Jogging at a certain angle (lathe mode)?

Aciera wrote:

I know some people will likely be rolling their eyes but a custom kinematic might be a solution for this.

Is this what is being done with the W axis in the 5 axis tilted drilling thread? While reading that thread I though it might be applicable to this topic, but I'm not exactly clear on what exactly is being done there, how the W axis works.

It's what many custom kinematics do. Including "5axiskins" it uses an angle value (usually A B and/or C axis) angles to transform a movement in X,Y and/or Z to the joints (ie motors).

branch available for test: dgarr/anglejog
sim config: configs/sim/axis/anglejog/anglejog.ini

Ref:
github.com/LinuxCNC/linuxcnc/commits/dgarr/anglejog
github.com/LinuxCNC/linuxcnc/commit/f186826988

see man page for usage info: $ man anglejog

dgarrett wrote:

branch available for test: dgarr/anglejog

Very cool!

I'm not able to test this at the moment, but looking at the code I'm wondering if it would be a good idea to decouple the input jog scale (anglejog.scale-in) from the axis & joint jog scales, and instead use a very fine-grained scale for the latter. E.g. fix those at 1 µm/count and do the appropriate scale conversion in anglejog. I'm imagining a rather horrible stair-step "line" to be the result of not doing this if using a coarser jog scale (say 1 mm/count). (Maybe I'm missing something though, from only reading the code.)

> I'm wondering if it would be a good idea to decouple the input jog scale

yes --
The original sim config addressed stairstepping by incrementing
MPG counts by 100 units so that a scale of .00001 would
correspond to .001 units. This type of s32 count-multiplication
is typically required when using an integer lowpass filter ($ man
ilowpass) on axis.N.counts and reduces stair-steps due to integer
counts handling at useful scales.

The updated branch includes a pin iscale-factor (default=10000),
and multiplies counts-in internally by the factor, divides the
current scale in-use by the factor, and outputs a corresponding
output pin current-scale-out for connection to axis.*.jog-scale.
The updated sim config increments counts-in by 1.


The branch update also provides for a jog-accel-fraction input pin
and scaled output pins cos-accel-fraction, sin-accel-fraction for
connection to axis.[NM].jog-accel-fraction pins. This facility is
useful in reducing shake for fine positioning (single count unit)
moves and often eliminates the need for filtering counts from an
MPG.

ref: github.com/LinuxCNC/linuxcnc/commit/d69b15cfe1ce40

arvidb wrote:

Aciera wrote:

I know some people will likely be rolling their eyes but a custom kinematic might be a solution for this.
Is this what is being done with the W axis in the 5 axis tilted drilling thread? While reading that thread I though it might be applicable to this topic, but I'm not exactly clear on what exactly is being done there, how the W axis works.
 

Just saw this:

It is the 5 axis bridgemill demo which appear to do exactly that. Meaning that the W axis is actually moving the tool along its rotational axis. Also mentioned on this thread: forum.linuxcnc.org/38-general-linuxcnc-q...ted-drilling?start=0

I'm far from being an expert but maybe this worth investigating the kinematics allowing this.