Rigid Tapping Trouble <resolved, wrong encoder>

[PFM Dave]

Hello all,
So the last step on my CNC retrofit is to see rigid tapping working (later with single point) to call the project complete. I have attached the CNC code and the report file from my machine. I went through the steps for the tech bulletins and also read posts here that may be of help. Still not good luck.

So the code is from Fusion360, it did not include a Q factor for the tapping line, I hand edited it. The code center drills a hole at X0 Y0, drills it to size and then tries to tap the whole. The first steps run just fine. The tap then taps the hole, pauses, turns two revolutions CW with no Z movement, the the spindle runs CCW and backs out of the hole. No I am not crazy I recorded the process in slow motion and watched it too many times. I am doing this on machinable wax so the two revolutions destroy the threads.

Some will notice the tap speed is 750 RPM, I picked this RPM to give the mill a bit more power. I am unable to get the Centroid Conversational programing to generate tapping code, that will be a different thread.

Reading other tapping posts I see no setting to change to prevent this so I do hope someone here can spot the smoking gun and help me to complete this project.

Regards,

PFM Dave

[cncsnw]

Just as an experiment, try hard-wiring your spindle brake so it is always released, and remove the SpindleBrakeRelease definition from OUT3.

Using SpindleBrakeRelease introduces a time delay after the spindle start command, before the spindle actually starts. It is conceivable that is affecting the CCW restart at the bottom of the hole.

[PFM Dave]

CNCSNW,
Thanks for the reply, so I understand you just for a test unplug my spindle brake so it is always free to turn, then Remove (like rename it?) the SpindleBrakeRelease definition from Out3. I am not 100% sure I follow you on that but will investigate it. I don't quite follow why this would introduce 2 CW revolutions after the bottom was reached and before activating the CCW spindle. It is these 2 CW revolutions with zero Z movement that appears to destroy the threads. I believe if in metal it would break the tap.
I see you on lots of posts so respect the experience. I will take a look.
Regards,

PFM Dave

[PFM Dave]

Update,
Well typing this for the second time.... Hummm
I took the advise of CNCSNW and disabled my physical spin break. I thin looked for any file similar to "SpindleBrakeRelease" and found nothing. So any hint on where to look for this would be helpful. I looked at the M5 Macro for the spin break and as a test added some time (.1 Seconds up by .05) to the G4 delay in the macro and tried my tap code again. It did improve but did not tap. The spindle slowed and stopped on its own, reversed spindle direction and back out on the Z axis. However the threads in machinable wax were still destroyed. It was not obvious as to when they were destroyed. I thought to make some parameter setting changes to see if I could get improvement also considered using some tougher plastic as a test. Knowing the parameter changes are out of my depth of understanding I decided to update my post here for some addition advise.

Thanks in advance,

PFM Dave

[suntravel]

Related reading:

https://centroidcncforum.com/viewtopic. ... 357#p88357

Uwe

[PFM Dave]

Suntravel,
Thanks for the link! I enjoyed the post but still not clear on my trouble. I do understand the Q value needs to be set however have no idea where it comes from. I am trying with a 10-32 tap and used a Q value from the manual listing for an 8-32 tap. I assumed the 32 pitch thread "should" match. As stated above I am not able to use intercon for reasons I cannot explain. It will not allow me to complete the form and therefore will not post code.

The code I posted above was from Fusion 360 and had no Q value. I will review the post you linked and look for the Fusion 360 solution provided. I would have hoped the post processor was updated now but it does not seem that way.

Can someone provide more insight to the "Q" value needed for rigid tapping?

I feel like it is getting closer but still not hitting the mark.

Thanks in advance to all.

PFM Dave

[suntravel]

fusion PP with mod for rigid tapping attached

Description of Q in G84 is in the mill manual.

Uwe

[cncsnw]

I thin looked for any file similar to "SpindleBrakeRelease" and found nothing. So any hint on where to look for this would be helpful. I looked at the M5 Macro for the spin break and as a test added some time (.1 Seconds up by .05) to the G4 delay in the macro and tried my tap code again. It did improve but did not tap.

This is an Acorn control, is it not?

Did you not use the Acorn Wizard to assign functions to your PLC inputs and outputs? For example, to drag the "SpindleBrakeRelease" function onto OUT3?

To remove the SpindleBrakeRelease function from OUT3, you would go back to the Acorn Wizard, find the I/O assignments page, and drag "SpindleBrakeRelease" out of the OUT3 box, so that box is left blank (no function assigned to it). Then you would tell the Wizard to write your changes.

[PFM Dave]

CNC Keith,
I looked on my Mill12 install for the sample programs you mentioned and do not find them, I searched on the Centroid Web Site did not find them, looked here on the forum as well, no luck. Can you please provide me a link to the test files you mentioned in a post now missing.

CNCSNW,
Yes it is a Centroid Acorn install however I did not understand what you meant so I was looking for a file. I follow you now and will work on another test tomorrow.

Suntravel,

The description in the manual is not clear to me and does not allow me to calculate a “Q” value by hand. Again the rigid tapping in the conversational programming is not working, required fields cannot be filled in so cannot post. Thank you very much for the modified post processor, I will give it a shot as soon as possible.

[PFM Dave]

I cut that off short sorry, Thanks to all who are trying to help this old guy complete this CNC mill upgrade to Centroid.

PFM Dave