Solved HEX Extruder HOT END leaking

I tighted mine just place while hot and so far I haven't seen it leak yet.

 

So, I just recently acquired one of these printers and it prints ok with the exception of the hot end leaking so I'm getting blobs on the print...and in some cases large blobs. I tried cleaning it while still in the machine, but in the process messed up the rubber boot as I pulled it off the hot end not know it was fully enclosed around some of the wires. How does one remove the hot end to clean it? I'm a noob and it's been a pretty frustrating process so far...

Also, when you guys mention tightening it while hot, where are you tightening?

 

There is a small wrench that came with the RoBo (or the hotend) -- says 4 / 4.5 on it. You place the open end of that wrench onto the flattened/squared sides of the threaded bolt that is between the heater block (where the rubber boot is/was) and the heat sink (the hexagonal fins up above)... then you need to either tighten from here while holding the heater block in place with another wrench, or do the opposite -- hold it in place while you tighten the heater block down below (this is the easier method if you have the hotend still attached)

I have had so many troubles with the Hex hotend that I'm really thinking it's a major weak point of the printer. I know the older J-head was also a weak point, for different reasons... it looks like RoBo needs to really figure out a hotend solution that works; the older one had problems because there were plastic components that would eventually melt. This newer hex one allows for hotter temps and more materials, but requires the fan cooling of the heat sink (otherwise heat travels up and melts the filament before it reaches the nozzle tip, causing a jam), and also has the leaking issue (due to the screw-in steel threading)

There has to be a way to engineer a better hotend than this.

 

Looking around the interwebs... is there a good alternative? I'm not interested in going to a boden cable. You have plastic bits or leaky bits it seams. Not many options out there... or am I missing it.
I've just stopped using PLA. it seems to be the only thing fluid enough to leak at all.

 

yeah, unfortunately I use mine in a classroom, running pretty much all day with kids in the room. Don't want to expose them to the nasty stuff put off by ABS etc.

 

Well, I contacted Robo and they asked me to initiate a parts replacement form. So, hopefully I can get this sorted out soon and get this hot end replaced. I appreciate the explanation on tightening it.

 

Hi,
So, my hot end is leaking (that just sounds wrong). I ordered a new one, and unfortunately, same issue. I've had my printer for a little over a month. Now... you're probably expecting me to whine and grouse about that, but actually, no, I'm not . The way I look at it, I've now got two extruders. I'm going to try applying some high temp thread locker, because clearly the extrusion processes with PLA is allowing the material to basically wick up through the threads. I suspect I'll have to heat things up a bit to make sure that I can get all of the material out of the threads prior to apply thread locker. I'll let everyone know how my results end up this weekend.

*EDIT* Booyah! I believe I have found a winner, in terms of a potential solution. I'm going to apply copious amounts of Loctite 2620 ultrahigh temperature thread locker, and I'm thinkin' that bad boy is not going to leak anything!

 

And then, if high temp equals the high temp you're looking for, you'll be stuck. Every time you get a clog you have to replace your entire hotend. Just heat and tighten as directed. It's not perfect, but its the way it is. Maybe someday there'll be a good crush washer or something to use.

 

Well, I read some of the posts.
Here's the problem. The extruder that comes with the Robo Will leak, mine did too.
I don't care what you do, it will leak again.
I caned mine and bought an all metal hex head kit from Amazon. End of leak problems.
Also can that 'rubber' boot. Use silicon high temp gasket material to hold the thermistor in place.
Now here's the trick you need to know! Screw the nozzle in the heat block (hot end). Now back it off jest over 1/2 turn.
Now screw the heat break in until it hits the nozzle. Now tighten the nozzle as tight as you can without breaking it.
The nozzle does not have to bottom up on the hot end. Forget about heating it first or tightening it again. It is good to go.
I have never had a leak after doing it this way. Experience is the best teacher. Frank

10hour Camen print, no leaks