Author: Santiago Ricoy
Email: [email protected]
Date: Last modified on 1/30/18
Keywords: laser cutter engraving etching burning cutting vector raster steel stainless plaster of paris
The photo above depicts our lab's laser cutter engraving text on a stainless steel water bottle. Should lab members need permanent marks on stainless steel (and possibly other metals), this is a frugal way to achieve a decent end result.
This tutorial's motivation is to teach a student new to the laser cutter how to prepare and etch stainless steel. The tutorial assumes the reader has the following background:
* Has experience using laser in raster mode, vector mode, and with the rotary tool
* Perhaps also know how to work with vectorized images in Inkscape, Illustrator, or another related program
The rest of this tutorial is presented as follows:
To complete this tutorial, you'll need the following items:
Since each job will likely be very unique in its area of application, I will leave the amount of plaster and alcohol up to the reader.
From the carton of plaster of paris, pour some of the plaster powder into a cup.
Add a small amount of alcohol at a time while mixing it with the plaster to create a paste. The consistency of the paste should be similar to a thick paint or Heinz ketchup.
On your substrate, use a paint brush to apply the paste. Usually two light strokes in the same direction is sufficient to cover the area you need. The coating need not be more than 0.5mm in depth.
Before the paste dries completely, it may be mostly translucent. However, when it is completely dry it will become an opaque white. You may use a heat gun to more rapidly dry the coating.
Note: The coating is not hard but actually still very much a powder. Thus, it can easily be disturbed by touching it.
Please brush off as much of the coating as possible into the trash before rinsing. Plaster of Paris is excellent at clogging drains.
Simply place your item, on the rotary tool or cutting table, and raster/vector normally within the coated area.
Due to differing metal thicknesses and stainless steel types, the settings below may not work well for other items. They did work well for the bottle pictured here though.
The bottle shown here is made of approximately 1/16th inch 18-8 stainless steel.
I recommend testing on objects of similar material, or creating a small engraving in an inconspicuous area on your object before making a larger engraving.
If you are viewing this outside of DASL, for reference, our machine is a 120W Full Spectrum Laser Pro 36×24 CO2 laser cutter.
Vector cuts, even at the settings mentioned may produce far too much heat for the thickness of an object and warp the steel (example above). Lower power yields a less consistent vector etch. Furthermore, vector cuts on stainless steel have a strong tendency to leave burn marks around them.
I have no reliable method to eliminate these problems yet.
As you can see above, the bottom “#vegasstrong” raster (cut off due to a poor plaster application), is much clearer than the top. This was achieved by turning off the air assist, but by using the more optimal settings above, similar results were achieved with air assist on.
Due to the powdery nature of the coating, with air assist on, more and more of it is blown off of thinner areas while rastering, leaving an inconsistent etch. This should emphasize the importance of applying a thin and even coat of plaster to the substrate.
NOTE: Turning off air assist is NOT RECOMMENDED as the laser manufacturer clearly notes in the manual. In almost all cases, at the settings mentioned above, this is unnecessary.
This tutorial's objective was to inform students of a frugal way to etch stainless steel using plaster of paris and rubbing alcohol.
For questions, clarifications, etc, Email: [email protected]