On 7 August 2018 at 11:39, Bengt Sjölund <beng...@tecno.se> wrote: > Looking for a g code generator for scroll jaws. > I have a Ø125mm 3-jaw chuck with 6mm scroll pitch and would like to be able > to mill my own soft jaws.
This sounds interesting, and harder than you might think. At first I thought it was just a set of curves at various radii, and to an extent it is, but the centre moves. In fact the curves are not constant-radius, but are probably close enough for practical purposes. Also, each jaw is different. Whether you handle this in the G-code or with an alternate workpiece placement is another question. The parts are easy to model in CAD. It might actually be easier to do it that way and then CAM. <Google> Hmm, the parts are not trivial to model in CAD. https://www.youtube.com/watch?v=EYBiWhxgHTo (You could model a scroll, then intersect it with the three jaw sections, then CAM each seperately.) In parametric G-code I would suggest that the answer is to start with the nominal mid-point of each inner and outer thread flank (separately) Then calculate how far the two edges of the jaw offset from that nominal mid-point.... No, wait, all this is utterly wrong! Either of these approaches will lead to a jaw that is a perfect fit in exactly one position and will bind in any other position. The outer flanks want to be machined to be at least as small a radius as the smallest part of the scroll that they can touch. The inner flanks want to be the same radius as the absolute max of the scroll radius. I doubt that they are typically cut with any "slope" across the face. They can only ever half line-contact with the scroll. -- atp "A motorcycle is a bicycle with a pandemonium attachment and is designed for the especial use of mechanical geniuses, daredevils and lunatics." — George Fitch, Atlanta Constitution Newspaper, 1916 ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
