I had an SM Original for around 2 years and used it all the time, loved it. I was mainly laser engraving with that and I found that the focus point had the lens of the laser several inches above the surface.
My SM 2.0 arrived earlier this month and so far I’ve mainly been engraving but now need to do some cutting.
However, on my SM 2.0, the laser is focussed when the end of the lens is less than 5mm above the surface I’m working on.
This is fine for engraving, but if I want to cut anything, especially if it’s 3mm thick, it gets very touch and go on whether the lens will start dragging along the surface of the material with the Z-Steps. That’s not happened yet but I am really struggling to make clean cuts all the way through. I figure I need more passes and a slightly larger z-step but can’t risk it dragging.
Any thoughts or tips?
Interesting update.
When I first started using my SM2 a month ago, I did the auto focusing calibration and have been using it since. I’ve been doing great engravings with it doing dot fill down to 0.05mm intervals, it’s been coming out great.
Now however I’m wondering if the focus has somehow been completely off as I just re-did the auto calibration and the focus point now sits the lens 23mm above the surface. Doing a test now to cut 3mm ply but I’m very interested to know if the focus has been out by 20mm for the past month, what quality the engraving will get to now, where they have looked perfect to me for the past month.
The actual lens is up inside the machine. You’re probably referring to the lens hood, which can be removed. It’s purely a ‘safety’ thing to reduce the chance of stray light escaping, but I’d recommend just removing it if you need the extra clearance and make sure you and everyone don’t look at the laser dot without goggles on.
On the 1600mW laser the diffuse reflection of the laser dot on wood is not so powerful to cause eye injury as long as you don’t stare at it even without goggles. But take proper safety precautions regardless. Just providing some context for the magnitude of the hazard.
And to round this out, on tile or metal or shiny materials capable of a specular reflection that is quite dangerous, never be without goggles when the machine is running with those materials. The ‘safe’ distance to be away without goggles on is something like 1500 ft.
1 Like
Wow that’s really good to know about the safety thanks.
I’ve always tried to be careful during use. Presumably the safe distance of 1500ft is without any sort of protection between you and the beam/reflection?
I have the unit running in the corner of my room that I’m in most of the day. I wear the goggles when the laser is in low power mode whilst positioning the start point, and then only ever run the laser properly when wearing the goggles and have the enclosure doors closed. Once I’m happy with the project running, I have modified a waterproof BBQ cover to fit over my enclosure and so sit on the other side of the room, facing away from the SM with my goggles off and monitor it via 2 webcams in the enclosure. Does that sound ok to you or do I need to be more careful?
Right, making some worst-case assumptions about laser intensity and something shiny directly reflecting the whole beam into your eye. It’s fairly pessimistic to be conservative, but not entirely unreasonable.
That’s good, the enclosure does a good (not perfect, but good) job of mitigating most of the hazard. When doing wood or diffuse reflection materials I personally am comfortable being around the enclosure without goggles on as any stray light through the cracks will be low intensity for a brief moment and I can just look away, but I do have mine located in a spare bedroom and I keep the door closed when in use so exposure is limited.
General laser safety applies - for a diffuse “dot” if you ever see an after glow of the laser after you stop looking at it for more than a few seconds or you develop a headache those are signs of the beginnings of eye injury. For specular reflections the eye can be injured faster than the blink reflex can protect it.
That sounds close to ideal. Anything opaque to visible light like a bbq cover will fully block the beam since the beam is visible blue light. The webcam idea has been used by other people as well, seems to work great.
1 Like
Great thanks!
One more note on the BBQ cover since I’m on that now.
I’ve modified it so it is weighted on top and technically only covers the top and two door sides (as it’s sat in the corner of a room so the back and left side are around 8-10cm (the thickness of the extractor tube) away from a wall and never in line of sight. Do I need to be concerned about any light coming through either the back or side enclosure walls and reflecting off of the wall? Would it still be dangerous levels of exposure by that point? Not a massive concern as I could just add something like this to the back and side walls.
The wall will have a diffuse reflection (unless God forbid your walls are shiny like foil wallpaper) and also reduced by the enclosure. I am not concerned but be mindful if you develop headaches or something, obligatory “this is not medical advice and I cannot promise it will be ok in every situation”.
1 Like
Great, that’s what I thought. Thanks for your thoughts on it.
I’ll probably at some point add some sort of blocking film to the back and side so when it’s in use there really is no light escaping at all but I’m happy for now.