Category: Laser Etching

Burning through varnish

A while back I did some laser etching onto 3mm thick plywood:

Varnish applied

and applying varnish AFTER etching I got the following result:

image

I applied the varnish to opposite side of the plywood which was blank. I then re-did the etching which resulted in the following result:

image

I found that I made no impression on the varnished surface at either 40 or 50% power so I sent straight to 100%. Based on what I can see I reckon about 60% will give me the same as the 50% pre-varnish did.

Thus, i makes more sense that you need to use more laser on something that has been varnished and that additional power I would suggest is around 10-15% to get the same kind of result.

image

I also tried a larger, non vector image to etch as shown. The settings were:

Grayscale

Contrast = 50

Bright = 50

White clip = 255

Grey scale conversion = Luma

Algorithm = Atkinson

Dot filled engrave

Movement = Dot

Fill interval = 0.14mm

Dwell = 5 ms/dot

Laser Power = 55

Jog speed = 3000 mm/min

Total time to complete = 2 hours and 39 mins

As you can see, the graphic did not fully print in places. I put this down to the plywood not being completely flat. The resolution there would be to sand the board before printing.

There are also a lot of lines, which I think is the plywood grain running through the image. I do have some less ‘grainy’ wood I can try again with but again, may be some sanding of the material prior is a worthwhile investment for a better result.

Even given the material was a little warped I think I’ll need to up the power a bit to maybe 65% to get a darker and more defined result.

The challenge here is that the print took over 2.5 hours and that is a long time with extractor fan running a full bore. It is easy enough for me to wear earmuffs but I might need to think about sound proofing the extractor somewhat or it is going to be very distracting in the shop, given it is one open area!

The best thing about laser etching wood is that the mistakes are much more recyclable than those from 3D printing filaments. I get the feeling that I have a lot more laser etching testing to do until I did a formula I can depend on.

Varnish applied

image

After etching the above images onto 3mm plywood, they have now been varnished. Prior to applying varnish they looked like:

image

Perhaps the varnish has now made then etchings a little darker but it has sealed in the carbon from the etching, prevent smudging which is a good thing.

image

I used the above varnish:

Timber Protect Quick Dry Clear Gloss 300g

which is available from Bunnings.

I also varnished the rear side of the plywood with the aim of repeating the laser etching process with the same image but this time on a ‘pre-varnished’ surface to see what the results will be.

Wood etching test

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The above is a etching onto 3mm plywood using the SnapMaker Artisan and the 10W laser. The laser power settings are listed in the bottom left of each i.e. 60%, 50% and 40%.

I think the 50% power setting provides the best output but 60% ain’t bad either. 40% however misses a few spots so isn’t adequate.

The next step is to put some varnish on the result and see what happens.