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edis

Bad surface on printed parts

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When i'm printing a tall part, i get uneven finished walls. One edge is always ribbed, like from vibration and in the vertical walls i get stripes with too less material. but it's like 1 stripe and then it prints ok again...

15xmko0.jpg

263h9g0.jpg

Can anyone suggest who could cause this? Interesting fact is that this stripe is not going though all part, it's on 2 walls out of 3... But i get this ribbed edge on all parts

 

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The vertical striping looks like 'ringing' - the head resonating back and forth as comes to a sudden stop in the Y direction at the corner. Reducing the acceleration and/or jerk settings may help with that (or just printing slower). Notice how the vertical ripples get further apart and less pronounced from left to right - the head is speeding up as it moves away from the corner, and the energy from the turn is being dissipated.

Is the horizontal striping too little material? It almost looks like too much in the photos. My guess would be a slicer-related problem, or something happening on the inside of the print at that height - is there somethign different happening inside there?

 

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I agree, that's possible. But then it should be the same in the other side, but now it isn't. Only this side and this edge affected. I was printing at 210°C, feedrate was 80mm/s/, but i've tuned to 80% with ulticontroller. So actually there should be actually 64mm/s, so not too much of a speed. Anyway, thank you for the tip, i'll try to adjust acceleration.

Yes. at this stripping it looks like there's too little material. I guess that can happen due to retraction, because in the inside there's a support material and in about that place it ends.

 

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Yes, I get ringing causing vertical lines. I also get vertical lines because I like to print at high temps. Not sure which is your issue as they look very similar. The ringing caused vertical lines appear typically on the left side of a flat face and fade out towards the right edge. The temperature caused vertical lines are more consistent and look very similar to lines that might be in the STL file. Here's a great picture of the lines caused by temperature and ringing (PLA):

(source is here:)

https://groups.google.com/d/msg/ultimaker/_1cPRgxGmOk/hDACjl0vO5QJ

outimag.jpg

 

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Keep in mind that the above picture applies to a given flow rate of plastic through the head. If you print faster or slower than jake did (he made the picture, not me) or if your layers are thicker or thinner, this will change the amount of plastic flowing through the print head and will affect the temperature. You need higher nozzle temps at higher flow rates for the plastic to come out at the same temp. Also different dye colors and different manufacturers of PLA have different viscosities at a given temperature.

 

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I suspect that the lines are not 'caused' by printing at too high a temperature, per se, but rather it is that at higher temperatures the plastic is sufficiently fluid to respond to and show slight variations in extruder speed, or vibrations in X and Y or something. Which is not to say that it's not an acceptable solution to that to simply print cooler, so the plastic is more forgiving. But lower temps also have their own trade-offs.

 

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Hey gr5, thanks for that excellent photo reference! I shows precisely what I have been thinking I'm seeing on various prints. A change in the surface texture quality usually happens when I switch filament, so this visual scale will help diagnose whether the new filament requires more heat or less heat than the previous. I wish I had thought to print out this sort of reference weeks ago.

The strange thing about the original poster's prints is the fact that it seems to be exhibiting totally different symptoms at the same time on the same piece. This makes me think mechanical sloppiness rather than temperature troubles, or at least in addition to temperature troubles.

 

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Can anyone give some points for me, how much is fast printing and how much is not.

I am printing this part: http://www.thingiverse.com/thing:21182

I am using settings:

Layer height - 0,1mm

Temperature - 210°C

Print Speed - 70 mm/s

Travel speed - 200 mm/s

Z speed - 10 mm/z.

I am using a a different kind of knurled bolt and my E steps are 794,4, this gives me a nice 100mm of filament when i order to extrude 100mm.

The problem is that if i print this part, it looks good untill the air channel starts to form, then i get signs of underextrusion, the wall becomes with a lot of small holes. So is 70 mm/s printing speed too fast here? if so why the bottom of this part looks really nice and solid. Or should i pump up my temperature to 220-230? when extruding by hand at 210°C the plastic flows so easy and for me it looks like it should be able to reach even higher speeds with these settings.

CIMG2314.jpg

Anyone could suggest what's wrong here?

Edit: It looks like i can't print at all with 0.2mm layer height. I build on glass bed with tape on it. First layer looks nice, but as more layers gets layed, the uglier it looks, for me it looks like its underextruding, but i've tried temperatures from 200 to 230°C, and flow rate from 100 to 130, but still nothing...

here's how it looks after 4 layers:

CIMG2313.jpg

 

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Hi 70mm/s is faster than what I usually print at (50 mm/s) but you should be able to do it no worries. I'd check your hobbed bolt is clean and in the right spot and the thumb screw is adjusted for good grip but not too much. Your temperature sounds OK but you could try at 220-230 for that speed.

 

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70mm/s shouldn't be a problem, but extrusion issues could also be caused by too little or to much tension on the spring at the feeder. It should be about 11mm long when filament is inserted.

 

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I wonder if you had 'Joris' turned on? (Lol, 'enabled' might be a better word....)

Anyway, I've seen similar stutter-lines in the middle of prints with that setting.

