So in a previous post I was asking for help with printing issues. I recorded a video and you can hear a thud, thud, this and I can feel the filament popping up and down when it does. At the same time the plastic stops coming out. I JUST cleaned the nozzle too. I took everything apart and got every single speck out of there. Everything spins properly as well but I still occasionally get those thud sounds and it screws up my prints. Also, the popping often will go away if I press the filament into the extruder. To me it seems like the gear is getting jammed for some reason and it’s skipping over the filament. Any more suggestions?
What you are describing is the stepper skipping. For some reason, it doesn’t have enough torque to fight the back-pressure and is jumping back a step (4 full steps, to be precise).
Watch the drive gear when you hear that noise, this may be obvious but i always hear that noise when i cold extrude by accident, the thud is just the drive gear skipping
@Matthew_Del_Rosso it’s not cold extruding. The machine heats everything up before it will run and I monitor the temps to make sure everything is working so I don’t think it’s that.
Heat creep softens the filament too high up and then it solidifies and makes a jam that causes some skipping (thumping noises) and then underextrusion. It keeps pushing and clears the clog.
There are several different approaches to prevent this. One is to make sure your retraction isnt too high. Another is to print faster (fresh filament is a coolant for the cold end). Make sure the heatsink is properly attached and the threads aren’t “floating” and the heatsink fan is working. And you may want to try printing cooler.
I think @Mark_Walker might be onto something. Your hot end has a short thermal break. You could pick up a cheap IR thermometer from harbor freight and measure the temp on the aluminum block.
My creatr had a similar design that I fought constantly.
Heat creep (still a possibility) generally does not happen till later in the print as it takes time to build up heat. This is happening at the very beginning which indicates some other type of obstruction. Given that you have checked everything else and cleared all obstructions there are several things that might trigger such a result.
You are too close to the bed. Not entirely the cause as you get the issue further up as well. It happens further up if you cause the gear to fill up with chip because the nozzle can’t move the filament through so close to the bed and later on it will slip again if the resistance changes for some other reason.
You are printing too fast and or too cold and the filament does not melt fast enough to be extruded out consistently. You can check this by raising the head about 30 - 40 mm off the bed and after everything is heated up (don’t leave it hot for a long time) extrude a constant stream and watch what it does. If it curls at the nozzle and never drops down then it is too cold.
Your filament is out of spec or over sized and is causing additional restrictions trying to feed through. This can be checked with calipers but if your printer is robust it should handle a small amount of variation. Take off the nozzle and see if you have any resistance feeding the filament through the extruder by hand.
In all cases if it consistently thumps then you could be chipping the filament and filling the hobbed gear with chip which will make matters worse and move the cause to a secondary location. This could lead you to think that solving the primary cause did not work. Make sure your hobbed gear is clean.
Judging from the photos, this is a cTC Prusa I3 Pro B, right? That extruder will never work reliably since it doesn’t apply proper pressure on the filament against the hobbed gear - there’s no spring. I have one of those and they suck - they just don’t work.
Get the 1.75mm / right side feeder version but you’ll have to remove some of the plastic of the tensioner arm or it won’t fit. (The arm has to point towards the back of the printer, therefore it collides with the x-carriage if you don’t cut it off.) Otherwise it’s a drop in replacement and will work much better than the original one.
However - it’ll never work really well. The whole extruder is flawed by design.
@Martin_Klein thanks for the link. The stock feeder doesn’t have a spring so I went ahead and ordered the one you posted. I’m hoping it fixes my issue here. I didn’t realize that you could just replace the feeder. You know, I’m learning all the noob stuff. Lol
Take a look at https://groups.google.com/d/msg/wanhao-printer-3d/TMq_vWHax9g/qtNYgAFxJkQJ too for further evaluation. Though it’s about a different printer, the issue was the same back then. You’re dealing with problems that were solved in 2013/2014 but somehow these cheap chinese kit sellers on ebay and elsewhere claim they are selling the “latest, new, improved 201X” edition of their printer every year without actually changing or improving anything.
@Martin_Klein we all have to start somewhere. Lol. I’m just waiting for the day we can just plug our brains Into a machine and download how to do stuff. Lol.
