Under extrusion

[frierson22]

This is probably going to be long, so I apologize in advance.
I can't believe I'm having problems again. Is this normal? Am I not doing my due diligence in maintenance and preparing for printing? Or do I just have a crappy printer?
I do print a lot when it is working well. Maybe I'm just wearing it out.

I'm using a Tronxy XY.

My current problem is under-extrusion. Not the first time, but the normal fixes aren't working now.
Nothing has changed about my slicer settings, so I'm pretty sure it's mechanical.

It started when my bowden tube fitting failed and I did not have a replacement.

I had purchased some capricorn tube, but had issues with the filament flow thru it, so I went back to the Bowden. I decided to try it again while I was waiting for the other to come in the mail. Again it didn't work, and I haven't gotten a decent print since.

I did some research online. First thing I realized was that I had at some point left a gap between the tube and the nozzle. Melted plastic was leaking out on the top of the hot end. I cleaned that up and made sure that the new tube was positioned correctly. The extruder was still skipping and filament was not flowing as it should. I changed the nozzle to make sure that was not the problem. I used a toothpick to clean out the hot end and even ran some filament straight thru while it was hot with no nozzle attached to make sure that it was cleaned out completely.

The next print I tried, the bed was not leveled correctly - too close to the bed. The print failed. I know that can cause a clog, so I tried to clean it and ended up changing the nozzle again, just to make sure. Still no luck. Bed leveled correctly - new tube - new nozzle. It started out looking good, but before the first level had completed, it was skipping and missing spots.

Next I worked on the extruder. I saw a video that says the extruder spring can lose pressure. You can add washers to increase the pressure on the extruder gear. So I did that.
The video also said that the gear could get plastic stuck in it so that it won't grip the filament. I tried to clean that with a stiff brush and toothpick. It looks clean.
The only other thing I can think is that I need a new extruder. The gear looks like maybe it is worn down? Maybe it just needs replacing?

Bottom line - For whatever reason, my printer acts like there is a clog in the nozzle even tho I am using a brand new nozzle and brand new bowden tube. I have tried several different filaments, so I know that isn't the problem.

Any ideas what else I can try? Thanks

[tlawrence84]

Hey, I had a similar issue with under extrusion, and with very extensive trouble shooting, it turned out to be the extruders throat tube that was a bit iffy. I had upgraded to a E3D v6 hotend, I replaced my extruder assembly, nozzles, tried varying temperatures on the filament, and made sure the nozzle was properly hot tightened, amongst many other maintenance checks (belt tensions, rollers tightened etc).

A good test I found to see if this is a cooling issue was to completely disable retraction and see if this would stop the block. This would mean completely cleaning out the nozzle, heater throat and bowden, and see if you can get a successful (albeit messy and stringy) print. This could identify if this is a cooling problem with the filament somewhere or if there is a hardware block.

[Roberts_Clif]

Clean and lube all bearings, Do not know what your normal fixes are.
I would dissemble the Hot-end and check every part carefully skip if already complete.

Short story.
Had under extrusion an after a log troubleshooting experience found that Slicer filament diameter changed 1.75mm to 3mm causing under extrusion.

Attached Photo of under-extrusion
3mm - 1.75mm.jpg

[frierson22]

Thanks for the replies. I'll definitely try the advice.

According to Tronxy, my extruder may be discontinued. Apparently my machine is very old - purchased in 2018 LOL.
I'm waiting to hear back if there is something available I can use.

I planned to change out the extruder and the hotend also just in case. I have to wait 6-8 weeks for replacement parts because nothing I can get quicker fits my machine. In the mean time, I'm just waiting, so thanks for new ideas to try.

I'm seriously considering getting something new. In spite of the problems I have had, I like the the Tronxy and their customer service is very helpful, if very slow because of distance. But I don't like the down time.

[Roberts_Clif]

Apparently my machine is very old - purchased in 2018 LOL.

My 3D Printers are older, an printing like they are brand new.

Have you pulled the Teflon filament tube to see if it is burnt or even melted inside the hot-end causing a clog

[frierson22]

I'm so confused.

I started going thru some of the fixes suggested here. To start I was going to try disabling the retraction to see what happened. I could not get the filament to flow thru the nozzle even before the printing started. So I took everything apart again. Replaced the tube and fittings and nozzle - again. I checked the hot end - shone a light thru it - looks perfectly clean. I added a washer to the extruder to make sure there was enough pressure to push the filament. After that the filament flowed so easily, I wondered if maybe that section of tube had a defect or something that was affecting the flow? So I checked the tube and sure enough it felt like there was resistance when I pushed filament thru the disconnected tube.

So instead of the 0 retraction, I tried to print a known file from my sd card. This is what I got - a stringy, globby mess with uneven sides. To this point, it's functional and strong, but ugly. I stopped the print because of a glob on the top surface that the nozzle was bumping into - probably would not have finished. I have succesfully printed this same gcode twice before.

20201220_152452.jpg

So I took the washer off of the extruder in case that was somehow causing over extrusion. I didn't get past the first couple of layers on this try. Globs of melted filament all over the print. Again this is from g-code that successfully printed before.

20201220_163854.jpg

When I watch the extruder work, I don't see any slipping or skipping like before.

Keep in mind that the clogged section of tube was brand new and I had an under-extrusion problem before I installed it.

Trying to print from previously proven g-code proves that it is a mechanical issue with the printer, right? All the belts seem OK.

How can I tell if the thermistor is bad. there is a spot on the end of the glass ball, but it looks intact.

Any ideas what else I can check? Thanks

Donna

[frierson22]

I'm printing again. A new hot end did the trick. Apparently I had "glue leakage". Thanks for all the tips and advice.