Engraving quality (anodised alu)

[Duus]

Hi,

We have just assembled our first laser build using the following parts:
AWC 608 controller
HY-T60 Laser power supply
SPT C70 laser tube

The machine is build using hiwin linear rail in a 9060 configuration on a welded steel frame.
The focal lenght is 2".

We are very happy with the cutting quality, and also to a degree with the engraving quality, however we have an issue with the engraving. It seems like the turning on or the turning off of the beam takes an amount of time which creates an error on the workpiece. When engraving letters on black anodised aluminum we see that the letters become wider than they should (in the direction of the movement). the error is approx. 0,5mm depending on parameters.
We have tried different speeds, and get better results when going slow. The fastest speed tested is 300 mm/s and the slowest was 50. I have attached a picture - but it is very difficult to see.

Can this issue be fixed, or is it something we should accept given the quality of the parts?

Best regards
Jakob Duus Dolriis

[Tech_Marco]

Can you post images of your machine? Is your machine equipped with 2:1 reduction gear? Check the belt tension also
In most case, the issue is caused by mechanics parts. Hardly could be an issue from the laser or from the controller


Marco

[Duus]

Hi Marco,

Thank you for the answer. I will go through the mechanical parts (belt tension). The x-y stage has reduction belt gearing.
The picture shows the machine (not finished...)

Jakob

[Tech_Marco]

One of problem I found from the picture you posted is that the Y motor is installed at the far left top corner. It is not a good design. The motor should be installed in the middle of the Y and use at least two axial coupling to minimize lagging. The design of your system may easy cause distortion and dragging. It can be seem during high speed engraving. You not be able to engrave a prefect square but rhombus.

By the way, for high speed engraving, you shouldn't go for "linear guide" but "Y wheel" type like what I'm selling.
Linear guide is idea for lower speed cutting. It provide an excellence linearity so it is good to cut long and straight item. Y wheel get less friction so it handle engraving better. But we shouldn't use Y wheel on a big gantry like 1800x1200 unless a little distortion is acceptable.

Try these files I posted:
viewtopic.php?f=16&t=2698

and

viewtopic.php?f=16&t=2693


Post the result at different speed like 50mm/s, 100mm/s, 200mm/s, 30mm/s, and 400mm/s (if you can)




Marco