On Sat, 10 Oct 2009 14:20:54 -0500, John Fields
wrote:

On Sat, 10 Oct 2009 10:11:16 -0700, Jim Thompson
wrote:

1/4"-20 tap calls for 0.201" tap drill (13/64")

Into a steel 1/8" panel, tap is hard enough to turn that handles flex
:-(

Is that normal, or do I need to go up one or more drill sizes?

---
IME it's not normal.

As someone else suggested, make sure your tap is sharp and use lube.

If you haven't done any tapping in a while, it may be that the tap isn't
being held normal to the panel when it starts biting into the metal,
which can cause it to bind up.

In order to make that go away, get or make a "tapping block" which is
nothing more than a block with a 1/4" hole drilled through it
perpendicular to the face being drilled, hold it against the panel,
insert the tap into the hole and start the tap into the panel that way.

Works great!

JF

Really good idea! When I can, I use my drill press to get a vertical
start. In this case, it's free-hand, so your "tapping block" is a
SUPER idea! Thanks!

...Jim Thompson
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