Dan:

   Laser machining uses the same concepts as normal CNC. I consider the focal point to be a small
ball endmill of .1mm id diameter. Like nay endmill, if you go too slow you burn, at the right speed you dont.

 This photo shown was with a 10 watt laser, run fast, and many passes (. the photo is how it came of the table,
no cleaning was necessary.. so long as the speed is right, it doesnt burn.

Art

COOOL!!!!

Interesting, how good of a surface finish can achieved using this method? Also if other materials (acrylic for instance) can be machined equally well or even, may be, some are better?

Dan

>>Interesting, how good of a surface finish can achieved using this method?

To be honest, I dont know. these are images from initial testing of the mode. Im finding things I wish to add more code to correct,
and lessons to be learned on how to best organize an image for burning. I suspect these initial images will be far surpassed as I
get further into learning how to deal with it. There seems little published on laser in a 3d context, most work seems focused on powerful
lasers ( 100 watt or more) to do 3d, but they do it in one pass. This is fine, but the bottom of their cut is likely very low power
as it would be 3.5mm away from focus, so this multi-focus method allows a set power at every level.. takes longer ,but the results
should be as good or better as the focus is also tight at all levels and power requiirements are much lower, Ive done them in pine at 5 watts.
 It does require a Z table motion though..

  I have tested acrylic, it also works there, but I dont have a good example to show as I find they need to be quite deep
to be photographed well. Here is an early test though in plexiglass...

Art

Interesting to follow your investigation in this field.

Dan

Here is a 3D engraving we did in Poplar using a 3W 445nm Laser Diode with an Air Assist.

Wow! That' impressive. The depth looks substantial. Could you post a snippet of the Gcode you used to do this? I am curious how it's done.

Hard to judge on the quality from the photos, but looks as though it beats any attempt to 3D engrave with a conventional bit in terms of speed and detail level...

Dan

Thanks Dan,

The Z axis commands control the laser power and the variable feedrate slows in the higher laser power (darker) areas to cut deeper.

This is not a fast engraving process by no means. It's only a 3W Laser Diode, but the focal point is around .005" so it does get fairly good detail.

The depth of cut was a little over 1/8". This is not from the exact gcode file to make it, but you will get the idea.

X2.511 Y1.048 Z-0.0138 F47.5
X2.518 Y1.055 Z-0.0143 F46.4
X2.525 Y1.062 Z-0.0139 F47.3
X2.532 Y1.069 Z-0.0132 F48.9
X2.539 Y1.076 Z-0.0187 F36
X2.546 Y1.083 Z-0.0240 F23.5
X2.553 Y1.09 Z-0.0239 F23.8
X2.56 Y1.097 Z-0.0221 F28
X2.567 Y1.104 Z-0.0214 F29.6
X2.574 Y1.111 Z-0.0217 F28.9
X2.581 Y1.118 Z-0.0217 F28.9
X2.588 Y1.125 Z-0.0216 F29.2
X2.595 Y1.132 Z-0.0222 F27.8
X2.602 Y1.139 Z-0.0216 F29.2
X2.609 Y1.146 Z-0.0208 F31.1
X2.616 Y1.153 Z-0.0199 F33.2
X2.623 Y1.16 Z-0.0199 F33.2
X2.63 Y1.167 Z-0.0199 F33.2
X2.637 Y1.174 Z-0.0197 F33.6
X2.644 Y1.181 Z-0.0191 F35.1
X2.651 Y1.188 Z-0.0190 F35.3
X2.658 Y1.195 Z-0.0194 F34.4
X2.665 Y1.202 Z-0.0191 F35.1
X2.672 Y1.209 Z-0.0192 F34.8
X2.679 Y1.216 Z-0.0191 F35.1
X2.686 Y1.223 Z-0.0191 F35.1
X2.693 Y1.23 Z-0.0191 F35.1
X2.7 Y1.237 Z-0.0192 F34.8
X2.707 Y1.244 Z-0.0191 F35.1
X2.714 Y1.251 Z-0.0191 F35.1
X2.721 Y1.258 Z-0.0191 F35.1
X2.728 Y1.265 Z-0.0192 F34.8
X2.735 Y1.272 Z-0.0191 F35.1
X2.742 Y1.279 Z-0.0191 F35.1
X2.749 Y1.286 Z-0.0192 F34.8
X2.756 Y1.293 Z-0.0195 F34.1
X2.763 Y1.3 Z-0.0198 F33.4

Hi John,

So you control both the feedrate and the Z depth... but why do you need them both? And how do you correlate/sync them? Isn't it easier having just one parameter to control?

Are you using your PicEngrave software for the Gcode?

Dan

Hi Dan,

Yes, we control both the feedrate & the laser power and you can set them independent from each other. The variable feed rate is done by a set percentage of the full feedrate based on the laser power values. It helps using both because you can expand the cutting depth range based on the shades in the image. Lighter shades has less burning power and speeds up the feedrate to cut shallower, where darker shades burn with more laser power and slow down the feed rate to cut deeper. A Depth Map image is being used. It's also possible to have the Z axis move the laser's focal point down into the deeper cut areas, use a A,B or C axis command to control the laser power and have a variable feed rate on each line of gcode also. 

Yes, PicEngrave is being used to generate the gcode for our 3D laser diode engraving.

Here is another example in Poplar and it's about the same max depth of cut.

Jeff

   

Jeff,

So the Z axis commands do actually move the Z? I got the opposite impression from your previous post where you said they were controlling the power of the laser.

Still don't get it - why you can't control just the feedrate and have the same effect. Is there not enough resolution/range for the feedrate?!

Thanks for the photo, I really like the results you're getting.

Dan