Mike Kutterbach’s demonstration of his technique for turning ultra thin bowls (25 to 35 thousandths of an inch thick or somewhere between 1/64 and 1/32 of an inch) was most interesting and very informative.
Mike starts by mounting a previously rough turned and completely dry bowl blank with a tenon on the lathe.
Mike prefers hard maple with uniform grain. A bowl gouge is then used to initially true up to rim and then thin and finish sand the blank in a step wise fashion from rim to bottom to a thickness of about 1/16 inch. A back light is useful in determining the thickness.
Mike cautions that each step should be finish sanded sequentially as it is difficult to complete after the entire bowl is thinned. The bowl is then removed from the chuck and remounted on a homemade chuck constructed of plywood with an outer disc of MDF. The center portion has been removed to allow for the insertion of a light connected with a hollow tube through the spindle to an external power source.
A step is then cut into the outer rim of the MDF ring to snugly fit the rim of the bowl.
The bowl is remounted using the tailstock for precise centering and support. It is then securely taped to the MDF.
Now for the fun part! The tenon is removed and finished sanded.
The remained of the finishing is completed using a sharp cabinet scraper and sandpaper, with the light on to gauge proper thickness. This stage is again completed in a stepwise fashion, from bottom to top.
Mike pointed out the difference in translucency between end and side grain and in any areas with irregular grain. He also noted that this final thinning with the cabinet scraper typically takes 3 to 4 hours! We all thank Mike for sharing this information and another fine demonstration with us.
