Replaced Orion Delta hotend; now, only certain filaments seem to work?

[StarManta]

We replaced the stock hotend in our Orion Delta printer with the E3D v6 hotend. Our first test print went great; however, we quickly discovered that the new hotend only seems to work with some of our filament. The filament should all be basically the same chemically - all of it is 1.75 mm PLA, and it all worked with the old hotend - but certain filament now simply won't go through the extruder - it just gets stopped there, like the extruder wasn't melting it to be able to push it through the smaller opening on the end. One of the colors that works is from the same manufacturer as one of the ones that doesn't, to show how weird the problem is.

Any ideas why this might be? How could we fix this?

[3dkarma]

What temperature are you printing at? If you're at the low end, differences in thermistors (actual vs reported temp) may mean that you're borderline on some of the filament.

Alternatively, do you have the heat sink fan installed and turned on all the time? Without it, heat creep can cause the hot end to block.

Edit: if you haven't updated your firmware to change the type of thermistor, you may be getting a lower reported temperature making some of the filament borderline.

[StarManta]

The problem happens at 180 (for preheating) and 210 (for printing) - all these filaments historically have melted easily at either of those temperature points.

The heat sink fan is always on.

Will it hurt my extruder if I push something long and narrow (and unmeltable) through it to check for blockage?

[richardphat]

The major difference is E3D full fins are made of aluminium, and the stock orion/rostock use PEEK insulator. The fan on the orion was designed to keep PEEK cool. The transition from PEEK to full Aluminium is questionable whether the current fan settings is overkill or not.

Have a laser temperature or infrared instruments, measure the temperature of the barrel, nozzle.
Pretty sure the barrel is almost dead cold. If that is the problem, you may need to lower that "PEEK fan speed"

[3dkarma]

Lots of people recommend sticking a guitar string up there to dislodge blockage, but I'm not a big fan of the procedure. Most nozzles are brass and if you're not careful you can damage it with a hard steel guitar string.

My procedure for clearing blockages is, with PLA loaded, to heat the hot end to 230 and let it stabilise, then set it to 110 and let it stabilise again. Slowly retract the filament by hand until it's completely out of the printer. If you got it right, you should see what looks like a straw at the end of the filament, meaning the filament has been drawn out of the melt chamber and should have brought any impurities with it. If the filament breaks off, your temperature is too low (try increasing it by 5C). If you get a string at the end, too high. Once you get a straw, repeat a few times until you're happy your melt chamber is clean.