What specs do I need to look at when buying a compressor?

I’m currently in the process of building my first DIY 90 watt laser cutter. Which is a fun project since I have near zero experience with laser cutting. If some find it interesting of course I’m happy to share my progress pictures.

Anyway, I’m currently researching my options for air assist. Of course I could just buy a ‘standard Cloudray pump’, but as most of you know, the results when using a real compressor are usually much better.

Unfortunately I don’t have a lot of space for a huge compressor. And since it will be used in a room which is directly connected to the house, it can’t make a lot of noise. So these restrictions realllly limit my options.

I found this nice compact compressor: Senco AC10304 Olievrije Stille compressor

But I have no idea if these specs will work for using it with a laser cutter. The thing I’m most worried about is the volume: 5 liters. Is this an option? Or do I need a much bigger tank?

Can anyone give me some specs I should keep in mind when selecting a compressor?

Or is it smarter to go for the standard Cloudray pump and upgrade later?

Thanks for all your help!

hi there i have a 80w co2 laser and i am using this compressor it is fairly small quiet but not silent i think to truly get silent it will be a lot of money

50L Ltr Litre Air Compressor Silent 2 x 750w 2HP 100PSI 7BAR Oil Free Portable

to be honest i dont think this tank is big enough if you are cutting at 25 psi the motor kicks in bit over a big job

my advise would be get the biggest tank you can

Thanks for your info. What is the absolute minimum tank volume I should keep in mind, you think?

when i was searching the internet for help on getting one some people was saying 25-30 litre so i thought go a little bigger and glad i did if you don’t mind the motor cutting in a lot them you can go smaller i guess but the more you can hold the better i guess hope this has helped

Absolutely! Thank you very much!

One additional question: what rate do I need? How many liters of air per minute do I need for a quality air assist?

I have an 8 gallon (30L) and it drives me nuts turning off and on when I’m using 30 psi on a plywood cut. It’s also a low cost ‘harbor freight’ type and is very noisy.

Spouse OK’d me a new one. The question is how often can you deal with it turning on? My 8 gal has driven me to want a 10 at minimum with an ultra quiet compressor, but preferably 15 or 20. 20 gal seem more difficult to find and costly.

This one ‘appears’ popular with laser users and is from Amazon

Most of where I read about suggested compressors, advise the largest tank you can manage. Size/money are the two main restrictions.

Went to @MichMich link, but couldn’t find a way to set it to english. Loved Screenshot from 2021-11-07 15-15-57


If it’s quiet enough. I wouldn’t mind if it turns on often. So there are many things that come in play here.

For example: wouldn’t a regular airbrush compressor work here? They are super quiet so in that case it wouldn’t be an issue if it keeps on running.

Or can’t they deliver enough air or pressure?

Edit: I’m trying to push more Dutch in this forum. That’s why I post those non translatable links here. :sweat_smile:

I speak every language, but Greek, you link is all Greek to me… :crazy_face:

Do you wish a 3 lb air nozzle pressure or 30 lb? It has to feed out the hole in the nozzle. Large nozzle hole more pressure, more lpm, smaller hole lower pressure less lpm.

One of my nozzles has a hole that is 6mm, the tube running to it is 1/2 that size, restricting air flow. I need higher pressure in the ‘feed tube’ to get the pressure I want at the nozzle. LPM is the same I believe…


It depends on the nozzle type. Universal Laser Systems for example has a small nozzle and tubing and requires significant pressure that the diaphragm pumps can’t create. For those, the oilless CAT compressors are great! However, if you DO have a machine with a larger nozzle and larger that the diaphragm pump can run, then by all means use the diaphragm.

The think is, diaphragm pumps (also used for aquariums) are cheap and usually tankless. The oilless compressors still have a huge problem with water condensing out of them, diaphragms do not. You need a water separator and it must be drained regularly. There’s also probs with the separator or a ceramic filter preceding it getting clogged- it’s not really something you can see, but it will choke the system and it’s hard to clean.

Also tank systems require time to build up pressure. You probably want to add a solenoid valve too so the compressor doesn’t keep draining through the AA cone and cycling on and off when you’re idling the system but don’t want to shut it down. A diaphragm is instant-on so you can just switch it with Ruida’s “WIND” input that only triggers while actively cutting, same as exhaust.

I have a compressor on mine with an 8 gallon tank. It is off via the Status control when it is not in ‘run’ mode. In run mode Status enables the initial solenoid allowing low pressure to go to the head. When ‘Air assist’ is enabled on a layer and that layer executes ‘Wind’ enables the bypass solenoid allowing full pressure from the compressor into the head. My compressors regulators set to 30 psi generally, so that’s full pressure with the ‘air assist’ enabled. This is generally known as the ‘ultimate air assist’ and all of it’s variation.

The real difference is that with most diaphragm pumps, they don’t fill a reservoir so there is no time for the air to cool and when it expands for it to drop below the dew point. The pump type has nothing to do with condensation, it’s physics.

Good luck with whatever you choose. I still haven’t made a choice myself.


Right, it’s about being tankless. Well, some compressor setups cool the air enough in the tubing to end up with condensation too. Diaphragm pumps wouldn’t have tanks as they generally don’t produce enough pressure to store anything.

It does depend on the model to some extent.

First of all: so many quality responses! Thank you all.

Based on your feedback my guess is that I will order a beefy diaphragm pump so I can initially get my machine going. I’ll upgrade to the ultimate air assist setup as soon as the rest is dailed in. En then take my time to check what my options are for upgrading to a real compressor.

This might also be better for the wife acceptance factor: if I add a huge exhaust fan AND compressor to my office at the same time my wife might no longer be very enthusiastic about my hobby. :sweat_smile:

I’m preferring the diaphragm compressor since this machine with a CCM axis can use it. It’s instant, no water problems (they got serious when our open membership shop really didn’t know how to respond, and more than once had water spitting out of the AA cone), and giving more volume of liters/min than the oilless CAT compressor could have done. And MUCH lower power. The CAT could produce more pressure but lower volume, but the extra pressure would not be helpful. The nozzle will likely vent so much that it will outrun the small CAT compressor which results in pressure and volume reduction, so ultimately the diaphragm compressor is outperforming it.

With the ULS, small air assist cone orifice and very small ID air lines, it needs tens of PSI to get flow out of the cone. So a diaphragm would probably not build sufficient pressure even with low liters/min actually flowing out of the nozzle.

I have a 30W laser that I run commercially for up to 14 hours per day when I’m busy. I use a 3HP 60 litre compressor set to 3 bar. This setup is large enough to run periodically and not overheat. However it is noisy so lives in the garage and I ran an airline under the floor to the room with the laser cutter.

Since you mention ‘olievrije stille compressor’, I suppose you live somewhere in de geburen. I use for my own build laser a silent compressor from HBM (HBM 9 Liter Professionele Low Noise Compressor | HBM Machines)
Very happy with it…

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Good tip! Thanks!

Pressure is ok and has enough buffer for higher demand jobs like cutting plywood. Almost 2 years in use now. Just added some valves and pressure regulators for the constant low flow feed (keeping the lens clear) and high flow for cutting acrylic and wood.

One important feature is a water absorber. My first cheap hardware store model started spitting water, when using a long time.
But you can also add a water absorber to the tube

I can’t speak to the professional laser cutters but typical CO2 lasers (like the ones you would build) use an open air tube (or a lens nozzle) forcing air on the cut. The pressure is zero in the line so all you really need is high flow. piston air compressors with tanks would be very loud, high energy cost and overkill in my opinion.
I use a low cost electromagnetic aquarium air pump that is about 60L/min, and just about silent.