New i3V owner: A few beginner questions

[DanSilov]

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.

[DanSilov]

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.

[printbus]

gmay3, how did your knob in http://3dprintboard.com/showthread.p...umbwheel-Model print? Looking at mine, my top side has the same mesh look that DanSilov is battling here. You can even see it in the picture I posted.

EDIT: Looking at the gcode, that was the last item I printed with a bridge speed of 150mm/Sec as set in the Makerfarm Slic3r config files. That seems awfully fast to my inexperienced judgement. For my knob, slic3r has a bridge layer under the top layers, and perhaps the bridge didn't work very well and the top layers aren't properly supported. My recent prints are coming out solid top (now I'm using a bridge speed of 70mm/sec), but I've also been dinking around with ABS since that knob.

[Roxy]

EDIT: Looking at the gcode, that was the last item I printed with a bridge speed of 150mm/Sec. That seems awfully fast

Agreed. I know my printer could not run at that speed doing bridges.

[printbus]

Your issues appear to be beyond what I can help with. If no one else jumps in, perhaps posting in the Tips Tricks and Tech Help forum would get more visibility than the few of us watching the MakerFarm subforum. Maybe using 3mm filament on a 0.4mm nozzle tip requires something special.

What do you think happened to the original small gear? Did it start to fall apart, or does it seem like it got hot and warped out of shape? Just wondering if that could be indicating something.

Do you use a print cooling fan at all? I think small prints like the small gear can be tough to print. Slic3r will default to slowing down the print to ensure 30 seconds per layer, but that's still a lot of heat being applied to a small surface area. Go 100% infill to boot and you could be dragging around in soft material that never gets a good chance to cool down.

Good luck, man.

[gmay3]

DanSilov, I would not recommend printing extruder parts with 100% infill however that print does look like it came out pretty good. I usually print them with 30% infill at a max and this could cut down on some over extrusion errors that could lead to a misshapen gear tooth.

As far as the knob goes, I can't see how your extruder would draw plastic in between the outer grooves in the knob unless something is mechanically wrong with your axes.

Try these and let us know that you have checked them:

1. Check all your belts and make sure they are tensioned pretty tightly (should ring out quietly when plucked)

2. Check for any wiggle in you x and y idlers by verifying that all delrin idlers are tight enough to the aluminum extrusions. You should have no play in any direction other than the axis is intended to move. Make sure the delrin idlers are not too tight where they limit rotation of the bearings.

3. Check the bottom of the x axis where the captive nuts meet the z threaded rods. Sometimes mine have come out of their holes underneath the x idler.

4. Try these prints again at 30% of your normal printing speed, just to rule this out.

Good luck and let us know how it goes!

[printbus]

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.

[DanSilov]

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

[printbus]

...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.

[DanSilov]

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.