Unfortunately I wasn't climb milling. Also knowing that it wasn't the most stable setup I also did it in 4 passes at 0.9mm per pass. But, and this is the big one. After the first pass where it did the arc'd approach each successive pass was a plunge. I think that's what pulled the backlash out of alignment.
What wasn't shown in the final photo, because I filed it away, was the last pass was just a shaving and as it separated the offcut it didn't need to follow the previous path and it really did look more like what it was supposed to. That's why the next time I told the CAM software to use the curved entry/exit for each layer. And it came out much better. Still smoother on the back side than the front which definitely has something to do with backlash. Each point where an axis changed direction on the compound curve is visible in the cut. So I probably don't have the backlash compensation set right. Or, now that it's been running CNC for a while the ACME nut has worn and I have more backlash. Possibly even more in the center part than the ends. This holder was for the Air regulator and filter/water separator. Still a few more brackets to cut for the other parts that make up the mist coolant. Then the power draw bar bits and pieces. Finally still need to figure out why when I asked for 3000 RPM with the step/dir that the encoder feedback only made it to 2960 RPM and therefore milling wouldn't start. Not close enough to target velocity. So there are other issues before I can start on the Ball Screw Conversion. John > -----Original Message----- > From: jrmitchellj [mailto:[email protected]] > Sent: August-02-21 5:42 PM > To: Enhanced Machine Controller (EMC) > Subject: Re: [Emc-users] Something went wrong. > > First, if you have a lot of backlash in the X & Y movements, you should > avoid climb milling. When the cutter grabs the work, it will take up the > backlash (and maybe break the cutter) > As for the way you have the work in the vice, I would ditch the round > stock, and clamp it lower in the vice. I think you have a lot of flex in > the setup pictured! Keep the horizontal part of the part within about > 1/8th of an inch of the top of the vice jaws. If you really want to > use the round, flip the part around (the z axis), put the round stock so > that it clamps the stock very close to the top of the vice jaws. That will > minimize the flex. > > --J. Ray Mitchell Jr. > > �I predict future happiness for Americans, if they can prevent the > government from wasting the labors of the people under the pretense of > taking care of them.� > > THOMAS JEFFERSON > > > On Mon, Aug 2, 2021 at 4:43 PM John Dammeyer <[email protected]> wrote: > > > Hi Dave, > > Things have gone from not too bad to worse. > > > > My Drill Chuck in the TT Holder and a pencil held for doing the tracing > > has vanished. Can't find it anywhere. I suspect it's now with the Dr. > > Who "Key to Time" box set along with a couple of other DVD movies that also > > vanished a few months back. > > > > I've been told the only way to find the existing DVDs is to buy new ones. > > Looks like I might have to order a couple more TT holders and drill > > chucks. I wanted a few more anyway but really. This is ridiculous. > > > > With respect to climb verses conventional I did the whole thing as > > conventional but if my X axis table can be moved when the milling cutter > > engages the work (due to backlash) then I'm kind of hooped. > > > > John > > > > > > > From: dave engvall [mailto:[email protected]] > > > HI John, > > > If I'm reading correctly it is? OK with conventional milling but off > > > with climb. Too weird!? I guess the next step would be to mill it > > > conventional and overlay with climb and see what happens. Maybe? a bit > > > of layout dye between runs. > > > > > > The alternative would seem to be that Murphy and all his cousins have > > > invaded your shop. ;-) > > > Where is the can of murphycide? > > > > > > Dave > > > > > > > > > > > _______________________________________________ > > Emc-users mailing list > > [email protected] > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
