Dave,
You are assuming I have a depth stop on my drill press. Without a stop, I felt that removing the bottom part was the best way to insure it didn't get hit with the clearance drill bit.
I usually use my drill press to just knock holes in stuff. Normally I would do this drill, tap, counterbore operation in my mill/drill which has a DRO.
Rick
-----Original Message-----
From: gingery_machines@yahoogroups.com [mailto:gingery_machines@yahoogroups.com] On Behalf Of David Patterson
Sent: Wednesday, June 01, 2011 4:02 PM
To: gingery_machines@yahoogroups.com
Subject: Re: [gingery_machines] new article available: Drill, Tap, and Counterbore
Rick I do the same in one setup, with the top and bottom pieces clamped in the mill. one hole at a time, but no disassembley of the pieces until complete.
Drill the tap drill to the proper depth or through both pieces, as required. Use a stop to set the depth.
Remove the tap drill, install the body drill, set the stop or use a dial indicator for the depth of the body drill. This will countersink for the threads if done right.
remove the body drill and counter bore or counter sink as required. An off center counter sink will move a part more than an offset counter bore.
Remove the clamps and tap the bottom piece without clamping it. Use the drill press or mill, manually(turn by hand), to start the tap. this keeps it inline with the axis of the hole. The tap will self center on the hole when started this way. All holes are finished, except for the tapping operation without breaking down a setup. if done right the only debur left is to the top of the counterbore or countersink and if you drilled through both pieces, the bottom of the tapped hole. This can be done with either a mill or drillpress.
Dave Patterson
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