Air assist is used to increase the quality of the laser process. Air is blown on the laser spot, which removes particles and fumes produced by the burn process. The laser beam is less distorted by those particles and has more power on the surface. Moreover, burn marks are drastically reduced.
The following descriptions mainly refer to the S6 and S9 lasers. For the S10, the nozzle is already delivered with the module, only the pump is missing here. For the S30 series, both nozzle and pump are already included in the package.
This is normally achieved by adding an air pump / compressor that blows air to the tip of the nozzle.
Most diode lasers do not provide such a system out of the box. I am not aware of any official upgrade kits, either. This has changed, most brands now offer air assist kits or nozzles for their products. Hence, most people build an Air Assist themselves. Basically, it consists of only two parts: the compressor and a nozzle with an air channel that is directed to the tip.
You can control the pump using a relay, which makes it very convenient, since the pump is only turned on when needed. You can read how to do this here. Here is a great video showing the effectiveness of the Air Assist and some explanations (at the end).
Compressor / pump
Sculpfun released its pump, which I tested and liked very much. It’s MUCH quieter than any other model I have seen so far. You can find it at the classical shops like AliExpress or Tomtop or even Amazon now.
I only use the Sculpfun pumps now, I removed all other types of pumps.
Never ever place the pump inside the enclosure or close to the laser! The pump will suck in dirty air, which will damage the pump and more important: the lens! Make sure to get very clean air at the pump’s inlet.
The most common question about Air Assist is what kind of compressor to choose. Since I tested only one (the one that I bought), I can only provide personal experiences about this one. If you look for this question on Facebook, you find at least two questions a day when you might find some more recommendations. You can also think about different approaches, e.g., small fans directly attached to the laser head. I also did a test (see below) and can tell that it is far from what a bigger compressor achieves.
Meanwhile, I would always recommend Sculpfun pumps instead of aquarium pumps. These deliver much better performance and are much quieter. There is also a retrofit package for fully automatic air assist, as included with the S30 lasers.
What I have taken from the numerous discussions: the airflow provided by the compressor should be around 60 liters per minute. I used the very common ACO-318 compressor (Amazon-Link). The power is absolutely fine. It is quite noisy, though. If you have your laser setup in a workshop, that might be not of interest. If you are in a home environment, you definitely need to check if that’s ok for you. There are a few others (e.g., see Tobias Vollmers page, in German) that have the same airflow rating but are much quieter (but more expensive).
Next time, I would try the Aquaforte model, I also saw quite some people using that. Since I now tested the Sculpfun model, I would always use that one. Of course, you also need some flexible tube to connect the compressor to the nozzle. This sometimes requires some adaptors, since most nozzles have a smaller inlet than the outlet of the pumps.
Stephan, a member of the German K40 community, calculated the following chart:
Air Assist Nozzle
Sculpfun released a dedicated metal air assist nozzle that should fit nearly all S6 and S9 modules. You can find it at AliExpress or TomTop (see Links page):
Official air assist kit
There are some complaints that the included hose is kinked or can be kinked easily. This is mainly due to the packaging, which squeezed it a lot. A tip from the Facebook forum is to briefly put the hose in hot water once, which removes most of the bumps and kinks. If you are still not happy with it, you can replace it with a hose of about 7.5 mm inner diameter, e.g., a silicon hose.
Sculpfun has released an official nozzle for the S9, as announced. Before buying the nozzle, you should check if you have a suitable model. There are older versions (usually sold before 10’2021) that only have a small recess for the lens. These models do not work with the Air Assist Kit! If you have such a module, refer to the 3D-printed versions below, those exist for this type of modules as well. Sculpfun has released a fitting nozzle for those modules! See below!
Installation is kept very simple and is easily explained in the enclosed info sheet. If you don’t have a compressor yet, you should take the kit with nozzle and compressor right away, they are optimally matched to each other. In the following video, the installation is simply explained:
Nozzle for older modules
Sculpfun now released a nozzle kit that fits to the modules without the recess for the longer version:
Adaptor for older S6 / S9 modules
Edit: I’m uncertain if this will work because most likely the nozzle is too long for the focus to be set correctly when mounted to an older module. – It most likely won’t work.
I have tried on the fly to develop an adaptor with which you can still mount the nozzle on a S6 / S9 module. The file can be downloaded here: Link (LightBurn file). You have to laser yourself a corresponding number of rings, so that the total height is about 8-9 mm. You may also need to slightly adjust the inner or outer diameter (a few percent at most) to make it fit perfectly. Unfortunately, I have not been able to test it myself yet, as I don’t have an old module available. If adjustments are necessary, I will change the template accordingly. You need to glue the rings together and also glue it to the nozzle, I guess (after you made sure that it works).
Self-built / 3D-printed nozzles
Most nozzles I have seen are 3D-printed ones. There are some CNC machined metal ones are out there, but I didn’t see them in action so far (except the manufacturer models). If you search Thingiverse or Facebook, you find many designs. You might need to narrow down your search to your laser model. If you don’t have the option to print a nozzle yourself, you can ask within the communities if someone will print it for you, or you could select a design and let it print at an online printing service. Mine is taken from the Sculpfun users group on Facebook (designed by Tom Timmerman). What I liked about this nozzle is that the air channel is directed directly to the tip of the nozzle. I’ve seen many designs where the air is just blown into the nozzle chamber. In my opinion, that creates a lot of turbulence within the nozzle and no directed output. You can download it here. It is worth noting that it will most likely only fit on a Sculpfun S6 laser. Different models might need a different design.
The above nozzle is for an S6 laser. Meanwhile, I also have an S9 laser available for testing. Here I use the following nozzle: https://www.thingiverse.com/thing:5183841. A version for the shorter module is available here: https://www.thingiverse.com/thing:5192752
The sealing ring ensures that the air cannot move towards the lens, but only downwards to the nozzle. Contamination of the lens is therefore avoided as far as possible. To install this nozzle, the black cylinder / pyramid, which is already installed as a simple Air Assist version, must also be removed. See also the pictures at Thingiverse.
Air Assist using small PC fan
This is a test I did for someone on Facebook, to compare the “normal” air assist with a design using a small 5015 type fan. This fan blows the air into a smaller nozzle that only directs the air angular at the nozzle. It is much quieter than the compressor version. Regarding this, I really liked it. But I also attached an image of the result, which might be a bit better than no fan, but worse compared to the compressor.
Finally, if you want to go PRO, you can connect your compressor to a relay that is connected to your control board so that your software can control it. See my other article for details.
Sculpfun pump 12V and 24V conversion
Two different Air Assist pumps were introduced in the S30 series. One model with 12V (5W, 10W models) and one model with 24V (20W). Ultimately, however, the pumps are electrically identical, you can make one variant the other (with the same power) by making a small change in the wiring.
In the 12V version, the coils in the pump are connected in parallel. This results in a resistance of 6 ohms at 12V and 24W power (twice 12 ohms connected in parallel) and thus a current of 2A.
For the 24V version, the coils are connected in series (twice 12 ohms in series = 24 ohms). At 24V and 24W and 24Ohm, this results in a current of 1A. If you connected this pump now simply to 12V, it would have only a quarter of the power (12V, 24Ohm ⇾ 0,5A ⇾ 6W). But if you connect the coils in parallel, you get the same as the 12V version and thus the identical power.
Just FYI: the small boxed attached to the pump contains an inverter circuit that creates AC voltage out of the DC input. Therefore, it contains two STC4614 MOSFETs to drive the coils (if you ever need to replace them).