High friction direct drive Tenlog D-6 Hotend

I have a full metal hotend direct drive IDEX printer (Tenlog D-6).
The image below shows the inner side of the hot end.

On extruder #1 consistently has high filament extrusion friction resistance. I tried tightening the extruder spring and shimmed it so it really would grip onto the filament hard (dual extruder gear system).
The only fix I have for this issue is to dip the filament in some 3-in-one machine oil to lubricate the heartbreak and nozzle. Of course, that now causes me bed adhesion issues (oil residue on the bed)(and this fix doesn’t last and often fails mid-print).
Please note that I also have tried the Zodiac nozzle and Bontech CHT nozzle to see if those options will help reduce the high filament friction I’m experiencing, and they both show the same result.

So I wonder if I use a heat gun to get rid of residual filament in the heartbreak and nozzle. Would applying the plastic repellent paint on the inner side solve the high friction problem?

I look forward to your response. This printer has become my least favourite to operate…

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Hi guys. i have no idea on this topic idea but am looking into the same problem, tell us your ideas!

If there is residue in there it might be from dirt on the filament accumulating. you can get a litle printable box that can fit a piece of sponge (I’ll link below) it can clean the filament as its fed but also a few drops of vegetable oil might serve the same purpose? on mine I do cold pulls frequently… actually every time I change filament now and often all the crud comes out at the same time.

What I meant about the residual filament is that after you remove the filament from the hot end, it will leave a tiny bit behind. I’m just not sure if I can just “drip” some of those plastic repellents in the long heartbreak, as seen with the picture above (with the leftover tiny amount filament still there).
Dust is not an issue as I already used the snap-on filter you showed me to apply some 3-in-one oil to get it to print in the first place.

Try this heat the hot end to extrusion temps power off the printer and try to manually push the filament. Is it hard to do?

If it is bypass the filament sensor and try again.

Because you changed the nozzle I am assuming there is no clog in the extruder. This to my mind leads to a filament sensor causing too much friction or a extruder tension or stepper issue.

I use one of these on occasion:

It helps stuck issues.

Manually pushing it out is stiff if I don’t apply the 3-in-one oil (easy to do otherwise)
The other symptom I have, if I don’t oil the filament, is that the extruder gear will chew the filament and grind it down until it can’t grab onto it anymore (in the case of using IIID max PLA+ filament, it just clicks and nothing extrudes)
The filament sensor you see in the image above (the translucent piece) has a tiny roller within to have the filament pass through; the friction of that is very negligible.
I have disassembled the extruder gear to clean them with a brass brush. Its teeth seemed pretty clean (when printing with IIIDMAX filament), so that would not have been the cause.
However, if I print with standard PLA and the oil runs out in the hotend, the filament will start to gum up the extruder teeth, and I will have to clean them with a brass brush.
I have tried raising and lowering the extruder spring tension, and nothing seemed to help except for adding lubricating oil right onto the filament itself.

I’d suggest the tension on the filament gears is too tight. Try backing it off so it doesn’t touch and then command a feed and increase tension until it moves.

Is your heat break lined? If so you may need a new liner too.

I should probably check to see if it is lined once my current print job is completed, as I’m unsure.
When I last checked, there wasn’t any lining that I could see. It just looked like a bare metal heat break.

It could also be heat creep prematurely melting the filament in the upper part of the hot end. sometimes the throat can be too deep in the heat block extending the nozzle out and increasing creep and decreasing nozzle temps a bad combination.

Have you tried a different brand of filament? I had tried a roll of IIID Max PLA+ and the diameter of the filament was not as tight on the 1.75mm. There were sections of the filament that were over 1.8mm. This could cause the additional friction in your heat break. Also, what hotend temperature and nozzle size are you using for this IIID Max filament?

Most of the time, I print with this filament on my other printers (ender 3 V2, CR-10 Max and CR-30) at 225 or 235C. However, on this printer to have it print at all, I have to not only add oil to lubricate the filament, but I also have to print at 277C and print at a super low speed of 20mm/s (the hotend is confirmed to be full metal and not PTFE lined)

If I may, pull the extruder off, take the nozzle off and see if the filament will easily push through cold.
If there is any resistance at all, there is a problem with the path between the extruder and the nozzle.
If it is easy to push through, put the extruder back on and run a feed at very low temp (below melting point) without a nozzle. If that works, heat the hotend up and check with an IR thermometer.
I never run PLA over 200C except for first layer at 210C. III3d Max PLA+ included.
Oil is not going to solve anything.

Hi there,
I have tried your method of taking the nozzle off, waiting for it to cool, and I couldn’t push the filament through. I also have been attempting to raise the nozzle temperature to 60, then 90 and the filament still won’t budge (I even grabbed a plier to grab onto it better and still no luck).

The weird thing is that this high resistance I’m experiencing only happens to one of the two hotends.
The other hotend on this printer works very well and doesn’t have this resistance issue.

So now, back to square one, if I shouldn’t raise the temperature or add oils to the filament to print correctly, would adding the plastic repellent inside the heatbreak help? Or should I disassemble everything and use a chemical and heat gun to deep clean the nozzle, heatbreak and the long metal tube that leads to the heatbreak?

Did you pull the heat block off to see if it is the heatbreak or the block?
I am starting to wonder if that heatbreak is damaged as in bent or dented. Maybe even swagged at the end causing the friction.
If you have a good set of drill bits you could use the chuck end of the bits to find one that just makes it through the good one and see if it will pass through the other.
You would have to make sure it was completely clean to be sure.
If it will not go through, use the sharp end of the bit by hand and see what it scrapes out. If you find any metal, replace the heatbreak.
Almost tempted to say replace it anyway.

I wonder if the heatbreak is making good contact with the heat sink. if you have any try some thermal paste in the joint and see if it improves things. I’m thinking this is heat creep related and if the fan is working then maybe this is an issue

Sorry for the late response, guys. I got COVID as I was so sick that I couldn’t respond promptly.

I felt better today, so I did a complete teardown of this proprietary hotend.
As I used a heat gun to slowly melt away the residue and get all the nuts and bolts loose on the hotend, I discovered that this hotend that I thought was 100% metal was, in fact, PTFE lined ant it was completely roasted.

I was so sure that it was a metal hotend because it has no PTFE exposed for the filament going into this metal tube:

I will contact TenLog support and try to source a proprietary full metal heatbreak to replace this.
Sorry for the oversight, @kitedemon , As I thought that there is no way this can be PTFE lined.

hey no worries I am glad you found the likely cause!