About taps...

Hi Guys!
Ok, I been at it for over 30 years.
But, I noticed a detail I have never properly addressed.
Taps.
I have generally... used hand-taps from day one.
I kind'a preferred the 2 flute plug tap.. they seemed to do well.
But then there is spiral, and again spiral..
I usually tap dead holes, so tapers are mostly not in the picture.
So... a lot of these taps I have qualify as spiral. I mean with a bit of a negative grind at the tip.
But, I watched this video from NYC CNC and he used the taps that were spiral.. I mean they look like a cork-screw... complete helical relief grind.
So I had one in 1/2-13 and ran it... was amazed.
It pulled the chip out of the top of the hole.
Now, honestly, I am in favor of form taps these days.
But, I'd like to hear your thoughts on tap selection for production CNC operations.
Again... my many thanks!!!
Mark

Hi Mark,

My 2 cents.

Blind holes - form taps are great. That spiral flute tap you spoke of works great in blind holes as you noticed, but in production I find that unless you have a powerful coolant stream going on them, they don't always release the chip. Meaning I would have a hard time walking away from the machine if it was going to tap a dozen or two holes or more.

Through holes I'll stick with spiral point. 2 flute on the smaller diameters, and never more than three. I also like the DIN length ANSI shank taps. I find the extra length comes in handy.

I wouldn't consider anything under three flute a hand tap. Two flutes are not that easy to get started straight. You know what does work great for hand tapping, is the spiral flute taps we've been talking about. They start real easy and are easy to get straight. Plus they tend to cut easy.

Holes where you want usable thread all the way to the bottom I'l go thread milling. Plus a large diameters when there are only a few or limited torque to drive a big tap.

Dave

snowshooze said:

Hi Guys!
Ok, I been at it for over 30 years.
But, I noticed a detail I have never properly addressed.
Taps.
I have generally... used hand-taps from day one.
I kind'a preferred the 2 flute plug tap.. they seemed to do well.
But then there is spiral, and again spiral..
I usually tap dead holes, so tapers are mostly not in the picture.
So... a lot of these taps I have qualify as spiral. I mean with a bit of a negative grind at the tip.
But, I watched this video from NYC CNC and he used the taps that were spiral.. I mean they look like a cork-screw... complete helical relief grind.
So I had one in 1/2-13 and ran it... was amazed.
It pulled the chip out of the top of the hole.
Now, honestly, I am in favor of form taps these days.
But, I'd like to hear your thoughts on tap selection for production CNC operations.
Again... my many thanks!!!
Mark

Click to expand...

Ugh why would you watch that hack...

I like spiral taps but find they can be a bit easier to break.

The ones with "a bit of a negative grind" are spiral point taps, often called gun taps.

The ones with spiral flutes are, surprise, spiral flute taps.

Spiral point taps are great for through holes. They shoot a continuous chip out the bottom of the hole. I will even use them by hand on some blind holes.

Spiral flute taps, as you found, do a good job of clearing the chip at the top of the hole. Like plastikdreams, I find them a bit fragile, especially in smaller sizes.

plastikdreams said:

Ugh why would you watch that hack...

I like spiral taps but find they can be a bit easier to break.

Click to expand...

.....and wilton don't make extraction fingers to fit them....

digger doug said:

.....and wilton don't make extraction fingers to fit them....

Click to expand...

Don’t fit form taps either

Spiral points push the chip ahead, spiral flutes pull the chips out, form taps form the threads through pure force of will.

Been doing a lot tapping and I learned one thing. There is no rule. Had tap that break in first hole and had tap that did 100+ holes before break. Now i tap on machine but only small depth and finish it by hands. Spiral flutes ofc. And just few days ago we bought machine for tapping which seems great so far

Spiral flute taps are great.....until you need to tap a deep hole on the cnc.

No CNC experience here but I like form taps wherever I can use them, spiral flute taps for aluminum and spiral point taps for everything else. If they never made another "hand tap" or 3-flute tap, I'd never notice.

I've tapped like a quarter million holes in the VMC in the last 2.5 years. Thru, blind, tiny, big-ish. I use form taps as a starting point for everything up to ~3/8". 95% of those 1/4M holes were done with form taps. Sometimes, I cannot get a form tap to behave. Sometimes it's hard to get the hole size just right, so that the minor comes out right. Sometimes even when the hole size is right, the minor is too small (material didn't flow as intended and left ragged crests). Then I go to a cut tap.

Spiral point are generally great if it's a thru hole, IF you have sufficient daylight under the hole as spiral point taps have a pretty long lead-in and need a lot of breakthrough.

Spiral flute are great for shallow blind holes, but deeper blind holes can be trouble if the swarf packs up in the flutes. The spiral flute tap only does its nice swarf extraction trick if the swarf stays in one piece. If it breaks mid-cycle, the next piece can jam into the previous piece and then you have a mess. I have peck-tapped with spiral flute and that works fine. I will try to program a generous retract so the coolant blast has more time to knock the swarf off the tap before it goes back in.

Regards.

Mike

Wow guys...
Awesome.
But, my observation is..
There ain't a clear answer.
I can accept that.
Thanks for all the in-put!
Mark