Re: General Tool Life Question

GM4T,

You might want to find a "shop" book, that would give instructions on
hand tapping.
While you might get them done the way you describe, It can't be good for
the tools, and you'll HATE breaking off a tap in the work! this is a
plate? Use a taper tap, run it deep enough to get "out" of the material
on the other side, and/or finish up with a plug tap.

Depending on the material, you typically want to go in a turn and a
half, and then back it out a half turn (OK so start with less until you
get the feel of it). For deep holes, back it out completely
occasionally to clear the chips. Use Tapmatic tapping fluid (one for
aluminum, others for steel, brass?).

Your 1 degree steps will probably NOT make a good thread. Why take
"more then an hour" to tap a 1/4-20 thread (3/4" depth), when you should
be able to do it properly in a FEW MINUTES? And done properly, will
result in a BETTER THREAD.

Did I mention using a tap wrench? And insure that you drill and start
the tap good and square to the work. Drill the holes in a drill press,
and use a tap starter, if needed (there are also ways to start a tap
using the drill press quill).

The last large taps I bought were sold in sets of three: taper,
bottoming, and plug. There is a reason for it!

SORRY for the rant! But your old shop teacher would be turning over in
his grave! ;>)

HTH

73's, Alan KM6VV


gm4t wrote:

>
> I actually am using one tap for each hole size. I wouldn't want to
> buy too many taps because this is a one-time project and I wouldn't
> need them anywhere else. When I tap the holes I do it very slowly and
> very little at a time using a plug type tap. I turn a very small
> amount, maybe like 1 degree or more before backing it out. Which is
> why it takes so long for me to tap one hole. But time isn't a
> priority for me. It took more than an hour to tap a 1/4-20 thread for
> 3/4". I use a lot of cutting fluid on it and the chips drip off in a
> clump.
>
> -GM4T