Difference between revisions of "Laser Cutters"

Revision as of 06:08, 22 March 2018

Usage

Use of this equipment is strictly for members only, before use, users MUST attend an induction. Incorrect use of this equipment can cause serious harm or death, if you are not inducted do not touch.

A user guide can be found here

Note that if you see smoke pooling aggressively in the cutter this may indicate that the fan covers have jammed - consult Mr Laserducky to verify this. Power cycle the extraction fan to hopefully fix it.

Protip: if smoke is solely departing from the top of your workpiece, you probably haven't fully cut through it. Check before removing it!

Using more than 60% power is highly inadvisable. The tube is underrated so that is almost at its maximum. The difference between 60% and 70% is minimal, and over 70% is overdriving the tube, eg it's at maximum output and you're just throwing more power at it anyway. Using more than 70% power is a really bad idea and you shouldn't be doing it ever.

The plastic window in the lid absorbs the cutting beam's particular wavelength, so from that view it is safe to watch - however the light generated by the act of cutting can sometimes be bright enough to cause concern, much like burning magnesium or similar. It may also be worth mentioning that we have no idea what class of laser the guide beam is, and it often reflects at the user, unhindered by the lid. Staring at either for too long is inadvisable.

Software

Software is Windows only, Windows XP through to Windows 10 is currently supported - it is installed already on both of the PCs. The software required is RD Works and can be downloaded from here

The design file can be designed in almost any vector graphics program, File formats known to work are:

• dxf - Autocad, Draftsight, Inkscapce etc.

The file should be layers with layers setup for each type of cut, We would recommend three layers as follows:

• Cutting, all inner cuts
• Cutting, the outer perimeter, i.e. the last cut so the material does not fall out before all the inner cuts are complete
• Etching, anything to be etched, i.e. text and images.

Once loaded into RD Works, the layers can be ordered to ensure the outer cut is last.

Settings for common materials

These date from before the new PSU, user beware! 30% of 'something' is now 30% of 'something else'!

1. 3mm Acrylic
   • Cut
     • Power = 30 %
     • Speed = 10mm/s
   • Etch
     • Power = 20 %
     • Speed - 200mm/s
2. 3mm ply
   • tbc
3. 6mm ply
   • tbc
4. Cardboard
   • Cut
     • Power = 30%
     • Speed = 20mm/s
     • Note that the offcuts from this fall and end up igniting later! Ensure you remove them.
     • You may need to disable the blower, to prevent embers being fanned into flames.
     • Note harder that corrugated cardboard loves to catch fire when the blower blasts air through the channels. Must be watched constantly!

Text to Etch

1. Create your cutting file
2. Open in Inkscape
3. Select text (Arial Bold works well), click Path / Object to Path
4. Save as dxf, untick "use LWPOLYLINE type of line output" on the Options box
5. Import DXF file into RD Works

Materials

Materials NOT to cut

Laser safe materials

The laser can cut or etch. The materials that the laser can cut materials like wood, paper, cork, and some kinds of plastics. Etching can be done on almost anything, wood, cardboard, aluminum, stainless steel, plastic, marble, stone, tile, and glass.

Cutting

Etching

All the above "cuttable" materials can be etched, in some cases very deeply.

In addition, you can etch:

Photo style engraving of mdf, this was my process

Import image

Select it then hit the BMP button middle top

Set dpi to 300 Set dither Set net graphic 100 lines,

Preview on view, if okay then apply to source

Set min power to say 25% max power 50% speed 200mm, worked for MDF, with good results

Test files

We have carried out a number of tests on common materials, we will publish the settings is the software section above, if you wish to carry out further tests, the test files can be downloaded from Boss Laser.

Suppliers of materials

Kitronic

Other Learning Resources

YouTube play list

Servicing

Lens and the mirrors need cleaning, ideally we need lint-free cloth for this. Cotton can scratch the molybdenum (assuming that is what we have). Note that the lens itself is likely zinc selenide, which is both toxic and fragile.

Our beam leaves the laser at an angle, this is probably due to minor mirror misalignment. Have a look at this video to understand why (1:15 or so for the pretty pictures) of why slight wonkiness matters so much to exit angle.

Alignment videos; coarse alignment https://www.youtube.com/watch?v=5YvOqH44n6c and the more relevant part 2 which deals with the 'mirror' stage of the problem https://www.youtube.com/watch?v=pl6dAWOkksM . Actual mirror alignment, eg squaring the beam path to the axis: https://www.youtube.com/watch?v=Vl6QKlwRKlk .

Laser MOT; https://www.youtube.com/watch?v=wupSN8mXlus

Once we have an ammeter, we need to have a fiddle to work out our power/output curves. https://www.youtube.com/watch?v=nZuatc3eIgU and https://www.youtube.com/watch?v=j5cIFxGu_1g for more information.

To break things with some authority, this is a useful reference. Note that the 'test' button fires the laser.