Extruder stopping and grinding ?

[ian 32]

Extruder stopping and grinding ?

I have a new interesting problem with my new ultimaker.

I am running slow good quality prints at 70 speed.

The prints run at a temp of 215 for PLA and no problems.

about 20minutes into each print, the PLA filament stops rolling into the print head and the extruder keeps on turning. This of course bores out a huge whole in the PLA and there is no other option than to top the print, open the extruder and pull the pla out with a pliers and cut it away.

I have lost about 5 meters of good PLA now and i dont really want to loose more...

these are my few ideas why this could be happening ?

(1) the bowden tube is too small, it is tight and if the diameter of the pla varies, that could cause a blockage and so the grinding.

(2) im running to close to the print bed, the pla has not enough chance to escape onto the bed and so causes a back log, resulting in the grinding.

here are some photos to help understand the situation.

please help if you can.

thanks.

Ian

[ian 32]

oh my god,i still cant post photos...........

[ian 32]

thanks to photobucket for the help.

[ian 32]

[ian 32]

[ian 32]

[ian 32]

4th attempt ruined.....

cleaned the extruder... printed the same model again. this time half the project printed fine, then no more filament and pufff. dead

any ideas guys ?

thanks.

Ian

[jcosmo 5]

I don't consider 70 slow

I've not had this problem, but a lot of people do when using the stock drive mechanism. It is very intolerant to changes in the diameter of the filament. You could try backing off the tension screw on the drive a whisker, but then you might get slippage if the filament has a thin spot. If you are watching a print and notice the grinding you could try to adjust it on the fly and add a little manual extrusion help to get it past the point of grinding.

Long term your best bet is to produce an alternate drive. There are a number on thingiverse, and posted here. Bertho and chopmeister both have one. Their designs are much more tolerant of filament change due to a bearing and spring mechanism.

[ian 32]

thanks for the tips.

i will have a goodlook at the other options for the extruder setup tonight.

I would be very curious to see what other members here have used and there feedback on what works and doesnt ?

best wishes.

Ian

[jcosmo 5]

For me it has been a case of just not over tightening the adjustment bolt on the stock

feeder. I've perhaps been lucky with the quality of the filament I got when I bought the UM, and have not bought any more since.

I do intend to build one of the others at some point though