Leg vise retrofit (2)

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Man with many vises
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This is a continuation from Leg vise retrofit (1) and describes how I made the X-cross linkage.

My goal was to make a deflection-resistant linkage that is still fairly compact. Here are the raw materials for this X-cross linkage. The two arms are made from 1/2" x 2" 6061 aluminum bar stock.
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The arm pattern was sized to print on a single sheet of legal (8-1/2" X 14") paper.
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After cutting the arm blanks to rough length and stacking with double-sided tape, glue on the arm pattern. Center punch the three holes. I like to use a centering pin to position the stock. Drill the 3/8" center hole through both arms.
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Countersink center hole for 5/16" flat head screw. Note that the other arm's countersink must wait until the arms are separated.
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Drill the 3/8" hole at the upper end and the F (or 17/64") tap hole at the lower end. Start the 5/16-18 tap by hand using the drill press to get it started straight.
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Unchuck the tap and finish with a tap wrench.
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Next, the two angled waste areas must be cut off. Here is what I did and you should use whatever method that you are comfortable with and can do safely. I used my tablesaw with a thin-kerf carbide rip blade and a tapering sled which held the arms securely. Paraffin rubbed along the cut line helps lube the teeth.
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Here is the long cut also with paraffin rubbed on the cut line.
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Use a belt or disk sander for the various roundovers per the pattern.
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A trial assembly to make sure the linkage will close.
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One more countersink on the outside of the other arm. I also deburred the rest of the holes with the countersink bit.
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Last is making a sex-bolt-like pivot axle. Tap drill and tap a 3/8" brass rod 5/16-18 about 1" deep (again, start by hand and finish with tap wrench as before) Then, countersink the entry.
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The length of the brass depends on the depth of your countersinks. Start at about 13/16" and countersink the cut end also.
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Here is the end result ready for a trial fit and length tweaking. The screws need to seat on the brass and the arms should rotate easily.
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Finally, after painting, is the completed X-cross linkage. I did add a thin plastic (like from a milk jug) washer between the arms to separate them slightly.
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Leg vise retrofit(3) will describe installation of this X-cross.
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