Quality varies front to back??

[dunginhawk]

Good morning... So I am starting to dial in my prusa i3v 12" hex a little bit more. I found some carriage issues i needed to resolve yesterday, which helped a bit.
Now everything is tight, functioning as it should, but im seeing an odd issue.

The following picture is from the front of the 25mm calibration cube. this is .2mm layer height btw, print quality is EXCELLENT.


This next picture is of the right side (left is the same) , quality begins to degrade.


Last picture is from the back. Worse yet. Now this is only across 25mm, so Y being unlevel over that space isnt a big thought. and the first layer is great, but its prevalent through the whole print. Im stumped on this one.


Can anyone help me to figure this out? If I can solve this last riddle, I will have the quality I want, the price we love, and life will be good

thanks

[MiniMadRyan]

Are you running a print cooler at all? It's weird that the front is nearly perfect, while the rear isn't when the movement is on the same axis. What are you using for a firmware, what slicing app? settings?

[dunginhawk]

A layer fan mounted on the left , and the hot end cooler. but the hot end cooler isnt directed much... so that could be causing issues.

So with the hexagon hotend even with PLA at 210 degrees do i absolutely need that hot end fan running?
It might be worth seeing if that is messing things up, as others have mentioned... but the layer fan on the left should be helping that side also..
just very confusing

[MiniMadRyan]

Hmmm...just a quick thought, try a print with the cooling fan disabled, and see how the quality comes out. Myself, my cooling fan is slightly mis-aligned, and as such it directs air more towards the rear of the part, which in some cases, results in slightly worse quality on other sides.

[dunginhawk]

so as my edit indicated. im probably getting some fan backwash (as it hits the back of the X carriage, from the hot end fan). am i ok to disable that for a print?

[MiniMadRyan]

I've disabled the hot end fan for short periods, but haven't tried anything for a longer period than say 5 minutes. Perhaps trying something like this: http://www.thingiverse.com/thing:335613 might improve the hot end cooling. Don you have the included shroud on the hot end fan?

[dunginhawk]

Yes, i am in the process of having that 25mm fan shipped to me... then its going in...

[gmay3]

dunginhawk, don't disable the hexagon cooling fan, it could cause your extruder parts to melt and deform. Instead flip the fan direction by removing it and flipping it around so it pulls the air up from the bed and out the front.

[dunginhawk]

thats a fantastic idea, same idea as clough42s design... not sure why I didnt think of that, but hey, thanks im printing right now with no layer fan, but shroud fan on. next ill try your way
thanks

[dunginhawk]

so strange as it sounds the layer fan seemed to be causing most, if not all of these issues... im not sure why that would be though. here are three shots, FRONT, RIGHT and BACK.
pictures arent as good as the part is.. the fingernail test is difinitive.. HUGE different between layer fan and no layer fan... NO IDEA why a layer fan would make it MUCH worse.
especially since the fan is blowing on the left side of chasis, so you would think the front and right would get less airflow from it.
Talking with Colin from MF he informs me that he never uses a cooling fan on the layers.. Didnt notice much improvement... With my rostock max i had 3 layer fans. ANyone else have a thought either way? ive always been told cooling fans are a must for PLA, Copper/Bronze, Ninja, and overhangs, or bridges.