Rigid Tapping Not Working - Summary <resolved, works great with photos> >

[RJS100]

This post is a summary of a previous post that got very long and hard to follow.

Machine: Benchtop PM833-TV converted to CNC.
Spindle Motor: JMC 2.6 KW AC servo; belt driven 1.8:1
Encoder: Direct spindle read

Tested rigid tapping with a simple routine created in Intercon. I am experiencing the same problems I was having with the g-code created with Fusion.
The first time I run the g-code, the tap comes to the top of the part and returns without tapping. The next time I repeat the same code, the tap taps down to .700 inches as programmed. All looks good. Run the g-code again, and it does not tap down to depth.

All of my rigid tapping parameters match the base line tapping parameters in the Centroid tech bulletin except P37 which is set to .5 instead of 3 -7.

I have attached the Intercon & report file below.

Here is a video illustrating:
https://www.dropbox.com/scl/fi/vgfn3db1 ... q955o&dl=0

Not really sure what to try next.

Richard

[cnckeith]

link isn't working

[cnckeith]

post the intercon file as well please.

[RJS100]

Oops... Here you go:

https://www.dropbox.com/scl/fi/vgfn3db1 ... q955o&dl=0


Thanks... Richard

[suntravel]

Why is P68 = 689 and not default 640 ?

Your G-code is S 689 like P68....

11.3.55 Parameter 68 – Minimum Rigid Tapping Spindle Speed (Rigid Tapping Parameter)
This parameter holds the value that the spindle slows down to from the programmed spindle speed towards the end of
the tapping cycle. The lower the value, the more accurately the Z-axis will land on target, but at the expense of
possibly stalling the spindle motor, which in turn will cause the Z-axis to fall short. If this value is too large, the
off-target error will increase. The suggested starting value is 640 RPM.

Set P68 to a lower value or start tapping at more rpm.

Uwe

[RJS100]

To achieve an actual spindle rpm of 640 rpm, I set the speed to 689 rpm. I will change the P68 to 640 and test again.

[suntravel]

P68 ist the speed at the end of the tapping cycle, so you must start at a higher rpm....

Uwe

[RJS100]

WIll do. Do you think 700 is a fast enough starting speed.

[suntravel]

I am tapping this size with 1500 rpm with good quality taps...

Uwe

[RJS100]

I changed P68 to 640 rpm, and tapped at 750 rpm.

Unfortunately, it did the same exact thing. Sometime the tap reaches the top of the part and returns back up, and sometimes it tapped to the correct depth of .700"

Richard