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  1. #1
    Join Date
    Jul 2008
    Location
    near Warragul, Victoria
    Posts
    3,718

    Default Lathe finishing tool

    Found this in a 1942 Machine shop book.
    Attached Images Attached Images

  2. #2
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    6,444

    Default

    Hi Morrisman, Guys,

    I use a "Shear tool" for fine finishing particularly if I'm going to run a ball race on it !

    shear.jpg

    The only problem with this kind of tool is that you can only remove a thou or so ! But you do get an extremely smooth finish. The cutting edge slopes back about 30 degrees with a few degrees of rake on the front face, and its not sensitive to height. If you wear the cutting edge you just move the tool up or down a few thou. I hone the edges to get it really sharp.
    Best Regards:
    Baron J.

  3. #3
    Join Date
    Oct 2004
    Location
    Southern Highlands NSW
    Posts
    1,894

    Default

    Morrisman's tool has the shear edge nearly horizontal.
    Baron J's is nearly vertical.
    I wonder if there's an advantage either way?

  4. #4
    Join Date
    Nov 2007
    Location
    melbourne australia
    Posts
    3,228

    Default

    The Hercus Textbook of Turning recommends the same grind for truing up a faceplate.
    Chris

  5. #5
    Join Date
    Oct 2004
    Location
    Southern Highlands NSW
    Posts
    1,894

    Default

    Quote Originally Posted by jack620 View Post
    The Hercus Textbook of Turning recommends the same grind for truing up a faceplate.
    The cutting edge would then need a radius, as it's against a flat surface?

  6. #6
    Join Date
    Nov 2017
    Location
    Geelong, Australia
    Age
    57
    Posts
    2,651

    Default

    Quote Originally Posted by nadroj View Post
    Morrisman's tool has the shear edge nearly horizontal.
    Baron J's is nearly vertical.
    I wonder if there's an advantage either way?
    I could well be wrong, but to me BaronJ’s tool looks like it’s sitting on its side in the photo - so the shear edge is similar.

    Steve

  7. #7
    Join Date
    Oct 2009
    Location
    Upwey VIC
    Posts
    187

    Default

    Quote Originally Posted by OxxAndBert View Post
    I could well be wrong, but to me BaronJ’s tool looks like it’s sitting on its side in the photo - so the shear edge is similar.

    Steve
    BaronJ's tool is shown in the correct orientation.

    This shape removes very fine wires of swarf, but needs low speed, very small depth of cut and good lubrication due to the cutting face sliding along the work piece causing heavy tool wear.

    Andrew

  8. #8
    Join Date
    Nov 2007
    Location
    melbourne australia
    Posts
    3,228

    Default

    Quote Originally Posted by nadroj View Post
    The cutting edge would then need a radius, as it's against a flat surface?
    It does. But do you think I can find any reference to it? It's not in the ToT as I claimed, or any of the lathe textbooks I have. Clearly I'm losing my marbles.
    Chris

  9. #9
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    6,444

    Default

    Hi Guys,

    I have occasionally unintentionally used my shear tool as a normal lathe tool ! However the swarf that you get from the Shear tool used properly is like a very very fine wool, "Fairy Hair" is a good expression to describe it.

    You can get a similar cut on an internal surface using a round tool ground with a flat on the end ground at an at an angle ! Really good for through holes but you cannot get right to a flat bottomed hole. The way I've dealt with that issue is to take the bottom edge of a bore off for a mm or so.
    Best Regards:
    Baron J.

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