Want to make your own air knife to cut things with? Unfortunately that’s not what these devices are intended for, but [This Old Tony] will show you how to make your own, while explaining what they are generally intended for. His version deviates from the commercial version which he got his hands on in that he makes a round version instead of the straight one, but the concept is the same.
In short, an air knife is a laminar pressurized airflow device that provides a very strong and narrow air pattern, using either compressed air or that from a blower. Generally air knives will use the Coandă effect to keep the laminar flow attached to the device for as long as possible to multiply the air pressure above that from the laminar flow from the air knife itself. These are commonly used for cleaning debris and dust off surfaces in e.g. production lines.
As [Tony] shows in the disassembly of a commercial device, they are quite basic, with just two aluminium plates and a thin shim that creates the narrow opening through which the air can escape. The keyword here is ‘thin shim’, as [Tony] discovers that even a paper shim is too thick already. Amusingly, although he makes a working round air knife this way, it turns out that these are generally called an air amplifier, such as those from Exair and are often used for cooling and ventilation, with some having an adjustable opening to adjust the resulting airflow.
Some may recognize this principle for those fancy ‘bladeless’ fans that companies like Dyson sell, as they use essentially the same principle, just with a fan providing the pressure rather than a compressor.
I wonder how much power you have to dump into it before it actually cuts things
You’d need air going fast enough to form a plasma and then some (space capsules don’t get shredded they melt). If you entrained some particles like sand though you could use much slower speeds.
Cut a wet paper towel? Relatively little. Cut a diamond ….
That of course is dependent upon the target’s material properties, structure, and desired end state.
The round version of an air knife is usually referred to as an “air operated conveyor” We use them to suck bulk material up and shuttle it through tubes to the hoppers on our fill form seal machines.
https://youtu.be/v9-IasNJjVA?si=KVWJhm0guVVgGTaa
This industrial product demo video is surprisingly entertaining. I love how long it takes to pan up to the ceiling to show how high into the air it can suck things up
Reminds me of a letter shoot :-)
you mean chute? like https://hackaday.com/2013/08/09/what-the-inside-of-a-pneumatic-transport-system-looks-like/
(I had a picture of skeet shooting, but with paper envelopes)
Ah, this is the link I was looking for: https://www.smithsonianmag.com/history/when-a-labyrinth-of-pneumatic-tubes-shuttled-mail-beneath-the-streets-of-new-york-city-180983472/
It’s great to finally see TOT on HAD. :)
TOT has been on HAD for almost 10 years actually! But the overlap isn’t always great enough to warrant a HAD post I think
We try to boost the smaller channels that you might not otherwise find, and that the algo won’t necessarily serve you. TOT is kinda outgrown our support, in that sense, but will never outgrow his place in our hearts! :)
TOT has been posted on HaD quite a few times over the years. Sometimes just mentions, but a lot of his videos have been featured.
https://hackaday.com/blog/?s=%5BThis+Old+Tony%5D
I can doom scroll through YT, but TOT is one of the guys I set aside time to watch. His videos is like getting a new episode of one of your favourite series.
I wonder what this + sawdust (or coffee creamer) plus a source of ignition would do!
Powder-Explosion Rocket Engine? Sounds like a shout-out to integza to me :)
Can you apply this as parts cooling ‘fan’ at a 3d printer? Its maybe lighter & smaller than a fan.
A powdered-fuel burner. It doesn’t have enough pressure to make a rocket and fuel will not reach long distances like in flamethrower.
This, apparently … https://www.youtube.com/watch?v=Bqwb-1yPlNM
Now with petrol, or TNT powder ;-)
I want to make an air curtain now for my knee mill to stop the chips blowing at me…