Let me correct myself yet again. Where I said > But now add the A axis. G01 X2 Z1 A360 F4. I just ran that on the mill and and it took 34 seconds Run G01 X2 A360 F4 and it takes 30 seconds Run G01 A360 F4 and now the rate changes to degrees per minute and it's still busy turning.
So when there are combined XYZ along with A how can the distance along the circumference be factored in so the ipm is correct? John > -----Original Message----- > From: John Dammeyer [mailto:jo...@autoartisans.com] > Sent: September-12-20 9:52 AM > To: 'Enhanced Machine Controller (EMC)' > Subject: Re: [Emc-users] G93 minimum value/behaviour > > Oops. I meant radius for the first Z dimensions. > I've fixed that below. > > > From: andy pugh [mailto:bodge...@gmail.com] > > On Sat, 12 Sep 2020 at 05:19, David Berndt <ber...@uberwin.com> wrote: > > > > > 2) Is there a minimum value for G93 feed rates. > > > > Not as far as I know. I just tried a test move of G93 G0 X100 F0.01 > > and it moved 1mm in 1 minute. > > > > > rotating A axis with something like G93 A45000 Z-1 F.2. > > > > I tried this G-code in the axis-9axis sim. It complained that there > > was no movement mode active. Putting in a G1 I got approximately the > > expected result, in that Z moved 0.5mm in 4.5 minutes. So I assume > > that the A axis was maxed out in the simulator. > > Bumping up the A axis max speed from 90 to 360 gave me a system that > > did 25 revolutions in 1 minute. > > > > Had you done a G0 move? > > > > G0 X0 Y0 > > G93 A45000 Z-1 F.2 > > > > Moves very fast. As G0 is modal. This ought to be an error, I think. > > (G0 X0 Y0 F10 is accepted. It is valid G-code but probably isn't what > > anyone intends. It says "set the feed rate to 10 and then perform a > > rapid move") > > > > G93 with G0 active, however, clearly makes no sense and appears to > > cause confusion. > > > I've had some discussions with Mecsoft and their CAM generation for the 4th > axis. I'm not sure the G93 solves this problem although > perhaps indirectly it does. > > Assume the rotation of the 4th axis is in line with the X axis and assume you > have a an object held in the 4th axis that has a taper. > So at X=0 it's radius is say 2" and at X=2" the radius is 1". > Now you want to cut a spiral slot on this taper from X=0 to X=2" in one > revolution of the part. In effect a very coarse tapered thread. > > The feed rate for the cutter size and mill rpm is 4 ipm. > > If this were a standard 3D move Y would remain the same, G01 X2 Z1 F4 > assuming the current position of X is 0" and Z is 2. > > The tool now moves down the hypotenuse of this triangle where the X and Z are > calculated to move at a rate to create an F4 speed > on this ramp. It should move the 2" X distance in 30 seconds. > > But now add the A axis. G01 X2 Z1 A360 F4. > > The X move completes in 30 seconds. The Z has moved 1" in 30 seconds. The A > axis has moved 4 degrees per minute so in 30 > seconds has moved 2 degrees. > > But wait, there's more. If the feed rate through the material has to be F4 > the A axis speed has to change in proportion to the Z > position. That's because the circumference at Z=2" is 12.56" and at Z=1" is > 6.28". > > If the diameter was fixed at 4" (Z=2") then F4 results in 3.14 minutes for > one revolution while at a diameter of 2" (Z=1") is 1.57 > minutes for one revolution. > > Is it even possible to cut this sort of spiral in one G-Code line or does it > require a long list of separate A and XZ moves? > > Or does somehow the G93 handle this situation. > > Thanks > 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
