Andy, you gave the answer: clearance and wobble. I own a 4-jaw self centering chuck, outer appearance like Olim himself made it in the bible. It was (and still is) rarely used and that might be the reason that it still works very accurately. Telling from the feeling when I tighten it on a really round workpiece, rattling it gently with in my right hand, the 4 jaws grip pretty evenly. To make sure, if you own a high speed grinder of the longitudinal (Dremel) style, have the jaws open a little less than the size of the bore of the chuck body. Then mount the grinder on the tool post somehow, run the lathe at highest speed and move in and out until there are no more sparks. Of course, this applies to 3 and 4 or more jaws. Manufacturers do this with a special bracket mounted in the jaws, but good old centrifugal force will do. You can adjust the grip radius of the jaw's inside by the amount of opening. This is the way I adapt my soft jaws for special workpieces; high speed is essential, although it's hard on the tool.
Peter Am 04.06.2015 04:27, schrieb andy pugh: > On 4 June 2015 at 03:19, andy pugh <bodge...@gmail.com> wrote: >> Until about 5 years ago I knew of 2 types of chuck. 4-jaw independent >> and 3-jaw self-centering. > Supplementary question: How do three-jaw chucks work anyway? > > When you thing about it, the scroll has to be free to rotate. If you > give it a lot of radial clearance and then visualise the setup, the > jaws, scroll and work can all wobble as a unit by that clearance (the > motion of the jaws in the tracks is interesting, and I think it > actually needs the clamped radius to reduce to happen. Is that the > secret? I don't see the same effect in the 4-jaw scroll chick where > everything gets the option to wobble by the scroll clearance. > > It stands to reason that chuck-makers understand chucks more than me, > so what am I missing? What second-order effect makes a 4-jaw scroll > chuck work? (I think, that even a three-jaw needs a second-order > effect) > --- Diese E-Mail wurde von Avast Antivirus-Software auf Viren geprüft. https://www.avast.com/antivirus ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
