Laser Power

[Robert Walters]

I bought a used ULS M-300 30W laser, it's about 7 years old.

I haven't played with it fully yet as I've been focusing on building an air scrubber for it. Just got my activated carbon an hour ago. YAY!

Last night I used it to cut a flange for the air scrubber out of 1/4" HDPE.
I used the settings the manual said for cutting acrylic (closest I could find).

I must have made 8 passes at 80% power, 1% Speed, and 1000 PPI (as well as other various settings). It only made maybe a 1/16" depth cut and bulged at the surface (of course).

I have the latest drivers and firmware.

Now...

I know that the tube's life is limited, but I'm not sure if it's the operator (me), the material, or the tube is the issue here (or a combination of the above).

Is there a way to test the tube's power without a real optical tester?
Like some material will always cut perfectly at some settings/depth/etc and if it doesn't then the tube's output is lower that it's rating?

Refurb tube is $1200, and I know I will be doing vector cutting more so that raster imaging, would buying a 50W tube for $3000-$6000 be worth it?


As far as the HDPE goes...
I'm not sure but it could have been remelting upon itself. Or maybe HDPE is just not something that cuts well with a laser (due to the heat and density).

Any thoughts would be appreciated.

[Mike Null]

Give ULS tech support a call to see if it's possible to change to a more powerful tube without extensive other alterations.

[Joe Pelonio]

Try acrylic, with 30 watts you should be just able to cut 1/4" at 100% power
1-2 speed, but HDPE has to be cut faster or melts too much, so more power is needed.


It may just be the low power rather than a problem with the tube.

[Mike Ireland]

Also check your optics and make sure they are clean and in good shape.

[Martin Boekers]

Epilog had me do a test with anodized aluminum when I had issues
a year or so ago. It's also a good way to check focus, adjusting the
height until it burns brightest.

I would call ULS Tech as they probably have a similar test.

Marty

[Gary Hair]

Marty,
No offense, but I'm certain your eyes aren't calibrated well enough to see the difference in the brightness of the laser beam. Attached is a diagram of how I was taught to determine focus. Just angle the anodized piece and set your focus about halfway. Run a vector line along the piece and where the mark is narrowest is truly in focus. Set your autofocus to that height and you are done.

Gary

Epilog had me do a test with anodized aluminum when I had issues
a year or so ago. It's also a good way to check focus, adjusting the
height until it burns brightest.

I would call ULS Tech as they probably have a similar test.

Marty

[Dan Hintz]

Gery's method is the best as it relies on nothing but the machine's capabilities... it also tells you if something is wrong with your optics (if you can't get a fine line on anodized Al, something is seriously amiss).

[Martin Boekers]

Marty,
No offense, but I'm certain your eyes aren't calibrated well enough to see the difference in the brightness of the laser beam.

Gary

No offense taken, actually I couldn't see the laser, but I can see the brightness
change per click on the switch that raises and lower the table. there is a noticable
difference each time I hit the switch.

I do like how you do it though, nothing like physics to "bring things into focus"

It takes the interpretation right out of it.

Thanks, another lesson learned!

Marty

[Robert Walters]

Also check your optics and make sure they are clean and in good shape.

That was the first thing I checked.
Went ahead and cleaned the lens and mirror.
Checked the previous mirror, and cleaned the cover on the back wall.

[Robert Walters]

Try acrylic, with 30 watts you should be just able to cut 1/4" at 100% power
1-2 speed, but HDPE has to be cut faster or melts too much, so more power is needed.


It may just be the low power rather than a problem with the tube.

I was able to cut a 1/2" circle using the above mentioned setting,
but in .110" cast acrylic (no paper either side), not .250".

[Ernie DeMartino]

Do you need to use anod aluminum? I usually use MDF.

[Dan Hintz]

Ernie,

Anodized aluminum is a very high-resolution substrate, which allows you to pinpoint the focal point within a few mils... MDF may get you within 1/8", which defeats the purpose.

[Ernie DeMartino]

Thanks Dan

[Robert Walters]

Ok, I get the lasered angled aluminum to set focal point.

So...
I grab a small arbitrary sized block of wood, place an arbitrary length of anodized aluminum on it, and laser a line (lets say in the X axis).

Now...
I can see that the smallest/sharpest point of the lasered line is at (let's say) 2" in the X axis.

Since I'm only moving the X axis when creating the line,
how do you convert that to a Z axis offset in a practical manner?

Unless I create a fixture, trying to measure the height at that point might bump the substrate, then have to rerun the process all over again.



Also, anyone know of where to buy some anodized aluminum off-the-shelf by chance?




.

[Dee Gallo]

I was able to cut a 1/2" circle using the above mentioned setting,
but in .110" cast acrylic (no paper either side), not .250".

What? I cut 1/4" cast acrylic all the time with my 35w. Try 4sp/100p/5000freq. Those settings work for me. Maybe it's your frequency that's off.

cheers, dee