Parting Difficulty

[Round in circles]

Part it off with a band saw then face it in a 2nd op.

I'd use one of the parting tools that have a wider top edge of the cutting blade than the bottom edge . Have the blade as wide as the tool post /holder will accept .

Like " coolidige " says .. once you have made a couple parting cuts overlapping side by side to keep the width of the parting clear of swarf , once you have gone in a few mm with the wide cut say 8 or so mm then take the part out the lathe and cut it with a band or put some gloves on & hack saw off whilst it is in a stationary lathe , reset it back up and face the end

I have an indexable parting tool where the cutter ( 3 mm.5 at the top edge and 2.5 mm at the bottom) has blade width is about 5/8 of an inch which can be slide forward to or back from the work .. anything that sticks out the tool holder more than 3/4 " causes no end of harmonic vibrations & chattering to get going.

One thing that does not seem to have been mentioned is that it's a very good idea to lock the saddle to the bed , for this is one place that folk don't often associate with parting chatter and breaking of parting tools as the unclamped saddle slips & slides around .

 

[coolidge]

Part it off with a band saw then face it in a 2nd op.

And by that I mean take it over to the band saw don't try sawing it on the lathe.

 

[eeler1]

One thing that does not seem to have been mentioned is that it's a very good idea to lock the saddle to the bed , for this is one place that folk don't often associate with parting chatter and breaking of parting tools as the unclamped saddle slips & slides around .

Most excellent point!

 

[JAB]

I never lock down the saddle and never have a problem. I suspect the gib should be tightened on the saddle. Doming, either left or right, is usually because of a dull, bent, incorrect sharping, or most often the blade is not set to true perpendicular to the turning axis.

 

[eeler1]

I never lock down the saddle and never have a problem. I suspect the gib should be tightened on the saddle. Doming, either left or right, is usually because of a dull, bent, incorrect sharping, or most often the blade is not set to true perpendicular to the turning axis.

Cool! Good for you. But it's good practice for the rest of us to lock down the carriage when parting. The OP needs help with good practice, and that one thing that might just be the ticket for him.

Agree with the rest, good points.

 

[samthedog]

Part it off with a band saw then face it in a 2nd op.

This is what I do. Unless I am working on a tube that I need to part off, I don't even bother with a parting blade anymore. The bandsaw is faster and wastes less material. It also means I don't need to worry about using a follower rest. Plenty of ways to skin that cat if you have the toys.