MEET BULL DOG
Anyone who enjoys carving largish bowls from a halved log knows that securing the blank for adzing can be a hassle. For years weve depended on heavy low benches that are drilled with holes for using a peg and wedge holding system. This is a simple solution that works, but it can be frustrating spending far too much time re-inserting wedges that continually vibrate loose from impact of adzing. There had to be a better way.
Last fall Jan Harm came to Country Workshops from Amsterdam, Holland to take the Ladderback Chairmaking tutorial. Jan is an industrial designer and teacher, and an avid carver of bowls and spoons. In our free time, we decided to brainstorm the bowl blank holder problem. First, we decided that the new device should be relatively easy to make, and that it would utilize off-the-shelf standard components. I introduced Jan to pipe clamps, something that is apparently unknown in Old Europe. We then looked through a pile of tool catalogs, searching for the perfect model. It needed to fit 3/4 pipe (easy) but it also needed a somewhat longer reach than standard pipe clamps, so that the pipe itself could be located below the working surface. The clamp would be secured at the ends using standard cast iron pipe flanges. For a heavy, beam-like base, we decided to bolt together eight 2 by 12s.
The clamp we settled on is Jorgensens Pony Deep Reach Pipe Clamp, model G3534. We got this from Grizzly for $16.95. Everything else came from a Lowes home improvement box store. The store didnt have 12-inch long bolts, so I bought 1/2 diameter All-Thread, and hack sawed the needed lengths. The materials bill came to about $100.
Making the slot for the pipe clamp was easy; I just sawed the openings in the two center clamps before bolting the thing together. Drilling the 12 inch holes turned out to be the biggest challenge. Thats a long way to drill straight from side to side. I decided to drill over-sized 7/8-inch holes for all 6 inner planks. For the outer planks, I first drilled a counter sink hole matched to my large washers, and then a 5/8inch through hole. Before bolting up the full assembly, I screwed the two inner planks together, and then mounted the pipe clamps screwing directly into the end-grain of the cut out slots.
I made this beta version 6 feet long. It is, indeed, very heavy; I can barely lift one end. Next time I make one Ill either do it 5 feet long, or I might use 2 x 10s for the inner planks. This would also create a lifting space at the ends. Im also thinking about cutting hand-holds through the planks toward the end of each side.
How does it work? Over-all, great. But there are a few problems that Im working on. When I took Bull Dog out for its first run I found that it would gradually loosen during some fairly aggressive adzing. (I was using thoroughly dry tulip poplar, and adzing very aggressively.) I discovered that the screw handle was gradually turning counter clockwise. Solution, a simple wedge like block is now inserted between the pipe slot and the clamp handle. Seems to work. Also, because the clamp fits quite loosely to the pipe, the jaws tend to cock backwards a little when the clamp is tightened. This causes the bowl blank to lift slightly above the work surface. Very thin wedges are my current remedy.
Over-all, Bull Dog really does its job. If you make one, please let us know how well it works, and what you did differently. You can do this as a post on our forum, where Ive also introduced this new pet.
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