Control point

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15 Dec 2020 01:01 - 15 Dec 2020 05:34 #192006 by smplc
Control point was created by smplc
Will tool nose radius adjust control point most interpolations of Debian 10 preempt-rt, LinuxCNC and Lathe screen?

Without tool nose radius compensated tangent tool geometry undercuts a downward angle profile.

I had a similar issue with Debian 9 preempt-rt, LinuxCNC and Lathe screen about a couple years ago. Eventually the control point adjusted from tool nose compensation tangent, not undercutting the downward angle and resolved then.
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Last edit: 15 Dec 2020 05:34 by smplc. Reason: punctuation

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21 Dec 2020 03:26 - 21 Dec 2020 15:14 #192605 by smplc
Replied by smplc on topic Control point
I have a USB that isn't boot able lately and Debian 9 preempt-rt and lathe program mous.ngc was saved on it. LinuxCNC Lathe simulation Tool Table settings was saved on it too. The 0.0312 tool nose radius did compensate the downward 30 degree angle of foregoing profile earlier without rounding the corner.

A 0.0312 tool nose radius compensates 0.0229 long on a 30 degree (210 deg) downward-angular plane. Thus the 0.900 diameter turned at [0.500 length + .0625 tool nose diameter] - 0.0229 = 0.5396. 0.5396 + 0.250 = 0.7896. As well was visible on the LinuxCNC Lathe digital-read-out and Single Block (step) but the 0.5396 currently steps at 0.5312. Compensation mignt not be effective until executing the downward angle. This is where the corner rounding occurs. It seems the tool nose radius isn't compensating beyond 0.0312 and maybe partially due to the Lathe Tool Orientation L2 but should have correctable components.

Known is the Tool Table lays out graphical tool geometry and compensates tool nose radius if not Dynamic Cutter Compensation. Dynamic Cutter Compensation overrules Tool Table Diam if syntax D and require L.

Control Point which, is established from absolute reference zero is leading direction of tool nose radius and X and Z coordinates. The Control Point always maintains its reference and when an interpolation tool nose radius compensates from leading directions.

Recently the 0.0312 tool nose radius isn't compensating the 0.500 length which, is start of the 30 degree downward angle. I might of forgot some tool compensation syntax or something in the Tool Table. Why isn't it compensating at its step?
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Last edit: 21 Dec 2020 15:14 by smplc. Reason: Replaced images

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21 Dec 2020 05:30 - 21 Dec 2020 06:31 #192609 by smplc
Replied by smplc on topic Control point
Although, I don't remember making previous adjustment but is a configs file with a setting that limits tool nose compensation diameter within its Lathe Tool Orientation.
Last edit: 21 Dec 2020 06:31 by smplc. Reason: term

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21 Dec 2020 17:15 - 21 Dec 2020 18:04 #192674 by smplc
Replied by smplc on topic Control point
I recovered the mous.ngc file from Debian 9 preempt-rt USB and defective boot and it appears about the only difference is that a G61 line is before the line with G42.1. The G61 is disfunctional during G42.1. Recovered lathe.tbl and it appears D0 but that doesn't allow laying out configured tool geometry with Debian 10 preempt and 7.9 rtai. Running Debian 7.9 rtai LinuxCNC Lathe simulation and still tool nose radius not compensating the 0.500 length before the 30 degree downward angle.
Last edit: 21 Dec 2020 18:04 by smplc. Reason: versions

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28 Dec 2020 16:19 - 28 Dec 2020 18:31 #193369 by smplc
Replied by smplc on topic Control point
Another lathe.tbl is D.0625 and may very well be to lay out tool geometry.

Whatever auto corner rounding doesn't seem to cause an inaccurate, outer diameter, right to left and 45 degree upward angle yet as it appears because compensated coordinates. A 0.0312 radius tool and the auto corner rounding size is a 0.0314 radius which, is bigger than my need.

Could it be that G64 is default when enabling G41, G42, G41.1 and G42.1? G64 P0 Q0 or G64 P0.001 before enabling tool compenation doesn't seem to disable corner rounding. G64 command won't enable if tool compensation already enabled.

Is a script file and where to disable G64 such if it's the cause?

wiki.linuxcnc.org/cgi-bin/wiki.pl?TrajectoryControl
Last edit: 28 Dec 2020 18:31 by smplc. Reason: rounding radius

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01 Jan 2021 18:18 #193746 by smplc
Replied by smplc on topic Control point
Could lathe sim not entirely be a lathe screen and could axis (mill) sim be in the background that effects tool compensation?

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11 May 2021 16:17 - 11 May 2021 16:24 #208564 by smplc
Replied by smplc on topic Control point
I realized some CNC lathes such as Haas at Settings has Cutter Comp A or B toggle which could be methods how tool nose compensates interpolations. Generally, set at A and other make and models comparably from my experience. LinuxCNC is probably comparable to B as I learned. I calculated enabled tool compensation and Theoretical Sharp Point coordinates and matches LinuxCNC digital read out. Supposedly, the Theoretical Sharp Point doesn't leave the workpiece. The corner radius is from the Theoretical Sharp Point and the tool nose radius just rolls over the physical corner of a workpiece. Thus the corners might just barely cut if any. I wonder if LinuxCNC has a Cutter Comp toggle. I wonder if some editions of Dynamic Cutter Compensation is comparable to Cutter Comp A.
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Last edit: 11 May 2021 16:24 by smplc. Reason: Added last sentence.

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12 May 2021 20:24 #208647 by andypugh
Replied by andypugh on topic Control point
LinuxCNC has cutter comp for lathe, but it is of a fixed type.
Cutter comp only matters when you are machining curves or tapers, ie it is the version shown in your picture where the X and Z tangents define the controlled point.

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