Threading issue
Close
Login to Your Account
Page 1 of 3 123 LastLast
Results 1 to 20 of 50

Thread: Threading issue

  1. #1
    Join Date
    Feb 2014
    Location
    Canada
    Posts
    41
    Post Thanks / Like
    Likes (Given)
    16
    Likes (Received)
    2

    Default Threading issue

    Hi Everyone,
    Hopefully someone can shine some light on this threading business.
    See attached photo. Yikes.

    This is my practice run on 1” round 4140 hardened alloy I just purchased.
    I tried the 4140 annealed and had much the same results, threads pulling.

    In the setup I have currently Arthur R. Warner HSS insert TNMC. I have EDGE level
    to adjust the height. I tried moving the insert up and down with not much change.
    Both inserts are new. Shaft runs nice and true 0.0003” and everything is tight.

    In the picture is a second insert I tried with TPMC (carbide gold color), no difference.

    The speed tried is 65 and 185, which may be the culprit, but since the thread on the final product is 15mm, length of the thread is 16mm and collar beside it is 25mm, I am paranoid going any faster of fear crashing the tool into the collar. (not in the picture as I am just practicing).

    I was even thinking if I need to ran faster to make the shaft where the collar should be, say a 16mm so I will not crash it, and then after the threading if successful press the collar onto the 16mm shaft. Unless of course there is another technique, like cutting threads away from the collar with upside down insert.

    I work mostly with stainless and never run into this to be a bother. So obviously, I am just not capable to machine 4140. I am ashamed of this embarrassing picture.

    dscn1379.jpg

  2. #2
    Join Date
    Jul 2004
    Location
    Houston, TX USA
    Posts
    29,348
    Post Thanks / Like

    Default

    The speed tried is 65 and 185
    17 and 48 SFPM on 1" dia. - 350 SFPM would be more like cutting speed. 4140 prehard will thread nicely. Flood coolant or at the very minimum dark cutting oil

  3. Likes Matt_Maguire liked this post
  4. #3
    Join Date
    Nov 2009
    Country
    UNITED STATES
    State/Province
    Massachusetts
    Posts
    274
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    77

    Default

    Quote Originally Posted by Ratz View Post
    I was even thinking if I need to ran faster to make the shaft where the collar should be, say a 16mm so I will not crash it, and then after the threading if successful press the collar onto the 16mm shaft. Unless of course there is another technique, like cutting threads away from the collar with upside down insert.
    Running in reverse with cutter upside down is exactly what I've done in such close quarters.

  5. Likes Ratz liked this post
  6. #4
    Join Date
    Feb 2014
    Location
    Canada
    Posts
    41
    Post Thanks / Like
    Likes (Given)
    16
    Likes (Received)
    2

    Default

    Quote Originally Posted by johnoder View Post
    17 and 48 SFPM on 1" dia. - 350 SFPM would be more like cutting speed. 4140 prehard will thread nicely. Flood coolant or at the very minimum dark cutting oil
    Hmm… I may be wrong, but I punched in the numbers. 350 SFPM works out to 22 revolutions per second. Since the length of the thread is 15mm that would give me ¾ of a second to do the cut and stop the spindle before it crashes.

    I can see this speed for turning but call me chicken for threading on manual lathe. Maybe I misunderstand your approach.

  7. #5
    Join Date
    Feb 2014
    Location
    Canada
    Posts
    41
    Post Thanks / Like
    Likes (Given)
    16
    Likes (Received)
    2

    Default

    Quote Originally Posted by Joe Gwinn View Post
    Running in reverse with cutter upside down is exactly what I've done in such close quarters.
    OK, good to know I am not dreaming. I never threaded this way, so I will do some practicing.

  8. #6
    Join Date
    Feb 2007
    Location
    St. George, Utah
    Posts
    802
    Post Thanks / Like
    Likes (Given)
    346
    Likes (Received)
    501

    Default

    Quote Originally Posted by Ratz View Post
    Hmm… I may be wrong, but I punched in the numbers. 350 SFPM works out to 22 revolutions per second. Since the length of the thread is 15mm that would give me ¾ of a second to do the cut and stop the spindle before it crashes. . .
    I think he must've meant 350RPM.

