I’m just getting around to setting up my K40, and I know I should add air assist. I have a 3D printer, and I recall seeing (way back when I first started looking at this) that people were printing their own air assist nozzles. QUESTION: if you did this, which design did you go with, what do you like (or dislike) about it, and if you were to do it again, which design/approach would you take? Thanks in advance for any replies, they are appreciated.
My nozzle is loosely based on the one here: http://www.thingiverse.com/thing:890705
I’ve made my own adjustments and changes to that design.
I designed my own from scratch, that did not cover the lens, but rather wrapped around it & focused the air in a conical pattern to reach 50.8mm (focal point of my lens).
Personally, I was happy with the design, however the throughput of air is very weak. It requires a much larger air source than I am using (2 pathetically weak aquarium style air pumps). I tried a small airbrush compressor also, but even the output of that was too weak for my design.
All in all, I’d say the conical nozzles that focus air directly downwards are probably a better solution than what I’m using.
@SirGeekALot , that was one of my first mod.
i design the following one to try to implement few ideas :
- setting the focus lenght (lens on air assit)
- air comming from the cone center AND from the side (to push fumes away toward exhaust)
- hold crosshair red laser
BUT experiences showed plastic Air assist could take fire (so i wrap it into foil )
Today I would go for a more simple way, a little coper pipe/needle (maybe with a 3d printed adapter) about 1mm over laser spot hit coming from 45° aside blowing toward exhaust . being close you will need a smaller compressor which will reduce noise and increase your confort.
No crosshair laser, but 2 single ray showing focus point at their intersection, so if you see 2 spots on material you are out of focus.
@SirGeekALot yes that it is the one i got. (but not very good, because coming from aside, it show hitting point only if you are at focus level)
but as I was saying 2 single dot ray (not line or cross), should be a better option. if you fit them each side of the head pointing to focal point. you are at focus when they crossed (in Z) telling you if you are in focus when you see only one dot on the material.
So to recap the laser dot show perfect positioning in XYZ, not like the hair crossed laser showing the hit spot (XY) IF at 50.8mm. (big IF) so not so handy. (I hope I am clear enought)
if you go for the other mod (the spring loaded bed at focal point) so that crossed laser would be a solution.
Don’t use a cross hair. The point where they cross will move as the material height )or bed height) changes. Use two separate straight lines or two dots like Stephane suggested.
I have a small opening on my nozzle that blows straight down into the cut. It absolutely helps with the cutting. I used to cut wood consistently at 13-15mA, now I cut between 9-11mA. Lower mA also means a longer tube life.
And I have yet to have my nozzle catch fire. 
Stephane must be burning with jet fuel.
yep, those one look good.
Done! I ordered 4. If I fry 1 or 2, I’ll have backups. Do they need any special driver circuitry, or just 5v DC?
Huh. Come to think of it, I ordered a five pack of lasers similar (except they’re 5mW, 4.5v, 650nm) to the ones in the link below (in 2014!) and should have them lying around. I never tried powering them, but now I think I will try them with 3 AA batteries in series to see if they work (or fry).
https://www.newegg.com/Product/Product.aspx?Item=9SIA86V2Z32250
Just 5V DC
generally they run about 4.5 to 5.5v … possible to run them lower, the light will just be dimmer
I use this one http://www.thingiverse.com/thing:343494
I added a set screw and use a right angle air fitting. I use a salvaged air pump from a respirator.
Late to the party. Might I suggest a simple gauge block?
I don’t have a machine yet, but, there is a use case I’m contemplating that I would like to try with an unfocused laser. With a gauge block getting consistent results should be a simple matter.
Gauge blocks works great if you’re consistently using the same material thickness. Otherwise, you’ll be adjusting the height for each thickness anyway. You want the focus point to be in the middle of the material for cutting, and on the surface for engraving.