> On Apr 11, 2024, at 11:49 AM, John Dammeyer <jo...@autoartisans.com> wrote: > > Where I'm still having trouble is understanding the compromises. > > Using G02 I,J motion it's possible to specify a feed rate and spindle RPM > that remains constant regardless of the spiral diameter. This approach > generated by the CAM software does a number of segments. But since a spiral > is continuously changing the radius doesn't this approach still create a > blocky segmented series of lines? Shouldn't there really be more like a new > line for every say one tenth of a degree of rotation?
What you should care about is just one thing: that the resulting spiral is within tolerance. If it is done with a series of straight lines or a series of arcs should not matter. I think the example g-code below is not real. What I mean is it is not what you would use because it does the cut all at once > % > N1 G17 G21 G40 G90 > (2 1/2 Axis Profiling) > N2 T1 M06 > N3 S2000 M3 > N4 G0 Z11.35 > N5 X-6.795 Y-2.3642 > N6 G1 Z5. F745.1 > N7 X-4.971 Y3.7182 F372.5 > N8 G17 > N9 G02X2.9354Y7.9767I6.0824J-1.824 F279.4 > N10 X0.0086Y-11.1633I-3.0663J-9.3249 F372.5 > N11 X-4.8878Y12.9255I-0.3348J12.4739 > N12 X10.8896Y-12.3617I5.6431J-14.0447 > N13 X-16.8958Y8.9702I-11.9852J13.1505 > N14 X21.6077Y-2.7715I18.1973J-9.3286 > N15 X-23.7802Y-5.6409I-22.9524J2.6529 > N16 X22.4641Y15.1503I24.9984J6.2225 > N17 X-18.2168Y-23.5731I-23.4829J-16.0603 > N18 X12.0427Y30.2156I18.8718J24.7892 > N19 X-3.5415Y-35.0813I-12.341J-31.5628 > N20 X-6.7258Y37.3924I3.4567J36.4587 > N21 X17.9557Y-36.5564I7.1836J-38.6957 > N22 X-29.1519Y32.2355I-18.7497J37.6857 > N23 X39.2113Y-24.4201I30.2257J-33.1012 > N24 X-47.7931Y-8.2457I-40.4241J24.6445 > N25 G1 X-49.1271 Y-2.0374 F745.1 > N26 G0 Z11.35 > N27 M30 > % > > On the other hand with the rotary table the motion is continuous for both > axis. > G00 G49 G40.1 G17 G80 G50 G90 > G20 > (2 1/2 Axis Profiling) > M6 T2 > M03 S2000 > G1 F100 A3600 X60 > G00 Z0.2362 > M5 M9 > M30 > > However the F100 is a joke because my A axis can't run more than 7 ipm or so. > I have faint memories of that from a previous discussion on how to set up > the A axis. My INI file says > DEFAULT_ANGULAR_VELOCITY = 90.00 > MIN_ANGULAR_VELOCITY = 0 > MAX_ANGULAR_VELOCITY = 180.00 > > I think that's in degrees per second because at a G01 F6 A3600 it takes 2 > seconds to do one revolution. Now that's still plenty fast if we are > slotting with a 3mm or 0.118" end mill. However the problem of SFM is now in > the picture. Again, a custom G-Code solution would likely be to do > something like the following. > > G01 F6 A360 X10 > F5.5 A720 X20 > F5 A1080 X30 > > And so on... Picking both X resolution and A distance to create a closer to > ideal SFM. I don't know if there is a G-Code that states the F rate for the > A axis is in degrees per minute so it's some sort of conversion from IPM. > > I only have the 4th Axis version of MECSOFT so I can't generate a fifth axis > program cutting a spiral with the mill using the rotary table. > > But I think I agree the best way to do this is probably still by hand or with > a support program that generate the G-code based on parameter input like > min/max SFM. > > John > > > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
