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  1. #1

    New i3V owner: A few beginner questions

    Hello everyone. I've just finished assembling my i3V, and while I had a lot fun building it, I'm yet to achieve reliable printing results. And since this is my first 3D-printing experience, I've would like to ask a few (maybe) stupid questions.

    - I've started with PLA, and I'm using configs for Slic3r provided my Makerfarm, and they set temperature for PLA 225 for hot end and 70 for bed. Isn't this a bit higher than most PLA guides recommend?

    - My first layer almost always looses a few first lines, because extruder can't seem to start extruding in time. Is there anything I can do to make this better?
    IMG_7997.jpg

    - Also, first layer always has these thick lines with visible gaps between them. For example, large extruder gear which I was trying to print, is really different in that regard from the one supplied in the kit. Is this a matter of Slic3r settings or something else?
    IMG_8002.jpg

    - The main problem I currently have is with extruder, which stops extruding after about 5mm printed. At first I figured out that it was the small gear that didn't have a bolt inside. Even though in the guide video Colin says it is optional, turned out after motor gets hotter, gear just slips. I've fixes this, but now I see there's another issue. After some time the large gear kinda tightens itself to the point that I can't even move it by hand (after disabling steppers of course), and I have to use pliers to loosen the front large bolt. But it then just goes and tightens itself again. Any advice, what can be done there?

    - Also, I can't seem to understand how to change filament. I also have ABS which I wanted to try, but the last piece of PLA inside the hot end is not possible to extrude all the way.

    - The hot end I have (hexagon) is somehow always takes too long to get to 225 degrees, and when it reaches 210 or so it starts going up and down for quite some time until it finally climbs to 225. Is it something with thermistor? I've made sure it is inserted all the way, but I din't cover it with kapton tape or anything.

  2. #2
    Looks like I figured out the problem with extruder large gear self tightening. I've disassembled it again and apparently I haven't tightened the second nut well enough. Hopefully this will fix this.

    I've also wrapped the hot end in kapton tape, and temperature looks much more stable now.
    Last edited by DanSilov; 07-20-2014 at 12:37 PM.

  3. #3
    Staff Engineer printbus's Avatar
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    Welcome to the i3v club!

    I've been using 225 degrees without issue. I've read on other forums that the uncalibrated thermistors tend to read high, so setting for a temperature of 225 might actually turn out to be lower in terms of a real temperature. Just a thought. Some people have described disabling the stepper motors, and then manually rotating the large gear on the extruder to get a feel for how the filament is extruding at different temperatures as a way to figure out the optimum temp setting. I tried that, but I found it hard to notice much difference.

    On your first layer, it could also be that you have too much space between the nozzle tip and the glass. I adjust mine so that a piece of paper is fairly snug between the two. If you haven't already, by all means calibrate the feed rate of your extruder. Mine was low by about 5%. That'd be another reason for not enough coverage on the first layers. I've been tweaking the Slic3r settings recently, but used the MakerFarm configurations for a number of things successfully. Google on extruder calibration for info - look for calibration videos my Zennmaster. Finally, if you try to move around the cold extruder tip manually, does it feel loose? Mine did, and I went back through the extruder assembly to eliminate mechanical play wherever I found any. See Post #17 in the Printbus build log for details on what it took to eliminate that play. I felt that having a solidly mounted extruder tip was important to especially the first layer.

    On the extruder, check to make sure the two bolts on the upper rail wheels don't rub against the large gear. Mine were rubbing. I didn't work through whether the rotation direction fits, but maybe that could be part of the reason why the gear tightens up on you.

    Swap out the filament by cutting off the filament with a length extending from the top. Using pronterface, turn on the nozzle heater and wait for it to get to temperature. Then using the "reverse" button on Pronterface, back the filament stub out of the extruder while gently pulling on it. I usually set Pronterface up for a long value like 50mm, and then gently pull on the stub while also releasing the spring mechanism. I don't like using the 0.1mm steps available on the LCD to control the extruder. I cut my filament with an anvil cutter that makes a very clean cut, and cut at an angle to make it easier to feed the new filament into the extruder.

