03-28-2015, 05:51 PM
I had in the recent past bought off eBay a high performance spiral flute Technical Hard Lube coated Prototyp (brand) Paradur Eco Plus tap, in 3/4-10UNC 2B. It's been sitting there a few weeks, so when Neil texted me to see if we could meet up at my shop, I decided to try the tap in a test piece to see if my 2HP Alliant/Prototrak machine could handle a tap that size under power.
For starters, holding it in the machine was a bit of an issue. It's an ANSI shank measuring .689", so I was able to squeeze it into an 11/16" R8 collet. My goal was to see if it would cut 2xD deep, so 1-1/2" of thread. I grabbed a random piece of 1018 cold rolled steel, 1-1/4" thick and about 3" square. I think it was one of the drops Russ had given me. I drilled 1-5/8" deep with a Ø 1/2" jobber length drill and then followed with a Ø 21/32" (0.656") drill. I believe I ended up with just over 1-1/2" of depth to the hole.
This is a spiral flute tap, meant to funnel chips up and out of the hole. If you've ever tried using the older ANSI style spiral flute taps you'd know they are notorious for breaking deep inside the hole with no way to get it out. Power tapping with a tap of this size takes a LOT of torque, and my Walter "GPS" software showed the tap needing 4.57HP and 58.5 ft-lbs of torque. I didn't run the software and see those numbers until now, sitting at my home computer and running the application.
I've got a 2HP motor with unknown torque. recommended tapping speed was 410 rpm, I put my machine in back gear and set it at 330 rpm.
Wanting to go to the bottom of the hole, I wrapped a piece of black electrical tape around the shank at the 1-1/2" mark. I applied a little ValTap tapping compound to the tap and a little ring of it around the top of the hole. Ignorance is bliss so I figured the machine wouldn't have enough power to break the tap, though it might slip in the collet or stall the machine and chips the cutting tips of the tap.
Much to my surprise and joy, it not only worked but it worked GREAT! I have no video, but here's some photos of the aftermath.
The tap after use, showing no wear and the depth-marking tape still on it:
![[Image: IMG_20150328_124232045_zpsyfo3th9s.jpg]](http://img.photobucket.com/albums/v466/kenm10759/Dads%20shop/IMG_20150328_124232045_zpsyfo3th9s.jpg)
A scale showing the depth of the hole:
![[Image: IMG_20150328_124329669_zpsnunsyenn.jpg]](http://img.photobucket.com/albums/v466/kenm10759/Dads%20shop/IMG_20150328_124329669_zpsnunsyenn.jpg)
The chips that the tap produced, all of which came right out of the top of the hole:
![[Image: IMG_20150328_124816932_zps1az6t1gt.jpg]](http://img.photobucket.com/albums/v466/kenm10759/Dads%20shop/IMG_20150328_124816932_zps1az6t1gt.jpg)
The finished tapped hole:
![[Image: IMG_20150328_124300413_HDR_zpsq5wsuaco.jpg]](http://img.photobucket.com/albums/v466/kenm10759/Dads%20shop/IMG_20150328_124300413_HDR_zpsq5wsuaco.jpg)
The slide rule style tap calculator showed 71% thread using a Ø 21/32" drill, looks like that's what I got and they're beautiful. No problems at all!
For starters, holding it in the machine was a bit of an issue. It's an ANSI shank measuring .689", so I was able to squeeze it into an 11/16" R8 collet. My goal was to see if it would cut 2xD deep, so 1-1/2" of thread. I grabbed a random piece of 1018 cold rolled steel, 1-1/4" thick and about 3" square. I think it was one of the drops Russ had given me. I drilled 1-5/8" deep with a Ø 1/2" jobber length drill and then followed with a Ø 21/32" (0.656") drill. I believe I ended up with just over 1-1/2" of depth to the hole.
This is a spiral flute tap, meant to funnel chips up and out of the hole. If you've ever tried using the older ANSI style spiral flute taps you'd know they are notorious for breaking deep inside the hole with no way to get it out. Power tapping with a tap of this size takes a LOT of torque, and my Walter "GPS" software showed the tap needing 4.57HP and 58.5 ft-lbs of torque. I didn't run the software and see those numbers until now, sitting at my home computer and running the application.
I've got a 2HP motor with unknown torque. recommended tapping speed was 410 rpm, I put my machine in back gear and set it at 330 rpm.
Wanting to go to the bottom of the hole, I wrapped a piece of black electrical tape around the shank at the 1-1/2" mark. I applied a little ValTap tapping compound to the tap and a little ring of it around the top of the hole. Ignorance is bliss so I figured the machine wouldn't have enough power to break the tap, though it might slip in the collet or stall the machine and chips the cutting tips of the tap.
Much to my surprise and joy, it not only worked but it worked GREAT! I have no video, but here's some photos of the aftermath.
The tap after use, showing no wear and the depth-marking tape still on it:
A scale showing the depth of the hole:
The chips that the tap produced, all of which came right out of the top of the hole:
The finished tapped hole:
The slide rule style tap calculator showed 71% thread using a Ø 21/32" drill, looks like that's what I got and they're beautiful. No problems at all!