  9. #7
    Join Date
    Feb 2014
    Location
    Canada
    Posts
    41
    Post Thanks / Like
    Likes (Given)
    16
    Likes (Received)
    2

    Default

    Quote Originally Posted by Gordon Heaton View Post
    I think he must've meant 350RPM.
    That would make sense. I will see what the cut of thread looks like at 350 and go from there. As I said
    185 made me nervous so I just may practice the upside down method going outwards.
    Thanks for coming up.

  10. #8
    Join Date
    Jul 2004
    Location
    Houston, TX USA
    Posts
    29,348
    Post Thanks / Like

    Default

    350 RPM on a 1" dia is 92 SFPM - suit yourself - but I do see the carbide cutting tools which will be happy at 22 revs per second or 350 SFPM

    I never threaded this way, so I will do some practicing.
    You will need a relief groove to start in

  11. #9
    Join Date
    May 2010
    Country
    DENMARK
    Posts
    3,027
    Post Thanks / Like
    Likes (Given)
    3993
    Likes (Received)
    12663

    Default

    Quote Originally Posted by johnoder View Post
    You will need a relief groove to start in
    A good rule of thumb for a thread groove width is 2 times pitch.

    threadstop.jpg

  12. Likes Ratz liked this post
  13. #10
    Join Date
    Nov 2009
    Country
    UNITED STATES
    State/Province
    Massachusetts
    Posts
    274
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    77

    Default

    Quote Originally Posted by Ratz View Post
    OK, good to know I am not dreaming. I never threaded this way, so I will do some practicing.
    Don't try this if your lathe has a threaded spindle. Having a spinning chuck unscrew itself and chase you around the shop is far too exciting for one's health.
    Last edited by Joe Gwinn; 09-12-2019 at 07:52 AM. Reason: typo

  14. Likes climb-101, Ratz, Bobw liked this post
  15. #11
    Join Date
    May 2010
    Country
    DENMARK
    Posts
    3,027
    Post Thanks / Like
    Likes (Given)
    3993
    Likes (Received)
    12663

    Default

    Quote Originally Posted by Joe Gwinn View Post


    Don't try this if your lathe has a threaded spindle. Having a spinning chuck unscrew itself and chase you around the shop is far too exciting for one's health.
    That sounds like the voice of experience You don't just happen to have a video?

  16. #12
    Join Date
    Jun 2019
    Country
    UNITED STATES
    State/Province
    South Dakota
    Posts
    37
    Post Thanks / Like
    Likes (Given)
    11
    Likes (Received)
    8

    Default

    I have threaded a lot of 4140 both annealed and hardened, almost every day. screws down to no.6-38 ( if memory serves) and up to 2"-12 always on manual lathes. first, high speed steel properly ground and sharpened is much more forgiving on speed, second a good lard based oil, or even baking lard ( I use it constantly) or dark cutting oil, applied every pass, will help keep your cutter clean, the metal welding to the end of the tool is your worst enemy. My dad threads even slower than I do, I have in the past ran as slow as 65 rpm on 1" bars with good results, just takes a lot of time and light (.005 or less) passes. first pass can be deeper, but need to get lighter with each pass. getting proficient with threading is all in practice...... and good cutting oil, don't be stingy with it!

    by the way I threaded the no.6 at less than 100 rpm, speed helps but it's not necessary for a beautiful thread. ( I made thumb screws for a browne and sharp 38" vernier caliper I bough my dad for Christmas,both fit better than the ones in my starrett and looked better too!)

  17. #13
    Join Date
    May 2017
    Country
    UNITED STATES
    State/Province
    Massachusetts
    Posts
    251
    Post Thanks / Like
    Likes (Given)
    226
    Likes (Received)
    113

    Default

    Can't tell from the photo, but how much stick-out? You keeping it under 3x diameter?

  18. #14
    Join Date
    Apr 2005
    Location
    Beaverdam, Virginia
    Posts
    7,171
    Post Thanks / Like
    Likes (Given)
    578
    Likes (Received)
    3338

    Default

    I thread a lot of 4140 both annealed and prehard from 1/2" to 1 3/8". I always use Kennametal grade KC5010 it has given the best combination of life and finish. That is on a CNC Lathe using water soluble flood coolant. For 1" threads I would go 500-600 rpm. The right insert I have found is very important. I have a 3.5" long thread I single point at 1,000 rpm, Kennametal NJF3008R20 KC5010 will usually get 200+ on each insert side. The same style in a KC730 will barely make a dozen parts.

