. .

Thread: Turning issues

Hybrid View

Previous Post Previous Post   Next Post Next Post
  1. #1
    Hello all.
    I am currently running a Samsung cnc lathe, making bushes.
    Occasionally I'll get a bushe or 2 with an odd knurling on them, but as of yesterday they are all coming out with it.
    The lathe was only serviced and rechecked a couple of months ago.
    All the inserts are new.
    I've attached a photo.
    Could anyone shed some light on this?
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	20240312_140700.jpg 
Views:	272 
Size:	198.3 KB 
ID:	32202  

  2. #2
    That's chatter or judder. The usual cure is to increase or decrease the speed and / or feed until it stops. Often people reduce the feed or speed but you may find that increasing them is a actually better solution.

    As you are machining brass, you may need to use tools with little or no top rake. In a twist drill this would result in flutes with no twist and on a lathe tool, the top of the cutting edge would be on the same plane as the centre line. Normal angles intended for cutting steel or aluminium would be 5-15 degrees but when these are used on brass, they want to dig in. If you want an exciting time, try drilling brass with a sharp steel cutting drill!

    They call it "face rake" here but either way, it should be a small angle or zero.
    https://en.wikipedia.org/wiki/Rake_a...l_Cut_diag.svg

  3. The Following User Says Thank You to Muzzer For This Useful Post:


  4. #3
    What grade brass is it? Did you change to new stock recently? Hard brass, cz121, generally machines very well with normal tools but more ductile types can be horrid.

  5. The Following User Says Thank You to JohnHaine For This Useful Post:


  6. #4
    Hello,
    Thanks for the replies, and sorry for the delay getting back.
    It's actually copper.
    Same stock as I've run for years.
    The tooling is the same also.
    Strangely enough, as of today it seems to have stopped happening.
    The other issue was the 13mm drill was making a hell of a noise, but that has also stopped.
    I've made these parts for Several years with no issue.

  7. #5
    Hello again.
    Problem has returned.
    Machine has been stripped down and cleaned, including coolant.
    The issue now only seems to be on the bore.
    Last edited by knucklebones; 27-03-2024 at 09:13 AM.

Thread Information

Users Browsing this Thread

There are currently 2 users browsing this thread. (0 members and 2 guests)

Similar Threads

  1. Dueti Issues
    By Bento Box in forum Boxford Lathes
    Replies: 0
    Last Post: 28-02-2021, 03:44 PM
  2. Help with X axis issues please ?
    By shindax in forum Laser Machines & Building
    Replies: 1
    Last Post: 23-03-2020, 04:59 PM
  3. Parallel issues
    By CrazeUK in forum General Discussion
    Replies: 15
    Last Post: 29-01-2017, 11:54 PM
  4. Engraving issues
    By D-man in forum Machine Discussion
    Replies: 50
    Last Post: 29-02-2016, 10:01 AM
  5. 50w laser - PSU issues?
    By calida in forum Laser Machines & Building
    Replies: 1
    Last Post: 09-02-2016, 04:25 PM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •