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  1. #1
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    Default parting off... or should I say ..how to break the parting off tool

    is there a trick to doing this


    I had to make a 5/16 dia x 3/8long section into a piece of ˝ inch dia ms rod


    I thought I’d use a one of the indexable parting tools from CTC


    I squared it up to the stock and made sure it was on centre. I took a cut on the left side and went in to about 3/8 (didn’t read the drawing ..again) and then did the right knowing I needed to go to 5/16 which it did. while doing both these cuts i noted it needed some oompff to get it to cut..a 2mm insert...I then went back to the same setting (as per the dro) to recut the left side to 5/16..i went in and it didn’t seem to want to cut…bit more leverage and snap…that’s the 2nd one I buggered up.


    Obviously I am doing something wrong ..but what

    What do I need to look out for

    any pointers much appreciated



  2. #2
    Ueee's Avatar
    Ueee is offline Blacksmith, Cabinetmaker, Machinist, Messmaker
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    Default

    Have you got a pic of the setup?

    I always part furthest from the support first, then closer. This was you are not relying on the weaker section of rod to not flex.

    Those tipped tools can be really finicky for center height, you have to get it just right. A bit of oil helps or better flood coolant helps too.

    Once the tool starts to cut well keep driving it in.....

    Not a tipped tool but this may help....

    https://www.youtube.com/watch_videos...Vp3FIA&index=2

    Cheers,
    Ew
    1915 17"x50" LeBlond heavy duty Lathe, 24" Queen city shaper, 1970's G Vernier FV.3.TO Universal Mill, 1958 Blohm HFS 6 surface grinder, 1942 Rivett 715 Lathe, 14"x40" Antrac Lathe, Startrite H225 Bandsaw, 1949 Hercus Camelback Drill press, 1947 Holbrook C10 Lathe.

  3. #3
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    Default

    What sort of spindle rpm are you using? I don't reckon my AL335 has enough speed and rigidity to really run my carbide parting tool properly - like you I've found I have to feed it pretty hard even at 1400 rpm, and even then it doesn't seem to cut as nicely as a HSS parting tool...

    will be be interested to see if anyone comes up with a better solution for you, as I'd like to get mine working the way I think it should...

  4. #4
    Ueee's Avatar
    Ueee is offline Blacksmith, Cabinetmaker, Machinist, Messmaker
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    How fast were you going Richard?

    Ew
    1915 17"x50" LeBlond heavy duty Lathe, 24" Queen city shaper, 1970's G Vernier FV.3.TO Universal Mill, 1958 Blohm HFS 6 surface grinder, 1942 Rivett 715 Lathe, 14"x40" Antrac Lathe, Startrite H225 Bandsaw, 1949 Hercus Camelback Drill press, 1947 Holbrook C10 Lathe.

  5. #5
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    Default

    The first thing I would ask is, what sort of lathe are you using? Some lathes are just not up to parting.

  6. #6
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    Quote Originally Posted by eskimo
    went in and it didn’t seem to want to cut…bit more leverage and snap…that’s the 2nd one I buggered up.
    I find, at that stage, where it requires you to force it, the insert needs to be reversed.....maybe feed rate is at fault for the quick wear, or, more likely, the Chinese carbide has still a way to go. I wasn't particularly happy with some 3mm ones I got from CTC...compared to the usual Iscar and Sandvik - at any rate.

  7. #7
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    Hi,

    On my Hercus 260 parting off with carbide is scary no matter what I do. Fast/slow, slightly above centre height or lower. Doesn't matter, just doesn't work well.

    Parted off a small piece today at work on a Harrison M300 (I think), like cutting butter with a warm knife. So much more rigid (and probably better built).

    Probably is coming down to the rigidity of your machine.

    Ben.

  8. #8
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    Apr 2009
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    Default

    eskimo,
    A rear mounted parting tool with a good supply of lubrication will solve nearly all of the problems. Speed and feed and tool on centre will handle the rest.
    Bob

    Quote Originally Posted by eskimo View Post
    is there a trick to doing this


    I had to make a 5/16 dia x 3/8long section into a piece of ˝ inch dia ms rod


    I thought I’d use a one of the indexable parting tools from CTC


    I squared it up to the stock and made sure it was on centre. I took a cut on the left side and went in to about 3/8 (didn’t read the drawing ..again) and then did the right knowing I needed to go to 5/16 which it did. while doing both these cuts i noted it needed some oompff to get it to cut..a 2mm insert...I then went back to the same setting (as per the dro) to recut the left side to 5/16..i went in and it didn’t seem to want to cut…bit more leverage and snap…that’s the 2nd one I buggered up.


