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Lasercutter - Setting and Examples

Page history last edited by Gavin Smith 9 years, 6 months ago

Using the lasercutter is a bit of a trial and error process, so it's important to record any settings and tricks you came across. Plus it's always good to show off your new toys. With that in mind, here's a page for anyone to stick up photos and descriptions of what they've made.

 

Note on Powers and why you shouldn't trust these Numbers:

The lasercutter is a precision machine, but there's a lot of things involved to get it to work. The mirrors have to be clean and in alignment, the bed has to be free of obstructions that can affect how level it is, the air assist has to be running and removing gunk, and the carriage uses fairly cheap bearings and can lose its level over time. Basically these settings are useful as a starting point, but you should do a small test cut (say a 20mm circle) before you start each job. There's nothing more frustrating than finding that you've done a half hour lasering job, but it didn't cut all the way through. 

 

List of Materials: 

Woods: 

     Interior Fijian Cedar, 3mm Ply,  Use this for your first project. 

Try cutting at: 10mm/sec, 45% power. 

This is a quite cheap and very easy to use wood. It comes with an 'A' grade face, and a 'C' grade face, which have different colours. You can use this to create two-tone effects easily:

http://www.flickr.com/photos/38462165@N05/6906748216/in/photostream 

 

     Spanish Hobby Ply, 3mm, from HobbyCo

Try cutting at: 10mm/sec, 45% power. 

This is a really nice wood with a good finish, but it's quite expensive. Available at HobbyCo, and other hobby stores. It comes in large sheets, which have to be cut down to size. 

Sticker usually says something like "Artesania Latina S.A." and "Ref: 29532". Be careful, there's at least one brand of hobby wood that fails to cut on the laser reliably, but the spanish stuff has always served us well. 

 

     MDF 3mm 

Try cutting at: <INSERT POWER HERE>

Very cheap, but easy to use and doesn't behave too badly when laser. MDF absorbes moisture, so consider painting or sealing afterwards. 

 

     Bamboo 5mm flooring

Try cutting at: <INSERT POWER HERE>

This is more expensive, but has a nice grain and finish. 

 

     Woods that don't work:

Not every wood is cut-able on the laser. If you'd like to try some others talk to Gav or Max and we'll test it. Here's some we tried and failed to use:

  • 6mm Fijian cedar. Doesn't cut reliably even with many passes and high power and just makes a charred mess.
  • 3.6mm exterior ply (E0, B-C-A Bond). This literally throws sparks when cut, and makes flames that come close to the laser head. Don't try, it'll just damage the laser. 

 

Plastics:

     Acrylic Plastic:

Acrylic is the standard plastic for lasercutting and it behaves extremely well. It's pretty cheap and easy to find, but some colours and styles are much more expensive than others. (Talk to Gav about how he found out too late that the platstic for the turtlebot cost over $300)

  • Clear:
    • 3mm
    • 6mm, 
  • Coloured: 
    • 3mm
    • 6mm  
  • Frosted:
    •  

 

     Delrin Plastic:

Delrin is an engineering plastic and extremely strong. It's not fantastic to lasercut, and is quite melty, but it's possible to do. Consider making your main chassis out of other materials, but using Delrin for things like gears. 

Try cutting at: <INSERT POWER HERE> 

 

Material  Thickness  Power  Speed  Focus  Notes
           
           
           
           
           
           
           

 

 

 

The Secret of Cutting Wood: (Out of Date)

This took several hours of experimentation to get, but seems to work nicely now. Make sure you follow the instructions exactly.

 

The following works on the 4.5mm Marine White Cedar ply that's in the laser room. As far as I can tell it's the same as makerbot wood.

  • Set the focus to 58mm (not the 62mm normally used)
  • Open the 'prop' button in engrave settings and for the 'cut' settings:
    • Change speed from 20mm/sec to 40mm/sec
    • Change power to 100% 
  • Plug in the air assist at the back of the machine. Yes, it's noisy.
  • Cut the material 4 times without moving the stock or refocusing.
  • Watch carefully to make sure it doesn't catch fire. Lots of smoke is OK. 2 inch long flames are not.
  • Put the settings back for the next user.  

