G32 and Feed per Rev Issues

[blowlamp]

I've just used these gcodes for the first time in TNG and came across a few oddities.

Firstly, when using G32 or G95 I found that TNG wouldn't start to feed the tool if the spindle happened to be above ~ 450/500 rpm, instead, all lathe carriage movement halted until I reduced the spindle speed.

When cutting a 0.6mm thread I found a pitch error, this turned out to be because I'd altered the onscreen feedrate widget to 70% and this was carried through into the G32 gcode (and G95 too actually), but cut a very nice thread when reset to 100%.

My spindle encoder has 100 holes including 1 index signal and gives very stable & accurate RPM readings up to the lathe's max of ~ 2500 rpm.

My Settings File is included.


Thanks, Martin.

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[PlanetCNC]

Perhaps index signal is not detected if RPM is too high?

[blowlamp]

Perhaps index signal is not detected if RPM is too high?

If I select 'From Index' in the Settings Menu I get perfect RPM readings up to the lathe's maximum speed.

I'm pretty sure TNG software v 2017.10.30 worked OK, in fact, up to the point that the steppers just couldn't keep up.

When the lathe does start to move there is no jitter or judder, it's like there's a switch that activates around 450/500 rpm to cut the feed.


Thanks, Martin.

[PlanetCNC]

I will definitely investigate this.

[blowlamp]

I will definitely investigate this.

That would be great!

Thanks very much.
Martin.

[blowlamp]

Quick update.

I got the RPM figure wrong - the feed cuts out if the spindle is much above 350 rpm.