  19. #15
    Join Date
    Jan 2005
    Country
    CANADA
    State/Province
    Saskatchewan
    Posts
    10,172
    Post Thanks / Like
    Likes (Given)
    1375
    Likes (Received)
    3641

    Default

    Quote Originally Posted by Ratz View Post
    Hi Everyone,
    Hopefully someone can shine some light on this threading business.
    See attached photo. Yikes.

    This is my practice run on 1” round 4140 hardened alloy I just purchased.
    I tried the 4140 annealed and had much the same results, threads pulling.

    In the setup I have currently Arthur R. Warner HSS insert TNMC. I have EDGE level
    to adjust the height. I tried moving the insert up and down with not much change.
    Both inserts are new. Shaft runs nice and true 0.0003” and everything is tight.

    In the picture is a second insert I tried with TPMC (carbide gold color), no difference.

    The speed tried is 65 and 185, which may be the culprit, but since the thread on the final product is 15mm, length of the thread is 16mm and collar beside it is 25mm, I am paranoid going any faster of fear crashing the tool into the collar. (not in the picture as I am just practicing).

    I was even thinking if I need to ran faster to make the shaft where the collar should be, say a 16mm so I will not crash it, and then after the threading if successful press the collar onto the 16mm shaft. Unless of course there is another technique, like cutting threads away from the collar with upside down insert.

    I work mostly with stainless and never run into this to be a bother. So obviously, I am just not capable to machine 4140. I am ashamed of this embarrassing picture.

    dscn1379.jpg

    You tried 'moving the insert up and down'? What the hell for? Set it slightly below centerline height and it should cut. Looks like you've got it set above centerline, and that just ain't gonna work in this universe.

  20. #16
    Join Date
    Feb 2014
    Location
    Canada
    Posts
    41
    Post Thanks / Like
    Likes (Given)
    16
    Likes (Received)
    2

    Default

    Quote Originally Posted by Joe Gwinn View Post


    Don't try this if your lathe has a threaded spindle. Having a spinning chuck unscrew itself and chase you around the shop is far too exciting for one's health.
    Thank you good point. I am OK there as my chuck is 8" D-4.

  21. #17
    Join Date
    May 2011
    Location
    southern in.
    Posts
    1,427
    Post Thanks / Like
    Likes (Given)
    1908
    Likes (Received)
    371

    Default

    Quote Originally Posted by johnoder View Post
    350 RPM on a 1" dia is 92 SFPM - suit yourself - but I do see the carbide cutting tools which will be happy at 22 revs per second or 350 SFPM



    You will need a relief groove to start in
    John, I think he is using High Speed Steel (HSS) inserts. May be a bit of confusion.
    JH

  22. #18
    Join Date
    Feb 2014
    Location
    Canada
    Posts
    41
    Post Thanks / Like
    Likes (Given)
    16
    Likes (Received)
    2

    Default

    Thank you. There should be hope for me then. I just keep trying with different tools. Interesting is
    that my HSS insert by Arthur R. Warner never failed me in 316 and 304 stainless.

  23. #19
    Join Date
    Feb 2014
    Location
    Canada
    Posts
    41
    Post Thanks / Like
    Likes (Given)
    16
    Likes (Received)
    2

    Default

    Quote Originally Posted by Dumpster_diving View Post
    Can't tell from the photo, but how much stick-out? You keeping it under 3x diameter?
    This is my latest trial. Still crappy. Material is sticking out 1.25". Using TPMC carbide 180RPM. This is a second try without chamfered start on this piece of alloy. It was late last night and I forgot.

    Come to think of it this is my first fine thread. Course threads always came up nicely in stainless.

    dscn1380.jpg

  24. #20
    Join Date
    Feb 2014
    Location
    Canada
    Posts
    41
    Post Thanks / Like
    Likes (Given)
    16
    Likes (Received)
    2

    Default

    Quote Originally Posted by HuFlungDung View Post
    You tried 'moving the insert up and down'? What the hell for? Set it slightly below centerline height and it should cut. Looks like you've got it set above centerline, and that just ain't gonna work in this universe.
    I have tried moving insert up and down, just to see if being below and above centerline would make a difference in cut. I have included a picture of EDGE level for everybody to know, that I am using some decent tools to find centerline. Other convincing fact of being on the centerline is during facing I have no nipple left what so ever.
    I will keep in mind your advise being slightly below is preferred. Thank you for posting.


Tags for this Thread

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
  •