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Tool How to drive taps

Tool
G

Greywynd

Active Member
Hey guys,

I get into a lot of tapping in larger sizes, 1-2”, sometimes bigger. Often this is field work, with limited space and resources. Is there any options out there, mechanical or hydraulic, for cranking and holding these taps?

Just kicking around ideas right now, but need to do something, my shoulders can’t take a lot more of this stuff!
 
12 point socket and cordless impact? Ive never tried it but might work
Ive used 12point sockets on smaller taps
 
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I do a lot of big tapping too. I bought square drives (8 point) for the big ones and I use a big socket wrench or a Johnson bar on them. It takes a bit of care to make sure that the big taps start straight but on the flip side it's a lot easier to see if the big ones really are straight.

Or you can buy a Starrett 91K Tap Wrench........

(see Starrett Tap Thread or ask @thestelster where to get one....)

IMG_0485 (1).gif
 
I have Lisle tap sockets good up to 1” taps, guess I need to hunt for larger 8 point sockets. Issue is manually cranking them, as often I’m doing multiples, as an example, today I’m tapping 18 1”NC holes from scratch. One or two is one thing, but 18 holes is another. At least these are on the smaller side.

Other problem I get into is space, a while ago I was doing M36 holes, and about 12” was all the swing I could get for turning the tap.

I’ve looked around online to see if I can find a hydraulic tapping head, no luck as of yet.
 
Impact, ive never ran that big of a tap, but an impact or slow rpm drill is how i normally tap holes (through holes that is)
 
We used a ratchet torque multiplier with an eight point socket driven by a big low rpm drill or a long handled 3/4" ratchet. You could even use 2 ratchet torque multipliers in series to get lower rpm. If that wasn't good enough I would use a big right angle speed reducer to drive the tap. You would need 2 people to apply it.
 
DPittman said:
I would have bet that an impact wrench would likely bust even good taps or dies. Now I know better.
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I'm on your original page. Doesn't seem like a good idea to use an impact driver on a tap to me. Too much instantaneous torque.
 
DPittman said:
I would have bet that an impact wrench would likely bust even good taps or dies. Now I know better.
Click to expand...

Susquatch said:
I'm on your original page. Doesn't seem like a good idea to use an impact driver on a tap to me. Too much instantaneous torque.
Click to expand...

It's hard on them for sure, after a while you start chipping/loosing teeth, but if the options are 2 days of tapping or 2 hours of tapping, I'll sacrifice a few taps for the cause, a slow speed drill is obviously much easier on the tap, but requires more operator skill


They actually sell taps with nut drives on the end as opposed to the square drive, now I don't know if using an impact is the intention by the mfg...but thats how they get used
 
phaxtris said:
It's hard on them for sure, after a while you start chipping/loosing teeth, but if the options are 2 days of tapping or 2 hours of tapping, I'll sacrifice a few taps for the cause, a slow speed drill is obviously much easier on the tap, but requires more operator skill
Click to expand...

My first thoughts were that taps are deliberately hard and therefore brittle. Most of us have probably broken more than a few and subsequently expanded our vocabularies.

I wouldnt be afraid to break a few teeth but I totally hate breaking taps off in a hole. It's a sure way to kill 100x as much time as could be saved. And that assumes I could get it out at all.

If nothing else, your reply prompted me to do a little research. I'm on a 2 hour ferry right now with nothing better to do anyway.

Seems there actually is such a thing as a tap designed to be used with an impact driver - they are called "Speed Taps". I would guess one might have better luck with one of those.

But their very existence suggests that using an impact wrench on regular taps might not be a good idea. I couldn't find any recommendations for doing so, but I did find a few others who do it.

I think threading with an impact gun is a practice I'll continue to avoid for the time being. But it would be interesting to see what the results of a few tests might reveal. In the meantime, I might also try and get a few speed taps to try.
 
Susquatch said:
I wouldnt be afraid to break a few teeth but I totally hate breaking taps off in a hole. It's a sure way to kill 100x as much time as could be saved. And that assumes I could get it out at all.
Click to expand...

Your right, if you are only tapping a few holes the chance of breaking a tap could outweigh the benefit of time saved, but tap a few hundred and it's a different story

I have ran standard taps with an impact, by either smacking a bolt on the square end or using a tap/ratchet adapter (not sure what it is called, you can chuck the tap in one end and use a 3/8 drive on the other), I'm sure I have broke the odd one, but not enough to actually have a memory of breaking one

More often than not a guy breaks a tap by turning it off axis, the twist and the sideways load they just dont take

Machine taps also fair much better, better chip removal

It works, and works well, I have tapped literally thousands of holes this way (some times a job could have 500 tapped through holes, not often, but it does happen, not doing that by hand)
 
I wouldn’t recommend running taps in with an impact wrench. I’m going to suggest that there isn’t one magical trick. You are probably already doing all the standard stuff, so I apologize in advance for reviewing the obvious). If you are doing that many large threaded holes, make up some tooling. As others have said make sure the tap is started straight. You said that sometimes the space is tight, make a few styles of tap guides that can be clamped, bolted, tack welded on (depending on the location). Also look into machine taps (spiral point, spiral flute) are easier cranking. Get some square drive sockets, or make up some hex-x-square drive sleeves (then you can get in with whatever socket/ratchet/driver that will fit. Make square holes in different sizes of heavy hex nuts). Increase the tap drill size a bit (slightly oversized is very little reduction in strength but significantly less torque to crank the tap). Play around with threading compounds - I usually use Rapid Tap because it cleans up nice but I believe there are better tapping compounds (I use Trefolex if I think it is going to be difficult).

You can still go with a Hytorq or Sweeny hydraulic wrench (various other brands too), pretty expensive but can be rented - they will still put considerable side loading. Perhaps make up a drive adapter for a Ridgid hand held Power Drive unit (get yourself further geared up and they will be calling you all the time).
 
Chipper5783 said:
Increase the tap drill size a bit (slightly oversized is very little reduction in strength but significantly less torque to crank the tap).
Click to expand...

^^^^ This.

I love this little trick and use it all the time. There is nothing magic about the standard drill and tap charts. In fact they don't always agree with each other.

I don't always use this trick to reduce the effort required. I usually use it when the fear of breaking a tap gets intense.

I love the info available in the android tap and drill chart app. It lists percent fit, material, and best drills, and also includes both metric and Imperial threads as well as metric drills for imperial and imperial drills for metric yielding a dozen choices of drill size for each thread. Absolutely great when the fear factor is high.

Thank you for reminding us about this!
 
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