Laser Cutting Frustration
If you are into Laser Machines, Engraving especially Cutting, you should know how hard and frustrating it is to find the right parameters to obtain a clean cut in the minimum number of passes.
This is especially true when you have cheap hobby machines like the NEJE or ORTUR series.
I this blog I will show you a trick that you can use to easily and quickly find your focus or laser height in a few steps without wasting time and material to test, and test, and test and …. you got it.
Now if you want you can see this short video explaining the process, alternatively you can continue to read.
How to find the right focus of height for your laser machine | Neje
Normally, to find the right parameters i.e., Power, Burning time, Axis Speed, and Laser Focus you run a bunch of different tests with different powers, speeds etc.. Between tests, you try to adjust the focus of the beam coming out of the module.
Typical boring slow Process
The focus can be adjusted through the small dial (if available) or by changing the height of the entire module which implies that you need to loosen the clamp holding the module, lower or raise the module trying to be as precise as possible and run again the test.
If you use advanced software such as LightBurn, life is much easier as you can do one test with multiple settings, and then repeat again the same test with a different laser height/focus.
If you use the software provided with the machine for example NEJE desktop app you need to run as many tests as many setting combinations you wish to try and for each combination to also change the height of the module making the job long, tedious and unprecise.
For Example, testing to cut through 3mm plywood:
- Power = 100%, Burning Time = 12ms, Passes = 1, Laser Module Height = 45mm.
- Power = 100%, Burning Time = 12ms, Passes = 2, Laser Module Height = 45mm.
- Power = 100%, Burning Time = 12ms, Passes = 3, Laser Module Height = 45mm.
- Power = 100%, Burning Time = 12ms, Passes = 4, Laser Module Height = 45mm.
- Power = 100%, Burning Time = 12ms, Passes = 2, Laser Module Height = 44mm.
- Power = 100%, Burning Time = 12ms, Passes = 3, Laser Module Height = 44mm.
- Power = 100%, Burning Time = 12ms, Passes = 4, Laser Module Height = 44mm.
- Power = 100%, Burning Time = 12ms, Passes = 2, Laser Module Height = 43mm.
- After you spot the almost right setting you want to optimize by reducing the power just to don’t have the machine running at 100%
- and forever…
Quick Process
From the boring method explained earlier, it is clear that you need to try a bunch of different heights so any setting combination will need to be run multiple times, the trick to easing up the process is to put your test piece at an angle and to launch the machine to cut a straight line going along the incline.
By doing so, you will effectively test all the possible focusing heights, and you will be able to see how the line width and depth varies along the route, even the ineffectiveness of the laser passed a certain focus threshold where there won’t be any line.
In the image below you can see the width difference between the ends and the centre of the line, also the missing length not engraved and the result on the back side.
Once you carry out or test you can check if the cut goes through the material, otherwise repeat with other combinations of Power, Passes etc..
Once you are happy with the cut is time to measure the height of the module with a meter or a ruler as shown in the image below.
Just mark the range with the cleanest cut from the backside, then you can use place a ruler against the module and measure the height with reference to some fixed point i.e. the laser itself or the module.
Hint: Try to keep the test piece with a fixed reference point so that you can take it out to check the backside, and then back to continue with other settings.
See how you can quickly adjust the height of your module without dealing with the clamp.
