Just spent five minutes watching someone explain how to manually focus and autofocus for a laser cutter (the material was plywood, not several mm of sheet steel).
The autofocus in the video was very similar to the plasma touch-off sequence to ensure the tip of the laser is a fixed distance above the material being cut.
I found a manual for the RayTools BM111 and my reading of the manual is that it takes a 0-10V and moves the focal point by 22mm. The term "auto focus" appears to be used in the context of "automate the focus adjustment" and not "automatically bring a surface into focus" (similar to a camera auto focus). The 0-10V input and 0-10V output appear to be the two legs of a servo driver mechanism (RC aircraft servos have an internal potentiometer to provide feedback of the current position).
It appears that there is two Z axis positions with a fiber laser:
The tip of the cutting nozzle which is blasting out compressed gas (probably oxygen)
The focal point of the laser itself which is changed by adjusting the lenses inside the head block
So it looks like a touch-off is required to get the cutting nozzle position set and then a 0-10V signal is used to adjust the focal spot for optimal cutting.
During the last week or two I did see a posting about a capacitive torch height sensor for oxy torch cutting. You may need this to have the tip of the cutting nozzle track the surface of the sheet metal.
This is very interesting. A client of mine has the 1.5kw raytools fibre laser up the coast near where my machine is. Bloody impressive thing to watch. He imported it from China for around 45k I think. If there is an option for dual heads on a CNC I would love to fit a 40-80kw diode laser to the side of my spindle for laser jobs or even laser engraving then routing out the part.
Looking forward to seeing what you guys get up to here
@lilow - I am going to leave this with Breezy to figure out the details.
I have one small request - when you get this beast up and running please paint the chassis pure white and stencil "Great White" on the side. You will then you will have "a shark with a frickin laser on its head".
Sorry - couldn't resist. I did resist making the comment that you were hot rodding an old Multicam when you posted your conversion progress a week or two ago.
Now it's December with a lot more info to get trapped on.
Have searched the web for individually built Fiber Laser tables.
So now, it's on with it.
Since October when I asked if anyone had built anything like it, there were no replies.
Have spent 2 months after hours doing the preliminary drawings, now onto pulling individual mechanisms out and designing the actuators for the mechanical advantage.
As I started 20 years ago with a standalone Plasma CNC, I've found a Fiber Laser torch height control that might work with Masso with the right talking to it.
All servo motors have been ordered.
Have an X axis right angle drive ordered along with the 2 Y axis planetary gear drives.
There will be times when I might need some help as I have never put a new machine together in this format.
The Z axis servo with brake and encoder arrived today, hooked it up, gets an alarm but that would be normal as nothing is connected or sorted.
A copy of the servo manual here - https://drive.google.com/file/d/1R1iMjjqeNttTzBQ2LUrLpD26qpfniI9Y/view?spm=a2g0s.imconversation.0.0.44703e5f5nywE5&usp=sharing
If I can get this running at 30 to 60 M/min with perfect accuracy with the Masso G3 control, there maybe backing to go with it.
Last night ordered a Fibre Laser sensor head along with the pre-amplifier.
These work on an older style system.
Windows XP is predominate when looking here.
These 2 components work in a mode, which produces a di-electric field.
As I commented to a guy here who runs 3 Masso G3's.
The reason I purchased these items below is that the height sensing is capacitive.
The same as a NPN or PNP proximity sensor.
3 wire, must have a + / - and a signal.
The 4th wire is shielding for the other 3 wires.
They all work on a dielectric field which actually produces a voltage as an object gets closer to it.
This I have never checked on a proximity sensor, but would think that voltage would change until it's tripped a circuit.
At a specified setting.
If it does produce the variance of voltage as it gets closer to a common point, it gives another voltage as it's further away.
Here is something for you, I couldn't understand why all Chinese built Fibre Machines work on -10v to +10v on the height control.
Focusing the Electric Field
When a voltage is applied to a conductor, the electric field emanates from every surface. In a capacitive sensor, the sensing voltage is applied to the sensing area of the probe (Figures 3 and 4). For accurate measurements, the electric field from the sensing area needs to be contained within the space between the probe and the target. If the electric field is allowed to spread to other items—or other areas on
Figure 5. Cutaway showing the guard field shaping the sensing area electric field
Definitions Sensitivity indicates how much the output voltage changes as a result of a change in the gap between the target and the probe. A common sensitivity is 1 V/0.1 mm. This means that for every 0.1 mm of change in the gap, the output voltage will change 1 V. When the output voltage is plotted against the gap size, the slope of the line is the sensitivity (Figure 6A).
A system's sensitivity is set during calibration. When sensitivity deviates from the ideal value this is called sensitivity error, gain error, or scaling error. Since sensitivity is the slope of a line, sensitivity error is usually presented as a percentage of slope, a comparison of the ideal slope with the actual slope.
I can set this height control to work way better.
The +/-10V is probably due to using "operational amplifiers" (aka op-amps) which historically use +/- 15V (the reason for 15V is kind of lost in the mists of time). I have seen +/-10V on VFD drives where a negative voltage indicates spin in reverse. Perhaps the voltage range is to minimise the noise interference (better signal to noise ratio achieved by increasing the signal rather than reducing the noise).
If you have a +10V reference you can convert a +/-10V signal to 0-10V signal by using a pair of resistors as a voltage divider (output would be half way between the input and the +10V reference).