cosmos_275
Hot Rolled
- Joined
- Jun 9, 2015
Part I'm trying to make: 1" OD 6061, sticking out about 4" from the collet. Drilled hole 12.0mm first. I have a 1/2 boring bar and I need to open it up to 18.0mm. Depth is almost 60mm. Boring bar is carbide and thru coolant using a CCMT-21.51 (Object moved). I previously tried this with a non-thru boring bar and I almost buried the thing. I have little experience on the lathe , so hoping someone will share some pointers.
My thoughts were 2 passes, one at 15mm and a second at 18mm. I figured the thru bit would get the chips out well... kinda. After a few parts run successfully, the thing got pretty jammed up deep on the first 15mm hole. I was able to scrape the crap off and change the insert. I was going full depth at the first diameter with 3 "pecks", then full depth at the second with 2 "pecks". Minimum hole diameter for the boring bar is 14.5mm, so really not much clearance at that first diameter.
After that, I thought to go more multiple depths (15, 30, 40, 50, 56) and do the larger diameter before going to the next depth on the smaller diameter. This seems to work better, but its still not inspiring confidence. I found a couple really long chips, so I'm thinking I should insert pauses to effectively peck. Previously, the "pecks" were a full retract out of the hole. My SFM is not very high (RPM 1500 or so), but I figured to do that because of the big stick out. I wonder I'm not approaching this right at all, but I don't know.
Should I be just going for one shot on the diameter (3mm radial chip) or should I be doing more lighter passes? The insert seems pretty tiny. Is pecking ok to do when boring or what's a better method to get the chips from getting too big?
Thanks
My thoughts were 2 passes, one at 15mm and a second at 18mm. I figured the thru bit would get the chips out well... kinda. After a few parts run successfully, the thing got pretty jammed up deep on the first 15mm hole. I was able to scrape the crap off and change the insert. I was going full depth at the first diameter with 3 "pecks", then full depth at the second with 2 "pecks". Minimum hole diameter for the boring bar is 14.5mm, so really not much clearance at that first diameter.
After that, I thought to go more multiple depths (15, 30, 40, 50, 56) and do the larger diameter before going to the next depth on the smaller diameter. This seems to work better, but its still not inspiring confidence. I found a couple really long chips, so I'm thinking I should insert pauses to effectively peck. Previously, the "pecks" were a full retract out of the hole. My SFM is not very high (RPM 1500 or so), but I figured to do that because of the big stick out. I wonder I'm not approaching this right at all, but I don't know.
Should I be just going for one shot on the diameter (3mm radial chip) or should I be doing more lighter passes? The insert seems pretty tiny. Is pecking ok to do when boring or what's a better method to get the chips from getting too big?
Thanks
I cannot drill it up. I was doing that before, but swapped it out of the turret for the 1/2 boring bar which I need for other features, so I'm kinda stuck with the boring bar. Any suggestions considering no drill?
