I would not recommend this “laser in the base” setup. I saw an evaluation that showed the throughholes in the work bed actually went through into the interior of the case, that’s absurdly unacceptable. These things produce metal dust that is really bad for electronics and optics. I don’t know if they’re all built like that. The pic for yours does indeed seem to have the holes go into the case. I don’t see where they’d be able to mount a second wall inside, and if they did the dust would be trapped. And if they were doing that they’d just have made the case wall a normal solid wall and bolted the work fixture table on top with open sides on the gap.
Not all “JPT MOPA M7” of a certain wattage are the same product. I know the 100W had an “-E-” and “-E2-” version. The manual for my 300W lists two different part numbers with very different performance numbers. AND when I contacted JPT to get that manual, they said they couldn’t give me a manual from just the part number, they had to have my unit’s serial number. Because apparently they changed specs without changing the part number??? That sounds hard to believe. Actually the manual covered the two part numbers, nothing about any sub-variants within a part number. Maybe the JPT guy I was getting the manual from had this wrong.
I believe the “autofocus” is a simple Time Of Flight sensor alongside the motorized up/down buttons.
I haven’t worked with one, but a ToF sensor is not likely to be accurate enough, or even work right in enough cases for me to want it. It targets a spot offset from the center, so it would be useless for, say, engraving a coin. Or any small object.
The depth of focus on a F160 110x110 lens is a mm or so.
There is a “true” dynamic focusing galvo system that dynamically changes the focus at high speed during the marking. It’s something in the optics, it’s not raising and lowering the Z mechanically which would be far too slow. AFAIK it works from a scan taken first to map the height but I don’t know much other than knowing all the “autofocus” galvo products on AliExpress aren’t this.
The head I use has two red-dot laser pointers that you manually set up to converge at the focal point for the current lens. It’s quicker and simpler. It will get you “ballpark” but often you need to adjust a bit by hand to get the “biggest spark”
So far I’ve used the 110x110 lens quite a bit and has been my go-to size. I played with the 50mmx50mm lens, it was neat to see how small I could make detail but its DoF was so shallow a 1" area of blank PCB wasn’t flat enough to stay in focus (I’m sure I could take measures to flatten it, just saying, it’s difficult)
All lenses have the same trade-off due to diffraction rules:
- the spot size diameter of the focal point is proportional to the focal length. Half the focal length=spot diameter is half. Smaller spot allows for greater detail, BUT, you have to decrease your line interval by half and take 2x more passes to get a smooth bottom.
- Energy density at the focal point goes up with the SQUARE of the reciprocal of focus. That is, the area of a circle is pi*r^2. Half the radius is 1/4 the area. So much more energy density
- The Depth of Focus (DoF) is proportional to focal length. So the work under a 70x70 has to be really flat. DoF has a mathematical definition, but not an absolute discrete limit in reality- you’ll always lose a little performance being out of focus within the DoF limit, and it’s not going to suddenly stop cutting when you are out of focus by 101% of the DoF limit.
Also, the primary reason these galvo machines “can’t cut thick material” is the angle of the beam. The beam starts at basically the center of that lens and has a significant diameter up there- probably about 10mm dia? I don’t know for sure, I’ll try to measure soon. It starts at that diameter at the lens and focuses along a cone until it reaches that min focal spot size. Now, the unique feature of the “F-theta” lens is that all the focal points the mirrors can send it to are on the same plane, rather than a fixed distance which would have made its focal points along sphere.
The diffraction rule’s formula for spot size and DoF also takes the dia of the beam going into the lens, and that varies by setup. And it’s the opposite of what most people would guess- starting with a beam 2x wider before going into the lens means it focal spot decreases to 1/2, energy density increases by 4x, but DoF goes down by 1/2- notably this is the same set of effects you get when changing to a lens with 1/2 the focal length. Except you are physically still placing the work at the focal distance written on the lens.
I measured my spot size on JPT M7 300W YDFLP-E-300-M7-M-R with an F160 110x110 lens as being about 0.025mm.
That looks like a RC1001 galvo head. A cheap system is going to be that or the SG7110/RC7110. I have the SG7110 but paid about $500 for the faster SG7210 as an upgrade. I looked online and I don’t see consistent numbers on the specs so I can’t say whether SG7110 or RC1001 is “faster”.
They’re a bit subjective in that either one can go significantly faster but would be too inaccurate to cut like that. I did see one of the low-end systems on Youtube showing some pretty distorted marking at full speed so really that should not be rated for making at that speed. But you do need to do some tuning to get it working right to begin with and I think most users don’t even do that.
from Shinola certainly is a massive help.