A question on the LightBurn forum prompted a quick-n-dirty measurement of the assist flow rate vs. inlet air pressure, which required a bit more oomph than the laser’s air pump can provide.
So a small air compressor with a buffer tank on a T fitting in the Basement Shop provides the air:
The far end of the green 50 ft hose has a horrific quick-disconnect 1/4 inch NPT to 6 mm tube adapter replacing the laser cutter’s air pump:
Protip: If you’re trying to run an actual air tool at the end of fifty feet of 1/4 inch ID hose, you’re doing it wrong.
Flow measurements come from the flowmeter inside the cabinet:
The normal dual-flow assist air setup has a flow control valve (the knob sticking up on the right) normally set for 2 l/min from the air pump:
I cranked that valve completely open to allow unrestricted flow with the solenoid (block in the middle) closed and varied the compressor’s output pressure while measuring the air flow.
Without further ado, the assist air flow rate as a function of the inlet air pressure just upstream of the Y fitting on the left:
Fairly obviously, the flow is not 5.5 l/min at 0 psi inlet pressure and the long & skinny air hose limits the flow above 15 l/min. The eyeballometric line looks pretty good in the middle, though.
Other measurements not shown here suggested the outlet pressure, as measured just downstream of all the plumbing / upstream of the flowmeter & hose to the laser head, is about 1 psi at 10 to 12 l/min flow, with 0.2 psi at 8 l/min. My pressure gauges have terrible accuracy at such low pressures, so I don’t trust those numbers, but the plumbing definitely accounts for most of the inlet-to-outlet pressure drop.
The nozzle on the laser head is 4.1 mm ID → 13.2 mm²:
A flow of 10 l/min produces a 13 m/s = 28 mile/hr wind through the nozzle, which seems adequate to blow the fumes out of the kerf, and the low-flow default of 2 l/min might be a 5 mph breeze.
More air pressure would produce more wind, but it’s not clear how much better the resulting cuts would be.
The Smell of Molten Projects in the Morning 
Long lengths of 3/8″ air hose will work. I’ve done a couple of builds that way when the “5000W” generator was unable to run the “2HP” compressor. Nominally 220V, 20A, but 4000′ and a carburetor was murder on the generator. On mains power, even a framing nailer did fine.
Protip: It can be spooky (sometimes dangerous) to unplug 300 feet of 90PSI pressurized hose. Best to drain the compressor before unhooking.
For less ambitious projects, I have a luggable 110V Husky compressor from Home Desperate that will run an underlayment stapler and finishing nailer with 30 second delays after 20 staples/nails. The floor looks beautiful and I’m glad the project is done. I hate particle board! That only needed 50′ of 3/8″ hose, so I could keep the compressor outside a window.
IIRC, the skinny hose came free-with-something-else at LowePot and passes enough wind for my limited uses. For sure: if I must nail another pallet of shingles ever again, somebody else will do it!
Love the ‘punk’ spikes. I have the same with small neodymium magnets affixed.
Now if only I could get rid of all the spam from Amazon that believes I might be interested in leather dog collars (for my wife!) :D
We probably read the same discussion on the LightBurn forum a while ago … :grin: