Power taping with drill press

[Kev In]

I was using a Tapmatic 50X in my drill press, but it’s not accurate enough for the 1/2” x 13 threads in the 3/8” and 1/2” steel I am tapping. I need the tap to be perfectly perpendicular or as close as possible.

As I have forward and reverse on my drill press I started to power tap. I was using gun taps, but I am now using OSG spiral fluted taps in the chuck. However, the taps spin in the chuck no matter how hard I tighten the chuck.

My drill press is:
22” with 3/4 chuck
#4 morse taper
Table has been milled flat and leveled with a dial indicator
Heinrich grip master vice
runout is .001

I need a simple solution to hold my tap in the drill press without it spinning.

Maybe a #4 MT to a tension/compression tap holder or collet? I also want the ability to release and drop the tap quickly vs. reversing as these are thru holes and the spiral flute taps are pretty short.

I am looking for some guidance and suggestions on how I can power tap with accuracy and without taps spinning in a chuck.

Appreciate the help.

Kevin

 

[Bigblue&Goldie]

A good drill chuck should work. Are you using actual tapping fluid? What RPM?

 

[Kev In]

I admit my chuck is not top quality. Upgrading the chuck is an option if I knew it would work.

Using tapmatic fluid and 180 rpm.

 

[cuog]

https://www.mscdirect.com/product/details/03734803

For rigid tapping I prefer these, they hold the squares on the tap so if its spinning, you broke it.

Just hunt down the right size for your tap, they don't like to label these in a particularly straight forward manner

 

[Cahark]

Try a plug or gun tap. That’s my first choice with a thru hole. Those bottoming OSG taps are great, but a plug or gun will have a more gradual taper, and will require less torque to tap the hole. Don’t forget cutting oil.

Truthfully Your chuck should have enough torque to hold the tap, but If all else fails and you only have spiral taps, you could grind three flats on the tap for better grip.


Sent from my iPhone using Tapatalk

 

[MattT]

Ditching the spiral flute bottoming tap and going back to a spiral point plug tap is the obvious first step. Spiral flute bottoming taps ain't something you want to use unless you absolutely have to.

Are you certain your spindle is perfectly aligned with the hole you're trying to tap? The chuck slipping and the inaccuracy you experienced with the tapmatic could both be caused by misalignment.

Going to a larger tap drill will get the torque down if the finished holes strength requirements allow it.

And a bandaid that'll often help on worn/**** chucks is tighten using all three key holes sequentially.

 

[dr_clyde]

I routinely power tap with a Jacobs ball bearing super chuck. Use a spiral point tap for through holes and a good cutting oil. I use Union Butterfield tapping fluid. Love it.

If the jaws are shot in your current chuck they won't grip as well. They may need to be replaced.

Not to mention the ball bearing design on a Super Chuck really allows you to get some grip on a tap.

 

[LXCam]

I'd suggest a set of lisle tap sockets and then a hex to square drive adapter. That's the set up I use in both my lathe and my mill for the smaller sizes.

Hopefully this link works:

http://www.lislecorp.com/divisions/products/?product=402

https://www.cpooutlets.com/lisle-70...Mz9OtAYTJAHXpmR25C9cN_22RDItaWRBoCOE8QAvD_BwE

 

[BillK]

I need a simple solution to hold my tap in the drill press without it spinning.

Kevin

Probably just need a better chuck unless your taps are totally worn out. I tap 7/16 holes pretty regularly in my seat and guide machine which is just a glorified gear driven drill press. I use a regular (not keyless) chuck and never have a problem. I actually don't tighten it up too tight, that way it slips before something breaks.

If you still have problems you might want to try an interrupted cut tap. They seem to handle hard material and heavy cuts better than a "normal" tap.

Proper lube is also important. I have been using CRC tapping and threading lub. Its a foam and comes in a spray can.

 

[BillK]

180 rpm might be a bit much too ? I use 74 rpm.

 

[Bigblue&Goldie]

180 rpm might be a bit much too ? I use 74 rpm.

I agree. I've only ever power tapped slower than that on manual machines.

 

[Kev In]

The slowest I can tap right now is 180 rpm. I would need to change a pulley or three or put in a 3 phase motor with a VFD which is a bit expensive for my immediate needs.

I have ordered a new Jacobs 16N 5/8” ball bearing chuck and a new arbor. Hopefully this upgrade will solve my tapping issue.

 

[matt_i]

If you take the tap and hold it in something like a Suburban Tool Master Grind and then place 3 flats on the shank at 120 degrees apart with a surface grinder then it will not slip. But you can crash it...and, you can also slip the Jacobs Taper at the chuck if its not well-assembled.

I usually power tap in the Bridgeport by just switching to back gear around 60rpm (from the 500rpm it usually runs at in open belt)

Asking the machine to tap a 1/2-13 is pretty ambitious, try one by hand with a spring loaded center point held in the spindle (workpiece clamped) and I think you'll see how difficult this is.

The tap holder linked above is also a good solution. Alternatively you could utilitze a tap-socket (like a 3/8" square drive that has an opposing square to drive the tap shank) and chuck on that OD (it should be soft enough so the chuck jaws can grip it). Although its not guaranteed to back out the tap without disengaging the drive. You might be able to fit something like an O-ring to the ID by some careful ID grooving as it also pilots on the straight shank of the tap as well for guidance.

 

[zkling]

https://www.mscdirect.com/product/details/03734803

For rigid tapping I prefer these, they hold the squares on the tap so if its spinning, you broke it.

Just hunt down the right size for your tap, they don't like to label these in a particularly straight forward manner

This is the way to do it, a true tap driver. Or get a MT4 tapping chuck. Even a ER holder and ER tap collet set.