 

 

Material Power Samples:

I cut a few objects at various settings so people get a feel for what it's like. Must emphasise that this isn't a hard-and-fast rule. How long since the lasercutter's been cleaned (mirrors smoked up), alignment, maybe weird stuff like water content of materials, etc. are going to change how much power to use. This should reduce the amount of trial-and-error required, though.

The brushed aluminium I'm particularly pleased with. The engrave didn't come out too well, but the vector cuts (2-4th line) are beautiful.  This photo was taken after giving it a thorough scrub with a rag and water, and the marking is very robust. 

 

Box-o-Tron Example:

Power: Engrave @ 20%, Cut @45%. Material is 3mm clear acrylic.

The Box-O-Tron script is a really fast way to make enclosures of any dimension. You can choose between Makerbot style with bolts, or more simple tab and slot construction. 

http://www.thingiverse.com/thing:404

 

If you're making any sort of project that uses a case, it's invaluable. Once it's created the DXF file, you can then edit it and add in cutouts for switches, LCDs, text for buttons, etc.

 

One small nitpick. The script likes to put an extra rectangle around the edge of each part. I deleted it manually, since that would mean the lasercutter would cut it twice.

 

Sample Glued Boxes:

Power: Engrave @ 20%, Cut @45%. Material is 3mm clear acrylic.

(The exact command used to make this design was './boxotron.py -l 50 -w 50 -d 50 --type slot -f box2.dxf' )

We've got a couple of different types of acrylic glue in the space. The first is a waterthin liquid dispensed from a needle squeeze bottle (I think it's a generic version of 'acribond 110'), and the second is a thick goop known as 'IPS Weldon #16'.

 

The thick stuff is great for when edges are uneven, but it's hard to handle and I generally end up making a mess. The thin stuff is a godsend to use. All you do is hold the box together and gently run the needle down the join. A really thin trickle of glue comes out and wicks into the area between the plastic. Hold it for a couple of minutes and it's ready to stand on its own. 24 hours later the join is cured completely and strong as an ox.

 

There's some more information on how to use the two types of acrylic glue here, and they put my technique to shame:

http://www.youtube.com/watch?v=hT6Ow_cBTps

 

Hole Gauge:

Power: Engrave @ 20%, Cut @45%. Material is 3mm clear acrylic.

 

This was derived from this part on Thingiverse. Very handy for knowing exactly how large a hole is produced for a given input size. In most cases the laser thickness ('kerf') is negligible, but it's good to check.

http://www.thingiverse.com/thing:2073

 

There was a bit of fiddling needed to get the DXF imported into NewlyDraw succesfully. The trick was to select everything and do Object-->'Convert to Path', before exporting.

This gives a perfect example of the speed that the lasercutter operates at. The text on the front is raster engraved. (the head zooms back and forth), whereas the holes are vector cut. However the text engraving took the most time as the newlydraw software had to sweep out the entire area, even the blank bits. 

 

Total time: 34:30sec.  (estimated)

Time to cut all the holes 2:30sec. (estimated)

So the lesson is to keep engraving to a minimum to speed up your times. Alternatively we could have done the engraves one at a time, minimizing the raster dead space, but that would have been trickier to set up and align. 

 

R3becca's Brass (Acrylic) Knuckles:

After a few prototypes in ~3mm acrylic I pushed Robots and Dinosaurs new laser cutter to it's limits with a custom design cut into 20mm acrylic. Many many passes of the laser along the same path were required but eventually it cut through. This creation was purely to experiment with thick acrylic and gain experience with the design process when using the laser cutter. This object will not be sold or used in anger, ie; it's art. :)

 

David's Antenna Mount:

This was a quick hack to allow David to run an antenna in the backyard. Worked well enough to pick up signals from Tasmania!

 

Max's Birthday Card (For Reef)

The 1st birthday cards at the newsagent were shockingly bad, So I bought 3 sheets of heavy card stock and headed to the Laser room.

The dark blue card only has blue on the outer third so it looks great once you laser down to the buff coloured core.

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