 

Can anyone suggest who could cause this? Interesting fact is that this stripe is not going though all part, it's on 2 walls out of 3... But i get this ribbed edge on all parts

 

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I think it was a temperature problem. Mostly... to print with 100mm/s i need about 230°C, or to slow down. At the moment i've got a better results by lowering print speed. It very depends of extruded filament volume... to print with 0.1mm layer height i can go with 210°C and 100mm/s, but with 0.2mm that's not enough.. Even if i start with 230C, it starts ok, but then my feeder starts slipping (after ~5-6 layers). And the spring i'd say is very stiff.

I think that there is something wrong with my machine. It's not a stock ultimaker, it's my custom made. To heat it up, i use single 6R8 7W resistor, at 19V it has about 50W of heating power. So i think there's a chance that the "core" is at given temperature, but nozzle is colder, and that's why i can get underextrusion. I'll have to check this.

No, i haven't enabled "joris". Does anyone know how stiff is the stock extruder spring?

 

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No idea what the standard spring is, but I preload my extruder spring (with V3 knurled bolt) to about 80Newtons force. (the spring I use has a rate of about 10N/mm)

This makes it grip enough such that you will only be able to pull the filament back out the extruder by using

a great deal of force.

You can measure this if needed with a very cheap digital readout used for aeroplane luggage weight checking. Cost me about 28 Euros.

http://www.conrad.de/ce/de/product/124148/VOLTCRAFT-HS-10L-Haengewaage-Fischwaage-Wiegebereich-bis-10-kg-Aufloesung-10-g

 

 

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@Edis

I've had those same print results before and it turned out to be a sudden wide variation in the filament diameter. When the size is set at say 3.0 and it suddenly drops to 2.8, you get a section which is under-extruded. It ends up uneven with lots of empty spaces and blobs within the print. It looks a bit like a raggedy sponge. This is always a horizontal problem that starts at a random layer and usually continues for a while until the filament changes size again.

Measuring the filament at a number of different places over a 5 or 6 foot run will give you an idea of what the average size is. Setting the average size, instead of the largest or smallest, will help minimize the variations in extrusion, but if it varies widely, you'll still get some of that texture.

The best solution is to pay the extra to buy higher quality filament which is a more consistent diameter. Faberdashery is the go-to place for very high quality filament. Unfortunately, it doesn't come on spools. It comes loose. If you have old empty spools, you could always wind it onto one, I suppose. Some people just throw it into a bowl and lay it horizontally under the extruder to feed it.

Anyway, that's one more thing you can check.

 

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thanks for the tips. But my fillament diameter ir pretty constant.

Now the plugged nozzle is different thing. I had some problems earlier with constant plugs, I've even had one total blockage of the nozzle. After that i've made a dust filter out of a sponge.

I do have a blockage in the nozzle some times, then i usually heat my nozzle up to 250-260 and after few secs it goes out with some pressure... but's it's easy to notice when there is a blockage. Dunno what's causing these plugs.

Here's an update from my progress. I've printed one part today with 0.2mm layer height at 225°C, and no chance, my feeder starts slipping after first layer when it speeds up and i've got nozzle block again... after cleaning i've tried again and nothing new. After that i've tuned my feeder, i've compressed spring now more tightly, so there is quite high force on the filament (i was thinking that it was way too much at first, but had nothing to loose), I have really big and strong spring there (1.5mm wire, 14mm diameter and 22mm in length). And after that it worked! I've printed whole part at 220°C and a layer height. Hope this will work from now on.

offtopic:. Today i've got my reprap heated bed, i've ordered from ebay, And it's a crap. Resistance should be 1-2Ohm, and in fact it is only 0.5Ohm.. Be aware of that :???:

 

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Did you consider checking the resistance when it is hot? Most resistors change their resistance significantly as you heat them.

It's good for a heater to *increase* it's resistance as it gets hotter - for self regulation, safety, and faster warmup.

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Nope, this is not this case. With such resistance it would draw 24 amps at 12V, 24A :eek: there is definitely something wrong with it. All specs says that it draws 10A when cold, and 5-7A when hot. I'm just unlucky i guess.

 

Did you consider checking the resistance when it is hot? Most resistors change their resistance significantly as you heat them.

It's good for a heater to *increase* it's resistance as it gets hotter - for self regulation, safety, and faster warmup.

 

 

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I don't think the heater resistance increases (significantly) when heating up: most of them are made from copper, some are alu, and only the pricier/better ones have proper constantan wires.

It still irks me that Ohm's law is so deeply disregarded in the making and marketing of heated beds? what is so wrong just mentioning the proper resistance of a heater? why such vague marketing BS like "it draws 10A when heating up and 5-7A afterwards"? it draws less after heat up because the PiD or bang bang code turns the heater on/off, so it will average to 5-7A, without even mentioning that people assume it's run at 12V?

This was one of the main reasons why I never tried a PCB based heater:

I just got a Helios heater (after 6+ weeks of wait time): it looks great, beautifully manufactured, 3mm thick fiberglass board, 2cm too small to be useful on the ultimaker, and not a single mentioning that it has 1.5Ohm. f'ing waste of time&money. at 12V, you get about 100W of heating power out of that heater, which may be just barely enough to heat glass to 110C... who knows (I don't), this is going back to the supply drawer, unless one of you needs/want it. I'll stick to my 110V/160W silicone pad heater. /angryrant

 

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yup, you are right Joergen. The specs shows the "right" techical values, resistance, layer thickness. It's an arguable thing that is it worth buying such heater or not. Personally i think this should work quite well, if it would be at least in an average quality.

Anyway, could you give more info about that helios heater you are talking about?

 

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