Well, I decided that the Little Underhill Bench needed to outfitted with two, not just one, but two wooden screw vises. I thought about buying a couple of screws and nuts from Lake Erie Toolworks. That would have cost me $300, give or take a little. But then I thought, how hard can it be? Plus I’m a guy who loves the process and the history of woodworking, I’m “semi” retired, so why not make them myself? That’s how it started…
I went to my bookcase, pulled out the “Woodwright’s Workbook”, in which Mr. Underhill discusses making your own screws at considerable length. Then I pulled out “Woodturning Techniques”, by Mike Darlow. His presentation is even more in depth than Roy’s. Hey, these guys are heavy hitters and between the two I found all of the information I needed to get started.
I decided to make a number of 2 1/2″ diameter, 1/2″ pitch screws. The first task was to layout and hand carve the master screw which is used in building the “Big Tap”. I have found out that tapping the nuts is the more difficult of the two tasks (threading the screw, tapping the nuts) and I decided to make a tapping “machine” as shown in the Underhill text (one from the Williamsburg Collection).
Master screw on the lathe, just carved and cleaned up with a triangular file
The major diameter of the screw is 2 1/2″. The minor diameter is 1 5/8″. Note that I’ve stripped the threads from about the first 8″ of the screw. That section will be inserted through the nut bland, then into the left support. Also a 60 degree V cutter will be inserted (held in place by an insert and set screw) about 4″ from the left end.
Filed and sanded to create slightly truncated threads which will be more durable.
The major diameter of the screw is 2 1/2″. The minor or “root” diameter is 1 5/8″. Note that the threads have been removed from the left section of the screw, approximately 8″ from the end. This portion will be inserted through the nut blank, then positioned into the left support to maintain position during the tapping process.
The parallel surfaces of the right support will be cut and angled at about 5 degrees, the pitch angle of the screw. My original plan was to use two “lunettes”. However, I opted for a single 1/4″ brass bar to use as a temporary nut. The left hand support is temporary and will be replace with the first “nut” made on the “machine”.
Right support showing temporary "lunette" and angled surface to match pitch. Note the abundance of paste wax. Trust me, use a lot of wax or oil
Think I’ll make another “simple machine” for threading the screws. Carving them is great therapy,
but one of these days I’ve gotta get this bench done and on to other projects.
I’ll keep you informed…
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Tags: handplaning, joined bench, Roubo workbench, Underhill style workbench, wooden vise screws
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