On Tuesday 22 May 2018 07:06:16 Erik Christiansen wrote: > On 22.05.18 04:55, Gene Heskett wrote: > > On Tuesday 22 May 2018 00:51:08 Erik Christiansen wrote: > > > On 21.05.18 22:19, Gene Heskett wrote: > > > > Thanks Erik. Writing about this makes me think of better ways to do > > it. > > Yep, thoughts can stay in a groove if not nudged. All that I was > referring to with the "seesaw" is: Grab a little 6" steel rule, pinch > the middle of it between a turned pointy bit of rod in the spindle's > chuck and the top of the horizontal tap hat. When the table is wound > either side of centre, the rule will tilt like a seesaw, being > horizontal only when the point is centered. It's most sensitive with a > reasonably sharp point. The method won't split a thou, but I have no > way of lining the DTI up with the spindle centre, and its reading > won't split a thou on the top of the cylinder, either. > > Erik A variation on that is a contact in an insulator in the mill spindle. Go low enough to hit it to one side, run the spindle at 500-1k revs so the wobble in the conact wire is equalized, and do a g38.2, first fast, then back away a couple thou, run the g38.2 again and record the contact. Pick it up enough to clear the top and run it to the other side and back down to the same z, the repeat the g38.2 sequence running y in the opposite direction, recording the 2nd slow contact. Subtract one from the other, and /2. That I can do right in the code, but its yet another tool change that ought to be done as the hole is being drilled. but I think it would be accurate enough for each 90 degrees the table is driven. Do that and record it, then sweep that spot with a 1/4" mill to make a flat spot so the drill will settle quickly on first contact, drill the hole. The flat would be a consistent height, so the drill can be brought to -0.002" or so, pause while it centers, then peck to depth. Turn table to 90, set new y from previous table, repeat the drill cycle. Turn table to 180, wash rinse and repeat, ditto for 270. Run the table back to -5, then to 0 to tske up the tables horrible backlash, change the tool to the tap and tap all 4 holes. Done. Mount the tap you sized the center hole for, add and tighten the grub screws, and stamp the size and tpmm on the face of the brass so it can be easily read while still sitting in the storage box. Drop in a pocket of the storage box I've already made. The tap is protected from contact with other taps, further dulling it, and it makes a good handle to retrieve it out of the pocket its in for storage. I made a box with 100 pockets, the pockets made from the square plastic extrusions used for deck rail balusters. All glued into one block with plastic solvent glue, and wrapped with 5/16" x 4" wide solid oak panel frame. 30 minutes or less per hat made, depending on how long I spend searching for the correct sized drill for the center hole for the shank of the tap. Or for the grub screws drill tap...
With 3 common drill sizes standards about, that can be fun, not. Time to skinny dip, make starter fluid, aka coffee, and take care of the missus. Later & thanks Erik. -- Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
