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Old 02-05-2012, 06:02 PM
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derekcohen derekcohen is offline
Join Date: Dec 2009
Location: Perth, Australia
Posts: 446
Default Re: Building a Bench in Perth

One Change Leads To Another

I was asked why I chose the Benchcraft tail vise.

The choice of tail vise was made on a number of factors, one of which was the space available for the bench. My bench is placed against a rear wall in my garage/shop. The length of the bench is limited by a cabinet, to the left, and a door, to the right. It comes down to the longer the bench, the shorter the tail vise ... or, the longer the tail vise, the shorter the bench.

The Benchcraft tail vise is notable in that the handle remains in one position, that is, does not "screw out" or "screw in" in length. This translates into a short vise, which means I can build a longer bench. The bench size increases from a little under 5' to a little over 6'. This may not sound a lot, but it is a massive change for me.

I was initially planning on building my own version of the Benchcraft wagon vise. However, when Chris Vesper visited with me last year, he mentioned that he had purchased the BC tail vise. When I asked why he had not simply built his own - since he is a top class machinist - he explained that the design of the vise places great stresses on the mechanism (it screws at the side of the captured dog so as to run close to the edge of the bench), and that to accommodate this, the steel work needed to be heavy duty ... and that the BC was built like the proverbial tank. He did not believe he could replicate it. That sold me on the BC for the tail vise.

I hope to get to the bench dogs tomorrow. These will be rectangular, not round, so I have to prepare them before I glue up the bench top. Why rectangular? Simply because I believe that they will hold work more securely than round dogs. They have a broader face and will not twist. Plus, I wonder how many bench (dog) builders realise that the dogs need to incline slightly (I am using 2 degrees) towards the work piece? This is difficult to do if drilling for a round dog. Yes, it is possible to cut and angle a flat upper section of a round dog, but this thins and potentially weakens the dog, making it more susceptible to bending under stress. A rectangular dog is more work, both in planning and build, but it worth it. This does not preclude one from adding holes for bench accessories, such as hold downs.

So today I plan to finish off the legs. Their dimensions are 5" wide and 3 5/8" deep. I have cut the tenons, and what is left is to prepare one for the leg vise and all for the mortices for the adjoining stretchers. While I will not complete the base until after the top is done (as the length of the stretchers is determined by the dimensions of the top since all facing edges will be co-planar), I need to have everything ready to receive the top once it is glued up just so that I can work on the top.

To decide the length of the legs I first had to finalise the height of the bench. The present bench, which I built 18 years ago, was a remnant from a pre-handtool era. Much modified over the years to better deal with the demands of handtools, it still retained that one feature of the powertool user - height. It is 34" high. Too high for comfortable handplaning at my 178cm/5'10".

Chris Schwarz recommends the "pinky test", that is, the height of the bench should be situated where your pinky joins your hand when your arm is held at your side. I did this and the result was a bench height of 30". To test this out I place a double layer of bricks in front of the bench, and planed a board while standing on the bricks ...

Interestingly, this did feel so much better. It moved the focus of strength from my arms and shoulders to my hips and legs (which is what one is taught in karate). So the length of the legs was calculated for a bench top of approximately 4" thickness (it will end up a little under that), and the tenons were cut. Pictures of the legs tomorrow.

One other point: One change begets other changes. With the lowering of the bench, I shall need to build a new Moxon dovetail vise. The whole idea of the Moxon is to raise the work up high. The existing vise was built for a 34" high bench. To work with the same ease, the new Moxon will need to work 4" higher. Hence a new, taller Moxon.
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