Makerbot replicator 2's extruder jam/clogged on small details

[Cuong Phong]

Hi guys, 

Since this group does not post many new thread, it makes me feel a little bit of embarrassing and nervousing to make multiple new thread. Therefore, I have been researching about Jamming and clogging before seeking for help. During my research, I came across many similar situations, but I still could find any proper way to solve my problem. 

I will attach a photo as a reference to make a clearer picture about what I have been experiencing with my printer so far. 

As you can see in the picture, I cut the model into 2 pieces in simplify3d because my rep2 can prints the bottom part perfectly. However, the top part, which is fairly small, make the printer clog and the extruder starts to make click sound. Load and unload filament are fine after the extruder jam/clogg.

What I have tested so far is:

upgraded firmware to sailfish ( really like it, but it did not fix my problem :P ) 

temperature, from 210 - 245 ( seem help a little when I increase the temp but Jam/clog still occurred )

speed, from 40 - 80mm/s 

extrusion multiplier, from .7 to 2 

different spool of filament, matterhackers, makerbot, sainsmart, hatchbox.

(sailfish) onboard preferences >> Acceleration: I reduce everything by half, can't remember if it helps, but problem still occurred.

Turned off retraction and prime.

Changed the filament drive, heater block, and nozzle. ( the nozzle is .4mm, but I might try to vary that number, worth a try right) 

I have 2 makerbot replicator 2 printer, and they both have the same symptom. One is bowden drive and one is direct drive. Except the bowden one is due to retraction setting ( clogged if I increase the retract distance to 4mm or longer. 

The only cause I can think of right now is the diameter inside the nozzle because I have a flashforge creator pro, and it never has any jam or clog ( hopefully it won't :P). The ffcp diameter inside the nozzle is fairly bigger than the rep2 nozzle. I want to try the ffcp nozzle on rep2 so bad, but the nozzle does not fit to the heater block... 

I'm pretty frustrated right now, and I cannot spend many time on it because I still have other stuff to do. Ohh man this problem has been bugging me for months. If anyone can help me fix this problem, then you deserve my tears. Nevertheless, any advice and suggestions are appreciated. 

[Christopher]

For me your problem seems to be a retraction issue. Therefore you may want to go through all the steps Ryan suggested in another thread: 

You're getting cold-end jams. The filament is getting hot and softening too high in the thermal barrier tube, which causes extruder pushing force to mash the soft filament against the walls, where it re-solidifies and forms a solid plug. This is a very common issue with PLA, particularly in machines that don't get regular tune-up type maintenance, and when doing prints that require a lot of filament retraction. 

Basic solution steps for PLA cold-end jams:

1. Put the printer in a "room temp" room. That means ~65-85F or so. You cannot print PLA in a very hot room (it will soften prematurely and jam) or a very cold room (prints will warp). This is the physics of PLA, nothing to do with the printer. 
2. Verify your extruder hardware is all working and configured properly. Specifically, make sure the extruder cooling fan (40mm fan) is blowing at full strength and pointing the right way (sticker not visible). Make sure the heat sink is firmly pressed against the cooling bar. Verify the jam nut holding the thermal barrier tube into the cooling bar is tight. Applying a little bit of CPU thermal grease to the M6 thermal barrier thread - cooling bar interface and the heatsink - cooling bar interface is a good idea to maximize heat transfer. (Don't use any on the hot end side.) 
3. Try replacing the nozzle to see if it's worn out / partially clogged. If the extruded strand curls to the side when you load filament, you may have a partial clog. 
4. A spring-arm idler bearing arrangement is highly recommended, but if you're happy with your custom extruder then by all means stick with it.
5. Put a small dab or thin film of canola oil on the filament before loading. Use sparingly and only periodically -- no need to soak it in oil. Some people like "filament wiper/lubricator" devices off Thingiverse, to clean off dust and apply an oil film at the same time. The oil acts as a heat-transfer fluid to help the cold end keep the filament cool, and also lubricates / acts as a release agent if a cold-end plug does form, so the extruder can just push the plug down into the melt zone.

[Cuong Phong]

Hey Christ, thanks for the suggestion. I will try those and let's see how it turn out. 

[Cuong Phong]

Hey guys, 

I found the solution for my problem. I replaced the thermal barrier tube and  lower the temperature to 205. After that, everything are solved. For anybody that have the same problem as my, this is caused by something called "heat creep".