I gotta be doing something wrong!

[tsteever]

So yesterday I had a jam with my PLA and I was able to get it cleared without taking things apart. Today I went to print and my PLA had snapped off (does this happen to everyone?) and I tried heating up the hotend to pull the remainder out. Nope, wouldn't budge.

So I took things apart. The nozzle came right off and the heater block is clean. The upper part and the heat break are jammed up as if the jam is up higher.

What is causing the jams in the heat break?

[voodoo28]

PLA dries up and becomes very brittle.

[Chadd]

So yesterday I had a jam with my PLA and I was able to get it cleared without taking things apart. Today I went to print and my PLA had snapped off (does this happen to everyone?) and I tried heating up the hotend to pull the remainder out. Nope, wouldn't budge.

So I took things apart. The nozzle came right off and the heater block is clean. The upper part and the heat break are jammed up as if the jam is up higher.

What is causing the jams in the heat break?

You could also have an issue with hotend cooling, that will cause jamming. If the area where the heatsink cooling fins isn't being cooled enough it can lead to jamming.

[printbus]

I think you said in another thread you just installed an e3dv6 hot end, right? Note that e3d recommends using as little retraction as possible. IIRC, they recommend 0.8mm retraction or less, saying the e3dv6 doesn't need much. Too much retraction can pull hot filament up into the heat break or worse yet, up into the PTFE tube if you're using 1.75mm filament.

FOLLOWUP COMMENT: I've had one or two situations with my e3dv6 where I initially couldn't pull the filament out after first warming up the hot end. Next time, try letting the hot end soak at temperature for a while - that might soften up any material above the block. In one of those cases, I couldn't pull the filament manually but was able to at least break it loose using the hobbed bolt and retraction commands. Sure I risked notching the filament with the retraction, but I figured I didn't have much to lose in trying.

[voodoo28]

Wow... .8mm seems very little.

I use the 1.75 with tube and have it set to 2mm, have not had a jam yet.
Anything below 1.75mm for me, I would get blobs.

I think you said in another thread you just installed an e3dv6 hot end, right? Note that e3d recommends using as little retraction as possible. IIRC, they recommend 0.8mm retraction or less, saying the e3dv6 doesn't need much. Too much retraction can pull hot filament up into the heat break or worse yet, up into the PTFE tube if you're using 1.75mm filament.

[printbus]

Wow... .8mm seems very little.

I use the 1.75 with tube and have it set to 2mm, have not had a jam yet.
Anything below 1.75mm for me, I would get blobs.

I'm sure variables like specific filament, actual temp being used, etc. make a difference. I think I'm currently at 1mm. I'm not trying to defend this one way or the other - just sharing what e3d recommends.

Here's the e3d wording from the usage guidance section of the e3dv6 assembly instructions:

"Excessively long retractions will cause issues by dragging soft filament into cold areas. E3D-v6 hotends need less retraction than most hotends. For direct extrusion systems you should use anywhere from 0.5mm-1.0mm, for bowden systems you might want to go up to 2mm. Retraction beyond 2mm is likely to cause issues."

The 0.8mm comes from their misconfigured slicer settings section of the e3dv6 troubleshooting page:

"A common issue is massively excessive retraction distances. In direct configurations retraction of 0.5 to 2mm is all that should be needed for ooze-free prints. We use around 0.6mm for ABS that oozes very little, and 2mm for the very floppy flexible filaments that like to ooze a great deal and need a good tug to pull back the soft filament from the melt zone. For PLA we stick with retraction settings no higher than 0.8mm."

[voodoo28]

Good to know... Definitely temperature plays a big apart in oozing as well.

Like you said Printbus, there are many variables. I just started using 2mm, but after reading that i think ill go back to 1.75mm and try to reduce my temps by a few degress.

[lakester]

I'm using a Hexagon. So far, no jams.

I heat up the HE, but only to the point the normal extrusion temp is indicated (PLA/225 for me).

I disengage the "guideler", and then ALWAYS push first, until significant extrusion happens, THEN I pull. Extrusion may not begin immediately, so I just maintain pressure until it does, occasionally releasing the pressure and reapplying.

The filament pulls out cleanly every time I do this.

Generally, I also try to avoid letting the filament bake in the HE for protracted periods of time, and I NEVER turn the machine off until the HE has cooled significantly. Heh..., I've found the part cooling fan a great way to accelerate this. (I guess this is only relevant if the HE requires fan cooling).

As an aside, I've been looking at the various Wade's Extruder re-mixes, in particular, the ones with the tilt bolts..., thinking it would be great to be able to peel the guideler away entirely when changing filament.

Of course, I've been looking at the Itty Bitty stuff too. So many extruders, so little time.

[rhonal89]

I was recommended by Colin to wait for the tempeture to be below 50c before turning the printer off. Are you waiting. Reason is if you turn your printer off right after is done printing heat will travel up.

[tsteever]

Yup, I am waiting to turn things off. I learned that lesson the hard way.

Yes, I am using a e3dv6 and I think it is a superior hotend compared to the hexagon. I haven't had a lot of time with it but the abs prints I have made were great. I think the issue is my retraction. I checked and dura was set for a 5mm retraction. I will reduce this to 1mm and see what I can get.

thanks!