Thanks Thanks:  0
Needs Pictures Needs Pictures:  0
Picture(s) thanks Picture(s) thanks:  0
Page 2 of 2 FirstFirst 12
Results 16 to 27 of 27
  1. #16
    Join Date
    Aug 2011
    Location
    Melbourne
    Posts
    2,951

    Default

    Yea, this metal working hobby is analogous to chasing rainbows. With each new machine tool purchase comes the need for the next one… and the next….. and the next…….

    When I first started turning, I thought the term "self centreing" in regards to the 3 jaw meant EXACTLY that. Needless to say that I soon learnt the importance of planning your order of operations since removal from the 3 jaw lead to other "unexpected" runout errors.

    PS I'd be pretty happy with 1 micron of TIR on the 4 jaw, not many jobs require that or better in the home garage….
    Simon
    Girl, I don't wanna know about your mild-mannered alter ego or anything like that." I mean, you tell me you're, uh, super-mega-ultra-lightning babe? That's all right with me. I'm good. I'm good.

  2. # ADS
    Google Adsense Advertisement
    Join Date
    Always
    Location
    Advertising world
    Posts
    Many





     
  3. #17
    Join Date
    Jul 2010
    Location
    Melbourne
    Posts
    7,775

    Default

    I was having a little trouble with the 0.001mm run out.

    Thats an imp 0.001" dial gauge so one div is 0.0254mm

    Stuart

  4. #18
    Join Date
    Aug 2011
    Location
    Melbourne
    Posts
    2,951

    Default

    Quote Originally Posted by Stustoys View Post
    I was having a little trouble with the 0.001mm run out.

    Thats an imp 0.001" dial gauge so one div is 0.0254mm

    Stuart
    Yep. That sounds more realistic.

    Simon
    Girl, I don't wanna know about your mild-mannered alter ego or anything like that." I mean, you tell me you're, uh, super-mega-ultra-lightning babe? That's all right with me. I'm good. I'm good.

  5. #19
    Join Date
    Sep 2007
    Location
    Melbourne, Australia
    Posts
    335

    Default

    Yes, You're right, It is imperial! so the runout figures are not as impressive as once stated.
    My bad.

    Still, I'm not making aeroplanes, so the this level of accuracy is good for my level of experience. I'm sure with more skill those tolerances would be better.

    haha, yes the milling is definitely expensive,but I think the wife prefers that I'm home in the garage!

  6. #20
    Join Date
    Aug 2011
    Location
    Melbourne
    Posts
    2,951

    Default

    Quote Originally Posted by oohsam View Post
    Yes, You're right, It is imperial! so the runout figures are not as impressive as once stated.
    My bad.

    Still, I'm not making aeroplanes, so the this level of accuracy is good for my level of experience. I'm sure with more skill those tolerances would be better.

    haha, yes the milling is definitely expensive,but I think the wife prefers that I'm home in the garage!
    Yes, I was still thinking that. 1 thou runout is still pretty good*

    * Well, it really depends on the job and the tolerances that are called for. But 1 thou TIR would be good enough for probably 90% of jobs in the shed.

    I usually make the comparison that I'm not building bridges, but aeroplanes is another suitable analogy!

    Simon
    Girl, I don't wanna know about your mild-mannered alter ego or anything like that." I mean, you tell me you're, uh, super-mega-ultra-lightning babe? That's all right with me. I'm good. I'm good.

  7. #21
    Join Date
    Jul 2010
    Location
    Melbourne
    Posts
    7,775

    Default

    Quote Originally Posted by oohsam View Post
    so the runout figures are not as impressive as once stated.
    I doubt I'd blink an eye over 0.001" run out on my 3 jaw. In fact I'd be surprised if its that good. Cant say I recall a number for mine.. I must have checked it at some stage surely? lol


    Stuart

  8. #22
    Join Date
    Aug 2011
    Location
    Melbourne
    Posts
    2,951

    Default

    Quote Originally Posted by Stustoys View Post
    I doubt I'd blink an eye over 0.001" run out on my 3 jaw. In fact I'd be surprised if its that good. Cant say I recall a number for mine.. I must have checked it at some stage surely? lol


    Stuart
    I think that's what was achieved on the 4 jaw Stuart, not his 3 jaw. I'm in the same boat, I have no idea what the runout would be on my 3 jaw. I dare say it would be very average and hence the reason I have never bothered to measure it!

    Simon
    Girl, I don't wanna know about your mild-mannered alter ego or anything like that." I mean, you tell me you're, uh, super-mega-ultra-lightning babe? That's all right with me. I'm good. I'm good.

  9. #23
    Join Date
    Oct 2011
    Location
    Adelaide
    Age
    59
    Posts
    3,149

    Default

    My normal limit is about 1 thou total movement on the 4 jaw - while I can get better that's the point where tail chasing starts coming into the picture. It also seems to be the point where unless I'm using ground stock that material out-of-roundness errors start becoming significant - that is, the material is not quite a uniform (constant) diameter.

