On 6/3/2015 10:27 PM, andy pugh wrote: > 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)
I think that this page gives some clues on the 6 jaw chucks. Sounds to me like they use a 3 jaw scroll and then each drive points connects to two jaws and there is a pendulum (rocker) between the two jaws. Note that the jaws are adjustable in "pairs". http://www.gb.schunk.com/schunk/schunk_websites/products/products_level_3/product_level_3_lathe_chucks/product_level_3_lathe_chucks.html?product_level_1=245&product_level_2=260&product_level_3=10984&country=GBR&lngCode=EN&lngCode2=EN Regarding how the 3 jaw chucks work - Google "3 jaw chuck mechanism" and it shows pictures. :-) Dave --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
