Friday, March 22, 2019

Something That I Keep Forgetting

The Sherline mill does not have enough power to do any serious milling of mild steel.  I am making some clamps to hold down this new sine vise to the table.  The clamps are L-shaped with the horizontal leg over the edge of the base and the vertical leg supporting the clamp while a screw in the horizontal leg screws into a T-nut.  I am patterning them after the clamps used with the Sherline mill vise, but taller to handle the taller base.

My first plan was to cut the L-shape out of a solid block of aluminum.  Then I looked at some 1" square aluminum tubing, thinking this would be less work.  Not really; hard to hold the workpiece high enough in the vise to get a clean shot in both x and z in one operation..  So I bought some 1" x 1" mild steel angle bracket stock.  First step, find my wraparound shooting glasses; chop saw on steel is pretty impressive and a bit scary.  Now you know what being downrange of tracers is like.

Trying to mill the rounded edge to flat was essentially impossible; not enough power.  I also found myself battling drilling holes in this 3/16" thick mild steel with the drill press; the results were nothing to be proud of.  I think I will go buy 3/16" thick aluminum angle bracket this coming week.  The Sherline can mill this fine.

Alternatively, I can solve the problem of not being able to adequately clamp the square tubing by starting with a 1" x 3" flat, and edge milling the edge sticking out the edge, reverse, and then split the two pieces with a small mill.

I may have found an adequate solution.  The back of the sine vise's base lacks enough clearance for the clamps that I made.  One of the clamps does not want to clamp down at all, apparently because of the screw that I am using.  It is at first glance the same as the other screw, 8-32, 1.25" long but with a smaller socket head.  (I thought these were a standard size for each screw thread, but I guess not.)  Guess what?  I only have one of this length of 8-32 screw.  So I guess that I will take this "special" screw to Industrial Hardware on Tuesday.  Of course, even milling acetal cause some rotation on the table.  But, if I slide the way too short clamps for the Sherline vise up to the end where there is not enough clearance, and tighten them down, they seem to provide enough resistance for the current cut.  I may build some rather different clamps for this side--effectively upside down, so a wall of steel prevents pivoting.  Actually, the two leftover ones that I made should work upside with shorter screws.

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