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Tool Offset Probe that I am working on for the new machine. The top was cut out with this machine the main body was cut out on my smaller/heavier duty machine.
I haven’t been on the forums here for a LONG time. Figure I should update the status of this machine
Now it’s closed looped. Finally got a VFD spindle for it. 2.2kw water cooled. Changed out the wasted board to PVC and did sheets vc one big sheet. This way I can just replace the ones that get really back vs the whole damn thing.
Open loop = no feedback. Tell it to move and you assume it moves. This is why you can lose steps and the machine not rectify it. Position is always an assumed position given the machine actually did what it was told to do. This is GRBL and Mach3.
Closed Loop = positional feedback. You tell it to move and an encoder/resolver tells you how much it moves, this data is fed back into the control loop and it uses it for the next motion command. The control system knows the reported position is the actual position and not an assumption. This allows the control system to kind of correct for lost steps or other issues. Theoretically, if you hit a clamp and can’t move, the Gcode wouldn’t keep telling the machine to move because the last command never finished (in a system that implements such control).
I’ve read some articles about open vs closed loop for CNC machines and opinions can vary. Since you are cutting as you move, if you cut off path, even if the machine corrects it, you still get a blemish on the part. Closed loop should allow for more accurate feed rates as the system can understand how the machine is moving and, in some systems, ramp up the power to move more inline with the commanded feed rate. also, my understanding is that only LinuxCNC runs closed loop for software based controllers. You basically have to be running at real time to be able to do efficient closed loop. At work, we have a closed loop system running at 1khz and it’s all embedded fpgas and dsp chips (not a CNC).
Wireless Touch Probe (/w its own offset G59.3 and G30. So when it tool change is needed, it goes to G30 I change the tool and it checks the offset and goes back to work.)
This is nice cause now both machines use the same motion controller and I can use the same PostProcessor.
The only thing I need to grab is touchscreen. And both setups will be the same.
I love these. Makes fixturing so much easier. If you have the option of use them, use them. You can machine/route around the part without worrying about clamps being in the way. The otherside effect is since this machine was completely designed in Fusion 360, In the CAM I can use the center of the puck as my origin. Or any aspect of the machine for example, the threaded inserts in the wasteboard. Since the positions are known I can set each one it’s own offset (if the part is small enough) Then set G54, G55 for side one and G56 & G57 as side two.
I finally now have a proper E-Stop that trips a relay which then drops the enable pin on the driver to low and sets the alarm pin on the VFD invert to high. This stops the motion instantaneously and the VFD shuts down and ‘brakes’ the spindle to a halt. (The VFD has an option for a braking resistor. Handy later when I build a tool changer)
The green button starts a job and the last button (mislabeled) turns the vacuum pump on & off.
Since I have a proper charge pump setup for active/e-stoped, i.e trigger the status LED to flash if a estop has occurred or an error like the gcode file is trying to extend beyond the limits of the machine.
These are pictures of the other mill making the vacuum vises (aka pucks)