A maker came in with a printrbot and when attempting nylon, a bunch of black gunk started oozing out of the top. Any recommendations on a full metal hotend alternative? @Brook_Drumm , have any of your customers had issues like this?
Did the person raise the temp for printing nylon? Or did this happen at “regular” temps?
I believe printing at 240C
At 240 C
I HAVE! … The original Ubis hotend that came with my Simple did this exact thing after about 20 hours of printing. I was able to continue printing with it but it always oozed after that - even after replacing the PEEK barrel.
The best alternative IMO is the E3D v5 since it is a direct swap with the original. I have the v6 and it was too short to fit the stock mount so I had to “improvise”. 
If you’re in the US, Filastruder (me) carries E3D hotends and has a 5% off coupon - ‘reprap’.
As for the height difference, you might be able to throw a sheet of glass or two on the bed to make up the disparity.
248 - 270 C with most of the prints at 265 C…
Isn’t that the correct printing temperature range and usual printing temperature for nylon? Could it be that the person had the temperature too low so it pushed the old plastic out the top instead of pushing the plastic out the end? I imagine this might damage the guts of a hotend that is not all metal too.
Please note that I have not printed nylon yet, but I did do a little bit of a google search and I was told that my current PTFE lined nozzle would probably not cut it for printing nylon.
260C will destroy a PEEK/PTFE pased hotend in short order. You can print nylon slowly at 250C.
Well, it seems @Tim_Elmore agrees that 240C is not going to print nylon. Trying to print it at 240C could have damaged the hotend.
Printing at 240C wouldn’t damage the hotend, you just wouldn’t see much flow out the other end, if any. I’m betting that hotend’s seen north of 255C.
t-glase seems to have a temperature that would work for even my hotend.
I wonder if the dude cleaned out all of the old filament before trying the nylon.
Thanks for all the responses! Keep in mind, this was to do a nylon cold pull where you extrude at 240C then retract it out at 140C. I am not certain how much time the nylon was in there, but I doubt long. Definitely not long enough to do any printing with it. http://bukobot.com/nozzle-cleaning
Hmmm. No I haven’t seen that ever. But I suspect we don’t have the full story. If you bumped to over 270, all sorts of bad things can happen. I only use taulman nylon that is no problem for the Ubis and its all white. Anything coming out the top means your tip is clogged and it doesn’t have anywhere else to go. If the nozzle wasn’t clean and you shoot the temp up really high, it will char pla or abs, especially if no filament is in there… The thin layer clinging to the side will turn to char and clog and cause all sorts of problems. This problem is definitely off the reservation. I suspect bad practices or bad filament. As long as it is cared for, and the material works under 270, there should be no issues. Obviously, clogging is due to all sorts of reasons.
An all metal hotend just opens up possibilities of higher temps above 270 and is safer for food grade stuff – cups and mugs… And the big payoff is lower manufacturing cost and simpler construction for improved scalability.
We are doing an all metal hotend for these reasons. Not because it is superior performance at all (at “low” temps). The downside to all metal is cooling. It will absolutely require a fan. Period. That is more cost and complexity although not a lot.
One thing I like is the sexy aluminum… It gets covered with a fan, but it is sexier than beige peek!! Most printers are going to cover it up anyway so it’s not that compelling. But it does make great product shots!
Btw, Printrbot has very specific size requirements so the all metal hotend will be a drop in replacement for the average work horse. For high speed performance, we are making a high performance Ubis that will lay down ridiculous amounts of plastic. It should out perform literally everything out there. It will be a little larger for more thermal mass and a larger heater, but who cares if you are extruding over 200mm a sec 
and beyond.
Carl will also be making an extremely large heater for a pellet extruder that we have on the road map don’t get too excited, it’s not for your bot, it’s for an extremely large format printer for crazy large prints at very high speed… And lower resolution.
Brook
@Brook_Drumm thanks for chiming in! I am not too familiar with printrbot so non-metal extruders are new territory for me. I don’t believe this nozzle was ever properly cleaned with a cold pull on nylon but I did have hickups trying to read the extruder thermistors at all on both my and the maker’s laptops via Repetier Host. They’ve only printed at 210 PLA before attempting the cold pull when the thermister began reading again. I suspect there is an issue with the thermister and recommend swapping out a new extruder for a quick repair.
@Brook_Drumm extremely fast extrusion at low resolutions for a large format printer…
I smell a car printer in the works.
If it stick like honey it’s definitely PLA. Don’t worry about that.
heat the ubis up, unscrew the tip while hot and clean it out with a touch. search the printrbot forums for the quick procedure. it does not take long and is worth the small time investment. I have to do this every few months. I print ABS, and Nylon Bridge mostly with no problem. I Do bridge at 250 and 30mm per so kind of slow but it works just fine