Extruder - Popping noise and not feeding

[terrymcc]

For quite some time, while printing, I hear a popping noise. It seemed random and maybe once every few seconds. I thought is was a belt skipping a cog or something binding, but could never "feel" or locate it. Print quality was OK. I recently did a "poor boy" stethoscope trick and the noise seemed to be coming from the extruder.

Last night, I started a 14hr print and about half way through, it stopped extruding. In the past (very infrequently) when I've had a stoppage, I just press the extrude button a few times while forcing the filament into the extruder and it clears and life goes on. I've never actually had to disassemble and clean the nozzle.

This morning when I try to force the filament through the extruder, I get the popping noise and although I can force some filament through, it doesn't clear and begin to feed properly. I am using PLA at 200 degC.

I can disassemble and sort it, but I was wondering if anyone else has encountered this. I don't know if the stepper is skipping steps due to high torque, if the planetary gear box has a problem, or if the gear is slipping on the shaft (not likely). The issue is definitely the source of the popping noise.

Whadya think?

[jimc]

hey terry, the clicking is the stepper skipping because it cant push the filament through the hot end. its quite common and its for the most part from 2 different things, assuming your using good grade and trusted filament. either your temp is too low or you hot end/nozzle is clogged. first we need to know which hot end you have. a v3 is the older style from maybe 6mos ago and prior. that one is round all the way from the filament drive down to the nozzle. the v3b is the newer one. that one has an aluminum block just above the nozzle where the heater cartridge and thermistor are. v3b pla runs at 210-225 or so and the v3 is 180-200. if you running in those ranges then its time to do a disassemble on the hot end and clean it all out. you probably have some hardened buildup inside making everything tight.

[terrymcc]

Thanks jmc for the prompt and thorough feedback. I cranked the temperature up to 225 and it didn't help so it must be clogged. I have been running my temperature 20+ degrees too cool all along. I have the version 2 extruder from a year ago. Would there be any advantage to move to the v3 extruder? I have the 19/12V setup.

I will tear it down and clean it...

[jimc]

ok, if you havent had it apart before then just unplug all the molex connectors at the extruder first, 4 total and take your time. let us know if you have trouble.

[terrymcc]

I disassembled removed the hot end from the print head and used a piece of .24mm piano wire to see if it was plugged. It seemed all clear. With the hot end off the print head, I fed filament into it by hand and with reasonable force got plastic out the other end.

The first drive issue I found was that the sprocket is loose. rotates about 20+ degrees. That's probably why I haven't seen much affect using retract.... I don't have an allen wrench small enough to deal with it. Anybody know what size I need?

With the hot end off and no filament being fed (i.e. bare shaft/gear protruding, I get the random cogging, popping, and slipping. Holding very little pressure on the gear with my fingers causes it to make noise and slip more. While doing this, the stepper motor also stops.

Any ideas on how to determine if it is a faulty gearbox binding causing the motor to slip, a bad motor, or a bad output from the Rambo?

[jimc]

yup terry, sounds like the pinion gear went in your extruder motor. remove the motor and take the 3 set screws out holding the gearbox together. pull the cover off. you will see 3 planetary gear and one pinion on the motor shaft. look at the teeth on the pinion gear. are they just bumps or worn to a sharp point?

also your printer came with the allen for the gear. its the really tiny one.

[terrymcc]

Yep, you nailed it. Teeth are gone on the pinion.

The Makergear website offers a 5:1 and a 13.6:1 gearmotor. I don't find any markings on the one I have. Any idea which one it would be? The pinion is 11 teeth, the 3 gears are 17 teeth, and the outer is 46 teeth. I guess I don't know how one works as I can't get either one of those ratios... I get 4.18:1.

Seems to be a problem with the website. It ignores clicking on one of the motors to add it to the cart. Guess I will need to phone Monday.

I think I will upgrade to the V3 19V hot end while I'm at it. Any reason not to?

Thanks for you help.

[jimc]

the gearing is 5:1 or actually i think 5.18:1 or something like that. just email support this way rick or josh can get you what you need. you should upgrade to the v3b hotend though. the one with the heater block. if your machine is older it will have the v3 with the round heater core. you can keep the machine at 19v like mine or upgrade to the 24v if you want but its not necessary really.