Extruder HELP!!!!

I have a EckerTech RepRap printer that I just built. After some problems getting the printer working, I had everything running fine yesterday and printed for a total of 11 hours, four different prints, but on the last print, the extruder started giving me trouble.

Early in the print, it stopped extruding. The hobbed bolt had chewed out the side of the filament. I cleaned the nozzle, cleaned the hobbed bolt, and started again but it only printed 6" to 12" before it plugged up again. I cleaned everything and tried again many times. I have tried higher hot end temp (up to 290C), lower temp (230), lower feedrate, lower flow rate, each time cleaning in between, and it does the same thing every time. The printed trace starts to get narrower and then the filament strips in the extruder drive.

The nozzle is 0.45mm but I don't have a .45mm drill bit and can't get one until Monday. I use the cleaning wire that came with the kit (0.43mm) but it isn't long enough to pass all the way through the nozzle. The extruded filament (when it IS extruding) is 0.63mm (0.025")

I can't, for the life of me, figure out why it quit working and started plugging! It is SO consistent in printing 6" to 12" and then chewing up the filament!

HELP!!!!

DianneB
Are you using PLA or ABS? and are you using 3mm or 1.75mm?

I think might have had the hot end a little high on your first prints and caused some char. Heat the hot end about 20 C below your print temperature gently pull on the filament with the tension off the traction wheel and see if you can pull it out this should take crumbs of char out with the filament do not snap it off if you manage to pull it out obviously cut the end of the filament off re-feed the filament. And while not printing make sure to shut your hot end temp off you do not want to have it sit there idling with plastic in the hot end will cause char hopefully you have not distorted the hot end liner.

Edited 2 time(s). Last edit at 02/01/2014 01:39PM by cnc dick.

I am printing with 3mm ABS. On the last print, it printed most of the first layer, about 15 minutes, before it chewed up the filament again.

I ground a small watchmaker's screwdriver to 0.45 mm and 'reamed' the nozzle before this print. Lasted a bit longer but still crapped out.

Try what I said the idea here is not to have the filament melted but just to loosen it up in the hot end and pull it out this should take some of the contaminants out try this a couple of times. But you stated that you tried all the way up to 290 which is a problem you probably distorted the liner they're not meant to run anywhere near that high that is if you don't have an all metal hot end

The Eckertech hot end is all metal and can go over 300°C without damage. There is just some debris in it.

I've used some 14 or 12 guage copper wire to pull out molten plastic. If you get the right combination of temperatures, it can pull everything out of the hot end bore.

---

Yvan

Singularity Machine

After spending most of a day troubleshooting I figured out that my nozzle wasn't plugging but that the software was trying to push the filament too fast.

I upped the temperature from 230C to 260C and turned the feed rate and flow rate down to 68% and got through a 4 hour print with only minor defects.

Don't know why that change was needed after the first 10 hours of printing but with the changes made, it seems to be operating properly.

Thanks gang.

I have been printing in ABS for a few years and recently I just cant make mine work.

My first nozzle lasted a while bit I think the PTFE became damaged due to an overheat and it in the end failed.

I replaced it and this cured the problem for hundreds of hours printing. But it started to slip on the bolt and clog it reputedly again. I think the PTFE might loose its properties after a lot of use.

Now as my printer is out of date I had to alter a new hot end to fit. I have had some success with this bit its still not really working.

May have to just slow it down. But it used to print at the same speed.

Been experimenting with different hobbled bolts I have made. Course, fine, shaped, straight etc. Some with more or less success but still didn't cure the problem.

I'm wondering if the plastic is just not as good or has gone off with age as its been sitting around a while now.

I have also concluded the hot end and extruder system is consistently the most problematic part of the whole printer.

---

Make your Mendel twice as accurate.
[www.thingiverse.com]

I have decided to put a friction drive between the hobbed bolt and the drive gear to limit the amount of torque the extruder can exert. By adjusting the friction just below what it takes to strip the filament I can eliminate repeated cleanings. By placing marks on the gear and the friction plate, I can also tell if the clutch is slipping while running. That will allow finding the maximum flow rate without stripping and having the filament stop.

Easiest and best way to clean a nozzle is to unscrew it from the hotend and with a stiff wire hold the nozzle in a gas flame and burn the crap out of it.
Don't let it get red hot, just enough to burn out the plastic. Wash it in water and your are good to go.

---

[regpye.com.au]
"Experience is the mother of all knowledge." --Leonardo da Vinci

Quote
regpye
Easiest and best way to clean a nozzle is to unscrew it from the hotend and with a stiff wire hold the nozzle in a gas flame and burn the crap out of it.
Don't let it get red hot, just enough to burn out the plastic. Wash it in water and your are good to go.

Unfortunately the hot end on my printer has the heater and thermistor directly mounted on the hot end so burning it out wouldn't be wise. Taking the hot end off requires removing a couple of nuts and dealing with the heater and thermistor leads while you work. Since I don't really have a problem with the nozzle (only the extruder stripping) I clean the nozzle on the machine - just run the Z axis up high and run a cleaner through the nozzle.

DianneB,
what hotend do you have? apparently the problem could be in the transition zone. Perhaps you need to increase the thermal barrier using active cooling. Do you have a fan in your hotend? In my opinion reducing the size of transition zone minimize the jamming problem

Javier