Once the magic smoke comes out, it won't work any more.
John Kasunich
jmkasunich@fastmail.fm
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Tue, 01 Apr 2008
Most of the CNC work I've done so far has been one or two pieces. But this job is different. I have a friend who works in a lab where they sometimes need the odd bit of metal. I've done jobs for her before, but this is the first one since I got the CNC working.
They needed 20 'pull blocks'. These blocks get glued to samples of tile, then they use a tensile tester to pull the blocks and tiles off of a substrate - it tests the strength of the tile cement.
The parts are made from 2" square steel bar, one inch long. Face one end, then face, drill, and thread the other end for a pull stud. I've been learning more about how to use EMC, and for this job I learned all about lathe tool offsets.
The above photo (blurry, sorry) shows the setup for the second operation. The facing tool is in the toolpost (on the left), the drill is in the tailstock, and the threading tool is clamped down with a couple step blocks on the right. I'm using tool offsets when I switch from one tool to the next.
The program first faces the block. Then it prompts me to drill the hole. It positions the table so a strap clamp bolted to the table lets me know where to position the tailstock, and I stop drilling when the nose of the chuck hits the clamp holding the threading tool. Then I retract the tailstock and hit 'Resume'. The program switches to the threading tool and makes a couple of boring passes first, to make sure the drilled hole is on center. Then it threads the hole M12-1.75. While it is threading, I debur the previous part.
The finished parts:
(posted: 01 Apr 2008 20:07) (permalink)