Nozzle & Crud

I am having a situation where my 0.5 nozzle keeps blocking during my prints. It happens about every 500g of PLA. Other times I get some crud extruding into the print. I have cleaned the nozzle very well but it continuing to occur. I am typically running at 200 degrees c and pushed it up to 230 degrees c and used a pair of pliers on the filament to push it though mid print to unblock it but I have no confidence in doing long tall prints, like a group of x-axis prints on one plate.

Any suggestions on how to resolve this would be appreciated,

Regards, James

Try adding a sponge or something right above your extruder entry hole so that any contaminants such as dust are cleaned from the filament before it is fed into the extruder.

---

--

Charles S.
Software Engineer
Prusa Mendel I2, RAMPS 1.4, Marlin 1.0 R2, Pronterface, Slic3r

Now I don't use PLA but I thought the temp for it was 185c. It might be you are burning it ant that's the crud you see. I saw this with ABS with too much heat.

You need to give details of your hot end and extruder as well as printing speed. The PID setting of the firmware can also result in the hot end overheating.

The 185 C setting for PLA was for the early hot end designs that had the thermistor taped over the nozzle with kapton. This tended to read a lower temperature than the actual nozzle temperature. Newer designs using a heating block with the thermistor inserted into a hole in the block read either closer or a little higher than the actual temperature. So, the usual setting in this case is 205-210 C.

Some hot end designs that use a teflon tubing liner to reduce friction have had problems with the teflon constricting the feed path which can seem like a clogged nozzle. I had this problem with a J-head Mk IV-B which I fixed by using a drill to clear the path.

Well I just broke the end on my nozzle cleaning it out so no printing anyway until I get a new one.

I have a geared extruder where the thermistor is held in place it a nylon washer and a screw onto the block. It does not sit inside the block, but the heater does. It does have a teflon tube about 65mm long and when doing the clean I did notice one end was a bit fuzzy.

I have a 25mm fan that sits under & behind the gear that is suppose to blow onto the top of the peek and teflon tube, it does not seem to be turning on and a spare I have does not seem to be starting up either. This would definitely be a likely suspect. I do remember seeing it in the past but must admit not looking recently.

re: PID settings, refer below.

Marlin firmware, GEN6.d, printrunPrint, slicer0.7.1 - Speed: Perimeters 40,, Small: 30, Infill: 50, Solid: 50, Bridges: 100



#define PIDTEMP
#define PID_MAX 255 // limits current to nozzle; 255=full current
#ifdef PIDTEMP
//#define PID_DEBUG // Sends debug data to the serial port.
//#define PID_OPENLOOP 1 // Puts PID in open loop. M104 sets the output power in %
#define PID_INTEGRAL_DRIVE_MAX 255 //limit for the integral term
#define K1 0.95 //smoothing factor withing the PID
#define PID_dT 0.128 //sampling period of the PID

#define PID_CRITIAL_GAIN 50
#define PID_SWING_AT_CRITIAL 47 //seconds

#define PID_PID //normal PID

#ifdef PID_PID

#define DEFAULT_Kp 22.2
#define DEFAULT_Ki (1.25*PID_dT)
#define DEFAULT_Kd (99/PID_dT)

#endif

#ifdef PID_PI
#define DEFAULT_Kp (PID_CRITIAL_GAIN/2.2)
#define DEFAULT_Ki (1.2*Kp/PID_SWING_AT_CRITIAL*PID_dT)
#define DEFAULT_Kd (0)
#endif

#define PID_ADD_EXTRUSION_RATE
#ifdef PID_ADD_EXTRUSION_RATE
#define DEFAULT_Kc (1) //heatingpower=Kc*(e_speed)
#endif
#endif // PIDTEMP

#define EXTRUDER_RUNOUT_MINTEMP 190
#define EXTRUDER_RUNOUT_SECONDS 30.
#define EXTRUDER_RUNOUT_ESTEPS 14. //mm filament

Edited 1 time(s). Last edit at 11/04/2012 03:50AM by 4xjbh.