Awl--
Will be doing about 500 pcs of a bushing, 1" dia x 1 7/8 long, drilled/tapped thru the long dimension, 1/2-13 reg tap, for my lazy buddy in Brooklyn. In 12L14, thankgawd... in a fadal vmc, 2 pcs per vise, 2 vises.
Now, even *I* can handle a job like this, but would appreciate a heads up/head start on a cupla points.
- Can I get away with rigid tapping in a regular ER25 collet, or should I get a "tap collet"?
- Speed/feed for a stubby drill (proly cobalt, but mebbe reg. HSS), with no separate spotting? I figger 18 ipm or so? It seems like many here go way beyond MHs speeds/feeds. Is it fair to say that because the hole will be tapped, it does not have to be as "clean" as a hole that is being drilled for shafting/sliding? Or would it be opposite, ie, should be even cleaner?
- With good clearance out the bottom, I should be able to tap this without pecking? How bout a second quick "clean up" cycle with the tap? I noticed a few samples were tight at the far end.
- IF we use an 11 mm drill, which is about .010 oversized for 1/2-13 (not a critical tapped hole), by about how much can the tapping speed increase? I typically have the rigid speed at S1000.2/F50.0 for 1/4-20, don't really tap that much.
tia.