Brand new J-Head jams on first use- What has anyone noticed about filament quality?

Has anyone switched from low grade PLA to something nice, either PLA or ABS? I'm using the cheapest black pla that I could get from eBay/China, regretfully, and it just feels cheap. It feels almost porous and it is a matte color rather than my previous roll which was fairly glossy. Print quality is really bad, and now I can't get above 5 mm without jamming.

Its gets to a weird stage where it's still extruding but "clicks" every few mm more and more until it jams. What does print comes out with NO layer adhesion. I tried to pull a cube off the bed with pliers and ended up with a few different slices that split off very easily.

Sound familiar to anyone? Also note that I've tried everywhere from 165 to 230 degrees and temperature only had a marginal effect. Firmware has been updated to new thermistor and Z axis is calibrated. Thanks.

is this a genuine J-head from hotends.com/ reputable reseller? do you have a fan on it?

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It's either junk or full of moisture. PLA sucks in moisture like a sponge but can be dried out. Search this forum or Youtube for how to. If that does not do it,, then stick with a good supplier.

Black filament is fairly notorious as junk can be hidden in it. Finding reasonable quality filament is a bit location dependent. Where are you located?

Heh, actually iv gone from only using the good stuff to using the cheapest out there and iv seen no loss in quality, however i still pay a little extra for my black and get it from a reliable seller. cause yah, black is notoriously tricky when it comes to sourcing quality.. However i do have a theory that black is primarily tricky mainly because it shows more imperfections in its high contrast ridges.

If your new to 3D printing i suggest starting out with good quality filament, that way your learning with the least amount of things to trouble shoot,. later when you get good at it then switch to the cheaper stuff, and your experience will increase your chances of being able to succeed with it.

Thanks for the replies.

I'm not too new, I've been doing this a while but the hot-end is only new because I had a knockoff that broke and so I ordered this one right from hotends.com. Is a fan blowing right on the PEEK the next thing to try? I'm doing it in a Minnesotan basement- it's dry as a bone.

Thanks.

I'm not sure if your PLA is causing problems - sounds like it might be. One way to learn more is to get something without dyes (natural) from the same vendor - or at least a different color - or better yet try another vendor. You might end up chasing ghosts otherwise.

It also sounds like you might be experiencing compound problems, which isn't uncommon.

Getting the right amount of kapton tape that allows maximum cooling and yet secures the wiring - especially secures the thermistor - isn't trivial. I just can't overstate how important this is on the J-head, at least MKV series - heat easily travels up the barrel and wreaks havoc. Do you think enough of the cooling fins on the insulation are exposed?

Edited 1 time(s). Last edit at 12/23/2013 12:55AM by tenacious.

I would quit using the feed stock the moment you suspect it. If you value your time and want to avoid heart ache, don't spend a second more with the feed stock. odds are it has large granules of pigment that are not properly mixed. this is also easier in black. I would bet that the vendor used low quality all the way, and what is causing your prints to fail is nozzle blockage. I made the mistake of using questionable feed stock in 2 of my printers. cost of changing nozzles and finally hot ends was a total of 250$, not much saved in that 8$ cheaper feed stock!!!!!!


my suggestion is to report the seller of that feed stock in the appropriate feed backs, and then go to a known seller in good standing.

currently china and other countries have a lot of money only interested sellers that see dollar signs, with no history of plastics or reprap use of these products. diameters are off, feed stock is porous, and full of large plastic chucks that do not melt. I tried going cheap as well but it just bites bad. one vendor sold me 5lbs of yellow that was 3.15mm! too big diameter!!!!, another sold me green feedstock that was good for about 20m, but the rest was oval shaped, I gave another vendor a chance with black pla, and this stuff was so brittle, and so full of large particles it destroyed 2 hot ends. after that i always read thru feedback and only purchase from ultimachine, makerbot, and one or 2 others that are reputable.


try another vendors pla, and give it a good 1-5m of feeding to determine that all the old junk and its debris are free of your nozzle. even then you may need another hot end.

if the hot end does not work well with another feedstock, then look at the hot end construction. is it made the same as your last one, is the thermister in the same location as the other one, does it have the same resistance as the other one at room temp? some vendors just put a generic thermister in the package and don't specify the correct temp table to use, or worse use the low precision with the spec +/- 5%, (enough difference for pla to not flow at mid temp, or to burn and crystallize at the other end of temp)

if above checks out ok, then there may be a gap on the inside from shrinkage in the ptfe tubing. any gap can destroy your hot end. clean out your nozzle, and make sure that the hot end is not blocked. stick a fine point needle up the hot end when it is heated. does it go in, if it does then it can be used to break up debrees.

Finally, have you purchased a new hobbled bolt lately? was it properly cleaned and removed of metal debis? metal flakes in hot end will also destroy them.

Edited 1 time(s). Last edit at 12/23/2013 01:38AM by jamesdanielv.