On Sun, 2008-07-06 at 18:32 -0600, John Thornton wrote: > Kirk, > > Any insert with a sharp edge and a high positive rake and with a good coating > for > aluminum will work well with Acetal, UHMW and other plastics. I've gone so > far as > to hone the edge with a super fine diamond stone on some inserts to get a > better > cutting edge. The profile might be accurate but the plastic will have some > give in it > as you cut so the sharper the edge the more accurate the part will be. > > John
Thanks for the replies, Leslie and John. I was using a triangular insert with a front angle of 89 degrees (almost parallel with the workpiece face) and a back angle of 29 degrees (29 degrees from the OD surface). The insert has a chip breaking groove approximately .030" wide. It worked fine in aluminum. The Delrin part path is here. http://www.wallacecompany.com/machine_shop/retainer_side_1-1a.png I take two roughing passes (~.080" each cut, violet lines), starting from the left on the first pass and finishing the second pass on the left. I then lead in (gray line) on the left and follow the finish profile (blue). I got a torn melted finish. Is it reasonable to use one tool for all directions; facing right and left, turning in and out? The more I think about it, I think the insert isn't sharp enough. I may dress it on my diamond wheel and see if it works any better. I like the DCGT inserts, but I am having a little trouble finding a holder (3/8" square shank) that will work on my Hardinge HNC. Youtube seems to have the best picture of the turret: http://www.youtube.com/watch?v=vwhz3Ho_Gx0 I need to get some still shots. -- Kirk Wallace (California, USA http://www.wallacecompany.com/machine_shop/ Hardinge HNC/EMC CNC lathe, Bridgeport mill conversion, doing XY now, Zubal lathe conversion pending Craftsman AA 109 restoration Shizuoka ST-N/EMC CNC) ------------------------------------------------------------------------- Sponsored by: SourceForge.net Community Choice Awards: VOTE NOW! Studies have shown that voting for your favorite open source project, along with a healthy diet, reduces your potential for chronic lameness and boredom. Vote Now at http://www.sourceforge.net/community/cca08 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
