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View Full Version : How many CFM do you need to do wood well?



john banks
03-16-2012, 9:58 AM
Looking to upgrade our Hailea ACO 500 which only puts out about 5 PSI. With a 38mm lens we can make a nozzle that reduces the cone to 2mm from 4.5mm and this allows us to cut 4-6mm hardwood with no masking and no clean up afterwards, even intricate designs work well that we couldn't do without the restriction. It works well because it is coaxial and really focussed into the kerf.

However, the beam width at the cone when we use our preferred 75mm lens for cutting is too wide and requires the full nozzle width to avoid reflections or drop in power. So we still need to upgrade our compressor.

We need 240V single phase 50Hz compatibility. Oil free would be best, but not essential with filtering.

Some suggest we need 5CFM FAD (7-8 CFM displacement). Some say we just need pressure which is easy to get with many cheap airbrush compressors, but I can't imagine the pressure at the nozzle is much when it opens up to 4.5mm?

Reason for asking, is that the quieter compressors which are based on refridgerator compressors are expensive to get this flow, about $2800 locally. We are looking for about 70dB rather than the high 90s you get off cheap compressors. Then I can get it quiet enough to not cause any disruption to a neighbour (or us in the workshop).

Michael Hunter
03-16-2012, 12:58 PM
I don't know in absolute terms, so can't quote any cfm figures.
However, for cutting wood, all you are doing with the air-assist is blowing out any flames that might spring up and moving a bit of dust.
Remember that you are trying to **vapourise** the wood rather than burn it - if you burn through, you will end up with a charred mess.
It is not like cutting acrylic and other plastics, when the air-assist is essential to actually remove molten material from the cut.

Dee Gallo
03-16-2012, 1:12 PM
I use a small compressor used in the nail painting shops... only 47 db, nice and quiet. It puts out 10 psi but can go up to 40 if needed. I get mine from Tri-City Paint and they are cheap (like$80) and they have a 2 year warranty. I've found they do wear out about 2 years into it, so they will replace it once. Then, 2 years later you have to buy another one. Pretty cheap for such a convenient and quiet mini-compressor. I usually keep one spare which I buy a year after the first, so I'm always under warranty. Model TC-18 is the small one (size of a brick) and Model TC-60 is the bigger one (although it is still tiny and quiet).

cheers, dee

john banks
03-16-2012, 1:27 PM
Thanks. Michael, I should underline how dramatic the improvement is when cutting wood with 29 PSI air assist (using a high pressure and high flow but far too noisy compressor) compared with 5 PSI with the same nozzle, or by getting what feels similar air velocity by narrowing the nozzle. Fonts like "curlz" can be cut in 5mm hardwood with no clean up. The 0.5mm parts at the end look amazing when they come out uncharred and in one piece, but I don't know if this is a feature of pressure or pressure and flow, hence this thread.

Dee, can you comment on whether you think this compressor would allow this?

Michael Hunter
03-16-2012, 2:02 PM
John - that opens a whole nother can of worms and could explain why people with similar powered machines are getting such different results (particularly with baltic birch ply).

Joe Hillmann
03-16-2012, 3:40 PM
I don't know in absolute terms, so can't quote any cfm figures.
However, for cutting wood, all you are doing with the air-assist is blowing out any flames that might spring up and moving a bit of dust.


I think air assist does a lot more than just remove a bit of dust. It gets that dust out of there as fast as possible so that it gets out of the way of the laser beam so the energy of the beam can be concentrated on the part being cut rather than the dust and smoke adsorbing it before it can get to the cut .

Rich Harman
03-16-2012, 4:39 PM
The distance from the cone to the material is going to be a factor too. If you are using a 40mm lens you can get by with less pressure. I use a 63mm lens, soon to be 100mm and use a Gast 71R compressor and I have no shortage of air.

Dee Gallo
03-17-2012, 2:42 PM
Thanks. Michael, I should underline how dramatic the improvement is when cutting wood with 29 PSI air assist (using a high pressure and high flow but far too noisy compressor) compared with 5 PSI with the same nozzle, or by getting what feels similar air velocity by narrowing the nozzle. Fonts like "curlz" can be cut in 5mm hardwood with no clean up. The 0.5mm parts at the end look amazing when they come out uncharred and in one piece, but I don't know if this is a feature of pressure or pressure and flow, hence this thread.

Dee, can you comment on whether you think this compressor would allow this?

I do not know about the amount of flow, but this compressor will allow you to go from 0-40 psi. The size of your hose and orifice will determine the flow, I think. I just use the connector that came with my Epilog, but if I could I would probably make it a smaller hose. I don't mess with the pressure, just leave it at 10 psi all the time. I don't use a compressor for airbrushing, I use a CO2 tank with a regulator. So, sorry I'm not too helpful on that point.