gregormarwick
Diamond
- Joined
- Feb 7, 2007
- Location
- Aberdeen, UK
I've always shied away from buying premium carbide deep hole drills, mainly due to the cost involved and anxiety about just breaking it in the first hole etc.
We machine a lot of 17-4 and suchlike, I've always tended towards simple cobalt drills for deep (16xD, 20xD) holes because it's tried and trusted, if slow.
Since we got our first machine with 1000psi coolant I've gotten a bit bolder about such things, and my confidence has been boosted by some successes with gun drills, which are also a fairly new thing to me.
I have a job in, 17-4PH H900, the parts have a 10mm hole 180mm deep. I decided to take the chance and buy a couple of these from WNT.
Followed the instructions to the letter, drill a start hole .02mm bigger than nominal, enter the hole at 200rpm and 1000mm/min, stop 2mm away from the bottom of the pilot hole, turn on the coolant and ramp up the spindle speed, then go. Instructions said TIR at drill tip not to exceed 0.015mm, couldn't quite get there (have to hold it in an ER25 for clearance reasons), but settled at 0.025.
Man, what a painless experience! 45 seconds per hole including slowing down for a cross hole and controlled retract. So easy. I wish I hadn't been so apprehensive about these drills! The cost was soon forgotten when I saw how much time it saved.
We machine a lot of 17-4 and suchlike, I've always tended towards simple cobalt drills for deep (16xD, 20xD) holes because it's tried and trusted, if slow.
Since we got our first machine with 1000psi coolant I've gotten a bit bolder about such things, and my confidence has been boosted by some successes with gun drills, which are also a fairly new thing to me.
I have a job in, 17-4PH H900, the parts have a 10mm hole 180mm deep. I decided to take the chance and buy a couple of these from WNT.
Followed the instructions to the letter, drill a start hole .02mm bigger than nominal, enter the hole at 200rpm and 1000mm/min, stop 2mm away from the bottom of the pilot hole, turn on the coolant and ramp up the spindle speed, then go. Instructions said TIR at drill tip not to exceed 0.015mm, couldn't quite get there (have to hold it in an ER25 for clearance reasons), but settled at 0.025.
Man, what a painless experience! 45 seconds per hole including slowing down for a cross hole and controlled retract. So easy. I wish I hadn't been so apprehensive about these drills! The cost was soon forgotten when I saw how much time it saved.
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