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tap handle for 4-40 thread

Bill D

Diamond
Joined
Apr 1, 2004
Location
Modesto, CA USA
I need to tap a few 4/40 threads by hand. In the past I have used a small tee handle tap wrench. The kind with a collet. It seemed kind of of big and heavy with poor feel for the work. Is there a better choice maybe something more like a pin vice? OR would the torque be too much for that. What about using my cordless drill. It seems like it could easily snap he tap if anything goes wrong.
Bill D
 
I need to tap a few 4/40 threads by hand. In the past I have used a small tee handle tap wrench. The kind with a collet. It seemed kind of of big and heavy with poor feel for the work. Is there a better choice maybe something more like a pin vice? OR would the torque be too much for that. What about using my cordless drill. It seems like it could easily snap he tap if anything goes wrong.
Bill D

we have ones like this we use when we have a limited number of holes, and they never seem to big or gangley. If we are doing more we run a tension compression tapping head set up

https://www.mscdirect.com/browse/tn...MI8vvIzMnC6QIVhobACh3-cQFXEAkYCSABEgLeqfD_BwE
 
Tap handles come in a range of different qualities and you don't say what specifically you were using. I find my little Starrett 93-A to be fine for that sort of work. It holds the tap firm and the t-handle isn't sloppy like on junk tap handles. That's where I find the most frustration comes is from using tap handles that have unwanted movement. It is also easy to remove the handle for those times that you want to use it like a pin vise.
 
I've seen guys make their own. Just a knurled aluminum disc about 1" dia with a thru hole tapped from the side for a set screw.

All taps 3.5mm/#6 and smaller have .141 shanks.
 
Turn and knurl a small piece of round stock. Say 1"to 1 1/4" in diameter. Drill an appropriate sized hole so you can force it over the square on the tap. If you're tapping aluminum, it could be a little smaller. D2, it may need to be a little larger.
 
The weight of any trap wrench at all, alone, can snap off a small tap.

Electronics person tip: take several small knobs from your junk box. Install a small tap into each one.

Starting with 0-80, up to about 8-32 or so. You may need to make an adapter bushing for some of the sizes.
That's why you have a lathe....
 
I've seen guys make their own. Just a knurled aluminum disc about 1" dia with a thru hole tapped from the side for a set screw.

All taps 3.5mm/#6 and smaller have .141 shanks.

Great minds think alike gbent posted at the same time. I have used these things on manual lathes and mills as well as CNC. On the lathe when cross drilling and tapping, a broken tap would have scrapped the fixture. Never broken one with these drivers.
The O-ring and a 1/8 steel ball keep the tap in the retracted position on a CNC lathe or mill while running.
TapDriverRS.jpg
 
Starrett 93-A, used it last night to tap a 4-40 hole and that tap is still in it now. No idea if they are as good as they were 30 years ago though. Definitely a lovely tool.
 
ANY SMALL CHEAP DRILL CHUCK WILL EASILY DRIVE A 4/40 TAP.OLD 1/4 CORDED ELELCTRIC DRILS ARE TRACH CAN ITEMS. Take the chuck off and throw the rest back in the trash where it belongs.Edwin Dirnbeck
 
I need to tap a few 4/40 threads by hand. In the past I have used a small tee handle tap wrench. The kind with a collet. It seemed kind of of big and heavy with poor feel for the work. Is there a better choice maybe something more like a pin vice? OR would the torque be too much for that. What about using my cordless drill. It seems like it could easily snap he tap if anything goes wrong.
Bill D


I bought a set of lisle tap holders that fit onto rachet wrenches of all sizes. it was like $30

70500 Tap Socket Set
 
If you really wanted to go gonzo an Albrecht Royal Sensitive Drill Feed shank with an appropriate chuck on it could be really nice depending on what exactly you're doing. Starts getting a little pricey at that point, though.
 
whichever handle I'm using, I use a guide block if the work doesn't have a spindle to guide me
I have several either rectangular or disk shapes with 1-2" of flat surrounding the tap hole
Most of my tap breakage I have attributed to trying to straighten out a tap after starting
 
Ditto the small tap wrench

low mass is key

you accidentally let go of the wrench and it whips around, tink. broken tap

smaller is better

anything that reduces the mass is key, so if knobs etc work for you go for it.

and dammit use gun taps, or roll taps
 








 
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