On Sunday 11 October 2009, Steve Blackmore wrote: >On Sun, 11 Oct 2009 08:47:27 -0700, you wrote: >>On Sun, 2009-10-11 at 10:27 -0400, Gene Heskett wrote: >>... snip >> >>> A far at the pair of 50's is concerned, they will also stop it fairly >>> quickly. Mine is maybe 2 or 3 turns from the full 2500 rpms, and some >>> might call that a little brutal, but I have been doing it for at least a >>> year with no ill effects that I have detected. A single 50 would >>> probably be fast enough, and certainly easier on the PM fields of the >>> motor. >> >>That brings to mind, my Hardinge has a screw style chuck mount which >>seems like Russian roulette when using aggressive decelerations. An A5 >>spindle is on my wish list. > >Been there, had an 8inch dia 4 jaw come off on me and dance around the >shop, the Lexan window, behind where I was stood is still cracked ;) >Easy enough to drill and tap a hole, fit a set screw, job sorted. > >Thankfully my current lathe has 3 studs with a camlock. The smallest >chuck I have is 6 inch diameter and it's 3 inches deep. I can stop that >in two turns from 3200 rpm without a brake, but why? I have yet to come >across a practical reason to do that, apart from a bragging contest.
A reasonable stop is one that might not pull an arm off if it gets caught. But how would one go about setting up the SawStop sensing system on a lathe? Any manually activated method is way, way too slow. In a turret head, cnc situation I could see where a stop in 2 revs from 3200 might up production by 2% in a lights out mode, but would it be worth the stress on the drive parts? Flat out, no. That is a brutal stop to do that in 0.0375 seconds. Even 10 times that long is gonna dump some serious heat someplace. >The only possible theoretical reason is tapping, the drag off the tap, >and the slowish speed means it stops pretty well instantly anyway. I >must be doing it right, over the years I must have tapped many tens on >thousands of blind and through holes and have yet to break a tap. > >These days I also "cheat" slightly and mainly use a Tapmatic SM4 >extending nose tap holder, makes life so simple :) > Yes, that _is_ cheating, and you are making me jealous. ;-) OTOH, most of the taps I might use are in the 8-32, 6-32 and 6-48 range for size. The 6-32 seems to be the most fragile, and I have had to edm to remove 2 of them in the last 5 years. Probably guaranteed breakage when you think you need such threads 90+% deep & use a fractional drill bit for the hole cuz that's all I have. Nobody to blame but me. Those were good Hansen taps too, but I went out to TSC and picked up a TI coated Mibro & finished the job doing as many holes with it as with both of the Hansens I broke combined. And it still looks sharp under a strong glass. Go figure. >Steve Blackmore >-- > >--------------------------------------------------------------------------- >--- Come build with us! The BlackBerry(R) Developer Conference in SF, CA is > the only developer event you need to attend this year. Jumpstart your > developing skills, take BlackBerry mobile applications to market and stay > ahead of the curve. Join us from November 9 - 12, 2009. Register now! > http://p.sf.net/sfu/devconference >_______________________________________________ >Emc-users mailing list >Emc-users@lists.sourceforge.net >https://lists.sourceforge.net/lists/listinfo/emc-users > -- 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> /* First check any supplied i/o locations. User knows best. <cough> */ - comment from drivers/net/ne.c ------------------------------------------------------------------------------ Come build with us! The BlackBerry(R) Developer Conference in SF, CA is the only developer event you need to attend this year. Jumpstart your developing skills, take BlackBerry mobile applications to market and stay ahead of the curve. Join us from November 9 - 12, 2009. Register now! http://p.sf.net/sfu/devconference _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
