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Robert Walters
10-04-2010, 3:14 PM
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
10-04-2010, 3:29 PM
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
10-04-2010, 4:50 PM
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
10-04-2010, 5:20 PM
Also check your optics and make sure they are clean and in good shape.

Martin Boekers
10-04-2010, 6:16 PM
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
10-04-2010, 7:20 PM
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
10-04-2010, 8:46 PM
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
10-04-2010, 9:01 PM
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":p

It takes the interpretation right out of it.

Thanks, another lesson learned!

Marty

Robert Walters
10-04-2010, 11:20 PM
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
10-04-2010, 11:22 PM
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
10-05-2010, 6:41 AM
Do you need to use anod aluminum? I usually use MDF.

Dan Hintz
10-05-2010, 7:03 AM
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
10-06-2010, 8:32 AM
Thanks Dan

Robert Walters
10-06-2010, 2:19 PM
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
10-06-2010, 2:24 PM
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

Andrew Mammoliti
10-06-2010, 2:35 PM
Ok so where do I focus lens when doing this test? Not to table but half way on the angle pcs?

Robert Walters
10-06-2010, 2:38 PM
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


Dee,

I believe either the tube is dying or the focus is off.

I'm still in the process of determining what is the culprit and many emails with Universal and a complete CPU reset and firmware reflash later.

One of the instruction sheets they gave me is a bit misleading, and telling me to do things I shouldn't. So working on resolving that now.

So far, I have a 0.21" difference between manual and auto-focus that can't be accounted for and I know for a fact that the AF (auto focus) worked perfectly a month ago and isn't loose or anything like that. So I suspect that the manual 'focus tool' I have is the incorrect one or is out of calibration.

Dan Hintz
10-06-2010, 2:56 PM
A bit of trig is needed to get the true focal point. Assume the aluminum piece is 4" long and set so the bare end is resting on a 1" block. Focus to the table, then lower the table 1/2". If your focus is set correctly, the middle of the piece is where you will see the sharpest line.

If it's not, find the distance from the middle of the piece to where the sharpest mark is. You have a 4:1 run over rise ratio... for every run of 4", you rise 1". If your sharpest mark was high by 0.5", your actual focus Z height is off by 0.5/4, or 0.125". In that case, you would raise the focal tool by 1/8".

Mike Null
10-06-2010, 3:01 PM
ULS should be able to give you a drawing for making a focusing tool. Make that and then set your auto focus.

I do not use or like auto focus as there is too much risk of damage if you forget what's in the machine or where it's located.

Robert Walters
10-06-2010, 3:43 PM
A bit of trig is needed to get the true focal point. Assume the aluminum piece is 4" long and set so the bare end is resting on a 1" block. Focus to the table, then lower the table 1/2". If your focus is set correctly, the middle of the piece is where you will see the sharpest line.

If it's not, find the distance from the middle of the piece to where the sharpest mark is. You have a 4:1 run over rise ratio... for every run of 4", you rise 1". If your sharpest mark was high by 0.5", your actual focus Z height is off by 0.5/4, or 0.125". In that case, you would raise the focal tool by 1/8".


Hi Dan,

Yeah, I had an epiphany shortly after I asked the question.

Using the illustration below, where:

a) Is the laser table,
b) Is the block height,
c) is the anodized aluminum, and
the blue marks 'd' determine where the sharpest point of the lasered line is,
and the '0' mark is the zero inch mark on your X Axis...


http://i51.tinypic.com/dr9j11.jpg

If the sharpest point of the lasered line 'd' is at #3 and that's 1.5 inches
from '0' mark.

The block 'b' is two inches tall, and 'a' is six inches long.

a = 6
b = 2
d = 1.5


it's:

(b/a) * d = 'f' (Focal offset)


or

2 / 6 = 0.333333333333333 * 1.5 = 0.5"

So the focal offset would be 0.5"


(Somebody check my math and explanation for errors/clarity if you wouldn't mind)

Dan Hintz
10-06-2010, 4:58 PM
Assuming your focus tool was set to focus at point 0, yes, you need to bump the focal point 1/2".

Robert Walters
10-06-2010, 5:17 PM
Assuming your focus tool was set to focus at point 0, yes, you need to bump the focal point 1/2".

Ah, you're right. I missed that =)
I'll correct it after I do mine and take a video to post.

I still need to find some anodized aluminum locally.

Gary Hair
10-07-2010, 1:21 PM
A bit of trig is needed to get the true focal point.

trig, shmig...

1. Tape the anodized piece to the table and to the block holding it up, that way it won't move.
2. Laser the line along the piece.
3. Where the line is thinnest use a square and extend that point to the edge of the aluminum.
4. Cut a piece of material that fits between the laser bed and that line and set your focus on that piece.

It doesn't have to be anything fancy, cardboard, acrylic, whatever. This measurement is not super critical for most substrates unless you are trying to use Cermark on gold and you need the max power you can get from your machine. The real goal here is to get you within a 1/64" or so of being "exactly" in focus. Most 2" lenses have about 1/8" of usable focal range so 1/64 isn't going to matter much.

