Why add a Fan at Extruder-nozzles ? (Page 3 of 3)

Facts and Science be Damned, I guess.

Is this an Arch-bridge with flat-top or a Flat-plank type bridge ??
Depends on how much of an Arch there is, will determine quality.
There's No way you can do a 50mm long Flat bridge ! ! !, without Supports .

??? I would Not call those bridges, in pictures, Good bridges ?
I call them complete Failures.
Very few of the layers were stuck together !

What I'm saying is, that No one can do Good bridges, that Long, without supports.
I'm talking about Good bridges, not just strings across the Gap.

I did not say that I could, No one can !

Oh, so you only wanted filament strings to go all the way across ?
I think to do that there would need to be Excessive Cooling, of the filament,
More cooling than wanted in a normal print, for good adhesion ?

I'd like to see some of your prints. Try that arched bridge I made. I couldn't bridge at all till I added the fans.

It's not overcooling or excessive cooling if it accomplished the goal and you still get layer bonding. It is no different from using supports. Just a different tool used in a different way. Everyone in the industry knows of the need and the advantage of a layer fan. Especially when dealing with PLA. If you are successful without out one then you have found the holy grail and should sell those magic numbers. Just know that what works for your current spool and color will not work for the next.

You have to ask why there are so many that support a fan and enclosures if they are not necessary. Even on CTC's forum their techs tell owners they need fans and enclosures for certain print jobs. So I feel in the future you will find them needed. You may just be lucky with your current jobs and have not had the correct thickness or density to warrant a fan and enclosure.

Well there is only so much you can do with one of these printers. They have inherent limits and you will find them at some point. The fans and the enclosures are just one of the many ways to bypass these limits and push the printer just a little further. Supports are Ok, but they leave marks that unless you post process remain visible. So sometimes those marks are not desirable. If there is a way to accomplish the same print without the supports and get similar quality then I would opt for that.

Don't get me wrong, I push for max quality. That is why this CTC Metal version I just got is my 5th printer. I however will not spend more than a grand for a printer and will just have to accept the fact that at some point whatever I print is the best I can get for the money I spent.  I know from the reviews that the CTC can exceed the Makerbot with tuning. So that is what I am after. Just have to correct some Chinese shortcuts on it by a Chinese company.

The $2500 Makerbot by the way comes with a layer fan built into the head. So even the makers are finding they are necessary.

Mosr prefer PLA as it is much easier to print with. Actually has pleasant smell when melted unlike ABS. PLA smells like hot sugar versus burnt plastic. The finish is usually superior to ABS as well. The drawback is it is not as durable and can not be used outside or in automobiles due to it being biodegradable and the sun and heat and elements will break it down with in two years.