Circular Pocket diameter off (Resolved)

[Ruben]

Hello to all.
I'm new to CNC, nevertheless, I needed to ask for advice.
I setup up my mill (PM-25MV) to run with the Centroid Acorn board using the current ver of CNC12.

I'm trying to do a 1-inch circular pocket and the diameter and enter 1.0 inch as the diameter, but the hole comes out bigger (1.115").
The only way I can get the 1-inch hole is to enter .889" as the diameter when programing the circular pocket using the 3/8" end mill.

Any suggestion would be greatly appreciated.

Thank You: Ruben

[carbuthn]

Unfortunately you didn't include your information from the wizard / report so that I compare to my PM-25 settings. There are several possibilities, turns per inch of the lead screws, backlash, slipping coupling or tool dimensions / diameter wrong.

After I got my machine tuned it was fairly close to desired hole size, a few spring passes often made it right on.

You didn't say which software you were using, I use Fusion 360 and in the tool setup you can leave or add material to leave on the wall of the hole, I often will cut the hole minus a few thousandth and tweak the hole size a few ten-thousandth at time till I have what I want.
Hope that helps, Chuck

[Ruben]

Hi Chuck

Here is my report. I'm using the Intercon software that came with the Acorn board to program the parts.
What I haven't setup is the turns per inch of the leads screw, and checked the backlash. I believe that may be the problem.

Thank You: Ruben

[Nigelo]

You cannot expect to successfully run any job until you have accurately calibrated TPI of all axis. In fact my advice is not to even try. When you are within the accuracy specs of your machine after accurate measurements (assume a few tenths of a thousandth of an inch), only then proceed to backlash calibration.

Then you can run some test jobs

[Ruben]

Thank You Nigelo for the information. That is what I intend to do, Calibrate the TPI on all axis.
Everything has a learning curve, This is why I opted to post the issue, to get advice from those with more knowledge about these subjects.

Thank You Ruben

[cnckeith]

Hi, be sure to set the steps per rev on your drive properly and make the wizard match, you currently have it set to 1000 steps per rev which is low for a milling machine, min. recommended is 1600.
viewtopic.php?f=63&t=1801

then go set the overall turns ratio. lots of videos and documents on this forum on how to do that.
viewtopic.php?f=61&t=1449

[cnckeith]

oh and please install the latest cnc12 for acorn v4.64
https://www.centroidcnc.com/centroid_di ... loads.html

[martyscncgarage]

HI Ruben
Could you please follow this post in order to provide more details about your build?
viewtopic.php?f=60&t=1043


What type Axis drives do you have? Make and model? Link to the manual
Axis motors? Stepper or Servo?
What ball screw pitch?
Are motors direct coupled to the ball screws or is there belt reduction? Do you know the ratio?
Pictures of your control cabinet and machine would be a big help

The more information you provide, the better suggestions we can make. As Keith pointed out 1000 motor steps per revolution seems low.
Get your electronics setup and then you can use the attached guides to help fine tuning things (don't go to fine tuning until your axis drives are properly configured and the Axis configuration is properly setup in the Wizard as well.
Do get upgraded to CNC12 4.64

Marty

[Ruben]

Hi Keith & Marty
Using Teknic ClearPath SDSK servos. (SDSK-2321S-RLN on the X,Y axis and SDSK-2331S-RLN on the Z axis)
Also the Ball Screw Kit from ArizonaVideo for the PM-25MV mill. Direct mount to the ClearPath servos. I measure the ball screw pitch and it was 5.
Included are pictures of the enclosure, also website link to the servos.

https://www.teknic.com/model-info/CPM-SDSK-2321S-RLN/
https://www.teknic.com/model-info/CPM-SDSK-2331S-RLN/

Just want to thank you for your help, also all the great YouTube videos which have been instrumental in setting the CNC mill up.

Thank You: Ruben

[martyscncgarage]

So did you get things resolved?
Did you set your motor steps per rev correctly in the Teknic MSP software and then in Centroid Wizard Axis Configuration?
Did you get your axis calibrated correctly?
Post a FRESH report