My number 1 recurring issue on my Ultimakers always seems to come back to extrusion. I do a lot of atomic cleans, I regularly replace the teflon coupler, I keep the extruder gear clean, with the advent of removable nozzles, I change nozzles a lot.
What I have not done until recently is lubricate the bowden tube. I did replace them with more slippery versions prior to the "+" upgrade which of course did come with new tubes.
The "+" upgrade certainly improved extrusion. Startups are much more reliable without my attention (prior to the upgrade I often manually primed the nozzle just to be sure of a good startup).
Recently, however, my "+"'s have started to sputter a little on the extrusion front. Having done all of the normal things that I have been doing I looked for something new that I have not tried and came across a suggestion to lubricate the bowden tube. This suggestion was made on the 3D Hubs forum and since I had not seen it on the Ultimaker Forum I did a couple of searches and did find some references suggesting the use of dust filters that also lubricate. The feedback was very mixed with recommendations that you not lubricate stuff going into the feeder.
I had used a filament cleaner on my Makertbot Clone and it did not seem to hurt so I decided to go ahead and try it on my Ultimakers. The results have been profound (in a good way). The only difference between the failed print, due to under extrusion, on the right and the near perfect print on the left was the addition of a filament filter that also lubricates:
The questions this leaves me with are:
- First, is there a reason that I should NOT be doing this (as in will I see some long term harm)?
- Second, what lubricant should I be using (right now I am using a high temperature nut oil)?
I do question myself as to why I have not done this before and wonder if my extrusion issues have been threshold related. Meaning that I start to see issues at a certain threshold of resistance. Say that "R" is resistance and R=100 is the point where problems start to occur. Changing a nozzle gives you a benefit of -10, an atomic clean might add a little to that as it may also clean the boundary between the nozzle and the teflon coupler so maybe a -15 with a nozzle change. Changing the teflon coupler gives you another boost, maybe a -30, depending on how bad it was. In the meantime, however, the bowden tube has been adding resistance. Say a +5 every month. Once you hit the 100 you can improve things with nozzle changes, atomic cleans, and new teflon couplers, but the inexorable creep of resistance building inside the bowden tube will ultimately take you to the threshold and beyond. Enter lubrication.
So...am I making any sense? Why is lubricating the bowden tube not a more popular suggestion?
[Update of 14 July 2016]
Feedback on the Ultimaker forum has been sparse but with a concern raised in regards to strength of the ending component. So I did a strength test with the before baseline being the results of a cooling based strength test that I did some months ago. The result was a surprise in that the lubricated part was stronger than the non lubricated part. I attribute this to the part being fully extruded. The parts from the original test were not badly under extruded but may have been a little.......
The second concern that I have seen on other sites was in regards to vegetable oils ultimately clogging. A suggestion was made to use silicon based oil so that is what I am planning on going forward.
Finally, below is a picture of the dust filter/lubricator in action: