[LinuxCNC/linuxcnc Issue#428] Inconsistent G33.1 behavior between implementation and the doc. About GRBL HAL

Issue #428 | 状态: 已关闭 | 作者: ReeseWang | 创建时间: 2018-04-11

Here are the steps I follow to reproduce the issue:

All in MDI mode:
1. Move to G54 X0 Y0 Z0.
2. “M3 S300” to start the spindle.
3. Execute “G33.1 X10 Y0 Z-10 K0.7”

This is what I expected to happen:

The mill rapid moves to X10 Y0 Z0 and then does a rigid tap which has a depth to Z-10.
Just as the Warning in G33.1 documentation says:

> If the X Y coordinates specified are not the current coordinates when calling G33.1 for tapping the move will not be along the Z axis but will rapid move from the current location to the X Y location specified.

This is what happened instead:

The mill did a linear spindle-synchronized move from X0 Y0 Z0 to X10 Y0 Z-10, which broke my tap.
I’m sure the rigid tapping is working normally if I do “G0 X10 Y0” first and then “G33.1 Z-10 K0.7”.

It worked properly before this:

(N/A)

Information about my hardware and software:

* I am using this Linux distribution and version (often, shown by lsb_release -a): Not relevant I think.
* I am using this kernel version (shown by uname -a): Not relevant I think.
* I am running …
* [x] A binary version from linuxcnc.org (including buildbot.linuxcnc.org)
* [ ] A binary I built myself
* [ ] A binary version from some other source besides linuxcnc.org
* I am using this LinuxCNC version (shown in package manager or, for git versions, scripts/get-version-from-git): 2.7.12
* I am using this user interface (GUI) (e.g., AXIS, Touchy, gmoccapy, etc): AXIS
* I am using this interface hardware vendor and chipset (e.g., parallel port, ethernet port, FPGA card): Parallel Port

#1 – SebKuzminsky 于 2018-04-11

Yikes!

I think the expected motion of your G33.1 X10 Y0 Z-10 K0.7 should be equivalent to:
~~~~~
G0 X10 Y0
G33.1 Z-10 K0.7
~~~~~

This motion would be analogous to (for example) G81 X10 Y0 Z-10.

I’ll look into it.

#2 – jethornton 于 2018-04-11

Docs should say it will tap on a traverse move from start to specified location. AFAIK it’s been like that from the start.

#3 – SebKuzminsky 于 2018-04-11

I, too, think that the observed behavior has been around for a long time.

Updating the docs to match this observed behavior is probably a good start, but is that behavior what we want it to be?

On a mill i think “diagonal tapping” is not ever useful, but maybe on a lathe it is, for single-point thread-cutting a tapered tread?

#4 – SebKuzminsky 于 2018-04-11

@cradek educated me some about this in IRC: G33.1 is not meant to be limited to tapping along Z, it is intentionally able to tap in any direction. This is not useful on an XYZ mill, but it is useful on 4- and 5-axis mills. It’s the documentation/warning that is wrong.

#5 – jethornton 于 2018-04-11

I’ll fix that ASAP

#6 – andypugh 于 2018-04-11

On 11 April 2018 at 19:36, Sebastian Kuzminsky
wrote:

> On a mill i think “diagonal tapping” is not ever useful, but maybe on a
> lathe it is, for single-point thread-cutting a tapered tread?
>
I think it could be.

Imagine rigid tapping a sloping hole on a machine with a tilting, but not
CNC-controlled head:
https://photos.app.goo.gl/2BemFuPi0w9MJoWg1

—
atp

#7 – SebKuzminsky 于 2018-04-11

Code inspection reveals that G33.1 (rigid tap) only accepts XYZ, not ABC or UVW axis words. So it’s not the case that the current behavior can be used on 5-axis mills. G33 (without the .1) does accept all 9 axis words, and might be used on 4+ axis mills for spindle-synchronized motion along arbitrary vectors.

#8 – jethornton 于 2018-04-11

Documents fixed.

原始Issue: https://github.com/LinuxCNC/linuxcnc/issues/428

Here are the steps I follow to reproduce the issue:

This is what I expected to happen:

This is what happened instead:

It worked properly before this:

Information about my hardware and software:

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