Recently I have been in the business of DIYing laser cutters and the key problem I have encountered is how to go about designing the Z-axis. I believe the majority of laser cutters achieve this by moving the entire bed, however, I was wondering if it would be possible to move the lens position in the laser head, most likely through an adjustable sleeve that houses the lens.
When I was in school the maker lab had a couple of these CraftForge Laser Cutters which had a moveable lens (I could see the nozzle physically moving up and down inside the cut zone). However, I was unable to find any detail on how this mechanism was achieved.
Has anyone used a laser cutter with a similar “moving laser head” configuration for the Z or are there potential issues with these design that I have missed as shifting the lens seems a lot easier and less prone to mechanical error as compared to shifting the entire bed (especially as the cut area becomes larger)?
The real question is why machine designers, who are well aware of the issues and complexity are choosing to move the whole bed?
This will normally be for optic and alignment reasons, where moving the whole emitter and path up/down, or adding additional alignments, is actually harder and more expensive than just moving the whole bed. It can also give improved access when setting work up.
For fibre coupled lasers and diode laser modules it is totally normal to move the whole head up and down.
That is very true. Moving the laser tube and all subsequent mirrors would be a real pain (for a CO2 laser).
However, I was thinking along the lines of moving just the nozzle with the lens, since the focal length is determined from the lens to the surface of the material to be cut. Something like this:
Perhaps the issue would be fitting the linear motion mechanisms to the limited space at the laser head… Damn this makes me so curious as to how the laser cutter in my school’s maker lab did it
Will keep looking around and update this thread with anything I learn.
If you look around there are optimizations to lighten the “moving” head as much as possible and adding that type of mechanism you mention would add both a motor and some linear motion elements to not only the laser head but also to the nozzle hanging off the laser head.
It can be done it just means you’ll be limiting your max scanning speed.
