I have done something similar to what you described. After looking at various designs, including the Benchcrafted, TFWW, and Derek's, I built my vise incorporating features of several and some of Derek's additions. I liked the double handwheel design of the Benchcrafted, though the TFWW hardware also has some nice design features. And, while I think the Benchcrafted hardware would be virtually impossible to beat in quality, I elected to order an Acme thread screw and a couple of zinc handwheels rather than the Benchcrafted hardware.
I got a 1"x3' 4TPI Acme thread screw for under $40, nuts for about $8 each, and the 6" handwheels for under $10 each. I lined the front jaw with leather, which I consider essential, and which is part of a piece I bought here locally in Anchorage from a scrap pile for $15. The vise is built of Canarywood, which I bought for another project but ended up not using. In total my vise cost maybe $100 and a little time, which I enjoyed. I've got enough screw, wood, and leather left over to make another vise so a vise could be made with a shorter (2') and smaller (3/4") screw for significantly less.
I did not like the Benchcrafted design and felt that both the TFWW and Derek's were superior in getting the clamps out of the way. My vise leans more towards the TFWW in terms of using 8/4 rear jaw with an 8/4 small shelf attached behind the rear jaw with a 4/4 front jaw. In retrospect I would more closely follow Derek's design with a larger base and better clamping area but still use 8/4 wood for the rear jaw. I also found clamping work to my small shelf behind the rear jaw (ala TFWW design) to be less than satisfactory and built the auxiliary I-beam fixture following Derek's lead. It improves useability significantly and raises the work @ 5/8" above the top of the vise jaws which, as Derek has pointed out, avoids scarring of the vise jaws while markiing out dovetails. I did not and would not recommend chamfering the front jaw for all the reasons Derek noted.
The 1" 4TPI screw provides quicker adjustment than the 3/4" 8TPI screw used by Benchcrafted. My cheap handwheels work just fine but are not as elegant as the Benchcrafted hardware. While I like the 8/4 rear jaw I find the 4/4 front jaw to provide all the clamping power I need though there is some flex in the jaw, which is to be expected with the heavy hardware I used. I could probably snap an 8/4 front jaw with it if I wanted to crank it down with the power provided with the 1" screws and I'm sure I could bend heavy steel if necessary. The Canarywood is more than sufficiently hard and stiff enough for this use. And, it has a unique and very pleasant aroma when being worked.
Overall, were I to build another vise I'd happily use the hardware and wood I used on this one but more closely follow Derek's design, particularly the larger base which will make the vise sit quite solidly on the bench - more solidly than any of the other designs I've seen. The I-beam support fixture is similarly a splendid idea.
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