Can't stop Hexagon hotend leakage

My hot end is leaking between heater and nozzle. It’s only a realy small amount when using PLA @205°, nothing that influences printint.
But things changed since I’m using more PETG @240°. Leakage is significant higher, after 2-3h of printing the nozzle is covered with PETG! This afternoon, I made the mistake to think it might get better if I tighten the nozzle only a little bit more. That realy tiny bit was already too much, I stripped my favourit 0.4mm nozzle :frowning: At least, the heater block is not damaged. I’m now printing again with the original 0.5mm nozzle, still leaking…

Is there a drawing that shows the hexagon hotend in a section view? I can’t find information where it’s designed to prevent leaking. To be more precise: Is it the contact surface of nozzle head and heater block, or like the E3D v6 Hotend where you tighten the nozzle against the heat break? In second case, I might try to tighten the heater to the heat brak a little bit.

It’s realy sad that the Hexagon seems to be a curiosity in 3D printing, there is nearly no information out there. Sometimes I think the e3d might be the better choice…

I hate to tell you this Sebastian but I think that you are being overly optimistic about the state of the heater block on your hotend. Brass is tougher than aluminum and the probability is that your “stripped” nozzle is fine, it just has aluminum filling the threads. (You should be able to verify this by using the pick that came with your TAZ and try cleaning the threads.

I have also stripped out the heater block on my extruder. Unfortunately, spare A0 heater blocks are not available as a separate item. To prevent recurance, I have built a second tool head so that I have a tool head with a 0.5 nozzle and a tool head with a 0.35 nozzle

I will admit the OHAI is kind of un-clear, but you torque the nozzle into the heat block then tighten the heat break down against it. I think this last step is where the leakage occurs. If the heat break moves while heated then you may no longer have a tight fit between the two sections. Which creates a gap to leak plastic out, the bigger the gap the more it leaks.

Thanks, I will have a careful look at it today! Sounds promising.

@geburges: there are no pieces of aluminum on my broken nozzle, that was the first think that I checked. Also the thread inside the heater looks clean.

1.5h of PETG printing and no leakage :smiley: :sunglasses: Thanks kmanley57!

To write it down in one place for next person having trobles:
The same procedure as for the e3d hotend applies. Here is how to change the Nozzle on a TAZ5, without the risk of stripping threads (nearly, I know there is always at least one person that can do everything :wink: ) or have leakage.
Things to note before:

  • If you touch the hotend with a tool, it will cool down quickly. That can trigger a thermal runaway safety function in Marlin that cuts off the power to your heater. In this case, switch your printer off and on again to reset the “fuse”.
  • Also if I reference to a tool, never work with force! For example, grab the wrench with 2 or 3 finger as close to the hot end or nozzle as you can. You will never need torque!
  1. Remove as much material from your nozzle as possible -> Cold pull.
  2. Heat it up to something slightly above the highest print temperature you are using. For example 250° of you are using ABS or PETG.
  3. Grab the heater block with a 18mm wrench and turn it clockwise (when looking from top down) only a little bit to be shure not to transfer torque to the heat break when changing the nozzle later. This will unscrew the heat break from the heater. Be careful not to damage the wires from heater! Only turn it a few degrees!
  4. If the hot end temperature droped too much in step 3, let the hot end heat up again.
  5. Hold the heater block with the 18mm wrench again and loosen the nozzle with a 7mm wrench. A piece of kitchen paper may be useful as a thermal barrier to unscrew it completely by hand.
  6. Insert the new nozzle with your fingers to be shure not to damage the threads of the heater block. Be careful, the nozzle will get hot in a very short time but it’s possible!
  7. Still holding the heater with the 18mm wrench, screw the nozzle completely into it. But don’t apply any force, only turn it until you feel the resistance of the nozzle contacting the heaters surface!
  8. Heat the hot end to at least 250°, max. 280°C.
  9. Using kitchen paper as a thermal insulator, grab the hotend and turn it counter-clockwise to screw it to the heat barrier again. Never ever do this with a wrench! Finger tight is exatly what you want! Again, be careful not to apply force to the wires.
  10. Let the hotend cool down again and print :slight_smile:

Sebastian,
When you say hotend leakage, are you talking about when the printer is just on, and the hotend is just there. The filament just drips out? That’s what mine does. I always wonder if this causes surface finish issues.

I think what you are talking about is oozing. My problem was leakage in the nozzle threading, thats something different. While my problem was not normal, oozing is not avoidable. When your hotend is at print temperature, the molten filament will start to flow out of the nozzle opening, there is nothing that will hold it inside.
That’s why you should heat up only a short time before you start a print.

I am wondering if a little Teflon tape would seal the nozzle threads enough to prevent leaks.

When you prime your nozzle / hotend before printing you can always do like I do, Retract say 10 mm or so and then wipe the nozzle with a green scotch bright pad to get off the dribbles.

It may be more easy to mount the nozzle corectly than to apply teflon tape…
Beside this, most teflon tapes are not as temperature resistent as the hexagon hotend is, so you will limit your printing temperature using teflon tape.

Actually Teflon Tape a generic term for PTFE is rated 200 - 300 Deg C and does not start to degrade until near 400 C. It would seem ideal for sealing those threads. Also the nozzle would not need to be as tight to prevent leakage.

http://www.cowie-tech.com/ptfeprop.htm

I will repeat my message as often as needed :wink:
Have a look on the link in my signature. You need no torque to get a sealed nozzle if you install or change it as usual for E3D Hotends. The design of the hexagon and the E3D is nearly identical, there is no reason to torque something. No idea why hexagon ivented this procedure.
You will never get a realy tight nozzle if you torque the nozzle to the heater block, at last if you change to another nozzle because the old one may have deformed the surface of the heater block a little bit. But on the other side, “torque” the nozzle to the heat brake and everything is alright :slight_smile:

Using the Teflon on the threads would do a real job on electrical conductivity for bed leveling I think. :nerd:

There is always a little metal that still touches, its not a 100% isolation. If you have ever used the stuff you will notice that… :wink:

I did Not think we are talking about the Mini, the only one with Automatic bed leveling. At one time TAZ was using a blue thread sealer on the nozzle threads, can anyone confirm that?

Is your heater block loose? I’m not sure of the hexagon, but with the E3D nozzle is required to butt against the heat break. If your heater block is loose (and your nozzle is tight), that may indicate a gap between the heat break and nozzle… Give the heater block a turn counter clockwise and make sure its tight.

If you have a small set of pliers, the top of the heat break thread (just above the heat break) has flat sides which the nose of the pliers can “grip” to aid in tightening.

I change nozzles on my hexagon hot end frequently. I always screw it in with a wrench until it looks like it’s all the way in, then torque it down enough where it just STARTS giving a bit of resistance. Never had an issue with leakage.

I think people thought that at first from the way the OHAI guide read.

The sealer is only used on the threads above the heater block.