I personally coined the expressions “smoke assist” a year ago when i was trying to explain to new users what the difference is on air assist and smoke assist, and what the two different techniques should be used for 🙂

What is smoke assist?

Smoke assist is a helping hand to keep your mirror or/and lens clean of the smoke generated by the lasing work.
The exhaust should only do the work of transporting the smoke from the exit to the end of the hose, nothing else.
The smoke assist helps moving the smoke from the cut area to the exit where the exhaust fan takes over.

With the smoke assist you can use less powerful exhaust fans, as the exhaust doesnt need to put the machine casing under negative pressure to clean out the smoke, the smoke assist helps with this.
Common airflow and air dynamics, what you want is a flow trough the machine with air, from the smoke assist fans -> exhaust fan.

Easiest solution for a smoke assist

Add fans, doesn´t matter what fans, i used my daughters hair dryer the first weeks and later changed to two 50mm 12v DC fans mounted in the front of the machine blowing air over the bed.
Later on i added more fans inside the machine on my laser head to keep the lens clear.
For bigger machines you need bigger fans, like 120mm computer fans.

This laser head is custom made by me, not a original product.

k40 intake fans
Here is the intake fans in my lid. You can mount them in the bottom or front piece, just add fans to help out with the input of air.

Notify of

Inline Feedbacks
View all comments

Could you technically run two air pumps and get the same effect? Like have a 60L/min pump mounted in front and blow in air and have a small fan push it towards the back of the case towards the exhaust?


Just wondering where you picked up the 12v to run the fans from, is there a spot on the PSU or the board?


This seems like a silly question, but I want to make sure I’m understanding correctly. Did you cut through the sheet metal of your machine when installing the fans?


Looking at the fans and how you installed them, isn’t there now a risk of a laser beam getting out of the encasing? Through the laser fans?

Thierry Perraut

Don’t you have to worry about laser light reflections through the front fans? i.e. light could reflect and exit the enclosure it seems.
I’m wondering if some 3D printed 90 degrees elbow would not help there for the intakes. Not as good for airflow, but better to prevent light from escaping. What do you think?

Great site, thank you.

Mujtaba Hussain


I am adding an air assist and got a 70l/min air pump but now I am wondering if it is better to instead add two 12v dc PC fans on the outside and one on the laser head with a 3d printed air assist nozzle. Which setup would be better?


Hi all, just looking at adding air assist but where’s the best place to tap into for the feed?


Thank you that was very helpful.


Hi I have just brought a K40. Like you, most youtube videos also recommend adding an air pump but not sure whats the best size 20w 40w or higher I just don’t know. What would you recommend and whats the best way to attach it to the machine? Please bear in mind I am a 68-year-old woman and not very electronically minded, please keep your answer as simple as possible. Thank you Carol.


Hi, You say a pump with 60l/hour, did you happen to mean 60l/min?


I am adding air assist to my K40. I think I will go for the Hailea pump, but what size hose do I need to buy to fit it? Is the coiled type easier to deal with?
Another question: should I go for a plastic printed nozzle that encloses the laser head (risk of melting?), or use a stainless tube on the side of the head that attaches with a plastic ring? Any thoughts gratefully received.


Hi HP, great info.
So how and where do you connect the pc fans to? I saw a schematic somewhere that the power supply only has a 5v and a 24v out?

I read a lot about people adding all sorts of stuff like laser pointers, fans, lights etc. but no one seems to talk about how they connect everything. I can solder, but I’m not well versed in the arts of volts, watts and ohms.


I agree with this. I’m good with electronics, can solder, know arduino, etc., but it’d be great to see some other folks secondary power supply setups for the other components they are running. I haven’t found any links for something like that. Maybe I need to document it and post on Instructables once I figure it all out!


I was going to comment on your “air assist” (that is why I ended up on the site), but no comment section.
I agree with your assessment. I actually have “that” air-assist, and it is much better than not having it. Without the air-assist, my lenses would require constant cleaning and wood would often catch fire. With this assist, I have had none of these problems (I don’t see any venturi effect as the lens itself blocks the path).
However, I was on a search because my newly purchased 25mm focal distance lens does work with this assist (the geometry of that system cannot bring the work piece close enough without interfering the x-axis). Having a fixed air-stream driving the smoke toward my exhaust path as your “brake line” assist makes a lot of sense (rather than blowing everywhere, then trying to exhaust it)…thanks


Looking at your picture, it would appear you have “something other than a stock K40″…your x-axis looks much larger than typical. To that point, I would not recommend anyone add any significant mass to K40 head (such as a fan)…the stepper motors/drivers cannot handle it and would start skipping steps quickly (especially while engraving at high speeds)


on the subject of motors, what is the current k40 motors rating? I`m looking to build a rotary and presume that ideally the motors should be the same so not to complicate the job.


Hi There,
Any ideas as to why all of a sudden our exhaust is blowing more smoke than usual when cutting timber / MDF. Never used to exhaust so much before but all of a sudden it seems to look like the side of house is on fire when we have the machine cutting. Having to cut at night as to not be so noticeable to neighbors.


thanks for your reply. Our temps are actually increasing as we are in southern hemisphere. Think this would still be same issue.


I am considering putting 2 smaller computer fans, maybe 50-80mm in the front of my machine with holes cut for air intake, along with a 150cfm squirrel cage fan at the exit from my building, will this work well?

My thinking is if I seal the lid better and have a larger exhaust fan that having the two little ones sucking in fresh air to blow over work piece would move the smoke out fast with less escaping into my house.


Thanks I already have the fan, it was off a Pellet stove that failed, so its free. I was going to mount it right at my window exhausting outside through a dryer vent type setup. It has flaps that close so rain doesn’t come in etc.