Tweakie.

I tried cutting some scaled down Tweakie-bikes out of .032" basswood.  The half scale and quarter scale (250 micron features) ones turn out great.  Basswood is not up to the task of 1/8 scale Tweakie-bikes.  They cut out,  but the bike is essentially made out of 125 micron wide ash and falls apart.

One issue with cutting things at this scale is the tendency of the assist air to blow the cutout bits all over the place.  I even have a couple of quarter scale Tweakie-bikes gone with the wind...

Finally got the Arduino to do the  laser power modulation.   Did the usual Drew picture test:  http://www.flickr.com/photos/jayfrase/12180276666/
When blown up you can see that my spacing is a little off.  Used PEP and had the spacing set at 0.009.  I tried it at 0.007 but got overlapping lines.  Guess I should have used 0.008.  Oh well, that's for next time.
The one problem I'm still having is the Arduino is getting off by the end of the print.  The file said the power level should have been 98 and the Arduino said it was 70.  Low by 18 steps.  I'm not sure why this is happening.

Didn't get a chance to attach the file.  Warning... Large file ahead.

I tried cutting some scaled down Tweakie-bikes out of .032" basswood.  The half scale and quarter scale (250 micron features) ones turn out great.  Basswood is not up to the task of 1/8 scale Tweakie-bikes.  They cut out,  but the bike is essentially made out of 125 micron wide ash and falls apart.

One issue with cutting things at this scale is the tendency of the assist air to blow the cutout bits all over the place.  I even have a couple of quarter scale Tweakie-bikes gone with the wind...

 

I got the tiny text test under a microscope...  the 50 micron tall text is barely legible if you know what you are reading (after all the beam is maybe 12.5 microns wide (about one wavelength of a CO2 laser beam)).  100+ micron text is readable.  I am seeing a little lag in switching the beam off due to using the MACH3 spindle speed command to control the laser (PWM generator is running at around 25,000/256 Hz so it takes a little while for power changes to take effect).  My gcode maker can put delays in before/after switching on/off laser, but I was not doing that so getting little light tapered wisps between chars.

I did a little calculation and figured for engraving images it would take around 3 hours per square inch (my mill/controller/power supply maxes out motion at around 20"/minute)...  but the resolution should be awesome!

Jay,
Very good for a beginning with an experimental controller.  Definitely shows promise.

Perhaps using a different wood would help some as well.

John Champlain

Here is another image of Tweakie-bikes cut with the 405nm laser in 1/32" basswood.  Focused beam width looks like it is around 12.5 microns (close to a single wavelength of a CO2 laser).  Full sized bike tubes are 1mm across.  Smallest one is 250 microns.   Tried to cut a 1/8 scale one,  but at 125 microns wide,  the bike structure is basically ash...  falls apart.  All bikes cut with two passes at 500 mW/6" per minute, assist air on...  final pass needed to make sure the cutouts fell out...  without it you tend to break things pushing out the pieces due to faults in the wood grain being weak places.

Looks incredible, and incredibly fragile.

Here is some gratuitous 405nm laser cutlery.  It is the EMC2 FLOWSNAKE pattern.  The flowsnake is a fractal like pattern known as a Gosper curve.  This one is around 1 inch across.  The edge measure 10.9 inches long and has 3077 facets averaging .0035" long.  You can't see most of the tiny detail in the photo...  crappy camera.

I generated the MACH3 gcode for this pattern from a 40 line long recursive program written for EMC2 based machines using my gcode processing program.  It can translate between the languages of about 50 different milling machines plus DXF, HPGL, GPGL, and a few others.  It can also generate time optimized 2D cutting paths.