Berd Air shoots only warm air...

sungod3k · 18 May 2021, 16:57

Hi,

I trimmed my printer for high volume printing, so model cooling is a big issue especially on spiral vase prints.
At work, we now have a raise 3d pro 2+ and were printing lots of anatomical life-sized legs for orthopedics. We print normal PLA with 1mm nozzle at normal temps and setting at volumes <10mm³/s

This was the perfect opportunity to get a berd air running to get the cooling up. If it weren't for inadequate cooling I could easily print 30% faster.

Now however I notice that the cooling air from the outside stays cool as long as its not getting heated up on the way to the nozzle. When I feel with my hand, the air that leaves the air duct is pretty warm. Almost as warm as the chamber temp.

I find this a bit surprising and the effect is that i can print maybe print 10% faster, but it seems to me the hole concept doesnt work inside a closed off printer.

So I wonder if someone else wants to share some experiences with pressured air cooling in a chambered system?

Phaedrux · 18 May 2021, 21:05

Can you increase the velocity of the air in the tube to cut the time it has to warm up? Can you insulate the tube to keep it from warming? Sleeving it within a larger diameter tube perhaps?

sungod3k · 19 May 2021, 06:03

@phaedrux The velocity probably not. The airstream the leaves the the little aliminium tube that wraps around the nozzle is pretty good.
When I first held my hand under it and compared just by feel, its feels more than sufficient.
There is probably some isolation that can be done, but Ive that needs to be substantial if thats supposed to overcome 40-50 chamber temp for extendet periods of time.

o_lampe · 19 May 2021, 06:40

@sungod3k
Is berd-air the right cooling solution for Vase mode parts? The nozzle doesn't stay long enough at the critical position for such a 'local' air stream (IMHO).
It would be cool (pun intended) to have an air stream following the print path. That would require active rotation around the nozzle or independent motion system for the air duct. Not easy to design...

deckingman · 19 May 2021, 07:33

@sungod3k How about chilling the air as it leave the pump? As an experiment you could make up a coil of some sort of flexible tubing and put it in a bucket of iced water. The inlet of the coil gets connected to the pump and the outlet goes to the printer. The larger the bore of the coil, the more surface area available to chill the air and the less restriction to flow. If that works, and if you want to spend a bit more money, then you could use a beer tap chiller - e.g. this sort of thing which you might be able to pick up second hand (plenty of pubs been put out of business due to the government's reaction to Covid) https://www.beer-tap-cooler.co.uk/beer-tap/beer-dispenser/accompanying-cooling-system/tap-system-as-40-2-line-wet-cooler/a-452453/

Nuramori · 19 May 2021, 08:32

@sungod3k depending on the compressor you’re using, it’s likely the pump is heating the air both in the compressor itself as well as the act of compression/forced induction. An analogy would be a turbo on an engine. The air is heated by the simple act of pressurizing it. Using the same analogy, you could use a pc water cooling radiator as an inter cooler and place it between the pump and the supply line to the nozzle, allowing for heat to be removed.

sungod3k · 19 May 2021, 09:57

@o_lampe yes true, that would be interesting. or even better if you melt the plastic before the nozzle to get better adhesion on long layer times and have targeted cooling behind it. but that sounds indeed complicated.

and yes vase mode is tricky in that sense, but the air flow is excellent and the distribution of air our of the berd air nozzle as well. if i didnt have the chamber this probably wouldnt even be an issue, but I learned to really value the closed chamber, it just make things a bit more reliable.
i will test some of my prints with the doors open though.

sungod3k · 19 May 2021, 09:58

@o_lampe yes i have such a chiller for my hydroponics that is of course a solution. ill try to get air from the outside and see if that makes a difference.

sungod3k · 19 May 2021, 10:02

@nuramori good point. i looked into that. One issue with the whole berd air system is anyway that the pump motor gets really hot. without active cooling I wouldnt leave that alone for longer prints.

however the pump itself doesnt get to too warm. i also checked on the air at different stages. before it enters the printer its at room temp as expected and even before it connects to the aluminium air nozzle its noticeably cooler than when it comes out of the nozzle itself.

mrehorstdmd · 19 May 2021, 11:26

@sungod3k You're printing PLA in a heated chamber?

sungod3k · 19 May 2021, 11:59

@mrehorstdmd heated chamber is probably too strong a word, but the enclosure is pretty tight and not too bulky. we have to filter the air so usually the doors are closed.

so far ive seen no issues keeping everything a bit warm (the 40C on the bed) and i have the feeling that layer adhesion is better when the whole model stays a bit warmer especially on single wall spiral vase prints.

o_lampe · 19 May 2021, 12:05

@sungod3k said in Berd Air shoots only warm air...:

the aluminium air nozzle its noticeably cooler than when it comes out of the nozzle itself.

Maybe opening the holes in the air-tube will help? It will reduce backpressure and thereby heat. Do you have a silicone sock around the heaterblock?
Chilled air is definitely a good idea, but adding a reservoir like an intercooler is not. It'll be OK if you run the pump at 100% all the time. But in many cases, the fan is PWM controlled by the slicer. A reservoir would cause a delay.
You could try to chill the air with a Peltier element, and cool that with a watercooled block.