Gary

Mike Null
10-07-2010, 2:10 PM
Gary

Right on.

Robert Walters
10-09-2010, 3:55 PM
The paper liner has been removed from both sides.
I just placed the piece on top of MDF to take the photo.


The "fuzziness" you see is the photo itself, the actual piece looks good.

I engraved this on the back of 0.110" cast acrylic a month ago:

PWR=50, SPD=50, PPI=750


http://i55.tinypic.com/2d0yrlh.jpg



Literally using the same piece of acrylic and the same settings,
This is what I've been dealing with for a week:

http://i52.tinypic.com/23902f.jpg

Looking right-to-left, it's getting better.
But no where near the quality of what was done a month ago.

Even some of those 1/2" circles took 2 or 3 passes to cut out.
iirc: PWR=100, SPD=0.7-2.0, PPI=1000


To top things off...

1) My focus tool is/was out of calibration.

2) Had a power loss while engraving last week and since then whenever I turned off the machine after being on for 40m, then turned on 15m later, the LCD display would show two lines of solid blocks. Many emails later with ULS, I had to reset the CPU and re-flash the firmware to resolve the LCD issue, which also cleared the Z-HEIGHT settings.

The star on the far left, still isn't very good, nor is it consistent.

I've been racking my brain here of what the issue(s) are, be it operator, settings, machine, tube life, etc.

Everything points to a focal issue, but I don't think that would explain the inconsistencies near the bottom of the star on the far left.

I am at a loss here.

Mike Mackenzie
10-09-2010, 6:02 PM
How old is that tube?

Did you check your optics? I might even run a test without the beam window. Just a test it is very harmful to the laser tube to run the system without the beam window in place.

Did you check your alignment?

Did you check the level of the table?

Are you sure that your color management in Corel is OFF.

Is the driver mode set to NORMAL?

Some things to look at but it very well could be the laser tube.

Robert Walters
10-09-2010, 7:29 PM
How old is that tube?

Did you check your optics? I might even run a test without the beam window. Just a test it is very harmful to the laser tube to run the system without the beam window in place.

Did you check your alignment?

Did you check the level of the table?

Are you sure that your color management in Corel is OFF.

Is the driver mode set to NORMAL?

Some things to look at but it very well could be the laser tube.


Mike,

Tube/machine is about 7 years old.

I've only had the machine a little over a month. I'm not sure why things have change so much in just a month as the two photos above show.

I haven't intensively played with it as I've been focusing on finishing the air scrubber I'm building. Until I was attempting to use it to make a part for the air scrubber.


With XY == 12,24 pointer beam is maybe 0.5mm high and 1mm left of center when placing tape over hole before hitting last mirror.

With XY == 0,6 pointer beam is dead center.

Just grabbed a level and checked table on all four edges.
Parallel edges are the same.

Corel COLOR MANAGEMENT = OFF (Confirmed)

Driver PRINT MODE = NORMAL (Confirmed)
(latest version of driver and firmware are being used)

Beam window (on back wall of machine) makes no difference in the results if removed.

I was even going to do some tests using the Z HEIGHT CONTROL,
but that feature is only supported on M-360 and later machines.

Mike Mackenzie
10-11-2010, 2:49 PM
Robert,

If the tube is seven years old it can work one day and be bad the next. Typical tube life is 3-5 years. This is very reliable data when ULS started to manufacture there tubes some 15 years ago they compiled data on every tube that was built and or replaced and continue to do so. This is extremely valuable for them to determine failures (why and What) caused the failure.

Even though some tubes are 5+ years old they are still in the Grey area of there life span.

I can notice that when we have a lot of laser tubes failing if we look at the installed date everyone will fall within 2-3 months of each other.

You also need to do a burn test with the alignment the red pointer is not always in the same spot as the laser itself. It does not matter if the beam is in the center of the carriage hole as long as the beam is in the same spot at the four corners.

You should also check the level with your focus tool. Focus in the upper left corner directly to the table, shut off the system and move the carriage to the other corners and check to see if the if they are the same with the tool.

Robert Walters
10-11-2010, 3:16 PM
Robert,

If the tube is seven years old it can work one day and be bad the next.


When tubes go bad, is it a gradual thing, or dramatic change?

I just got the docs this morning from TS regarding table alignment, beam (not pointer) alignment, and tuning.

Once I work on those items, I may need to see if I can get my hands on a power meter.

Dan Hintz
10-11-2010, 7:52 PM
It varies... it can be gradual and you never notice it until it's too late, or you can pop a cap (heh, no pun intended) and the RF board goes kaput in a heartbeat.

Robert Walters
10-12-2010, 1:37 AM
or you can pop a cap

Got soldering iron, will travel :)


(heh, no pun intended)
Hitting the range with a few hundred rounds is cheap therapy :cool: