On Tuesday 10 November 2009, Chris Radek wrote: >On Tue, Nov 10, 2009 at 09:17:07PM -0500, Gene Heskett wrote: >> Assuming I keep the area wet with cutting oil at a high enough flow that >> I don't wind up with a muddy slurry, but do have enough chips to act as a >> wick and keep the mill wet from the cutting oil they absorb (or the oil >> level in the tuna can is high enough), and the 1/8" 2 flute carbide upcut >> spiral mill is turning 2500 rpms, how fast can I feed it while doing a >> 0.020" deep cut per pass without breaking it? Slower and deeper, or >> shallower and faster for best tool life? > >Unfortunately you could use a LOT more spindle speed for an 1/8" end >mill.
Tell me about it, like 10x more rpms. But those bearings would probably self destruct in an hour of that. >If you can keep it lubed I think you should try no more than >.060 deep (half a diameter) and you should turn up the spindle all >the way and try feeding faster and faster until you break the first >one. Then back off 25%. I think you might even be able to get up to >10 ipm or so (.002/tooth) depending on the stoutness of your machine. >If it wiggles around much, you'll break the tool much faster since >it'll sometimes try to take huge bites. That's a given, this machine can set up a chatter entirely too darned easily. >I know how tempting it is to be conservative and make dust instead of >chips, but it works so much better if you make chips. If you got a >10-pack, I recommend you don't worry about experimenting and >sacrificing one or two! If I set that program to go to -0.130" depth in 3 passes, that's about .0475". I'll up the speed to 8.5 ipm and check for effect. Success depends on rigidity. And this one really isn't. I'll snug up the ways if I can, its been a while since I played with those. All I can do for the cheap rotary is to crank on some drag from its lock screw, which seemed to help a lot. I'm cheating a bit, based on the finish I got on the first sprocket with an already used mill, and that was full depth of .125" in one pass, a hard push IMO, by telling it to do the depth in multiple passes till it gets to the depth with it thinking the mill is .135" in diameter, then for the last repeat cycle at the final depth, tell it the mills real .125" diameter, so it will be taking .005" more off the whole thing, removing any artifacts of the previous multiple passes while its at it. On screen at least it looks 'purty'. ;-) Run time is long though. 12+ minutes to do all 4 passes. If my table can keep up, I need to recheck its max speed with the stop screw dragging. Toss in that its a 425 motor since it was a bit stiff new. I've done some 'adjusting' and I think it turns easier now. But I should dis the worm holder and auger out its mounting holes with a chain saw file as they restrict the worm engagement. I need to drive it over another 2 or 3 thou & let emc wear it in until it really fits well. End play in the worm is another place where I need to make it drag & then break it in again. Cheap 99$ Grizzly table, what can I say? Thanks Chris. -- 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> Isn't it interesting that the same people who laugh at science fiction listen to weather forecasts and economists? -- Kelvin Throop III ------------------------------------------------------------------------------ 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
