However not all those watts are going into the heatsink, but even so, this is what a 30W heat sink looks like:
So just comparing the Aero to purpose-built heatsinks, I'm starting to think that the Titan Aero heatsink may not be very efficient, and in a hot environment probably less so. My printer is located in an un-cooled garage and temps get hot in there. So I think there are three things that come to mind with the way this is failing.
1. Retraction. Where the problem began was at the point where the extruder would probably be performing more retractions as it worked up the beard and head of the model, and that suggests that it was possibly too aggressive on the retraction. However, I am only using 1mm retraction currently, and the rest of the model was perfect so that suggests that retraction was probably OK. The filament was hanging lose on the spool so it was not caught up there. Likely the retraction setting is fine.
2. Heat. The problem began hours into the print and probably as the mid-day temps in the garage were ramping up. Everything in the extruder, stepper and the heatsink will get hotter and expand. When that happens it makes sense that things would get tighter and that could lead to some binding. When everything cools off, it works fine. Since the heatsink is also a mechanical part of the design that holds the bearings, there could be some binding in the extruder related to heat expansion. Although there is a fair amount of slop in the design, two areas that seem to be less tolerant of misalignment are large gear shaft which needs to be aligned between bearings in the plastic base and the aluminum heatsink, and the alignment of the large gear shaft and the stepper's shaft. To get an idea of what the expansion could be (ballpark), I used the calculator linked below, to see what the temp difference of 32-49 degrees C would mean for a 10mm length of Alumunim. The linear expansion would only be 0.00374mm. Even at 3x that amount, I cannot measure it with my calipers, so it probably is not going to be a factor.
3. Bearings. I had read in one forum that E3D had some problem with bearings which they had changed the lubricant out on due to a corrosive effect it was having on their poly-carbonate covers for the Titan extruders. The replacement lubrication however was not up to the task (https://e3d-online.com/blog/2018/01/22/bearinggate/). A redditor(https://www.reddit.com/r/3Dprinting/comments/7ho3kx/titan_aero_extruder_grinding_filament/), suggested that since the supplied bearings are crap anyway, just swap them with ceramic bearings like these:
Given the above possibilities, I think that retraction is not a problem since I am running only 1mm currently. The heat and bearings seem to be the most likely cause of the problems. I can't really make the Titan Aero a better heat sink, so I can only add more airflow.
So the plan right now has several parts
- Add a more powerful fan to cool the Titan Aero heatsink. (DONE)
- Swap the bearings with the ceramic bearings linked above. (DONE)
- Add a heatsink and possibly a fan to cool the stepper, and reduce the stepper current. (DONE)
- If the above fails, run the printer only at night or with a room AC in the garage to cool the ambient air - or find a better way to cool the extruder.
Everything above except for #4 is done now and I am gonna test it tomorrow. Getting the bearings out was interesting though - I found a post on Reddit where "CHenderson2010" suggested using water and freezing it with some canned air (just read his post). I didn't think it would work, but it did, and that was after bending the tip of a long nose pliers trying to pop the bearing out, so thank you Interwebs!
(I Updated this part below on 9/26/2018 to remove some incorrect info and clarify some other info)
An additional problem I have noted with my Titan Aero is that the filament path has several points where there is resistance when installing a new filament. This resistance is probably not the cause of any jamming, but I would like to reduce it anyway.
The first point of resistance is where the filament must thread into the guide. I may print the part below to see if that helps:
Update - I printed the top piece of the above part and it does help align the filament, but I did not use the tube part since the stock tube worked after adding a chamfer - see below.
The next point where I could feel resistance, is where the filament feeds into the PTFE tube that goes into the heatsink. I added a chamfer to the inside edge of the PTFE tube to help with that, and the filament no longer catches.
The last point where there could be some resistance, and it is harder to tell with this one, is at the ramp for the filament to feed into the heat break tube. This is the hardest to fix and seems to be the least of the problems however so I am not going to worry about it.
- Try the filament guide linked above. (DONE, using the top part only)
- Chamfer the inside edge of the PTFE tube going into the heatsink. (DONE)
I will update if any of this helps (after I re-test).
Update 10/19/2018: After the mods, I have no longer been having problems with the Titan Aero jamming. I think the two mods that did the most to fix the problems were the filament guide (which I only used the top part):
And the new bearings:
The fan and stepper heatsinks did help in my case, but generally if the stepper is not getting hot, and the printer is in a climate controlled area, those may not be necessary.
Now that the Titan Aero is working, it has been reliable and I can finally call it an "upgrade".