The designer opted for a fixed bed and this adjustable focus head https://a.co/d/bL2HNDZ but looks a less adjustable than current trends
As I’m married to a fixed bed with this design, when researching adjustable focus laser heads, there doesn’t seem to be a lot of information out there. So far I’ve found references to Russ Sader and his lightweight laser head and and another company American photonics K40 - Adjustable focus Head upgrade – American Photonics
Most of the post’s are from 2-4 years ago and I guess I’m surprised there aren’t more widely available options or more at least more evidence of their use.
When simply googling adjustable focus laser heads, this is the frequent result.
It looks like you may be conflating two concepts: the ability to change lenses of different focal length and the ability to adjust focus for a given lens. The former provides for providing different cutting properties with each lens while the latter allows for optimization or adjustment of focus within a given focal length of lens.
Of the links you provided, I think the American Photonics is the only one offering variable/adjustable focus. The others to me look like they offer the ability to accommodate different focal length lenses although I may have missed something.
Most CO2 lasers rely on a fixed focus approach where the material is brought to the laser’s optimum focal length rather than the laser being brought to the material. You may want to consider a solution that allows for varying the bed height or being able to otherwise vary the height of the material on the bed in order to achieve focus. Perhaps by stacking risers of known height below the material.
When you install a lens in a lens tube, the point of focus is fixed with respect the the lens tube. (This is why you can make a focus block, as the focal point is also fixed with respect to the end of the nozzle on the lens tube.)
The lens tube can move within the lens tube holder on the laser head.
Assuming you have your beam path dialed in, there’s little reason for you not to vary how deep you set the lens tube in the laser head’s lens tube holder.
For my engraving, I bought an extra 4" focal length lens and set it up in this Cloudray lens tube in the “wrong” spot pointing the “wrong” way so that the focal point is an extra couple inches from the end of the nozzle (which I also widened slightly). That gives me plenty of clearance so I don’t crash into my chuck rotary, and it also means that my purge/cooling air stream basically doesn’t reach the surface, so it doesn’t blow soot and smoke onto the project.
I’ll often use that “engraving” setup and another lens/lens tube configured for cutting in the same job. I set the bed height/focus with the “cutting” lens tube, which puts the bed slightly too low for the “engraving” lens tube. Then I jog the machine to a clear space, swap lens tubes, jog back over my stock, and just loosen the lens tube holder clamp and let the lens tube slide down to touch my “engraving tube” focus block. It’s not bottomed out, but that doesn’t matter.
If you have a fixed bed, you could get some focus adjustment by creatively setting up your lenses/lens tubes and varying precisely where you have them clamped in. Of course, it will depend on lenses, lens tubes, and how your specific laser head holds/clamps the lens tubes, but you’ve got a lot to work with.
Thanks for the reply! I am definitely looking at bringing the head to the material.
Is there a specific reason that affects performance as to why it’s a suboptimal setup, other than there’s little hardware or support? Which is definitely reason enough to consider an alternative solution.
The knob for the table is in the front of the machine and very easy to adjust. I use a stepped guide to get me where I want to be which depends on the lens tube, nozzle that I use. You can also stack them …
If you’re cutting anything of depth, such as 10mm acrylic, you need a 4" lens focused in the middle of the material. Easier to dial in with the table knob than with the lens hold down.
Broken tube, cut wires, and beat to heck enclosure. These I knew ahead of time. But what I didn’t know was that parts of the PSU flyback were scattered everywhere. Even in the tube compartment.
This thing is in such bad shape that I can’t possibly think of any normal use that could cause this kind of damage. I almost think it had to be intentional
For what I paid, it would have been a steal if the PSU worked.
