After turning a bowl recently from a solid chunk of log, I thought it might be interesting to try my hand at a segmented bowl. After researching the procedures, I figured I better start with a clamping system to glue the stacked rings. There are a wide variety of clamping devices listed on the various turning sites but they are all discrete units. In my little shop, there just is not any more room for an additional piece. I am at the point where when something comes in- something else has to go!
Therefore, the problem became, how to make a sturdy, stable clamping device that at the same time would be easy to disassemble and store. A couple of trips to Lowes; rummaging through the salvaged hardware box and some scrap 2×4’s yielded the following bowl clamp.
2×4’s, set on edge, create the top frame of the clamp.
The top of the workbench forms the clamp base. Holes through the top frame, aligned with the workbench dog holes provide the connection points for 5/8” all-thread.
Glue, screws, and lag bolts secure the top frame sections together.
A piece of 1” all-thread applies pressure to the segment rings. A captured nut holds the all-thread in the top frame. The nut is inserted/epoxied into a recess in the top frame.
A built up plate applies the actual clamping pressure. The plate swivels on the all-thread. Two stop nuts, one reversed, capture the pressure plate on the all-thread leaving just enough clearance for swiveling. Recessing the bottom nut prevents it from contacting the segments.
I needed a method of cranking down the pressure. I had an old bandsaw tensioning device with stripped threads- just repurpose the crank. I re-drilled the crank hole to ½” and ground the 1” all-thread to fit. Tighten the allen set screw and we are in business!!
The finished system-
A little completely unscientific test indicates some pretty good pressure-
The dimensions of the clamp were arbitrary and pretty much set by the materials available. As built, the maximum height is approximately 13” and an adjustment range of about 3.5”. The 5/8” all-thread nuts lower the unit for smaller dimensions.
I think my first project will be a mortar for the pestle shown lying on the bench. The pestle was a flea market gift from a friend. If the mortar turns out, I will present him with them both, as a set.
-- Lew- Time traveler. Purveyor of the Universe's finest custom rolling pins.