I had issues once with vibrations of people walking by, couldn't really notice at the time but could see a difference.
1) nozzle temp variations.
2) Z movement variations.
3) Loose head.
My first thought was #3. You can test this by grabbing by the nozzle (hot with gloves in case the problem doesn't happen with a cold nozzle) and shaking it back and forth to see if the nozzle is loose versus the two rods holding it. Maybe play around the bearings or anywhere else in the head. Then the centrifical force whips the head to the outside of the intended circle. This seems easiest to test and lest likely.
#1, nozzle temp - there is a serious known problem for at least some UM2's with the latest software which made significant changes to the heating such that the head temperature can bounce around quite a bit. You can check this by plotting the head temp by connecting with USB or just by staring at the temp while printing.
#2 - if the Z doesn't move fully you get an overextruded layer. This seems most likely as it explains why the rings are almost perfect - in other words the "problem" seems to occur on an entire layer but not the layer before or after. Unfortunately I see that every10th or so "ring" only goes part way around. So maybe the Z stage finally moved half way through printing that layer.
Grease the Z. Move it up and down. Check for stickiness.
Of all the theories, #2 is hardest to test so I would check for the other 2 first. Also #2 is most likely I think.
cleaned it with a cloth, and greased it with the green stuff ...... didn't help at all. Also oiled the 2 Z axes.
I notice that when I raise the bed, turn off power and try to push down i can't. Even when manually turning the Z rod it's feels like i need to put on to much force to rotate. I know from other UM2's that the bed will (almost) come down just by it's own weight.
Do i need to clean the Z screw with some dissolvent ? what stuff would be recommended ?
and temp stays stable, and can't feel play in the head.
to check some more I printed a 60 cm cilinder spiralize, came out perfect. printed a 11mm cilinder spiralized, came out not so perfect (but better than the cilinder with infill).
getting convinced it's the Z axe causing the poor quality.
Did you by chance open the print bed cover at the back? If yes, check that it's sitting properly again there and not scratching the z bars. I found I could remount mine slightly tilted to the front...
nope, never took it off ....
If you have a UM2 can you let me know how easy your bed goes down > lift bed, turn off motor, can you push the bed down with little pressure ? will if move by itself after you give a little twist to the z axe ?
I just tested and it took a 7 pound weight to lower the table (at first nearly double that but then starting 20mm down it only needed 7 pounds to start it back up. On lifting 7 pounds lifting (estimate with 7 pounds in one hand, lifting bed with the other) was enough to lift it also.
7 pounds is 3kg.
hmmm, think that's not the issue then, just tried, 2,6 Kg was enough to push it down (after a half spin help to get it going)
tested by putting a small electronic kitchen scale on the plate and push as far as possible at the back.
Looks to me like over-extrusion. Since nothing changed, something had to have changed
Since already checked for some possible causes, Could you also check:
- the consistency of the filament diameter, and
- that the hobbed barrel is clean?
I first checked the printer and had about 1mm play in the right front-back axe. Caused by a loose pully. But this was not it.
You're right it was simply overextrusion. Turning flow to 96% gave a perfect result.
So as i had a good first print with same settings i think it can be the fillament (colorfabb pla).
Anyhow problem solved.
Yeap, ColorFabb PLA/PHA may require flow below 100%. I think this is because their very tight tolerances for the diameter. Most filaments have diameter below the standard. If you calibrate E with such a filament and then go to CF, then you will most probably over-extrude.
How much influence does filament have on print quality? Is colorfabb really the best, are their cheaper alternatives that perform similarly?
I'd say the best is relative, i'm not an expert on all kinds but for sure whats best depends on what your making.
I never tried cheap chinees stuff, but for example the dutch homebrand from makerpoint seems good to me (only used the white pla). I would say just try some thats easy to get in your area..
It makes quite a bit of difference on print quality. Don't buy just anything off of ebay. UM of course has good quality filament.
Faberdashery in England is pretty amazing. Maybe the best according to many (I haven't tried it). I don't think anyone sells it in USA but fbrc8.com plans to sell some soon (they have some in stock but the web store doesn't have it - I suppose you could call them but maybe easier to ship from england).
In australia there is also an amazingly good filament, diamond age.
If you want your filament shipped within USA then one good choice is printedSolid.com. They have colorfabb filament. They are a fast, responsive seller of filaments.
Beware that other filaments won't fit on the back of a UM so you might have to put it on the floor. Which works quite well actually.
- 3 weeks later...
I'm no expert, but I have bought no-name PLA of ebay at a quarter of the price of the colorfabb filament I previously purchased. Compared to the stuff I got with the Ultimaker (translucent blue) and the colorfabb filamanent, the ebay stuff either performs equally well or outperforms both of those by a huge margin (luck of the draw, basically). With one roll I bought I can print waaay faster than with either branded filaments (the table was shaking too much, so I had to slow down the Ultimaker) and issues like stringing are far fewer and the cheap stuff outperforms the brands for bridging by a wide margin.
Mechanical performance seems pretty similar; i.e. the cheap stuff seems to do the same thing as the brands.
So, YMMV. I'd say, take the plunge and try out one reel. They are a third to a *less than a quarter* the price of the brands if you know where to look, and you might just be surprised by the results.
I don't think that quality is necessarily is an issue with cheap filament, but consistency is. Unless your hours and frustration are free, it typically is worth spending a little more to know what you get every time.
In australia there is also an amazingly good filament, diamond age.
Diamond age is actually from New Zealand.
Have you checked that your side fans are really running? I had a similar print and the connector for my fans had jumped out so I didn't have any cooling during the print. I didn't notice this until way later ...
Drafty room by chance? or intermittent air conditioning/heating turning on and off? I had this happen as well, i think it was my AC turning on and off.
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