• ### "Impossible" Woven Laser Cut Celtic Knot

It's not perfect, but I'm happy with how this turned out.

Material is EVA Foam from Michael's hobby store.  3mA power @ 6mm/sec.

Practice run on cereal box cardboard.
Yes, I cheated, it's laser cut in 13 pieces.  All the glued joints are hidden underneath the overlaps.

• ### Self-Improvement

You know how 3D printers print stuff to improve itself?  I've just done that with my laser cutter :-)
Nothing fancy, just a bracket to hold the smoke assist fan at an angle.

https://www.thingiverse.com/thing:3370541

FYI: Smoke assist fans are placed towards the front of the laser cutter to create an air flow towards the back of the laser cutter so smoke would get sucked up by the Exhaust Vent instead of lingering in the cutting area.

• ### Vector Engraving

```import svgwrite
import math

dwg = svgwrite.Drawing('test.svg', profile='tiny',width='100px',height='100px')

a = 0
n = 15
x0=50
y0=x0
r=x0
for i in range(0, n-1):
a = 3.14*2 * i / n
x = x0 + math.sin(a)*r
y = y0 + math.cos(a)*r
b=0
for j in range(i+1, n):
b = 3.14*2 * j / n
x2 = x0 + math.sin(b)*r
y2 = y0 + math.cos(b)*r
print(i,j)
dwg.add(dwg.line((x, y), (x2, y2), stroke=svgwrite.rgb(0, 0, 255, '%')))

dwg.save()
```
• ### \$12000 Epilog vs. \$400 K40 Laser Cutter

I decided to get Expanded Metal Sheet from HomeDepot while I wait for the honeycomb bed.

Box on left is cut by a \$12,000 Epilog Mini, one on the right is by my \$370 K40. I ran the engrave at 300mm/sec @ 5mA, vector cut at 5mm/sec @5mA (one pass).
The Epilog is definitely better, but I'm hopeful that with time I will be able to get closer to the Epilog's result with the K40.

• ### Trimming the exhaust vent

The exhaust vent inside the K40 juts in quite far and actually obscures the laser path when Y is zero.

Unfortunately taking out this vent to trim it on the bandsaw require removal of the gantry that is in the

way, in turn this would require re-aligning mirrors.  I decided to do it differently.

## Ooops...

Incidentally, later I discovered that I did not trim enough to clear a 3D printed air assist nozzle and had to trim for the second time.  So, if you decide to do this, be more generous in trimming. :-)

• ### K40 Exhaust Fan Hack

Sorry, I don't remember where I learned this from, but someone noticed that there is quite a gap between the fan and the cage on the stock exhaust fan.  Adding a nut decreases that gap and hopefully improves efficiency of the fan.

Had to trim the top of the fan to screw the plastic cap in.Nut was just a bit too tall.  I had to shim the cover with two cardboard pieces so the fan would clear the cover.

• ### Non-destructive window vent

Before I start punching holes on the wall, I want to make sure that this laser hobby is not a passing fad for me, so I came up with this temporary vent solution.  I cut foam core pieces to perfectly seal any gaps below the wood and also between the two sliding window panes.

• ### Suggested Mods

• [x] Shortened exhaust duct (gives you a lot more room)
• [x] Install 100-150CFM fan near the outdoors to suck instead of push the air through the pipe.
• Added a coolant temp gauge
• Added some additional outlets and fittings to the back (12V and air assist)
• Found a hose adapter on Amazon the fit the duct slot perfectly
• Added a stylish cabinet handle (Menards) to lift the cover
• [x] Added an air assist nozzle