Homing based on motor stall - possible?

[wolfkabal]

Hi all! Have loved my Acorn on my Grizzly G0619 conversion for years now (paired with a Gecko G540). I recently took the dive and acquired the OneFinity (Woodworker) CNC. Hobby/Prosumer CNC Router - on the same vein as a Shapeoko XXL or X-Carve. It uses the Buildbotics controller, which I'm 100% not a fan of.

Based on my experience with the Acorn and CentroidCNC, I was thinking of simply throwing this onto that unit. One thing the Onefinity/Buildbotics controller does though is homes based on motor stalling - no limit switches. It homes until the motor reaches an end-stop, detects a stall, backs off, and sets the homing position. I'm not a huge fan of this, but for this type of machine, it's not too far fetched.

So my question, does the Acorn support some type of stall detection and/or homing based on this?

This won't stop my conversion, and if I have to add limit/homing switches, that's fine - but was curious of the capabilities.

Thanks!

[cnckeith]

what motor drive as they using?

[martyscncgarage]

Hi all! Have loved my Acorn on my Grizzly G0619 conversion for years now (paired with a Gecko G540). I recently took the dive and acquired the OneFinity (Woodworker) CNC. Hobby/Prosumer CNC Router - on the same vein as a Shapeoko XXL or X-Carve. It uses the Buildbotics controller, which I'm 100% not a fan of.

Based on my experience with the Acorn and CentroidCNC, I was thinking of simply throwing this onto that unit. One thing the Onefinity/Buildbotics controller does though is homes based on motor stalling - no limit switches. It homes until the motor reaches an end-stop, detects a stall, backs off, and sets the homing position. I'm not a huge fan of this, but for this type of machine, it's not too far fetched.

So my question, does the Acorn support some type of stall detection and/or homing based on this?

This won't stop my conversion, and if I have to add limit/homing switches, that's fine - but was curious of the capabilities.

Thanks!

Not enough information provided. Provide examples of the motors/drives used. Video clip of it operating.
Clearpath has such a feature....

Marty

[Bender_Is_Great]

TI DRV8711 driver chips are used in the buildbotics controller.

[martyscncgarage]

TI DRV8711 driver chips are used in the buildbotics controller.

No, then.
There are no stepper drivers built onto the Acorn. That would make it too limiting. Acorn allows viturally any drive that can take step and direction input, from the most basic stepper drivers to AC Servo Drives.

I know Clearpath SDSK Closed loop motors allow homing to hard stops.
It should be trivial to add some decent proximity sensors for homing.

Centroid has been around for over 30 years and all they specialize in is CNC Machine motion control. True customizable PLC.
I like the idea that basically the same control that can drive their A590 5 axis CNC Head/Block machine, is driving Acorn:


Good luck!
Marty

[mschoonmaker]

@wolfkabal

I too have the Onefinity Woodworker CNC machine, and as my local makerspace uses the Acorn controller on their CNC, I'm interested in changing out the controller to the Acorn.

I have the same question; can the Teknic/Clearpath servos be used with the Acorn WITHOUT adding limit switches (Onefinity calls it "stall homing", Teknic/Clearpath calls it "hard stop homing")

[suntravel]

The stepper/servo drive must have an output which is triggert by an torque level reached, than you can use this output for the Home input on Acorn.

Uwe

[martyscncgarage]

@wolfkabal

I too have the Onefinity Woodworker CNC machine, and as my local makerspace uses the Acorn controller on their CNC, I'm interested in changing out the controller to the Acorn.

I have the same question; can the Teknic/Clearpath servos be used with the Acorn WITHOUT adding limit switches (Onefinity calls it "stall homing", Teknic/Clearpath calls it "hard stop homing")

I believe so, but you would manually have to set the control once homed.

Need to understand the CP homing process...

[rk9268vc]

i use clearpath SDHP servos and in their MSP software you can set up auto hard stop homing on enable. So when the mill is powered on, they all auto home to the hardstop and back off a set distance. then i just need to remember to hit the reset home button in cnc12

the auto homing is a feature of the servo driver, it doesnt need cnc12 to tell it to move, it is automatic

if you ever want to rehome, just disable and re-enable the servos for it to run again

it is a good idea in the MSP software to only auto home using like 25% torque or less to avoid wrenching on your ball nuts
you need to use their software to tune the servos anyways, it is trivial to enable the homing. like 2 clicks in the upper right

[cnckeith]

i use clearpath SDHP servos and in their MSP software you can set up auto hard stop homing on enable. So when the mill is powered on, they all auto home to the hardstop and back off a set distance. then i just need to remember to hit the reset home button in cnc12
it is a good idea in the MSP software to only auto home using like 25% torque or less to avoid wrenching on your ball nuts
you need to use their software to tune the servos anyways, it is trivial to enable the homing. like 2 clicks

yep! i played with this a few years ago, you can get it to work with Acorn. i never got around to documenting it $20 prox switches just work so well.....