Sorting thru my taps...

[Noworries]

I was organizing my tap drawer yesterday. My largest non npt is a 3/4-10... I have only ever used my 1/2 and larger taps to dress up threads so i got to thinking how difficult would it be to tap a 3/4 hole by hand in 1/2" or better steel. Anyone with experience doing this?

 

[ez-duzit]

I have. Used an extra-large adjustable wrench with a cheater because, at the time, I didn't own an adequate tap handle.

 

[lilscorpion]

It’s doable but you will need leverage. The filler the tap, the more you’ll need. You’ll want to use tap magic or some other cutting/tapping fluid.

Oh and I’ve hand cut 1” fine threads.

 

[dutchgray]

I have a tap wrench which is 21 1/2" long and some big taps, but I think M12 might be the largest new thread I have tapped by hand. Makes light work having a large tap wrench though.
I might have to try out one of my real big taps and report back, 1 1/2" Whitworth is probably the biggest I have.

 

[Sliceddeuce]

I Put The tap in my Index 745, toss it in low and flood w/ Tap-Magic. Done deal. Unless the part is on the long side..then it goes on the lathe, set the gearbox for correct pitch and watch the old boy work.

 

[karacjohnson]

we do at work quite often, typically use rapidtap and just use a 12 point socket to hold the tap with a ratchet. we do this up to m30 without much effort.

 

[matt_i]

If your tap is centered over the pilot hole and the tap is sharp, its not that big of a deal.

Rigid setup with a spindle machine as several described above is of course the most reliable way to keep the alignment.

I would do this with a magnet drill press if the part/assembly could not be put into a stationary machine.

 

[Milton Shaw]

I have threaded 2" pipe with Ridgid threaders by hand. I now have a 300 power threader that sure does make it a lot easier. I have pipe taps but have not had to use them except to clean up threads so I cannot say how hard they would be to turn.

 

[Monza Harry]

The bigger machines at work often "Get Scared" and leave the bottom 1" or so untapped. so the mould-makers (that includes me!) have to finish the eyebolt holes, I've done 8 2-4 1/2 NC holes in an afternoon, this past Wednesday it was 8 1 1/4-7 holes 3/4" deeper. our big wrench is around 4' long though, a 2' wrench wouldn't be very good you would likely end up breaking the tap because it would be very tough to apply even enough pressure at that torque level. Harry