Laser

we had to characterize our lasercutter’s focus, power, speed, rate, kerf, and joint clearance.

Presentation of laser cutter

The model is a “cheap” Chinese Laser Cutter CO2 model, CE compliant modified and rebranded under MlLaser name. It’s a 150 Watt CO2 Tube. The Laser Cutter is composed of several units : The LaserCutter , an external exhaust , a watercooling system and an air pump.

The CO2 laser tube at the back (a little bit dirty )

The air pump and the watercooling

The external extractor

The wonderful manual extractor command

The control panel. The laser button is normally deactivated, for this test I reactive it.

The software

The machine works with Lasercut 6.1, a common software for many Chinese CO2 Laser.

It import files in formats like .dxf or .ai , but not .svg

Cut configuration

Focus testing

The laser cut had a automatic Z leveling. Head have a inductive probe at the back, just put a metal plate on the material and launch auto Z leveling.

Is auto leveling correct? We’ve tested it.

For testing this, We take measure with caliper. In order to have enough space, I have to temporary modify the machine.

Because We have removed the honeycomb tray, we are too short on Z axis, so we put some MDF to raise. During test, we have seen machine have a security after auto leveling, it’s impossible to raise the tray after, only lower it. It’s OK to test focus only in one direction, we have to bypass that!

How? after auto level, I measure with a caliper. Then we simulate a fake Z by holding the plate much lower than my real height on an empty space. After we replace manually Z at the “autofocus height”, after we can go up and down because machine think my Z is much lower.

My tests with manual levels, green is the normal autofocus level. Point are from left to right, higher to lower tray level.

Measuring heights (we are using a fixed point on the head, the air blow tube because we can’t go between nozzle and material)

We can assume that auto level make the best kerf at the top of material.

Kerf

Kerf is the measuremend of the space freed up by the material which is burned by the laser.

when you cut one time, the space is too small to be measured.

We decided to do it 10 times, and divide the total space by 10.

inkscape

​ first, we used inkscape to define a draw with 10 parallel lines.

transfert

then we have to prepare the transfert of the drawing to our lasercutter with inkscape

lasercut

After preparing and exporting the drawing, we import it with lasercut

you can resize the drawing

change the speed and power of the laser

and sending it to the lasercut equipement

the cutting

the result

measure

The difference, for 10 cuts is 2,5 mm so our measurement defines a free space (kerf) of 0.25 mm for one cut.

power and speed

we tried to make a usefull documentation for the users of the laser cut.

the speed and the power required depend on the material to be cut.

We tried with cardboard 3mm, PMT 3 and 6 mm

the result

The outline has been cut with 100% power, 20% speed for the PMT 6 mm.