Prusa i3v help

[printbus]

...about 3/4 through a long print (it had been running for about 4 hours) the extruder motor started to just buzz and not push the filament through. I adjusted the pot on the motor driver, but that did not help. When I removed the filament it worked fine, so I loosened the two screws that hold the filament tight, but that didn't help either. Any thoughts? should I loosen the screws more, or is the motor just overworked?

From one problem to another, huh? 150mm/sec is a pretty fast print speed. There's probably a few who can do that on highly tuned machines, but I think most of with i3v's don't go above 100mm/sec. I do most of my printing in the 75mm/sec range as a compromise in speed, noise, and print quality.

What happens with the extruder gears when the extrusion stops? If the gears stop moving, focus on the motor. If the motor is getting hot it could be overheating and skipping steps. If the heatsink on the extruder's stepper motor driver is getting hot, the driver chip could be overheating; some add a small fan above the RAMPS board to keep the motor drivers cool. If the set screw on the small gear loosens or falls out, the small gear can start to slip - especially as the printer warms up. Do the gears rotate manually ok, without any catching caused by damaged or clogged gear teeth? If none of these possibilities pan out, maybe try swapping a couple of the motor driver boards around as a last resort.

If the gears keep moving when the extrusion stops, you're likely finding the hobbed bolt is chewing a notch into the filament. Nearly everyone seems to battle this at some point, and several things can cause it. Adjustment of the guidler bolts might help, but I don't recall ANYONE ever finding that was all they needed to do. Califdan just concluded his problem was the stock spool mount creating issues as the filament spool emptied. A few have found bits of metal clogging the hot end. Some have found the extruder nozzle needed to be cleaned/reamed with something like a guitar string. Too low of a print temperature can sometimes lead to stopping at random. Filament can have diameter variances that can catch on the top of the hot end. A few have used vegetable or grape seed oil as a lubricant in the hot end. Aggressive retraction settings combined with retractions that occur too frequently will cause the hobbed bolt to rotate back and forth in the same area of the filament, cutting away at it. The channels in the hobbed bolt can get plugged with filament, causing the hobbed bolt to become ineffective.

In my case, all I would have to do to recover is pull the filament out of the extruder, cut off the damaged part, and re-feed it. I'd then print fine again for minutes, or for hours. My issues seem to have been overzealous retraction settings and a spool of filament with bumps in it just large enough to not pass into the hex hot end.

You can look at printer moves in a gcode viewer to see how often retractions are occurring. Sometimes the tail end of prints can be a problem since the print area often gets smaller and smaller, and retractions are occurring with less and less extrusion in between them. For my 1.75mm filament, I usually configure Cura for 1.2mm retraction distance and a minimum extrusion between retractions of 0.5mm; both settings are significantly different than the Cura defaults that are optimized for the Ultimaker printer. On long prints that don't have a complex perimeter structure, I disable retraction as a final precaution.

[UltraSaucy]

From one problem to another, huh?

lol yea story of my life

What happens with the extruder gears when the extrusion stops? If the gears stop moving, focus on the motor. If the motor is getting hot it could be overheating and skipping steps. If the heatsink on the extruder's stepper motor driver is getting hot, the driver chip could be overheating; some add a small fan above the RAMPS board to keep the motor drivers cool. If the set screw on the small gear loosens or falls out, the small gear can start to slip - especially as the printer warms up. Do the gears rotate manually ok, without any catching caused by damaged or clogged gear teeth? If none of these possibilities pan out, maybe try swapping a couple of the motor driver boards around as a last resort.

The motor stoped turning, and just twitched back and forth. When I removed the filament, the motor and gears turned fine. I put the filament back in and manually turned the extruder (using the lcd) and everything worked fine for a little while, but then it started to buzz again. I let it cool for a bit and then started up another print of something I had already sliced (in slic3r), and it worked fine for the first few layers but then it started to buzz again. Could it be that the Idler is pushing too hard on the filament? the filament isn't getting chewed up, and it is feeding ok when the motor turns, so I would say it is a motor problem. I havent checked to see if the motor driver is getting hot, but I will do a few more tests once I get home from school.

[printbus]

Could it be that the Idler is pushing too hard on the filament?

IMO, about the only way that could be a problem is if the bearing in the guidler plate isn't rotating with the filament. I know I'm not the only one that had to clean up the bearing slot in the guidler provided by MakerFarm quite a bit to get the bearing spinning. Try marking it with something like a Sharpie and seeing if it rotates as you feed filament. If not, you need to fix that.

You've ran through the extrusion calibration, right? If so, what kind of esteps/mm are you running? I just want to make sure you're not trying to drive the extruder motor unrealistically fast. A value of 900 steps/mm seems to be about the average.

I thought of a few more issues people have found related to extrusion stopping. They may not fit your symptoms but I'm going to capture them for completeness as a future reference. Depending on how washers were added as spacers to the hobbed bolt, some have found the bolts on the top two delrin wheels on the X-carriage can rub against the large extruder gear, causing at least intermittent problems with extrusion. Also, if the large gear wasn't tightened onto the hobbed bolt properly when it was installed, it can slowly tighten up towards the hot end and eventually cause the hobbed bolt to bind up.

[paintz2007]

Got mine running after a 5 night build, very impressed with the out of the box printing. Couple issues I need to track down ( corners lifting on pieces and on small areas it not cooling fast enough or is too hot, leaves a glossy blob almost)

[paradiddle65]

The issue with the small perimeters being globby can be solved in your slicer settings. You should be able to choose a slower speed for small perimeters. Could also consider adding a fan and duct to your extruder if you don't have one already ( this notably improved my print quality)