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| madjackghengis:
Hi Chris, I just wanted to note that it probably is high time you get nice and gushy with cutting off, you have a nice lathe, and you're working with aluminum at the moment, so you've got the basics, you just have to figure out where you get off track, and correct that. A solid tool post is a necessity, a good sharp cut off tool, with proper clearance up front, a bit of top rake, supplied by a applying the blade to a grinding wheel leaving a bit of curve in the top, and taking off the corners of the tool, to prevent them from causing the tool to catch and dig in, challenging the sturdiness of your tool holding, with the edge just enough about center that it pulls down to center under cutting pressure, and you should be there. What a lot of folks do when chatter starts, is back off, when actually increasing pressure usually will stabilize the total flex of the tool, and keeping the depth of cut consistent will keep the blade from springing up, and going into chatter. I stone off my cut off tool before every use to make sure it's as sharp as possible, and with good clearance, and seldom even use my back mounted cutoff tool holder, now that I've got all the variables well understood and accounted for. Not to stick my nose in your business, but I'd like you to be a happy camper, and it's much easier as a machinist, if you can cut off things. I found the rounding of the corners by accident, doing a round nosed cut off tool for a radiused bottom on cylinder fins, and was told by my thirty years senior machinist friend rounding the corners was probably the biggest issue for cut off tools, as they are the main reason for the tool diving into the metal with enthusiam. I now hate to take a piece out of a chuck to put it on a bandsaw or power hacksaw and now avoid it at all costs. Call me what you want, but get happy, and enjoy that lathe to its fullest, I know I dreaded cutting off for years and years. :poke: :headbang: mad jack |
| raynerd:
Yea, it is 100% my technique. I`ve spent £45 on a RDG parting off tool and couldn`t use it. Blaming the tool I spent another £25 on a parting off tool at the recent midlands show. Same problems, chatter and literally no cutting! Tried to apply more pressure and the tool end dug in and snapped. I know, I do need to sort it out. I`ve had mixed results. Sometimes it works OK, like parting off the cylinder top and bottom on my little stuart, but other times its a no go.... ....talking of the Stuart :poke: I best get back onto it!! :bang: :bang: :bang: Just one more puzzle :doh: |
| kwackers:
You've broken the one you bought at the Midlands Exhibition? :doh: What I do to part off is engage the power cross feed and wait for the part to drop off whilst supping my tea. :med: |
| AdeV:
--- Quote from: craynerd on November 18, 2010, 11:43:40 AM ---Yea, it is 100% my technique. I`ve spent £45 on a RDG parting off tool and couldn`t use it. Blaming the tool I spent another £25 on a parting off tool at the recent midlands show. Same problems, chatter and literally no cutting! Tried to apply more pressure and the tool end dug in and snapped. --- End quote --- Does the tool definitely have a cutting edge ground into it? I have a parting off blade here (reminds me, I must make up a toolholder for it...) which was blunt as a chopstick when I first looked at it. I ground some relief on the front & top, but then I went all QCTP & haven't touched it since... |
| Stilldrillin:
--- Quote from: craynerd on November 18, 2010, 11:43:40 AM ---Yea, it is 100% my technique. I`ve spent £45 on a RDG parting off tool and couldn`t use it. Blaming the tool I spent another £25 on a parting off tool at the recent midlands show. Same problems, chatter and literally no cutting! Tried to apply more pressure and the tool end dug in and snapped. I know, I do need to sort it out. I`ve had mixed results. Sometimes it works OK, like parting off the cylinder top and bottom on my little stuart, but other times its a no go.... --- End quote --- Chris. Have you got too much overhang/ flexing? http://madmodder.net/index.php?topic=2759.0 David D |
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