-
Welcome back Guest! Did you know you can mentor other members here at H-M? If not, please check out our Relaunch of Hobby Machinist Mentoring Program!
Do you have some hints for parting off?
- Thread starter HMF
- Start date
You guys make this seem so easy. Scares the daylights out of me on my Craftsman 12x36.
I get chatter, broken blades, climbing part over the blade & a major adrenalin rush when I hear the lathe go "SNAP/BANG". I've broken a couple of gears on the reverse tumbler, the last one was in the apron. I've tried slow speeds in back gear, slow speeds in direct drive, faster speeds in back gear & fast speeds with aluminum parts. With/without cutting oil, lubricating oil, on center, below center & above center. It usually takes me a long time to part off a part, because the tool grabs the part & I have to back out then "start over". Not fun.
I HATE parting on the lathe. I generally use the band saw & then face both sides. It works best for me, probably because I'm afraid I'll break my lathe once again.
I get chatter, broken blades, climbing part over the blade & a major adrenalin rush when I hear the lathe go "SNAP/BANG". I've broken a couple of gears on the reverse tumbler, the last one was in the apron. I've tried slow speeds in back gear, slow speeds in direct drive, faster speeds in back gear & fast speeds with aluminum parts. With/without cutting oil, lubricating oil, on center, below center & above center. It usually takes me a long time to part off a part, because the tool grabs the part & I have to back out then "start over". Not fun.
I HATE parting on the lathe. I generally use the band saw & then face both sides. It works best for me, probably because I'm afraid I'll break my lathe once again.
Last edited by a moderator:
- Joined
- Jan 22, 2011
- Messages
- 8,031
Mark, can you take a couple of pictures of your typical part off setup? Perhaps we can offer some suggestions. There shouldn't be any reason that you can't do it. Yes, it is a nerve wracking experience at first, until you do it successfully a couple of times.
I have a Craftsman 12x36 lathe, with a QCTP on it. I use the QCTP for parting, along with other tools to do the work. Most of my bits are carbide, except for threading & parting.
The biggest problem with parting is it cuts fine to begin with, then it starts to chatter big time. I usually part by hand after a boring operation. If I have to cut a longer piece, I use the band saw then do a double face cut to make it square.
When the tool starts to chatter, I increase the feed a little bit, as it seems to get worse if I lighten the cut. I've also discovered there is a fine line between too deep a cut & stalling the machine. Most times it takes several cuts to completely part off the piece, as it will grab & leave a huge chip in the groove. I also know this machine isn't quite stiff enough to do much parting as I can see the tool post/compound flex under a heavy load.
I'll see if I can add some pictures here, these are old ones I took as I was learning the process.
The biggest problem with parting is it cuts fine to begin with, then it starts to chatter big time. I usually part by hand after a boring operation. If I have to cut a longer piece, I use the band saw then do a double face cut to make it square.
When the tool starts to chatter, I increase the feed a little bit, as it seems to get worse if I lighten the cut. I've also discovered there is a fine line between too deep a cut & stalling the machine. Most times it takes several cuts to completely part off the piece, as it will grab & leave a huge chip in the groove. I also know this machine isn't quite stiff enough to do much parting as I can see the tool post/compound flex under a heavy load.
I'll see if I can add some pictures here, these are old ones I took as I was learning the process.
Last edited by a moderator:
The short blade seems to work better. I had the bar grab the tool once & it chipped out the inside of the blade, which caused the blade to tilt, causing all sorts of problems. The dates you see in the pictures, I had the lathe approximately 2 months, so the learning curve was rather steep.
Parting is an operation I understand, have done it, but it still scares the crap outta me! I've broken gears, tools, ruined work pieces & other things doing this. So, my trusty Clark 4x6" bandsaw gets a pretty good work out. ;D
Parting is an operation I understand, have done it, but it still scares the crap outta me! I've broken gears, tools, ruined work pieces & other things doing this. So, my trusty Clark 4x6" bandsaw gets a pretty good work out. ;D
Last edited by a moderator:
MarkBall2 link=topic=1756.msg11773#msg11773 date=1303654891 said:
Or 10-15-20-thousand in shift.
3 seconds is a long job for a Davenport. They're usually a second to a second and a half. If the parts weren't coming off too hot to touch you were running the job too slow.
The cut-off tool is usually mounted upside down to clear chips.
Since the cutoff tools are usually circular the actual cutting part is only as long as it needs to be to cut off the part. Anything longer is wasted cam space.
The width of the cut off tool is only as wide as it has to be to prevent flexing. The deeper the cut the wider the tool.
Ct-off feed was 1/2 to twice the feed for forming.
As long as ther was coolant flooding-and I mean floodin- the tool and the chips were clearing well it was not uncommon not to have to sharpen the tooling for a couple of shifts.
Last edited by a moderator: