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Thread: Inserted Carbide Parting-off Tool

  1. #1
    Join Date
    Mar 2008
    Location
    Barrie, Ontario, Canada
    Posts
    5,234

    Default Inserted Carbide Parting-off Tool

    So--I have to ask---I have read a lot of various reports about carbide inserted parting off tools. I have only ever used HSS parting off tooling, and it scares me right to death every time I use it. I know the correct set up, speeds and feeds, exact center height, lock the saddle, use lots of cutting fluid to flush out chips, keep the tool at exactly 90 degrees to the central axis blah, blah, blah. I know how to sharpen my tools and the correct relief angles required.--And even so, about one time out of five the blade digs in, the lathe gives a mighty groan, and either the belt slips, the tool breaks, it pulls the piece out of the chuck, or I manage to slap the e-stop button and then go and change my shorts!!!!--I do NOT want to mount an upside down -run my lathe in reverse-mount my parting off tool on the wrong side of the saddle cut off solution. I want to know from people who really have and use inserted carbide parting off tooling.--Is it really better? My 10" x 18" lathe has speeds ranging from a low of 115 RPM (which I generally use for parting off) to a high of 1620 RPM in about 6 available "stages", and it doesn't lack for power. I do not have flood coolant. I do not have power feed on the cross slide. If the inserted carbide parting off tooling is really that much better, I might just be able to afford the seemingly outrageous price they want for one. I find that for 95% of the parting off and grooving I do, that .093" (3/32") seems to be about right. The largest stock I would ever part off is probably 2" diameter steel.--Opinions, please.---Brian

  2. #2
    Join Date
    Feb 2010
    Location
    Spokane
    Posts
    1,147

    Default

    Quote Originally Posted by brian Rupnow View Post
    So--I have to ask---I have read a lot of various reports about carbide inserted parting off tools. I have only ever used HSS parting off tooling, and it scares me right to death every time I use it. I know the correct set up, speeds and feeds, exact center height, lock the saddle, use lots of cutting fluid to flush out chips, keep the tool at exactly 90 degrees to the central axis blah, blah, blah. I know how to sharpen my tools and the correct relief angles required.--And even so, about one time out of five the blade digs in, the lathe gives a mighty groan, and either the belt slips, the tool breaks, it pulls the piece out of the chuck, or I manage to slap the e-stop button and then go and change my shorts!!!!--I do NOT want to mount an upside down -run my lathe in reverse-mount my parting off tool on the wrong side of the saddle cut off solution. I want to know from people who really have and use inserted carbide parting off tooling.--Is it really better? My 10" x 18" lathe has speeds ranging from a low of 115 RPM (which I generally use for parting off) to a high of 1620 RPM in about 6 available "stages", and it doesn't lack for power. I do not have flood coolant. I do not have power feed on the cross slide. If the inserted carbide parting off tooling is really that much better, I might just be able to afford the seemingly outrageous price they want for one. I find that for 95% of the parting off and grooving I do, that .093" (3/32") seems to be about right. The largest stock I would ever part off is probably 2" diameter steel.--Opinions, please.---Brian
    HI Brian,

    --Is it really better?
    Yes. (Read that literally, as in Yes, period. )

    I find that for 95% of the parting off and grooving I do, that .093" (3/32") seems to be about right.
    I would encourage you to find the thinnest/narrowest one available, you will have fewer problems with chatter, especially on the lighter machine such as yours. As for stickout and rigidity on the thinner blade, that shouldn't be a problem. See if you can find the fairly recent thread I posted about parting a 4" or 5" diameter with an .093 blade. Come to think of it, I have numerous heavier blades and corresponding inserts, and I can't recall the last time I used one of them to get greater rigidity on a long stickout.

    I do not have flood coolant. I do not have power feed on the cross slide.
    Both these things are bad, but they can be compensated for.

    As for the coolant, a trick I use is to put a long snout (hypodermic needle) on a bottle of cutting oil, even coolant would work. The needle allow you to place the cutting fluid on the cutting diameter where it needs to be and then it gets all over the sides of the cut as it flings itself out. I use the needle on the flood coolant also to direct the stream deep into the cut.

    The lack of power feed should be no problem for a person such as yourself, given the projects that you have posted here in the past I think you have demonstrated the large reserve of patience necessary to turn that handle at the necessary consistent rate.

    You have the necessary spindle speeds, I can't imagine anything that would require something slower, but you would be very pleasantly surprised if you get to part aluminum confidently at 600 or 800 rpm. As long as the spindle has the necessary lack of slop, you will wonder why you waited so long. Yes, the upfront cost can be intimidating, but with care and practice it will eventually prove to be the more economical approach when considering spoiled work, broken tools, doctor appointlments, etc.

    Dave

  3. #3

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    I started out with a Jet 9/20 lathe and parting was always a iffy deal at best. I sold that lathe and got a Grizzly G4003g and have not had any problems with parting since. My view is that more power more rigidity and more mass makes the difference between success and failure, I wish I could give you some useful advise but I do not have anything that would help. On the brighter side I can say that I got your I.C. Hit n Miss engine running today. Making the parts was easy getting them to do what they are supposed to was a different deal.

    krankie frankie

  4. #4

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    I'm a recent convert to inserted carbide parting tools, having used HSS blade types for many years. I've got a 30 year old UK built 11x24" lathe, which is pretty rigid anyway, but inserted carbide is a revelation for parting off. It will happily part off 2" dia EN1A steel at 200 rpm. I don't use power feed for it, nothing against it, its just that I'm probably still a bit twitchy after all those HSS years, and like the ability to 'instantly' wind back out if something goes wrong. I don't use flood coolant either, even tho the lathe is fitted for it, too messy really. I just use a spray container (intended for watering house plants) filled with coolant diluted at 5-1, rather than the recommended 20-1. Its recommended that if the tip chips (they don't last for ever), you throw it away and put a new one in. Being mean, I've found that I can resharpen them on a green grit wheel. I can touch one up about 4 times before the edge of the insert is level with the face of the holder.
    'It may not always be the best policy to do what is best technically, but those responsible for policy can never form a right judgement without knowledge of what is right technically' - 'Dutch' Kindelberger

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