Laser cutter
We have a Laserscript LS6040 laser cutter that was supplied by HPC Laser in Elland.
This equipment must only be used by inducted persons who have received appropriate training.
Use by those who have not been fully trained on laser cutter operation and safety is forbidden.
WARNING: misuse or carelessness can result in fire, injury and damage to the equipment.
Contents
Specifications
Materials
Only materials which are on the approved list must be used. Do not cut materials you are unsure about, including any standard plywood or MDF not bought as laser materials.
WARNING: use with non-approved materials can result in:
- fire
- injury
- toxic and corrosive fumes
- damage to the machine.
Approved materials list
- Laser safe MDF
- Laser safe plywood
- Acrylic a.k.a. Perspex
- Note that cast acrylic is much preferred over extruded and while the latter can be cut, it smells terrible
- Cardboard
- Polypropylene
- Polyethylene foam
Stock
Members are encouraged to purchase their own sheet material stock. However, occasional sheets can be purchased from Bridge Rectifier at the cost + 10% to cover the postage costs associated with replenishing stock.
All stock usage, whether for induction or workshop, or personal use, must be logged.
A new wiki page should be created for each order and use recorder against it as material is used.
If buying stock, Kitronik tend to have the best pricing for bulk orders of common laser materials, and Plastic Stockist have a wider range of acrylics, but generally at higher prices. (Note: I don't recommend buying plastics from ebay, as not all sellers label them correctly. If you do, make sure it's "Perspex" (a brand name for acrylic) and has that name printed on the cover film. Not all "acrylic" from ebay is actually acrylic or laser safe! Davidhayward (talk) 22:14, 15 January 2017 (UTC) ).
Most vendors offer birch laser ply and poplar laser ply. Poplar is cheaper and less dense than birch, so can be cut more quickly, though birch is more durable.
File Formats And Software
The PC next to the laser is set up with LaserCut, which reads .dxf files and its own proprietary .ecp files. Many editors can create .dxf files; the lasercut tag at Thingiverse also has many examples to freely download. To import a .dxf, go to File > Import and locate your file. ECP files are useful to save for things you might want to cut again at a later date, as they can retain information like cut speed and power (see #Cutting).
Editors
- Inkscape (Free, OSS)
- Draftsight (Free but closed source; has command line+GUI, and uses same keyboard shortcuts as Autocad)
Inkscape and Draftsight can both export .dxf files, which you can then put on a USB key and transfer to the LaserCut PC.
There's nothing there!?
If importing your design into LaserCut results in nothing showing up, don't panic.
First, zoom out to see if it's just elsewhere. Next, drag select the whole canvas area to see if the scale you saved your .dxf at was just very small. If there's still nothing showing, next try re-saving your design and making sure it's specifically an R13 or R14 ASCII Drawing .dxf file. Note that .dxf has been through many years of revisions, and not all revisions are compatible with all software.
Additionally, Inkscape users might run into an extra problem whereby nothing shows in LaserCut despite exporting to one of the safe versions of .dxf. In such a case, re-save your design as "Standard SVG" before exporting to DXF, as the default "Inkscape SVG" file format seems to include some extra features that can make .dxf files incompatible with LaserCut.
Cutting
Always watch the laser. Do not leave it cutting unattended.
No matter how used you become to the cutter or a given material, if something goes wrong a fire can start quickly and you must be there to act. Hit the emergency stop button be ready with a CO2 fire extinguisher. By using the right settings and being vigilant, you should be able to prevent any fires before they start. An occasional small flash of flame as the laser cuts is normal. If you see a flame persistently following the laser, that's bad, you're using the wrong settings or material; stop the cut and put the flame out at once.
(Will be updated later with screenshots from LaserCut)
Below are some example settings for cuts done with with a clean, freshly set up cutter. For the reasons covered below, any speed/power chart you see for laser cutting is only a starting point. If the laser is a little dirty when you use it, you may require a slower cut to punch through your material.
| Material | Power | Speed (millimetres per second) |
|---|---|---|
| 3mm Acrylic | 70% | 12mmps |
| 3mm MDF | 70% | 20mmps |
Note that at the time these settings were recorded, 70% power 25mmps led to 3mm MDF cuts where the parts didn't drop out cleanly and had to be popped out manually, and likewise for 18mmps 70% cuts in 3mm acrylic.
Be kind to the cutter by running it at less than 100% power. Running the cutter at full power will drastically shorten the life of the laser tube without significantly speeding up your cuts. At our introduction event, we were advised on 80 - 90%, and some maker spaces run theirs at 70% power.
Once you've imported your .dxf file, any line colours you set in Inkscape should show in LaserCut too (If you used other software, you may have to select lines and manually change their colours in LaserCut using the row of coloured buttons at the bottom of the screen). On the top right of the screen is a list of colour groups along with cut, speed and power settings. Double clicking on them will bring up a dialogue where you can edit speed and power, and select whether lines/shapes of those colours are cut or etched. You can also move colours up and down in the list; colour groups at the top will be cut first. This is useful for making sure all of your operations are done in the right order (if this is a job you're likely to repeat, you can go to File > Save As to save a .ecp file, which will retain the colour groupings and settings you've put in).
The cut power required for a given piece of material will vary depending on not just the type of material and thickness, but also how recently the laser was cleaned, how heavily it's been used since, how well the beam is aligned, how parallel the bed and the XY gantry are, and how close to the end of its life the laser tube is. You may sometimes find the laser cuts with more power at the centre of the bed than at the edges. Have extra material on hand and be prepared to do some testing to get the right settings each time you start a new cutting session.
If you cut with too much power or too slow, particularly with woods, it'll burn and blacken parts. Even at best, wooden parts will have browned edges, but this charring is only a few microns thick and can very easily be sanded off. Yellow stains on the surface of wooden parts are from resins burning and resettling on the surface of the wood. Overpowered cuts or cuts reflecting off parts of the bed in contact with material may also leave scorch marks on the surfaces of parts; these can either be sanded off, or prevented by applying paper masking tape to the material before cutting (annoying to peel, but will give you cleaner parts). With acrylic, leaving the films on each side will result in cleaner cuts, but messier etches.
If you cut with too little power or too fast, the laser won't go all the way through the material. This is especially visible with small parts when they don't drop out of the sheet into the bed. If you're cutting a sheet of large parts, adding some additional ones small enough to fall through the struts of the bed is a good way to make sure the laser is getting all the way through your material (when the cut is complete, without moving the sheet material, you can carefully poke them, and if they don't fall out, you then can simply rerun the cut to get all the way through).
