Shaft bending
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Thread: Shaft bending

  1. #1
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    Default Shaft bending

    Im trying to turn inconel 718 parts from 45mm down to 18mm, 300 mm in lenght. I turned the rough bar from 45 to 44 and centre it so it was all running true. I grip the 44 part in jaws clock up the tailstock end to under a thou, bring in the tailstock and its still under a thou.

    I have tried turning down to 30mm at low cut depth but after getting to 30mm its about 8 thou out once tails removed. After ive machined down to 18mm its about 16 thou out

    Anyone got any tips to avoid this happening

  2. #2
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    "Box tool"

  3. #3
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    There may be too much stress left in the original shaft, or it's getting "fresh" stress from the cutting process. You may have to thermally stress relief when you get to ~20mm and then finish cut with sharp tools, or do some bending and hope it stays straight for the remaining cutting.

    And I note with some amusement your mixing of MM and inch values in your post.

  4. #4
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    I’ve similar trouble with long 303SS PARTS. We had to bend them back to straight. It’s pretty easy ounce you get the hang of it. Ours were only .300” where it needed to be bent back so we just used the back end of a tool holder in our manual lathe to push against the part. Used a indicator on far side. 18mm inconel is gunna be a fair bit more difficult to bend tho lol


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