JCIrish
Plastic
- Joined
- Apr 25, 2010
- Location
- Michigan, USA
In need of some guidance with selecting a drill that will be the best fit for my setup:
-manual lathe (SB9 w/ 1hp and VFD), "flood" coolant from a squeeze bottle, soluble oil
-drilling through holes in 1" stock that will then be bored to just under 3/4"
I have a few questions, the more I learn about this the better as I have a fair amount of drilling in Ti to do. So far, I've had success with PTD cobalt 135 split drills, running at about 30sfm, with lots and lots of pecking. The cobalt holds up pretty well, but sometimes starts to bind in the hole after a couple inches. I have the tailstock aligned within 0.001 side-to-side and it's within 0.001 vertically (can't be sure whether it's indicator droop or actual runout), and putting some clamping pressure on the tailstock ram seems to help with alignment and reduce the rubbing of the bit in the hole. The last job I switched to a PTD HSS split point since some folks mentioned a thinner web might decrease pressure, and it did seem to be easier to push, but after about 2.5" the outside edges of the lips started to break down. This was with a 1/2" bit, the cobalt was 3/8".
So I guess I better get to my questions:
What size/type drill has worked well for you drilling 6al4v in a lathe this size? I know carbide in both solid and inserts is popular for CNC, but I don't want to risk chipping an expensive bit. I would go with an insert drill, but from what I've read it may be better to go with a good Guhring or OSG in HSS, maybe with a coating?
Should I be able to push a larger drill (say 5/8") to leave less for boring, and if so do I drill progressively or all in one shot?
I've read about grinding a back taper on the drill to minimize rubbing the walls, but I'm not in a hurry to go grinding on an expensive drill, unless it's a good idea.
Do coatings matter to me?
Any suggestions as to drill material, insert vs. solid, point, parabolic, toolholding, speeds, feeds, coolant, anything I can do to try to improve on wearing out HSS in under 3", or having to buy a 5 pack of drillbits to get through 12" of stock. I'm working on my freehand sharpening technique, but if I can buy a Guhring or OSG ex-gold and get a lot more life out of it before sharpening, I'd like to go that route. If a spade or insert drill is better, fine, although other posts seem to point more toward solid drills.
Well, I guess I just wrote a novel, but I'm hoping someone wiser than me has been down this road before on a smaller manual lathe and can point me in the right direction. Turning, boring, even threading and parting are actually fun with 6al4v, but nearly every Ti part I make has a hole through it and the drilling is slowing me down and eating my drillbits.
-manual lathe (SB9 w/ 1hp and VFD), "flood" coolant from a squeeze bottle, soluble oil
-drilling through holes in 1" stock that will then be bored to just under 3/4"
I have a few questions, the more I learn about this the better as I have a fair amount of drilling in Ti to do. So far, I've had success with PTD cobalt 135 split drills, running at about 30sfm, with lots and lots of pecking. The cobalt holds up pretty well, but sometimes starts to bind in the hole after a couple inches. I have the tailstock aligned within 0.001 side-to-side and it's within 0.001 vertically (can't be sure whether it's indicator droop or actual runout), and putting some clamping pressure on the tailstock ram seems to help with alignment and reduce the rubbing of the bit in the hole. The last job I switched to a PTD HSS split point since some folks mentioned a thinner web might decrease pressure, and it did seem to be easier to push, but after about 2.5" the outside edges of the lips started to break down. This was with a 1/2" bit, the cobalt was 3/8".
So I guess I better get to my questions:
What size/type drill has worked well for you drilling 6al4v in a lathe this size? I know carbide in both solid and inserts is popular for CNC, but I don't want to risk chipping an expensive bit. I would go with an insert drill, but from what I've read it may be better to go with a good Guhring or OSG in HSS, maybe with a coating?
Should I be able to push a larger drill (say 5/8") to leave less for boring, and if so do I drill progressively or all in one shot?
I've read about grinding a back taper on the drill to minimize rubbing the walls, but I'm not in a hurry to go grinding on an expensive drill, unless it's a good idea.
Do coatings matter to me?
Any suggestions as to drill material, insert vs. solid, point, parabolic, toolholding, speeds, feeds, coolant, anything I can do to try to improve on wearing out HSS in under 3", or having to buy a 5 pack of drillbits to get through 12" of stock. I'm working on my freehand sharpening technique, but if I can buy a Guhring or OSG ex-gold and get a lot more life out of it before sharpening, I'd like to go that route. If a spade or insert drill is better, fine, although other posts seem to point more toward solid drills.
Well, I guess I just wrote a novel, but I'm hoping someone wiser than me has been down this road before on a smaller manual lathe and can point me in the right direction. Turning, boring, even threading and parting are actually fun with 6al4v, but nearly every Ti part I make has a hole through it and the drilling is slowing me down and eating my drillbits.