you need the strength there to drive the bowl, and if it gets too thin, then that hammered-in tenon will split that mortice. That's one of those "lessons" I mentioned earlier.. Now the really funky tools come out to play. Apparently I needed a hook tool.
Not being totally useless in the shop, I had made my own hook tool. I used a piece of a tine from an old horse drawn hayrake, a forge made from a frying pan, and a bit of scavenged 2X2 to make my hook tool. These things are apparently supposed to be used on the bottom of the turning, on the surface moving away from the turner. Kind of on the pull stroke. I started out turning the blank by hand and holding the tool in various orientations to try and get a feel for what angle and direction I needed to use to make this weird thing work.
A few tentative attempts were required before I gained the confidence and learned the appropriate technique to get shavings to flying. And fly they did! It was then a matter of working my way down to the bottom of the bowl. I can't say much about the smoothness of the surface, but that's likely a technique problem. Or perhaps a sharpening issue? There are a lot of ridges in the surface, but no tearout. Hmmm, maybe I need a selection of various shapes and sizes of hook tools? More tools? Of course!
Now what do I do about the core? I can't work any closer to the centre with my hook tool. That Sorby bowl gouge to the rescue again! I kept working the core down until I finally intersected the mortice and the bowl flew off the lathe. I managed to catch it before it hit the floor (reflexes still OK so far...). So now I have some cleanup to do on the inside, and a bit of sawing to get the base off.
The base makes a handy way to hold the bowl in a vise whilst working on the last bit of the core. I attacked the inside of the bowl with a chisel and a hook knife and very shortly the bottom was smoother than the rest of the turning. Then I sawed off the waste from the bottom.
And it's a bowl!. I packed it in a bag of fresh shavings to slow the drying process, and that's where it sits now, waiting for the first crack to develop...
Bah. I had to delete half my pix from this post 'cause the Forum software limits you to FIVE images. You get the idea anyways...
Last edited by Bill MacDonald; 05-20-2008 at 07:25 PM.
Wood Hoarder, Blade Sharpener, and Occasional Tool User