Laser focusing methods for a large, open membership of new users is often rather error-prone, and some errors can damage the machine. So, one night I came up with this idea, and it looks pretty intuitive and awesome, as well as accurate.
They make green laser pointers that project a cross. There will be one mounted off to the side, and project at an angle. Since it’s at an angle, the green cross center will shift with the height but the red dot will not. The cross and red dot converge at the focal point. You can see it moving to one side or the other with Z UP/DOWN so pretty intuitive to make them converge without thinking about which way it needs. Clear acrylic is a problem, as this projects through and all you see is it on the honeycomb. I believe we can easily explain that you need to put paper on top of acrylic (or very black stuff) to see the cross there.
We need a mount. This green cross module is 9.2mm diameter. It needs to be adjustable, accurate and hard to shake or bump out of place.
This is a CNC’ed aluminum tube mount, but it is meant for a larger tube and does not fit. I don’t see sticking something in here as a shim to make it fit. Also, this design is poor as there’s only one screw to tighten the tube ring and the angle of the pointer, instead one tends to engage first and leave the other loose. It needs to be strong and rigid and exposed to a lot and I don’t picture 3D printing as a good option.
Mounting on the tube has pros and cons. The tube with the lens inside can be raised and lowered for machines without a powered Z, but we DO have a powered Z, so the tube should stay up. But someone might mistakenly move it- at least the focal point will not be thrown off if it’s mounted on the tube. However, the tube is removed to access the lens, and the pointer and wiring there complicates this.
I’m picturing replacing this inductive prox sensor (that method has risks) with the pointer mounted at 45 deg, or even a bit more horizontal. Same 2 attachment screws up top as shown. The mount would need to stand the pointer off more than the prox sensor so there’s no Y offset that would require a weird mounting angle. It is good to keep the weight down so the head can move fast. Again, needs to be adjustable in angle and height and the pointer should be removable.
I worried about interference with the machine when the axis moves far-left, but the pointer is under the XY support at that point. It looks clear to poke a little further out than the current piece. The module must be set far back enough that the cone can be unscrewed downward without interference. The laser module can be rotated with its cross. When looking at it from above, the cross will likely be at 45 deg, not vert/horizontal, since the right horizontal side of a cross projection would partially clip against the cone in this orientation.
Thoughts? Anyone want to fab one?