    Obviously I am doing something wrong ..but what

    What do I need to look out for

    any pointers much appreciated


  9. #9
    Join Date
    Jul 2006
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    Default

    I think I have found the problem from watching Tubalcain on youtube and will elaborate after I answer your questions

    Quote Originally Posted by Techo1 View Post
    The first thing I would ask is, what sort of lathe are you using? Some lathes are just not up to parting.
    Hare forbes AL960

    Quote Originally Posted by Jekyll and Hyde View Post
    What sort of spindle rpm are you using? I don't reckon my AL335 has enough speed and rigidity to really run my carbide parting tool properly - like you I've found I have to feed it pretty hard even at 1400 rpm, and even then it doesn't seem to cut as nicely as a HSS parting tool...

    will be be interested to see if anyone comes up with a better solution for you, as I'd like to get mine working the way I think it should...
    Quote Originally Posted by Ueee View Post
    How fast were you going Richard?

    Ew
    RPM was 420

  10. #10
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    Quote Originally Posted by bwal74 View Post
    Hi,

    On my Hercus 260 parting off with carbide is scary no matter what I do. Fast/slow, slightly above centre height or lower. Doesn't matter, just doesn't work well.

    Parted off a small piece today at work on a Harrison M300 (I think), like cutting butter with a warm knife. So much more rigid (and probably better built).

    Probably is coming down to the rigidity of your machine.

    Ben.
    a factor of course, but I reckon its more the setup I had as I describe below


    I was turning a piece a 1/2 x 7inch piece with live centre.
    I needed the 5/16diax 3/5long section about half way along.

    Now going by what I understood from mrpete, I should have not done that (due to total lack of rigidity). I should have been a lot lot closer to the chuck?...may have worked..

    Thanks all for the input...and i note what most of you say about rigidity...more learning to come

  11. #11
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    Quote Originally Posted by eskimo View Post
    RPM was 420
    For what it's worth, I'd say that is WAY too slow for the diameter you're playing with - ideal speed for the average carbide turning insert on that diameter is probably close to ten times that, although I'm sure you can't go that fast. I would suggest trying at top speed and see if that improves things...

  12. #12
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    Mar 2011
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    I was always told not to use a centre when parting. The bar flexes and pinches the parting tool in the cut.
    Also as fast as you can go for that diameter and carbide parting tool.
    I try to part at most 1/2 inch out from the chuck.
    David

  13. #13
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    Aug 2012
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    Eskimo you are not alone. I recently purchased an AL960b. Having a play on the weekend I managed to bust my cheap "freebie" HAFCO parting/grooving tool. Working with 1045 steel @50 diameter. I decided on my second use a the lathe (ever) that I would conquer the parting issues "up front". At least that was my plan. Instead the tool and the 1045 had other ideas. I found it was cutting great, chips flying in small spirals, then a loud chatter noise. I pulled out and noticed some steel stuck in the groove. I decided to part down the other side thinking this would create a clear swarf part. Instead when it got to the chatter part (deep - 20mm at least) it broke..

    IMG_2839.JPG IMG_2835.JPG IMG_2836.JPG IMG_2849.JPG

  14. #14
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    As soon as you hear the change in sound and chip change when parting,it is the lathe telling you that you are going too slow (hi probability surface speed has diminished) or your feed is wrong, could be too slow or too fast. It also appears to me that you have not used any form of lubrication, that is also asking for trouble as well. The H&F parting tools are low grade as well, my first one only lasted a few weeks.Suggest you buy a good quality parting tool,use plenty of lubrication and start with the recommended surface feet speed and reduce your feed rate as you get further into the cut. I have a similar lathe to yours and use the power cross feed set on the lowest setting with plenty of lubrication and have no problems.But always listen to your machine especially when parting.
    Bob



    Quote Originally Posted by variant22 View Post
    Eskimo you are not alone. I recently purchased an AL960b. Having a play on the weekend I managed to bust my cheap "freebie" HAFCO parting/grooving tool. Working with 1045 steel @50 diameter. I decided on my second use a the lathe (ever) that I would conquer the parting issues "up front". At least that was my plan. Instead the tool and the 1045 had other ideas. I found it was cutting great, chips flying in small spirals, then a loud chatter noise. I pulled out and noticed some steel stuck in the groove. I decided to part down the other side thinking this would create a clear swarf part. Instead when it got to the chatter part (deep - 20mm at least) it broke..

    IMG_2839.JPG IMG_2835.JPG IMG_2836.JPG IMG_2849.JPG

  15. #15
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    Quote Originally Posted by Jekyll and Hyde View Post
    For what it's worth, I'd say that is WAY too slow for the diameter you're playing with - ideal speed for the average carbide turning insert on that diameter is probably close to ten times that, although I'm sure you can't go that fast. I would suggest trying at top speed and see if that improves things...
    but but but...that seems scary at those speeds...but I take your point

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