Have I ever told you I hate parting tools?

Have broken a couple of those myself. Went back to a hss cutter and haven’t broken a cutter since…
 
I made a brief foray into carbide insert parting. It didn't go too well, so I went back to HSS. While I still occasionally have a few problems they aren't as costly regrinding a HSS tool is cheaper than replacing an insert or worse $$, the holder.
For cutting through tubing or pipe, I find using a left or right ground tool works better than a flat front. As Dabbler mentioned, if the tool brakes through a thin wall section of the tube, it will catch on the thicker portion and cause problems. However, if the front edge of tool is skewed to one side, only the point will break through and the tool will still be supported by the rest of the cutting edge, helping to prevent it from springing forward.
HSS allows easy regrinding of the tool to suit the cut and and is much less likely to break. I believe the inserts are better suited for CNC, but as the OP is showing, it appears they can be a PITA on those machines as well.
 
I really like what you are suggesting, it makes sense and I am going to use your method of dressing the tool. After my 1st. reply I found my collection of cutoffs that I got when the shop I worked for was bought out. I was able to take whatever I wanted in tooling and these were something I took. Nice stuff, Armstrong, Williams, Empire tool and assorted jobber blades, all tapered. Although hard to make out, the one the magnet is holding is cut like you menti359C8125-28EC-4DD4-815D-59210F691DD5.jpegoned and is angled as you said.B872C1C5-76A0-4EA5-887C-F5FAB3DC8954.jpeg
 
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I use only HSS parting tools, I always grind them with about a 10 degree angle on the cutting edge, use lots of cutting oil and slow spindle speed and try to keep the feed rate to maintain a continuous chip. I have very little problem with breaking tools. It seems that most of the "real machinists" use power feed for parting. I still haven't had the courage to do that. I would like to put a rear tool post on the cross slide just for parting, but that project never seems to make it to the top of the list. Maybe some day.

Ted
 
I have broken every HSS parting tool I've tried. changed to an insert type, and its been smooth sailing ever since. Couldn't say why, but maybe carbide is more "me" proof. :laughing:
 
I've never successfully modified a parting tool like you did, but I generally have little problem with parting any more. I found that parting under crossfeed power was best, and a continuous lubrication to keep chips from wedging the cutter to the side or jamming it. A jammed parting tool will give you that result you had.
If you have a CNC you could program it to stop the cut, back up a bit and let the chips be flushed, and then resume the cut. I suspect your cut of .001 is too light to produce a continuous chip that curls and then breaks, so the small chips jam easier.
 
Back many moons ago when I was attempting to learn the trade I was taught that parting on a manual lathe was considered a "quarter speed operation". Meaning that at whatever the speed the material was initially turned at the parting speed should be one quarter that speed. As an example, if you were turning a part at 1000 rpm the parting speed should be 250 rpm with plenty of cutting oil.

As for tooling I don't use the insert style. I prefer the T profile (P type) HSS, or carbide tipped parting tools. My go to brand is Empire. I'm not sure why, probably because i started with them and have always had good luck using them. I used to be able to purchase the double ended carbide tipped models for around $40.00 from name brand vendors. They're now in the $80.00 range so it pays to be careful.

It would be interesting to know if any of the professionals on the board were given the same training as to "quarter speed operations" or whether it was something specific to the training program of past German generations.
 
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