Tapping bottoming hole in 4140HT, prefilled hole with Tap Magic EP-Extra

Experimented with various brand/style taps. This WALTER/PROTOTYP 7606556 TIN coated tap is absolutely the best. Previous best (OSG) lasted about 100pcs before breaking. This new tap has done 200 so far but still looks brand new under microscope. Edit; have done 800pcs on this same tap now and still looks new. Edit Edit; we did 4000pcs and only used 4 taps, so they lasted for about 1000pcs each.

[@Cheezeball99999]

Huh. Can't say I've ever seen the chip come out so readily or so straight. That's cool.

[@hotsledder1]

Agree and is why I decided to show it. With 4000 pcs to tap on this job, I didn't want to be picking chips out of the bottom of the holes from a spiral point tap. This spiral flute tap is absolutely amazing & very free cutting.