E-stop did not stop VFD, spindle or IoT Power Strip

CNC Brands Onefinity
1

My CNC & Spindle have been working just fine until last night I had to hit the e-stop on the BB Controller, the CNC stopped but the spindle kept spinning at 18k and the vacuum connected IoT Power Strip continued to run. Since the spindle did not stop and my Z-20 slider drops after power shut down the end mill plunged all the way thru the waste board and beyond (secondary issue). Is there a setting in the Buildbotic controller or the VFD to have all items stop upon e-stop activation?

Thank you for your help

Brian

Onefinity PRO Journeyman (BB controller)

PWN CNC 2.2kw 220v Spindle System (v5 VFD)

2

Hey Brian,

yes, the original Buildbotics.com controller and its Onefinity software and hardware fork supports an “estopped” mode that stops all motors including the spindle and any router which is controlled over a relay by pin 15 (“tool enable”) on the 25-pin I/O port. However if it is a buildbotics-forked Onefinity controller, you got to know that the big red mushroom-shaped button on top of the housing DOES NOT stop anything else than the CNC Controller’s internal power supply. Therefore, this button is nonsense because it does not provide a global safety function for the system.

You may however easily convert this to using the real “estopped” mode which buildbotics-type controllers provide by rewiring the big red mushroom-shaped button to the “estop” pin 23 on the 25-pin I/O port. See the HOWTO posting below.

The “estopped” mode can also be activated by clicking the yellow/red button displayed on the top right of the user display.

The professional way to implement a safety stop for a CNC machine with a VFD/spindle is to use a ISO 13849 Safety relay such as a Omron G9SE (datasheet), wired as follows:

Omron_MX2_Manual_-_ISO_13849_Safety_Relay
Omron_MX2_Manual_-_ISO_13849_Safety_Relay581×276 20.1 KB

After the emergency stop is entered, you cannot restart the system before having pressed the reset button. This is the standard in VFD control cabinets:

Mechatron_Control_Cabinet_with_Omron_MX2_and_Omron_G9SE
Mechatron_Control_Cabinet_with_Omron_MX2_and_Omron_G9SE1602×855 109 KB

3

HOWTO convert the big red mushroom-shaped button on top of the buildbotics-forked Onefinity Controller housing to use REAL “estopped” mode

Problem: On the buildbotics-forked Onefinity CNC controller of Onefinity PRO, X-50 and Original Series, the big red mushroom-shaped button on top of the housing DOES NOT stop anything else than the CNC Controller’s internal power supply. It does not stop the spindle or the router. Therefore, this button is nonsense because it does not provide a global safety function for the system.

Solution: Rewire the big red mushroom-shaped button to use REAL “estopped” mode which will stop the spindle via its VFD, or any router connected over a relay on pin 15 (“tool enable”).

HOWTO:

  1. Make sure the Controller is disconnected from power. Open the case according to the video for v4 version (power button is a rocker switch) or v5 version (power switch is a pushbutton).

  2. Cut all cables (red and black) that are connected to the big red mushroom-shaped button.

  3. Wire the two power cables that were going into the big red mushroom-shaped button directly to those which came out of it (which go to the AVR mainboard), red to red, black to black. You can now reassign the button to another function.

  4. Now connect one input pin of the big red button to “EStop” (Pin 23) of the 25-pin I/O port, and one output pin of the button to “Ground” (Pin 25) (=Logic low).

Onefinity_Buildbotics_Controller__IO_Configuration_Tab__Setting_estop
Onefinity_Buildbotics_Controller__IO_Configuration_Tab__Setting_estop1287×1141 109 KB

  1. Now in the “I/O Configuration” tab of the user display, activate the “estop” button function for real estopped mode (image above). If you connect a “Normally open” Switch (NO), then “estop” must be set to “normally open”. If you connect a “Normally Closed” Switch (NC) you must set it to “normally closed”.

Of course you can also install a big red mushroom-shaped button in a place where it is better accessible, e.g. on the front of the machine. You can buy buttons with their own external housing:

XALK178E
XALK178E475×468 63 KB

By using a “Normally Closed” switch, you make sure that “estop” is active in case the button is missing or one of its wires broken.

                POSSIBLE
PIN	 NAME	I/O	VALUES	        DESCRIPTION
---+-------+---+-----------+-----------------------
23 | EStop | I | Open, VIL | Emergency stop switch
---+-------+---+-----------+-----------------------

LOGIC 
NAME   MINIMUM MAXIMUM   DEFINITION
------+-------+---------+----------------------
VOL    0       0.76 VDC  Logic output low
VOH    2.6 VDC 3.3 VDC   Logic output high
VIL    0       0.6 VDC   Logic input low
VIH    2 VDC   3.3 VDC   Login input high
V3.3           3.3 VDC   Voltage found on V3.3
                         Output when unloaded

Pin 20 should measure 3.3 V against ground.

5

Hey Brian,

yes, by rewiring the big red mushroom-shaped button to pin 23 (“estop”) and 25 (“ground”), the controller will behave exaclty as if you click on the red/yellow estop icon on the top right of the user display, which means, it will not only stop the stepper motors, but also the spindle and the router as well.

If I find the time, I plan to make a photo howto of the conversion procedure. At same time I plan to show how to place a big 120 mm fan into the top of the case, and to place the red button to an external position on the front of the machine.

What it will not do, is to cut the power to the controller. So if you need an emergency power off (which is not the same as emergency stop) as well, e.g. for cases of fire, I would additionally wire a different emergency button in the global power supply of the entire system. and place it next to the door. This way you could make the entire system powerless before using a fire extinguisher.

Which grub screws do you exaclty mean? A photo would surely help if someone is interested in trying this out. Or a link to the video. The “spindle drop” problem usually arises when converting from Z-16 to Z-20 slider with its steep ball screw. On the Z-16, the ball screw is not as steep, so a 2.2 kW spindle does usually not drop on Z-16.

The correct way to prevent spindle drop on poweroff, i.e. that stepper motors begin to move by gravity when their holding current is cut, is to replace the Z stepper motor by a stepper with integrated brake. That is a stepper whose axle is blocked permanently (the axle is braked) as long as its brake is powerless. To use the stepper, you need to apply 24 V DC to the brake so that it releases the axle. This prevents spindle drop on power cut. Onefinity offers this for the Elite/MASSO Series here, but this closed-loop stepper motor is not compatible with the buildbotics-derived Onefinity Controller of the Onefinity PRO/X-50/Original Series. For these you would either use an open-loop stepper motor with brake and need to create a circuit that implements:

Brake is fixed (brake release power is cut) at:

Alarm Signal active
Enable Signal inactive
Error in the power connection of the motor
Error in the power connection of the brake

…or you would first need to implement access to the internal axis control lines, in order to be able to attach an external stepper driver for closed-loop steppers.

The word “forked” above is a link! If you click on it, you get the explanation :slight_smile:

It means that Onefinity one day took a copy of the Buildbotics CNC Controller firmware and also of the Buildbotics hardware design, which are both free and open, and started to modify it, to have their own version of it, that suits their CNC machines (available under onefinity-firmware and onefinity-pcb).

The original Buildbotics.com CNC Controller supports many CNC machines, stepper motors and spindles and accessories, and is available under a free and open license, so anyone can fork it.