Messages

1

Show"N"Tell ( Your Machines) / Re: The Laser Project.

« on: June 04, 2014, 03:37:12 PM »

Thanks! I will use my lab's goggles, don't worry 

Make SURE that they block the wavelength of your lasers...  not all goggles work at all wavelengths...

2

Show"N"Tell ( Your Machines) / Re: The Laser Project.

« on: June 04, 2014, 11:37:21 AM »

Thank you very much for sharing. Is it against forum rules to ask for your laser source?

DTR laser shop...  google will find it.  My .5 watt laser is from a 12X Blue ray writer.  The new 1 watt is from a 16X blue-ray writer.  I also built a 3 watt 445 nm head.  It has a beam around 5 mils wide.  I run it around 2.5 watts max.  He has a new 5 watt diode,  but the beam is even bigger.

Those G2 lenses produce the highest output power from these lasers.  There are some 3 element lenses that can produce a smaller beam from the 445 nm lasers,  but they seem to do it by clipping off then ends of the rectangular beam.  You lose around 30% of your power with the 3 element lenses.

My laser driver is a Flexmod P3 from Illumination Supply.  I power the lasers with a 9 volt regulated 3 amp wall-wart type power supply from Ebay.

Oh,  and don't forget you MUST use proper laser safety goggles!!!!!!  Mine are made by Eagle Pair...  DTR has a link on his web site.

3

Show"N"Tell ( Your Machines) / Re: The Laser Project.

« on: June 03, 2014, 12:58:09 PM »

Hi texaspyro, I'm very impressed by your results. Can I ask you how you managed to get such a tight focus? Also, would you recommend your setup to cut ~mm sized features in kapton?

The laser that I used is a 405 nm single mode laser.  Single mode lasers can be focused to very small sizes and their beam is much less rectangular than the typical laser diode beam.   I focused the beam manually by eye (use proper goggles) and then tweaked the beam by rasing and lowering the laser head on the mill.  (One way is to place the material on a sloped angle and draw a line on some easily marked material like Kapton.  Then examine the mark with a magnifier and see where the mark is thinnest).   But the location that I came up with was pretty much the same as the manual focus point I came up with.  I can't see much focus diffeence over a +/- 0.25" change in laser height.

I can cut Kapton,  but not very well.   It chars and the char seems to block the beam.  Using enough power to cut the material limits the feature size and quaility of the cuts.

Also,  after I bought my 700 mW laser (which I run at 500 mW max),  a new 1+ watt laser is now availabe.  I have not tried it yet...

4

Show"N"Tell ( Your Machines) / Re: The Laser Project.

« on: February 01, 2014, 08:14:39 PM »

I did some tweaking on the feed/power level when cutting the .032" basswood and have been able to cut tweakie-bikes where the features are 175 microns wide.  At 150 microns wide they are a bit too fragile to handle... the structure is barely more than ash.  I need to find some material that the 405 nm light does not char like wood does or melt/fuse like most plastics.

I've also been engraving some desktop name stands for some friends... on small wooden matches with 500 micron tall letters... I am becoming a connoisseur of dollar store match sticks.  One side is always finished quite well.  The others are usually rather rough.  Plus the boxes are handy for transporting teeny-tiny tweakie-bikes.

A friend is getting me some UV curing resin to try some stereo lithography.

5

Show"N"Tell ( Your Machines) / Re: The Laser Project.

« on: January 29, 2014, 10:33:23 PM »

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.

6

Show"N"Tell ( Your Machines) / Re: The Laser Project.

« on: January 27, 2014, 10:15:52 PM »

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.

7

Show"N"Tell ( Your Machines) / Re: The Laser Project.

« on: January 27, 2014, 09:22:32 PM »

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!

8

Show"N"Tell ( Your Machines) / Re: The Laser Project.

« on: January 27, 2014, 04:32:58 PM »

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...

9

Show"N"Tell ( Your Machines) / Re: The Laser Project.

« on: January 27, 2014, 02:45:36 AM »

I did the "Engrave TWEAKIE in a grain of rice" test.   Not having any rice,  I marked a piece of Kapton.  I can read the 100 micron tall letters with a hand lens,  but the 50 micron ones will need a microscope.  I can tell there are individual letters, but can't make them out.  I could probably improve things with some proper attention to focusing.  the laser is just focused by (remaining) eye right now.

10

Show"N"Tell ( Your Machines) / Re: The Laser Project.

« on: January 26, 2014, 06:07:23 PM »

I've never heard of vellum for solder stencils. That sounds interesting.

I have tried just about everything that looked like it might work for stencils (and a few that didn't).   So far the best results (cutting tiny features that hold up to the Toothbrush Scrubbing Test From Hell) have been with the vellum and the Bright Orange (24 lb?) copier paper from Staples.  They both seem to hold up will with use (but I've only done maybe a dozen boards with one stencil) and couldn't cut cleaner.  I have cut  0.15 mm pads spaced 0.15mm.

Something else that works very well cut-wise is self-stick vinyl.  But it makes nasty vapors.  Also the sticky had some advantages (keeps it in place on the board) and some dis-advantages (hard to align, particularly on larger boards).

I first found the vellum a Michael's on clearance...  and it looks like they have stopped carrying it.   I found the red vellum at Hobby Lobby.  This place also looks promising:  http://www.hyglossproducts.com/Vellum-Translucent-Paper-p/58203-1.htm

For very nice Kapton stencils for cheap try OSHSTENCILS.COM   Kapton stencils are good for several hundred boards.