coated aluminum and wood etching

Today we etched a logo into the painted surface of a thermos mug and a wooden sign.

Try to use the lowest power possible and only move up in power if the paint on your aluminum surface is very thick. We want to avoid reflecting the laser beam back in the direction it came from off the metal surface, as this could potentially damage the optics and laser tube by energy redirection.

A good choice for wood is 1/8 inch Birch which can be purchased for about $14 for a 5 by 5 foot square.

The rep rate range for our lasers is between 4 and 150 kHz. Use lower rep rates for smoother edge along cut lines and depths, and higher rep rates to cut all the way through thicker (> 1/4 '') materials.

A trick Seth taught us is to purposely defocus the laser after and autofocus by backing the the Z direction by 1-2 mm (move the bed downwards). This can save you time by making your cut lines purposely not go all the way through, while at the same time broadening ("bolding") the line. This will have roughly the same effect as a medium single pass scan, but much faster.

Rotary Roller Examples

Boss Laser recommends that on some occasions when shallow etching glass, whether on flat or rounded materials, you will be better served by first attaching wet non-shiny newsprint to the glass. The challenge is that the laser chamber is dry and with air flowing briskly during operation, the engraving run must be paused periodically to take a brush to re-wet the newsprint.

Here is a video showing Seth's engraving and the use of wet newsprint

I have attempted to engrave a very detailed 5 inch bird onto a cylindrical 7 inch tall glass. I am now also engraving the main parameters of power %, scan gap interval in mm, and laser pulse frequency in kHz. This way when I engrave up to four birds on one glass, after several cycles of hand and/or machine washing, I'll know which set of parameters holds up the best.

Right now,  I am experiencing inconsistent results, even in back to back runs on the same laser with no change of tool position. I speculate that air flow consistency and possible soiling of the optical head on the relatively long 25 minute runs may cause deterioration of engraving performance. I tried to improve the former by standing attendant to the control knob on the compressor to even out the air flow manually as needed, but some flaking issues persist. I may also try wet newsprint. You can compare the two back-to-back engravings below.


First run ... relatively clean

Second run that same day, ... aborted due to excessive flaking.

Rotary Roller Tool

It is important that the laser is first completely off and powered down BEFORE disconnecting the Y-axis controller cable and replacing it with the cable to the rotary roller accessory. Failing to do so will result in the X/Y/Z limits to be incorrectly set when you have returned to linear mode after removing the Rotary Roller tool.

Materials

There is a company that sells waterproof papers

https://terraslatepaper.com/


laser engravable name bars, paperweights and card mount/holders. They also sell laser tape and Cermark tape, the latter can be used to engrave raised designs on uncoated metal.

https://www.johnsonplastics.com/


LED strips and bars for side illumination of cast acrylic etchings

https://www.superbrightleds.com/


3M company recently launches at thee CES show in January a free no account needed on-line tool to help determine what type of adhesive is optimal for joining any two substrates together. Though it is mainly geared to the medical device industry, the tool is easy and quick enough to work for any general purpose.

https://findmyadhesive.com/