Corner rounding

Semi-finish turning an outer diameter profile with a right hand tool, .0312 tool nose radius (TNR), tool nose orientation (TNO) 2 and enabling cutter compensation (G42). No rough turning outer diameter at this time due to example and wire frame. Program coordinate Z-.5000, DRO, tool nose compensation only Z-.5312 which, isn't far enough and should be Z-.5396 before, executing descending 210 (30) degree angle. When executing 210 angle a small radius is left at .5000 dimension. End point of small radius isn't seen on DRO, Step and simultaneous into 210 degree angle. Did the program not read ahead for next line, is a droop, reenable cutter compensation or no correspondance with TNO of particular tool path? After executing 210 is Z-.7896 which, is accurate cutter compensation and -.7500 dimesion. Suspected is that the 210 is mostly an accurate angular plane if correct cutter compensation at -.7500 dimension. Simulation showed that rest of the profile tool nose of cutter compensation accurate.

Attempted to use a TNO 6 and TNR .0312 as demo and if Z-.5000 would compensate accurately. And attempted to use TNO 2 and TNR .0156 as demo and if Z-.5000 would compensate accurately. Either didn't. The rest of profile remained cutter compensation accurate.

Tried G61, G61.1 and G64 P.0005. It didn't correct the unexpected corner rounding. Is a feature in AXIS lathe control panel to enable and disable if corner rounding?

Yes. 210 degree angle must intersect centerline of .0312 tool nose radius tangent before executing it's path. Therefore Z-.5000 requires an additional -.0396 to intersect that angular plane. If not the tool nose radius undercuts the angle.

I haven't cut a physical workpiece of this particular dimension with lathe yet. I opened my mous.ngc program with sim.axis lathe. My CNC micro lathe isn't configured with 7i92.ini and .hal hostmot2 file yet. .ini might require [LATHE] = TRUE and LATHE = 1 to enable lathe mode.

I know from industrial experience operating CNC lathes, single block and GE Fanuc and Okuma controls that tool nose compensation offsets itself as described. Nonetheless centerline of tool nose radius is expected tangent of angular plane before executing it's path. It might vary and some CNC controls could compensate X and Z tool nose radius simultaneous and tangent of angular plane but seems seldom while already on longitudinal path. If X and Z compensation X might leave a faint witness mark, a shallow groove and slightly undercuting.

Aware that LinuxCNC AXIS lathe control could compensate slightly differently than an industrial control but it seems comparable. Except that one plot Z-.5000 didn't offset itself far enough. Again could be an X and Z simultaneous offset but it appears a magnifide radius is left and might be an undercut. It's such a small amount with a .0312 tool nose radius and Z-.7896 tangent that it might not matter. Such if a .0625 tool nose radius then it's could be a lot more error if not compensating beyond centerline of Z-.5000.

Not sure if it's LinuxCNC tool nose orientation. It appears +X is bottom half of front view and wire frame. Then tool nose orientation would be 2 (P2). Not sure if cutting troughs with compensation is part of P2, Python interpreter and that Z-.5000 plot. Known that some industrial CNC lathes won't compensate accurately unless per system, tool geometry, orientation and tool path. Reminder leading edges of tool nose radius is touched-off and it's where compensation occurs rather than centerline.

Travel expected diagonal and simultaneous to nearest point if X and Z compensation from Z-.5000. That tool nose radius would undercut an angular corner before executing 210 degree angle. Could then what appeared corner rounding be an angle due to computer screen graphic or resolution? The corner does look as if it has an arc to it.

Usually if diagonal X and Z compensation it's lead-in depending on geometry and coordinate of tool before executing tool path.

Mismatch of a continuous profile rare unless backlash or variance of indexable carbide insert and tool nose radius due to mold or honing.

Understood. Resemblance. My desription alike a component of mechanical drafting or engineering.

.6000 OD
.9000 OD
.5000 x 14.036 degrees

Control point equivalent to tool nose radius tangent on 14.036 degree angle at X.6000 Z.1; Z-.0267 lead-in and Digital Read Out. Next plot at X.8974 Z-.5223. Last plot would of been expected nearer X.9000 Z-.5267.

My calculated plots are X.6000 Z.1; Z-.0271 and X.9000 Z-5271. They could be about a couple minutes off.

Anyhow, it still appears as if corner rounding with control point. Is it automatic corner rounding? Automatic corner rounding is complimentary with Mach4 earlier builds and can be enabled or disabled at control panel Motion Mode or G61. Such any auto corner rounding with LinuxCNC preference is to disable. Any auto corner rounding and if a bigger tool nose radius corner rounding might not get any bigger if not miscompensating.

Foregoing lead-in on tangent angle of workpiece to compare compensation. Generally my angular lead-in coordinates are X_ Z0.020 depending on tool nose radius and not to leave a witness mark before profile.

Understood.

A tool nose radius is useful to increase feed rates, to resist wear and improve surface finish. Convenient about tool compensation is that virtually any tool nose radius could offset itself within boundary of workpiece geometry.

I can probably work around the round corner meantime. I'll program a specific size radius on corner outer diameter taper mid-way length and monitor accuracy. Maybe programming a miniature radius could correct it. Or, disable tool compensation (G42) and calculate tool nose radius in program. This could make it complicating but cutter is expected where to be and could prevent lead-in and lead-out errors.