I have been trying to research an issue with our Makerbot Replicator 2X and cannot find a good existing answer. So I figured why not hop on some forums to see if anyone has any insight into our issue. We have been using our Makerbot for almost a year now with no real issues to speak of. About 2 weeks ago our right extruder began to "leak" material after its completed task. This was causing random material to be deposited throughout the print and not extruding the first couple of lines of a print due to the chamber being emptied. First we changed temperatures to see if that would have any affect. We have been running the ABS side at 230 this whole time with no issues but figured it was a starting point. Lowering the temperature all the way to 210 showed no improvements. We then replaced the nozzle hoping that might be the issue, no improvements. So we tore down the machine further and noticed that the thermocouple wire was damaged and not making a good connection. Hoping it was giving us false temperature readings we replaced it. Still the issue persists. Next we tried cutting a small section of the filament and running the load program thinking it may be a motor issue causing the filament to be pushed through when it shouldn't be. The filament would be extruded as expected until the end of the cut section. No material is being pushed through yet the extruded continues to leak material out. The below picture is from such run. You can see where the "print" finished and the "leak" started. I am at a lost right now as to which direction I need to go. Any input would be greatly appreciated.
@maxpowers2430 have you looked at the plunger assembly? If its pulling in to much I can see it creating positive pressure where even after its stopped it takes awhile for it to normalize.
Like the old manual glue guns, if you push the stick in too much it would put pressure on the melted glue so even after you release it still comes out.
You could try loosening the plunger a lil at a time to see if it gets results. Its easy to test and doesn't require anything more then a screwdriver and a allen key.
I adjusted the screw that applies tension to the spring which is accessible without tearing anything down. Nothing changed as far as the leaking is concerned. I don't know if what you mentioned was a 2X assembly so I took a picture of it taken apart. I will try an upload a video and pictures of what the issues looks like while printing.
Here is a picture of a cancelled print. It was to be a pentagon with a raft underneath. As you can see the initial purge is missing on the blue ABS filament. It then starts extruding when the motor begins to fill the void in the chamber created by the leaked material. After the initial purge the extruder continues to leak material that collects around the nozzle until it finally releases onto the platform, bottom glob of blue ABS in the center of the platform. It then continues to make a zig zag pattern as the other extruder was creating the raft.
@maxpowers2430: Ill see if I can also find something that shows what I was talking about.
@maxpowers2430: Side note, are you working with the cover on?
Yes, the cover is on.
I ask becauce even with the reduced temp with the cover on the ambient temp you be too high for the abs to harden fast enough. You could look into a active cooling solution
@maxpowers2430 something like this, http://www.thingiverse.com/thing:223995
This can only happen if (Like @KylevT KylevT says) there is pressure pushing the filament through. I suspect the pinch gear is creeping. If you do a filament load on the other extruder and don't put filament in it, does it happen still to the malfunctioning one? I suspect if you could pull off the guide tube while it was happening and feel it, you would feel filament being pulled into the extruder. Maybe there is a voltage leak? Firmware upgrade due? Another damaged wire? A slight short?
See, without pressure, the filament doesn't want to go through, so either something is making pressure that is slowly being relieved (like a plugged nozzel - which you already eliminated), or it is still extruding when it should because the gear is moving. I don't have an R2X........so I can't look to see what might cause it. You could do the plunger assembly upgrade, but it doesn't sound like the problem.