Galvos and Alignment

You have noticed that one of my previous pics had the laser drawing very close to the side of the test container. It “should” be drawing directly below, so why wasn’t it?

I started to investigate several alignment issues last night:
-drawing off center
-“one” warped edge on square test (left side is bent)




I started by poking the Laser itself to see if it was pointing at the mirror straight.
The leads are long for the laser so it sticks out a bit from the PCB. I found it quite easy to eyeball the horizontal and vertical alignment of the laser and found that it was just fine. OF course, by poking it I misaligned it quite fantastically! I had lasers hit the wall occasionally and decided it was time to put on the supplied laser safety glasses. I will NOT be shooting my eye out with a 3D printer !! (Try explaining that to grandma !!)

Next was the galvos. Making sure that the galvo magnets are not touching the aluminum damper in the armature is important. What I didn’t realize yet was that the ROTATATION of the galvos around the armature is CRITICAL. The rotation sets where the laser is going to draw. This is why my test patterns were drawing off center.
(see second pic above. Top down view of vertical galvo)

Rotating the galvo on the vertical armature sets the Y axis (reference printer orientation is with the PCB facing the camera, See pics)
Rotating the galvo on the horizontal armature sets the X axis.

The galvo on the vertical axis is very loose on my printer. It doesn’t like to stay in its’ place. Eventually, I will have to do something about this. I would like to glue it but if I do, it had better be in perfect alignment or I’ll be stuck with it for good !!

So I have the patterns drawing in the center of the glow paper, I have a nice focused beam thanks to removing the clear layer from the mirror but I still have two odd problems.
-ONE side of the square is warped
-The square is not square (sides are not parallel)

I found the warped side problem. Earlier in the build I had to remove on mirror from the armature and stick it back on. Somehow I managed to get the thread under the end tip of the mirror. That curves the mirror surface at the end (..and where the laser draws). I still have to fix it but at least I know what’s causing it.

More to come…

Jason