    Michael

  10. #24
    Join Date
    Jul 2010
    Location
    Melbourne
    Posts
    7,775

    Default

    Hi Simon
    Well he said "
    I checked the runout on the 3 jaw chuck itself, and it was 0.001mm I think thats pretty good."
    So yeah not runout, but

    As far as runout in the 4 jaw, as others have said I doubt the stock is that round.
    So oohsam if you want to practice more, you'd be better off turning the piece you have turned already and clocking on the area you have turned....Then you can play as long as you like. I wouldnt bother trying to get closer than 0.001" on unturned stock. The best you could likely do is opposite jaws the same.

    If you're going to be doing this sort of set up often you might want to make a bump center.... I've never bothered myself so I cant say how well they work. I do like my wiggler though.
    http://www.gadgetbuilder.com/CenterFinder.html
    scroll down


    Stuart



  11. #25
    Join Date
    Oct 2007
    Location
    Alexandra Vic
    Age
    69
    Posts
    2,810

    Default

    Lots of ideas being tossed around, but a couple of things become evident from the pics posted in third post.

    1, as someone mentioned, mounting in a set of normal jaws rather than reverse jaws would give much better workpiece support as the jaw clamping surfaces are at significantly longer.

    2, the work appears to be hard up against the front face of the jaws. Unless the end against the front face has been accurately faced perpendicular to the length of the bar, the interference between the face and jaw face, competing with the short section of jaws clamping the work would tend to pull the work out of true.

    For a given chuck with all of it's inherent inaccuracies, the OP should get a better runout using a set of normal jaws, and setting the work with the chuck end slightly clear of the chuck body if it is greater diameter than the bore through the chuck and spindle.
    I used to be an engineer, I'm not an engineer any more, but on the really good days I can remember when I was.

  12. #26
    Join Date
    Sep 2007
    Location
    Melbourne, Australia
    Posts
    335

    Default

    Quote Originally Posted by Stustoys View Post
    Hi Simon
    Well he said "
    I checked the runout on the 3 jaw chuck itself, and it was 0.001mm I think thats pretty good."
    So yeah not runout, but

    As far as runout in the 4 jaw, as others have said I doubt the stock is that round.
    So oohsam if you want to practice more, you'd be better off turning the piece you have turned already and clocking on the area you have turned....Then you can play as long as you like. I wouldnt bother trying to get closer than 0.001" on unturned stock. The best you could likely do is opposite jaws the same.

    If you're going to be doing this sort of set up often you might want to make a bump center.... I've never bothered myself so I cant say how well they work. I do like my wiggler though.
    http://www.gadgetbuilder.com/CenterFinder.html
    scroll down


    Stuart


    Thats some interesting stuff there...cheers for the links!

    Quote Originally Posted by malb View Post
    Lots of ideas being tossed around, but a couple of things become evident from the pics posted in third post.

    1, as someone mentioned, mounting in a set of normal jaws rather than reverse jaws would give much better workpiece support as the jaw clamping surfaces are at significantly longer.

    2, the work appears to be hard up against the front face of the jaws. Unless the end against the front face has been accurately faced perpendicular to the length of the bar, the interference between the face and jaw face, competing with the short section of jaws clamping the work would tend to pull the work out of true.

    For a given chuck with all of it's inherent inaccuracies, the OP should get a better runout using a set of normal jaws, and setting the work with the chuck end slightly clear of the chuck body if it is greater diameter than the bore through the chuck and spindle.
    See, this was my conundrum.
    I had the workpiece up flat against the jaws, but you are right, i was not sure if it was flat enough as I did not face it off. I wanted to face it off, but could not get it to sit centre enough in the jaws to face it off effectively.

    Once the lathe was it was really clear that it was out and was vibrating, not much, but enough for me to not be comfortable with it being mounted in there.

  13. #27
    Join Date
    Jul 2008
    Location
    near Warragul, Victoria
    Posts
    2,500

    Default RUNOUT

    Hi

    Yesterday i was doing the exact same thing you are ! I was getting the same results . The round stock is only being held in the jaws by a short length on its end , you have to expect runout in that setup . There is probably nothing wrong with your equipment . To test the chuck runout, use a smaller diameter bar , only 20mm from the jaws . Mike

Page 2 of 2 FirstFirst 12

Similar Threads

  1. Mounting and centering lathe chuck on rotary table
    By variant22 in forum METALWORK FORUM
    Replies: 11
    Last Post: 19th March 2014, 09:00 PM
  2. 10" 4 jaw Self Centering Chuck D16 Mount
    By bob colles in forum METALWORK FORUM
    Replies: 12
    Last Post: 30th June 2011, 06:03 PM
  3. TOS 4 Jaw 125mm Self centering Chuck
    By stevew in forum METALWORK FORUM
    Replies: 5
    Last Post: 8th September 2010, 01:37 PM
  4. Centering square stock in a 4 jaw chuck
    By Dingo Dog in forum METALWORK FORUM
    Replies: 2
    Last Post: 11th April 2008, 09:13 AM
  5. Chuck not centering
    By Sir Stinkalot in forum WOODTURNING - GENERAL
    Replies: 5
    Last Post: 17th May 2003, 12:36 AM

Tags for this Thread

Posting Permissions

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