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  • Machine tapping in lathe

    i have a batch of parts to make, normally i'm an ones and twos type machinist, so i have no need to be quick as set up usually takes longer than the machining. The job i'm doing requires a tapped blind hole so i bought my first spiral flute taps today.

    Now i don't know the best way of using these in a manual machine, i figure the normal way is a tapping head or clutch of some sort. I don't have one but figured my battery drill might be the way to go, so i chucked up some drill rod and clamped the battery drill in the lathe chuck, as the battery drill has a rubber cover around the end i was able to make an indent at the centre with a dead centre.



    from then when i tapped the hole i just loaded the battery drill in, used a spring centre to set it all up and tapped then backed out, worked quite well, which got me thinking does anyone else do something similar?







    i can't believe how easy these tap in comparison to normal hand taps, a vast improvement, previously i could make about 4 of the parts per hour, i did closer to 8 after sorting this out and finally bolting on my rear tool post to save setting up the parting tool each time.

    Brian

  • #2
    Brian,

    Why don't you just put the tap in the chuck that is in the tailstock and use the lathes power to tap? Just wondering. I have tapped a lot of holes using the lathes power and never had a problem. Am I missing something?

    Brian
    OPEN EYES, OPEN EARS, OPEN MIND

    THINK HARDER

    BETTER TO HAVE TOOLS YOU DON'T NEED THAN TO NEED TOOLS YOU DON'T HAVE

    MY NAME IS BRIAN AND I AM A TOOLOHOLIC

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    • #3
      Maybe he's afraid of bottoming-out the blind hole tap?
      If it works, then RUN IT!

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      • #4
        I worry about breaking taps in the lathe because you can't tell how much pressure is on the tap. I often thought it would be nice to have a chuck on a live bearing that you can hold with your hand and then let slip if the tap starts to feel tight.
        Andy

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        • #5
          I power tap in the lathe often, although I'd be a little careful with a spiral tap in a blind hole. I usually tap to a comfortable depth and finish by hand. This may not help you since you have a volume of work. That said, I love spiral or gun taps and only buy the best brands, usually from McMaster Carr. Bob.

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          • #6
            Originally posted by vpt View Post
            I worry about breaking taps in the lathe because you can't tell how much pressure is on the tap. I often thought it would be nice to have a chuck on a live bearing that you can hold with your hand and then let slip if the tap starts to feel tight.
            I vaguely recall seeing products like that.

            A couple nights ago I had the idea of de-tensioning the drive belt to use it as a clutch while starting taps on the lathe. It is a huge improvement over the risky bumping of the motor. Don't know why I didn't think of it years ago.

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            • #7
              If the tapped hole is M8 or under, I just put a Morse taper holder in the QCTP, then a drill chuck to it so that it sits loose in the taper, attach the tap to the chuck, bring the thing close to the workpiece, grab the chuck in my hand and press jogging button until the tap bottoms out and the chuck starts rotating in my hand, at which point I reverse the jogging. M6 and M8 I have tapped at 1000 RPM, goes plenty fast Zip in, zip out, ready.
              Amount of experience is in direct proportion to the value of broken equipment.

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              • #8
                Power threading on the lathe

                Here is the best way to power tap and thread on the lathe for sizes about 3/8" and under.
                These tools are a simple DIY project well worth the little time it takes to make them. The first picture is for tapping. You make up a knurled handle with a drill chuck on one end and the other end is drilled and reamed for a .001 slip fit with a dowel pin, piece of drill rod or some other smooth and accurately sized steel rod. The idea is for the knurled part to be able to slide and turn freely on the rod. Drill your hole with the drill chuck in the tailstock, remove the drill bit and insert the tapping tool in the chuck. It only needs to be hand tight because there is no force on the chuck in the tailstock.
                With the proper tap tight in the chuck on the tapping tool, slide the tailstock up to where the tap is 1/2" to 1" away from the hole in the part which is held in the spindle. Turn on the lathe to a slow speed and slide the handle to the left to tap the hole. When the tap is deep enough, reverse the spindle. If the tap bottoms out or hangs up for any reason, the handle will simply turn in your hand and not break the tap or damage anything. I have tapped 0-80 holes this way many times without breaking a tap or having any problems. Your hand is the clutch. You grip the knurled part only tight enough to do the job.
                The first pic shows the tap chuck setup. In use it would have a tap in the left drill chuck.

                Tap Chuck


                You can do the same idea with a die too. This pic is a die chuck.


                This is my big tap chuck on the left, the die chuck in the middle and the little tap chuck on the right. The small one is better for taps from #6 on down because it's lighter weight and has a finer feel to it. The dowel pin is out to the right of the small chuck so you can see it's just a straight rod. If you want the rod to be retained in the tool you can use an ejector pin for a plastic injection mold. Those have a head on them and are hardened and ground.

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                • #9
                  We do it all the time with a 3/8 impact. Larger taps 1/2 impact. Important
                  thing is to back out to get rid of the leading chip. We do this with a soft impact
                  setting. Also for everybody, my kid recently bought a Dewalt 3/8 battery
                  impact. I cant beleive this thing, the power and the battery, he took a whole
                  Bronco apart down to the frame on the same charge. check those out.

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                  • #10
                    The die holder is a great time saver.

                    Chuck has 3 jaws, tap end is square?
                    Just grabbing the tap up a little on the round?

                    Thanks

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                    • #11
                      Yes - hold the tap on the round shank.

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                      • #12
                        Instead of holding the tap i have a couple sets of square drive socket sets that I use just for the taps. One set actually has an integrated o-ring to hold the tap in the socket. I cut off a couple ratchet extensions so I can use them in the drill which is awesome!

                        I love the tools toolguy! I especially like the idea of the shaft inside the tool to allow free horizontal movement! Thanks for the great ideas!
                        Andy

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                        • #13
                          Originally posted by Toolguy View Post
                          Here is the best way to power tap and thread on the lathe for sizes about 3/8" and under.
                          These tools are a simple DIY project well worth the little time it takes to make them.
                          Damn it! More projects!
                          Definition: Racecar - a device that turns money into noise.

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                          • #14
                            I have the tap in a chuck with a straight spigot sliding in the tailstock, and I can hand hold up to 10mm. At 10mm I need to wrap the chuck with rubber and use gloves for grip. 8mm, just the gloves. And this all assumes a slow speed - less than 100rpm. Faster needs too much force for my hand.

                            12mm and up needs a lever attached to the chuck, though I still hand hold the lever. It gets a bit hairy, knowing when to let go - before it gets wrenched out of my hand.

                            Maybe the OP is finding how nice a well ground new tap is !

                            I prefer to tap in my mill, letting the tap pull the quill down, although I wouldn't do blind holes that way.
                            Richard

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                            • #15
                              I'm with bborr1 on this on at first because I have a small South Bend heavy10 so it is easy to feel the tap thru the tailstock movement.(down to m3x5 no problem) But now with my Leblond Servoshift or my Clausing Metosa (both with very large tailstocks and moving mass) I am glad Toolguy showed us a a cool tool! Thank you Dean
                              www.neufellmachining.com

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