Commodus
Aluminum
- Joined
- Oct 22, 2007
- Location
- Vancouver BC, Canada
Hi all, I have a hard time parting things off accurately and just generally well on the lathe.
I use an carbide insert-style parting tool, angled (slightly, maybe 5 degrees or less) so as to leave the burr on the stock and not the part. With 4140, I have the most success running at about 600rpm (with around 1"-2" diameter parts),and just feeding it in by hand, fairly forcefully. I've played with tool height a little, finding it works best if I'm a little below centre. The part (I'm talking fairly small parts here, usually less than a half inch long) heats up quite a bit, such that it will sizzle coolant sprayed onto it, so I flood the cut with coolant, thinking that perhaps it prevents possible binding of the tool in the cut?
Still, the whole thing seems a bit more 'dramatic' than I would like - the process seems very sensitive to feed rate and likes to squeal and chatter unless like I say, I'm quite forceful with the feed.
Also I have difficulty doing it accurately. I usually just touch on the face and zero my dial, then move in my desired distance, plus the width of the tool, of course. I can achieve accuracy within about .008 either way easily enough, but anything past that is a bit of a crap shoot and I'm not sure why? I guess maybe it's because I don't get a very positive touch on the face - the tool flexes a lot from side to side. Clearly that's not enough accuracy, half that variation would be too much!
I'm wondering if anyone has any tips for me...I was thinking tonight that maybe I could put some masking tape on the face of the part and move in until I tear that, and use that minus a few thou for my zero. But I can't try that until this bloody long weekend is over so I'm in suspense until Thursday, heh.
Thanks in advance!
Commodus.
I use an carbide insert-style parting tool, angled (slightly, maybe 5 degrees or less) so as to leave the burr on the stock and not the part. With 4140, I have the most success running at about 600rpm (with around 1"-2" diameter parts),and just feeding it in by hand, fairly forcefully. I've played with tool height a little, finding it works best if I'm a little below centre. The part (I'm talking fairly small parts here, usually less than a half inch long) heats up quite a bit, such that it will sizzle coolant sprayed onto it, so I flood the cut with coolant, thinking that perhaps it prevents possible binding of the tool in the cut?
Still, the whole thing seems a bit more 'dramatic' than I would like - the process seems very sensitive to feed rate and likes to squeal and chatter unless like I say, I'm quite forceful with the feed.
Also I have difficulty doing it accurately. I usually just touch on the face and zero my dial, then move in my desired distance, plus the width of the tool, of course. I can achieve accuracy within about .008 either way easily enough, but anything past that is a bit of a crap shoot and I'm not sure why? I guess maybe it's because I don't get a very positive touch on the face - the tool flexes a lot from side to side. Clearly that's not enough accuracy, half that variation would be too much!
I'm wondering if anyone has any tips for me...I was thinking tonight that maybe I could put some masking tape on the face of the part and move in until I tear that, and use that minus a few thou for my zero. But I can't try that until this bloody long weekend is over so I'm in suspense until Thursday, heh.
Thanks in advance!
Commodus.