Star Wars: A New Hope Poster

[atrueresistance]

I signed up to be a rematch Santa on reddit for the Star Wars gift exchange. When their first Santa does not deliver, the poor Redditor get's placed in the rematch pool. If there are people willing to send more than one gift, they signup as a rematch Santa. Then everyone gets a gift

My idea was to engrave this.



It turned out well.....


It took somewhere around 8 hours. I think the first mistake was wood choice. Pine doesn't seem to be the best to engrave. . .

I did measure 3" with a calipers from laser to board, moved up 3.4mm and set focus on a black powder coated piece of steel, and then moved the Z back down 3.4mm. that has helped immensely with cutting.

Code: Select all

( PicEngrave Pro 5.0.24 - for MS Windows US Version )
( Date/Time: 11-14-2015 at 11:12:59 )
( Image File: 10658412_1 )
( Analog + Feed Rate )
( 25.0% Feed Rate Change )
( 2850.0000 units/min. )
( Image size in mm: 200w x 199h  )
( Pixel Resolution: 0.2 mm  )
( Line Spacing: 0.2 mm  )
( Max. Cut Depth: 12000.0000 mm  )
( Min. Cut Depth: .0000 mm  )
( 3rd Axis Safe Position: 0 mm  )
( Start Position: image center  )
( Horizontal Axis Offset: 0 mm  )
( Vertical Axis Offset: 0 mm  )
( Engraving Angle: Left 45°  )
( Spindle On/Off Enabled  )
( GRBL Code w/G28 EOF  )
( Metric Mode  )
( X Axis Align  0 )
( Y Axis Align  0 )


Not giving up yet. Trying a dithered version that is a couple hours in, which is already looking better.

[Picengravertoo]

TTL engraving with a dithered image works better with grainy woods like Pine or Oak. It's more forgiving of the irregularities in the wood because the laser is either full power or off.

We do allot of engraving on Poplar wood with varied intensity even 3D engravings. We look for boards that does not have allot of grains/knots and does not have a green tint. Lowe's in our area has a good selection of Poplar, but Home Depot does not carry much. Poplar engraves slightly better then Birch Ply and Basswood engraves very good too.

Sometime you should try engraving the back of a mirror. The Negative selection in the Analog/PWM engraving profile will reverse the power values. White areas will engrave at more power and will burn white when looking at the front of it. It's also like a Lithophane, except it looks the same when it's backlit or not. If you can find mirrors with the white backing that has an even coat, you can actually get a range of shades engraving them, but it takes some trial and error to get the min/max power & feedrates just right. The gray backed mirrors do not laser engrave very well though.

6852854S.jpg (186.79 KiB) Viewed 7994 times

White Artist Canvas & white leather gives the best 8bit grayscale results. Here are two varied intensity engravings from the same image and one was done on Artist Canvas and the other on Leather.

2534182S.jpg (192.48 KiB) Viewed 7994 times

5641607S.jpg (182.73 KiB) Viewed 7994 times

You need real good fume extraction when laser engraving these materials.

[atrueresistance]

Very Nice! I don't think I'm quite ready to tackle other materials yet as wood seems to be difficult yet.

So I thought it was because I didn't convert the image to B&W initially. So here is after editing to black and white.

Code: Select all

( PicEngrave Pro 5.0.24 - for MS Windows US Version )
( Date/Time: 11-15-2015 at 18:28:33 )
( Image File: 10658412_2 )
( Analog + Feed Rate )
( 20.0% Feed Rate Change )
( 2794.0000 units/min. )
( Image size in mm: 152.4w x 151.638h  )
( Pixel Resolution: 0.1524 mm  )
( Line Spacing: 0.1524 mm  )
( Max. Cut Depth: 12000.0000 mm  )
( Min. Cut Depth: 470.0000 mm  )
( 3rd Axis Safe Position: 0 mm  )
( Start Position: image center  )
( Horizontal Axis Offset: 0 mm  )
( Vertical Axis Offset: 0 mm  )
( Engraving Angle: Left 45°  )
( Spindle On/Off Enabled  )
( GRBL Code w/G28 EOF  )
( Metric Mode  )
( X Axis Align  0 )
( Y Axis Align  0 )


I was reading the embaser forum and saw some settings like above. It is definitely better then the first attempt. Still really dark. So does that mean I just need to up the units/min?

3hrs 45Min in

[Picengravertoo]

When you reduced the Pixel Resolution you are overlapping the burn lines and is why the darker burning. Your focused better, so you need to increase your feedrate (units/min) to lighten up the engraving also. Also when you TTL pulse engrave with a Dithered image, the Min 3rd Axis Depth should be zero so the laser turns off completely in white areas.

Also I noticed you did not re-size the image after changing the Pixel Resolution. There is an Auto sizing selection in the image editor and you input the Pixel Resolution you will be using and adjust the Pixel Width or Height until it shows the engraving size you want. Do all your editing/sizing first and then save the image, reopen to Dither 1bit B&W. The Atkinson Dithering Algorithm works best for us.

[atrueresistance]

Finished around 3:30am. 8hrs 34mins. Did a little sanding.



Thank you for the suggestion, after I get off work I'll fire up the machine again.

I know when I bought the SO3 it was listed as rapid 2500mm/m/100ipm. Not sure how faster it will go.

[Picengravertoo]

We are able to test run at 175IPM (4445mm/min) max with grbl 9J using a fixed S255 on each line of short incremental move raster gcode with our PicSender streamer. We calculated the toolpaths perimeter and it times out the run correctly for that feedrate. We can't engrave that fast because of our LD's limitations. I believe your limiting factor could be the streamer your using for one & second the grbl your using because S commands are for spindle speed & with such a large range (0-12000?) and it's not for laser control. The S commands do not execute in real time with standard grbl because of the slight dwelling. This is how our grbl settings are for raster engraving images with a laser diode. Try changing these settings in the grbl your using and see if it improves the performance.

$0=30 (step pulse, usec)
$1=255 (step idle delay, msec)
$10=18 (status report mask:00010010)
$11=0.005 (junction deviation, mm)
$12=0.002 (arc tolerance, mm)
$120=12000.000 (x accel, mm/sec^2)
$121=12000.000 (y accel, mm/sec^2)

[Picengravertoo]

I cutout the border from your original image in Corel Photo Paint so I could optimise the toolpath with Skip White Background. I opened it in the PEP5 image editor and resized it with Auto and a .006" (.1524mm) Pixel Resolution to an engraving size of 6" X 6" (152.4mm X 152.4mm) I then adjusted gamma to .8 and sharpened to 12 then saved the image. I reopened it and used the Atkinson Dithering Algorithm with a .050 Error Constant to eliminate allot of the Black speckles/dots.

In PEP5 is used a feedrate of 175IPM (4445mm/min) and a Feed Rate Change of 45%. White ran at 175IPM & Black at 96.25IPM (2444.75mm/min). I also used the extended edge with 10 Width in Pixels at 100IPM so if there is any white on the edges, it will slow from 175IPM to 100IPM before reversing to reduce the stress on the mechanics. The Min was set to 0 and Max 255 (EmBlaser's grbl) and I engraved at a right 45 angle.

This was done on Birch Ply using our EmBlaser with it's grbl and it only took 1:39:29 in time to engrave compared to your 8 hours 34 min?

Evidently, you are not getting near the feedrate out of your SO3's grbl that you should be getting and it's the biggest reason your engravings are so dark and take so long to engrave.

DSC00695S.jpg (251.89 KiB) Viewed 7832 times