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View Full Version : Does anyone have a 12watt laser?



Robert Ray
01-30-2008, 10:55 PM
Hi, first post, my name is Robert Ray, and I am a laser-o-holic... like Kim Vellore :D

I just picked up a used 12 watt Laserpro machine off ebay, which when it arrived today I quickly tested.

I am trying to cut 1/64" plywood, which cuts great with a 35 watt laser at 100% power and 10% speed at 500ppm 2" lens.

With the 12 watt laser and a 1.5" lens, I had to reduce the speed to 2% to cut, but got serious carbon edges. Looks like cutting with a 35 watt and being 1/4" out of focus.

I tried all kinds of speed/power/frequency settings, but cannot get a usable cut so far.

Does anyone else have a 12 watt system that they can get cuts out of? If so, what are the general settings used? Lens used?

Thanks,
Robert

Richard Rumancik
01-31-2008, 12:03 AM
I cut 1/64" birch plywood with a 30 watt/1.5" lens and I get black edges. I wouldn't say it looks as if cut out of focus, however. The kerf is narrow and the carbon deposit limited to the edge itself. I believe it is caused by the adhesives used to bond the layers. When I cut business cards from this plywood I need to run the edges over paper towel or cloth to remove the carbon from the edges. You don't seem to have this problem when using a 30 watt - have you tried the same batch of material on both machines?

If it looks out of focus, then maybe it is. Perhaps you should ignore the focus probe and test the laser cutting at different height increments and see where the kerf is narrowest. That will be your optimum focus. Then compare that setting to the focus probe you are using and try to determine what is wrong.

For the Mercury, the same focus probe is used for both the 1.5 and 2" lenses, but the lenses go in different slots. Does the 12-watt unit you have use the same system?

Kim Vellore
01-31-2008, 12:14 AM
Hey Rob Welcome... Try cutting plain paper or card stock and change the focal length for different cuts and see if the cut looks narrow enough. Once you get the exact focal point then you should try to cut the wood with different power/speed combination.
You could also raster Anodized Aluminum to get the focal point.

Kim

Gary Shoemake
01-31-2008, 9:12 AM
IN the printer driver box you should have a place to set your dpi. use 200-250 and ppi on auto. If you are placing too many dpi in a small area especially wood it will char. also make sure that the air assist is up toward max air flow. I cut 1/8 to 1/4 all the time and get very little charring using these settings.

Robert Ray
01-31-2008, 10:43 AM
I really goofed on this one. Let's call it the $3700 mistake.

On my 35 watt with a .005" kerf from a 2" lens, I can cut .018" plywood clean at 10% speed.

I figured that a 12 watt laser with a .003" kerf from a 1.5" lens, I should be able to cut the same .018" plywood at between 5% and 6% speed.

Math being roughly like this:
35/5 = 7 We will call this 35 watts divided by 5 thousandths kerf = power density of 7.

12/3 = 4 We will call this 12 watts divided by 3 thousandths kerf = power density of 4.

4/7 = .57 * 10 = 5.7% speed. So if I set the speed to 5.7%, I should be able to cut the .018" plywood.

Well here is where I goofed. I have never physically measured from my lens to the material, just took it at face value that I have the 2" lens that I ordered with my machine.

I opened up the new laser nozzle and much to my horror, I seen the lens sitting in a slot about 1/2" higher than my lens sits. I figured that they had put a 2.5" lens in it.

Turns out I have been using a 1.5" lens all along on my 35 watt, and the new laser was shipped with a replacement 2" lens instead of the 1.5" that is standard with the 12 watt.:eek:

New corrected math:

35/3 = 11.7 We will call this 35 watts divided by 3 thousandths kerf = power density of 11.7.

12/5 = 2.4 We will call this 12 watts divided by 5 thousandths kerf = power density of 2.4.

2.4/11.7 = .2 * 10 = 2% speed. So if I set the speed to 2%, I should be able to cut the .018" plywood.

I tried, and yes I can cut through, but I have about .020" of carbon on each side of the plywood cut.

The Venus laser does have slots for 3 lenses Richard, just like the Mercury does, 1.5, 2, and 2.5" lenses. I will try putting the 1.5" lens in the 12 watt, and try the 200 to 250 ppi tonight Gary, thanks for the tips.

Richard Rumancik
01-31-2008, 9:25 PM
35/3 = 11.7 We will call this 35 watts divided by 3 thousandths kerf = power density of 11.7.

12/5 = 2.4 We will call this 12 watts divided by 5 thousandths kerf = power density of 2.4.

2.4/11.7 = .2 * 10 = 2% speed. So if I set the speed to 2%, I should be able to cut the .018" plywood.

Robert

When you compare "density" don't divide by the kerf width; divide by the beam diameter (or kerf width) squared. This is because of the round beam.

In this case 35/(3x3) = 3.88 and 12/(5x5) = .48.
.48/3.88 = .12

I am not sure if the speed relationship holds, but if it does, then you would get .12 x 10 = 1.2 speed. This might not be a practical situation.

On the bright side, if you use the 1.5" lens on the 12 watt then the density relationship is simply the ratio of watts: 12/35 = .34. All else being equal it should cut at about 1/3 the speed as the 35 watt.

Let us know if this theory works in practice.

I suspect you will have to use the 1.5 lens for most jobs on the 12 watt.

The speed relationship only holds between the two machines if the vector speed is the same. I don't know if that is the case. GCC never actually spec'd the vector speed on mine.

You might find that the supplied probe does not give you the exact (optimum) focus. This is because of tolerances on the lens itself, the lens housing, and the probe. You might find you can get a better focus if you go higher or lower than the probe. If so, you may need to make a special probe. You can make one using round rod and a shaft collar with setscrew (hobby shop).

I'm sure you will find uses for the 12 watt once you familiarize yourself with its capabilities.

Robert Ray
02-01-2008, 10:24 AM
I wanted to experiment with the 1.5" lens yesterday, but disaster struck. The sewer pipe clogged, as did the bathroom sink drain, and we had to take the vanity, then the wall out to access it. Once inside the wall we found a 60 year old cast iron stump that used to be a pipe corroded off at the concrete slab foundation.

This is one of those jobs that requires refinancing my mortgage, and leads to a new bathroom remodel as well as a kitchen remodel because the other side of the wall is the kitchen sink, also clogged. Ugh!

Looks like I will be working more hours making laser kits while everyone else is sleeping for a while! :eek:

The good news is I can sell everything I can make with my lasers.;)

Bill Cunningham
02-02-2008, 7:50 PM
I fixed a corroded off pipe like that once by inserting a piece of plastic drain pipe that was a little smaller (about .5" smaller) as far down as it would go. One we found the ending depth, we pulled it out, and wrapped the plastic pipe with resin soaked fiberglass matting (not the woven cloth), then shoved it back in as far as it would go and using a piece of 1/8" flat bar, slipped it down between the plastic pipe and the cast pipe, and packed the fiberglass down as tight as we could, then let it cure .. Bingo fixed forever, and then firmly embedded plastic insert became the head of the new drain.. Saves digging up a lot of concrete..