    Following a hint I found elsewhere, I used a dab of automotive muffler cement to affix the thermistor to the hot end. That seems to have worked pretty well.
    Last edited by printbus; 07-20-2014 at 12:08 PM.

  4. #4
    Thank you, makes sense that thermistor might show lower values. I've tried to print with anything between 180 and 225 and it worked well with PLA every time.

    I've checked the hot end, and it's all tight. Also, leveled the bed with the sheet of slightly thicker paper. Should I use something really thin?

    Haven't yet calibrated the extruder, will probably get to it later, after I finally finish printing spare parts for the extruder

  5. #5
    Staff Engineer printbus's Avatar
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    Quote Originally Posted by DanSilov View Post
    ...leveled the bed with the sheet of slightly thicker paper. Should I use something really thin?
    That gap is just one of the tweaks you get to figure out. When everything else is right and coverage doesn't seem to be pretty solid on the first layer, adjust it thinner. I've read how some people eye-ball the skirt while it is being extruded and manually adjust the Z-rods as necessary to get the "squish" they want. Since they may jump in with it later, I'll point out that there are also some proponents here that recommend incorporating an autoleveling approach that turns the whole leveling and gap issue into a matter handled by firmware.
    Last edited by printbus; 07-20-2014 at 03:01 PM.

  6. #6
    Well, extruder and printer works reliably for hours now, but results are somewhat mixed. I've printed extruder and a knob from Thingiverse, and every time the top layer has this visible mesh and the lines are very thin. I've tried to adjust Flow Rate via printer display during the print and set it to 110, but it looks like there's no difference.

    IMG_8003.jpgIMG_8004.jpgIMG_8005.jpg

    I've also checked bed level before printing the knob yesterday, and in all four corners I could barely slide a piece of paper under the hot end.

  7. #7
    Engineer-in-Training gmay3's Avatar
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    Hmm, what speed and temperature settings did you print this knob with?

    Could be two issues I can thing of. It looks like the top layers are either not sticking well to the previous layer which could be a temperature, speed kind of thing. Also make sure that the two screws on your greg's extruder that have springs to tighten the filament to the hobbed bolt are fairly tight. Maybe just try an additional turn or so. Maybe the hobbed bolt isn't gripping your filament as tightly as it might need to.

    In slic3r try increasing your Extrusion Multiplier, it's probably set to 1 by default, I would try changing it to 1.1 or 1.2 and seeing if the thickness of the top layers improves a bit.

    If you haven't already check out the calibration thread first!

  8. #8
    Staff Engineer printbus's Avatar
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    I'd also like to know what nozzle size you have on the hex hot end.

    Your issues look almost like, but not as bad, as when I forgot to load Slic3r with a configuration file and it ran with the defaults. It was trying to print my 1.75 filament with settings assuming I was feeding 3mm. The entire print came out very "stringy" like your top layers look.

    I know gmay3 is pointing at another print for flow test, but I'd maybe find a single-wall calibration test to try. That would help identify whether all layers are light on the extrusion or there's something going on with just the solid fill on the top layers. As to a source for one, Gmay3 links to a zennmaster youtube video for the feed rate calibration; zennmaster also has another video where he fine tunes the extruder settings using a single wall print test. You'll need a set of digital calipers to measure the wall thickness.

  9. #9
    I have hex 40mm hot end for 3mm filament, and I definitely loaded respective settings in Slic3r before generating G-code.

    If this is related to temperature (duh, everything is probably related to temperature ), I might try to reverse the fan that is always on. It's flowing full speed inside the wooden box, and most of air eventually gets down to the print.

    Haven't yet checked two screws on the extruder, but I remember not tightening those too tight, as it looked that filament grips there well enough.

    Currently still at work, but will start with some calibration as I get home.

  10. #10
    I print always at 100%, not trying to go faster at the moment, need to get some good results with normal speed first The knob was printed at 210/70 with PLA. Interestingly enough middle layers stick very well to each other, I have some good-looking results with extruder gears, both small and large. But with large it's the same story – top layers look like a mesh.

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