Fix for Mid-Print Jam and gear stripping

There's hundreds of reasons can cause a jam. This fix might not apply for your situation, but I thought I’d share my troubleshooting story with XYZ Da Vinci owners, so that you have one more area to look for.

My Da Vinci 1.0 stopped extruding at mid print a week ago after 3 weeks of use. The symptom is that I can feed the filament using “load filament”, I can print the first layer, but as soon as the printer picks up speed after the first layer, I get jam. The feeding gear starts to strip the filament.

I tried everything available on this forum, including swapping heating connector with a Dean’s plug, reaming the tip, submerge the tip in acetone, and raising the temp to 230C, and even changing the spring loaded silver gear with a grooved custom ball bearing wheel. None of the above worked

Until yesterday I found out that the problem was caused by careless assembling from the factory. I noticed that the feeding throat has some thread left above the tip, then I assumed it is not all the way screwed into the tip. So I decided to tear the extruder down to single parts to prove my hypothesis. End result – I was right, and the lack of few more turns of the feeding throat caused a lot of trouble for me.

Sorry I didn’t take any pictures during the fix, I will describe it at my best with some drawings.

The tip has a 2mm ID for the filament to go through, and also another 6mm ID for taking the feeding throat. So there’s a 2mm ring like cross section if you look from above down into the extruder tip. If the feeding throat is not screwed all the way in giving a good seal, there will be a chamber of 6mm diameter deep multiply whatever height depending on how deep the feeding throat is screwed in, between the bottom of the feeding throat and the top of the tip. While I was using XYZ’s filament, it didn’t give me any problems since their filament is pretty high in quality and was dry. Even if the filament fills the small chamber, it could still transfer heat well enough. But after I changed filament and it wasn’t as dry as the stock filament, the filament started to introduce air bubbles into the chamber, then the heat can no longer be transferred quickly enough to the new filament feeding through. This is why the printer was fine when pushing the filament slowly through, but as soon as the printer speeds up, new filament can't be heated fast enough and created a resistance, then the feeding gear would start to strip the filament, once stripping started and cumulated, the gear can no longer push filament until I clean it.

After taking everything apart, I simply removed the stuck filament, they weren’t burnt so cleaning was easy, lucky me this time. Screwed the feeding throat back on really hard. Now the filament goes through a straight tube that keeps narrowing without going through a gap along the way which eventually will trap plastic and create a jam after some time.
After putting everything together, don’t forget to re-calibrate the bed since the tip is higher now. My printer is printing flawlessly since the fix.

One tip for those who want to take apart the extruder tip, remove the heater first, then insert the shank of a drill bit of proper size into the heating hole, then hold the drill bit vertically with a vise and use a long wrench for the job. This will give you enough leverage to unscrew the feeding throat. Do it slowly since you’d have to break the melted plastic first. Heating it with a torch might help. Also, DO IT AT YOUR OWN RISK! I don’t take responsibility if you break your printer. Be careful since there’s no way to buy parts from XYZ yet.