Thursday, June 23, 2011

Acetal Spoils You For Aluminum; Aluminum Spoils You For Steel

I am building some squares to hold round tubes in place, and when I went to Gem State Metals today, the square tube size best suited to hold 2" OD round tubing was made of steel.  After you are used to drilling and tapping acetal, you realize how much harder aluminum is--and the step up to steel is yet another startling step!

With acetal, you put the tap in the drill press, and you can usually turn it by hand just grabbing the chuck and giving it a good hard set of turns.  With aluminum, I find that I either need the tap wrench to get leverage, or use the chuck key--and even then, it may take a couple of tries at it, backing the tap out to remove debris and going back in again. 

With steel: wow!  There's no way to do this by hand, and even using the chuck key for leverage only lets me get a few turns before I have to back out and complete the operation with the tap wrench.  Of course, once you have a few threads turned in square by the spindle holding the tap, you can pretty well complete the operation freehand.

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