Centroid Community CNC Support Forum

Friends machine.
Machine Specifics:
3 Axis CNC Knee Mill
Acorn driving closed loop DC Brushless servos
Durapulse GS3 VFD Low RPM tuned to within 20rpm of commanded speed.
100 Renco Line Driver/Differential Encoder its what he had. We thought we would give it a go.
CNC12 P34 = -400.00000 - Spindle Encoder Counts/Revolution (Verified 400 counts to one turn of the spindle on the PID screen)
Rigid tapping settings are all pretty much the default settings.


Issue:
When trying to run a tapping cycle created with Intercon
When it gets to the G84 X0.0 Y0.0 Q0.313 Z-0.9 R0.1 P0.10
Line, the control faults with a "Z Axis Max Rate Exceeded" and a 330 Canned Cycle Error: Normally, yes, we would run a 1000line encoder. Is the "Z Axis Max Rate Exceeded" error a direct result of the low encoder count or something else?
Thanks in advance.

Marty

Z axis max rate is set to 20 but not sure what the thread pitch is that you are cutting. Maybe 20 is too low?

Dave C.

the programmed pitch and rpm determine the Z axis speed that the machine needs to move, the error message is saying the the machine configuration Z axis rate is lower than the programmed pitch and rpm need for the tap to move up and down the hole without breaking it.

so pitch could be wrong, RPM too high or Z max rate too low. and has nothing to do with the encoder counts.

cnckeith wrote: ↑Sun May 30, 2021 8:08 pm the programmed pitch and rpm determine the Z axis speed that the machine needs to move, the error message is saying the the machine configuration Z axis rate is lower than the programmed pitch and rpm need for the tap to move up and down the hole without breaking it.

so pitch could be wrong, RPM too high or Z max rate too low. and has nothing to do with the encoder counts.

AH! (Slaps self on the side of head!)

24TPI thread

Axis Slow Jog Fast Jog Max Rate Deadstart Delta Vmax
(in/min) (in/min) (in/min) (in/min) (in/min)
1 20.0000 20.0000 75.0000 5.0000 5.0000
2 20.0000 20.0000 75.0000 5.0000 5.0000
3 10.0000 10.0000 20.0000 5.0000 5.0000

Also a couple other things don't look right now that I look at his report...will investigate further.
Thanks Dave_C & Keith!
Marty

Your program feed rate is for 32 pitch, not 24. Can't help with the rest, but at 640rpm you are only moving 20ipm.

We resolved the issue
Working on correcting the encoder counts in the Logosol drives. Then he'll fix the turns ratio. Well then bump up the max feed rates.

Update on this project.
Got the drives (Logosol) configured properly, and the turns ratios corrected.
Also upgraded the spindle encoder from a 400 line to a 1000 line encoder.

Rigid tapping:
We seem to be able to tap in MAX two passes ok. Tested in machinable was and thread were perfect.
But trying to do peck tapping is yielding "438 Spindle slave position error" as SOON as it starts the tapping cycle.
Has me scratching my head.
Hoping those more familiar with Rigid tapping and its settings can lend a hand.
FRESH Report attached.

Marty

Marty,

I'm not sure if this will help or not, it's been years since I set my mill up, but I had a similar issue when I tried to do rigid taping.

The way I cured my problem was to set part thread start position high enough above the part so the spindle had time to establish before it started the thread. The ridged taping cycle does not work well if you define "short" thread depths! You can do short threads by making the hole appear deeper than it really is, IE a false top location.

Dave C.

Dave_C wrote: ↑Mon Jun 21, 2021 11:34 am Marty,

I'm not sure if this will help or not, it's been years since I set my mill up, but I had a similar issue when I tried to do rigid taping.

The way I cured my problem was to set part thread start position high enough above the part so the spindle had time to establish before it started the thread. The ridged taping cycle does not work well if you define "short" thread depths! You can do short threads by making the hole appear deeper than it really is, IE a false top location.

Dave C.

Thanks Dave. May give that a shot. Right now Intercon defaults to .1" above the part.

I find it odd that it will tap a full depth hole or a hole with two passes ok. But not multiple....

Marty,

Here is my old video with some info on what I changed, at least I think it is there!

https://youtu.be/772VcHhFSV0

Dave C.