On Saturday 05 September 2009, Jon Elson wrote: >Gene Heskett wrote: >> You can't do anything about the surface of the raw material, but when >> machining, the surface should be well flooded by some relatively oxygen >> free fluid which will cover the cutting edge, and the freshly cut surface >> as quickly as possible. 2 schools of thought here, compete for how you >> do it. >> >> Either assumes the cut will be as deep as the spindle has power to do as >> that removes the unwanted material with fewer miles on the cutting edge. > >One other thing is the direction of cut. If the material is fed against >the direction of the cutting >edge, noramlly called "conventional milling", the cutter enters the >material by scraping along >the just-cut material until pressure builds enough for it to punch >through. This scraping increases >wear. The opposite is when the material is fed WITH the cutting edge, >there the cutting tooth >punches hard into the uncut material, and takes a slice that slowly >decreases in thickness. >This is called "climb milling". >This mode produces a lot less wear on the cutter, but it requires a >"tight" machine, as this direction >of feed has the cutter pulling the work, and machine table, toward it! >If you have a lot of backlash >in worn Acme leadscrews, this direction can cause the work to jump into >the cutter, wrecking parts >and breaking cutters. But, on a machine with tight screws, especially >ballscrews, the results, in >terms of surface finish and cutter life will be quite significant. > >Jon
Also very well said, thanks Jon, for plugging a hole I missed. And I can testify about the sloppy screws bit as I have 2 to 3 thou of backlash in my setup. I have tried climb cutting, but in my case I have to take a really large increment in order to get the entry angle of the cutter steep enough that it doesn't pull the table and attack. With a .010" z increment, I have to feed the y about .1" per x pass. Because I don't have enough spindle power to take a .010" cut per flute, the bit wear seems to be a wash here, either is pretty darned hard on bits. I really would like to get an X3 & put in ball screws, but as a hobby, I can't justify that big an outlay for no more time than I have left to enjoy it, darnit. -- Cheers, Gene "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) The NRA is offering FREE Associate memberships to anyone who wants them. <https://www.nrahq.org/nrabonus/accept-membership.asp> It is impossible to enjoy idling thoroughly unless one has plenty of work to do. -- Jerome Klapka Jerome ------------------------------------------------------------------------------ Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
