Turning a Madrone Burl Bowl - Part 4

I "wet sand"the bowl with the walnut oil. I believe that it greatly reduces the time spent sanding and dramatically reduces the amount of fine sanding dust that I have to deal with.

After I re-oil the bowl, I hand sand with Klingspor cloth backed, aluminum oxide abrasive (see Fig. 8). I start with P100 grit and progress to P120, P180, and then P220 respectively. I finish the process with 3M’s 320 grit silicon carbide abrasive paper that I purchase at my local home center. (Note: Klingspor uses the European grit sizes while 3M uses the American designations).

Silicone carbide abrasive is sharper and will produce a better finish than aluminum oxide abrasive. However, the tradeoff is that silicon carbide is much softer and I end up using more of it.

Final Details
Once I finish sanding the outside of the bowl, it is time to add any decorative touches like beading or line detail. The bowl is still round at this point so any decorations will be uniform. Once I finish the interior of the bowl, the exterior will have moved just slightly out of round. If I wait until after I finish the interior of the bowl to incise these lines, they will not be uniform around the bowl.

I always like to use details in odd numbers—usually in groups of three. There have been studies that corroborate this, but I won’t go into the reasons now. I use a small rattail file that I sharpened to a small “V" point to make the lines as shown in Fig. 9. It cuts the wood beautifully! The file is brittle, however, so be sure to keep the tool rest close to the bowl for additional support.

Turn and Refine the Interior
I now start to turn the interior of the bowl, dividing it into three sections: the wall, the corner, and the bottom. I finish each

section in turn starting with the wall, using the 5/8"deep bowl gouge to do the majority of the work. However, I always make the last cut with a ½" gouge. I find that it takes a smaller cut and I can get it much sharper than the larger gouge.

The question that always comes up is wall thickness. This depends on the size of the bowl and the species from which it is turned, but my walls usually end up being approximately 3/8" when finished.

Apply a liberal coat of the walnut oil to the interior of the bowl. I use the half-round scraper (shown seventh from the left in Fig. 10) held to a 45 degree angle and take a Light shear cut up the wall of the bowl (see Fig. 11 below). This will remove any tool marks that were left earlier by the gouge.

Once I have the wall section the way I want it, I move on to the corner and will NOT re-visit the wall section again. It has already started to go out of round and will continue to do so as I remove additional wood from the corner. I use the 5/8" gouge to remove the bulk of the wood from this area.

I re-oil the wood and, with the half-round scraper lying flat on the tool rest (see Fig. 12 below); I take a very light cut. The tool rest should be slightly ABOVE the centerline and the scraper should be held so that the handle is higher than the cutting edge. This prevents the tool from digging in deeply if it should catch. Take very light cuts until the surface finish in this area is perfected.

Wet sand the interior of the bowl. If I have a little tearout, I use the drill motor and a sanding mandrel to power sand the interior. There are many systems available; I use the Merit 3" Power-Loc discs. Hand sand the interior following the same progression used on the exterior (see Fig. 13 below).

Turn the Bottom
Remove the bowl from the faceplate and reverse chuck it on the Stronghold chuck equipped with mega-jaws (see Fig. 14). I discarded the little rubber stoppers (because I found that they caused the oiled wood to discolor) and replaced them with wood faces that I made from maple and screwed to the jaws. This method gives nearly a 360 degree hold on the rim of the bowl. You can use a jam chuck to do this as well.

Figure 11: I use the large half-round scraper at a 45-degree angle to shear scrape the interior "wall" section of the bowl. I always oil the bowl before making these cuts.

Figure 12: The half-round scraper is held flat on the tool rest in order to take a light cut on the bottom of the bowl. Note that the handle is higher than the cutting edge.

Figure 13: Finish sanding the interior of the bowl.

Figure 14: The Stronghold chuck is fitted with wooden faces to hold the bowl so that the bottom can be turned.

Go to: Turning a Madrone Burl Bowl - Part 5