Laser alignment (bad focus lens?)

[fantasy2]

Hi all,

Please help me out, as my customers begin to complain:
Since I bought a HX6090 machine I have a problem with the laser beam. I aligned all mirrors to get the beam in the centre of all three mirrors and cutting went well, except that the edge on the left side of the workpiece was always tapered and the right side was perfectly perpendicular.

Last week I went for a cleaning job and removed the lenses. I aligned everything again which took me two days to get all the beams death center again. The focus lens was also removed and everything was cleaned(including the lens holder).

Up to the last mirror and down the tube, everything is fine, but when I put in the lens in the holder, the beam always goes to the left side, which explains the taper! Now it is even this bad that I have to remove the nozzle to get a clean cut.

Does anyone know what is wrong?! Bad lens? Bad horizontal alignment of the tube?


I also want to buy an extra lens holder for different lenses, has the alignment of recent 60Watt+ laser cutters been improved? Does anyone know where to buy these holders and maybe some better alignment mirrors? Ebay doesn't have many and machine suppliers do not seem to be interested...


[edit]
OK, was googling around about lenses, what is the correct orientation of the znse lens? What would the result be if it was upside down?

[lrob]

Check the cone on the bottom of the lens holder. Mine did not always fit properly, which caused the same problem you are having.

[Tweakie]

I am sure you know this already, but for best results your lens should be fitted with the curved side towards the laser tube and the flat side towards the work. When the lens is fitted opposite to the above, the focal point is elongated so you will get a greater depth of field but a reduction in cutting power.

Tweakie.

[FanFan]

Hello, I am very interested in knowing how you ultimately solved your problem. I am just starting to learn about alignments. When you were lining up your various mirrors did you do all your tests/checks in one location or were you checking at both end of travels for each axis. Thanks for any reply. Fanfan

[fantasy2]

Hi Fanfan,

The problem is solved and I learned a lot about the alignment. Like tweakie said: check how the last lens is fitted. Mine was upside down..

Also, begin at the tube, make sure it is level and horizontal and work your way to the last lens by continuously checking the location of the resulting beam. I moved the XY axis a lot to be sure the location is the same on every corner of the bed.

Another thing that I learned is that the screws to change the angle, not only affect the change in angle of the beam but also the height! Try to turn the screws so that the mirror is death center. I had the problem that the screws of the last mirror were turned too much so at the beginning of the tube, the beam was not in the center but in the end it was(creating an angle!). This ended up to be the reason why I started this topic.

The laser almost works perfectly now but the alignment of one of the mirror seems to change when I am using the engrave mode of the laser(probably due to vibration). I am thinking about replacing them with higher quality alignment equipment and use some locktite to lock the thread..