Inconsistent extruding from nozzle

[Reaping miner]

Hello all! My name is Niels and i am a 3d printer newbie. I have watched tons of guides and tutorials on 3d printing. I suppose I spent around 20-30 hours doing that while building my printer. I do have some electronics skills and i am sort of handy as well, so i figured i should be able to construct a functional 3d printer. (Heck, i made my own WiFi-controlled LED plant grow light, with adaptive spectrum!)

I have a problem i can not seem to figure out and i can not really find on the internet. I did have a few other problems which i managed to solve on my own, including filament stripping, underextrusion and not perfectly level X-axis (Horrible noise).

My setup:
Prusa i3 - Steel, 12V, NEMA17, igus-drylin bearings, Ramps 1.4SB, DRV8825 drivers
Wade-style extruder, E3D V6 all-metal hotend (1.75mm), Mk3 aluminium heatbed. 0.3mm nozzle

Problem:
I am trying to print my PLA at the reccomended temperature of 220C on painters masking tape (yellow, cheap). The heatbed is at 50C (Worked better for adhesion than 60C). The print itself is a single walled upright bar, with bottom, no top. Layer height 0.2mm, speed 50 mm/s.

I observe gaps in extrusion, as shown in the picture. I see a nice steady stream of plastic flowing from the nozzle, and then suddenly nothing, and a little later it just continues. (In bad cases, when it continues it curls up at the nozzle and makes a mess, dragging everything along).

Diagnostics performed:
Simple extrusion through hotend in pronterface - 10 mm @ 100 mm/s occassionally hear a popping sound and see an irregularity (bump and decrease of flow) in the plastic stream, when extruding @ 10mm/s this becomes more pronounced.
Simple extrusion without hotend in pronterface - 100 mm @ 100 mm/s, perfectly extrudes 100mm of filament. (I did have to add about 20% steps/mm in Marlin to ~1950)

Tests:
Tried temperatures between 200-230 - No real difference
Tried extrusion multiplier between 100-110 - No real difference
Cleaned the barrel and nozzle very thoroughly with chloroform twice (Dissolves PLA) and used a toothbrush inbetween the two treatments. - No difference
Cleaned the hobbeld bolt with a toothpick and compressed air (was some slight grindings from skipping extruder from before) - No difference

I believe after spending about 10 hours on failed prints and searching for solutions on the net, i can say i honestly dont know what i could do more. (Except for maybe a extra extrusion test WITH hotend, although i did calibrate the extruder with the hotend before.)

Personally i suspect filament flexing/bending or snagging in the hotend barrel, getting softer/melted after a little while and releasing the pressure allowing for further extrusion. But as far as i know this should not happen.

Regards,
Niels

PS: I have the same question on a different forum, but i later thought this forum might be more appropriate.

[noiseboy72]

I guess the first question would be if you have assembled the hot end correctly, with the PTFE tubing leading all the way down to the threaded heat break.

I had these problems with the E3D and this was my issue. The PTFE tubing was slightly too short and was moving up and down in the heat sink, allowing the filament to buckle in the gap.

[Reaping miner]

I guess the first question would be if you have assembled the hot end correctly, with the PTFE tubing leading all the way down to the threaded heat break.

I had these problems with the E3D and this was my issue. The PTFE tubing was slightly too short and was moving up and down in the heat sink, allowing the filament to buckle in the gap.

This was not possible, the top of the hotend (the heatsink of the hotend) does not seem to allow any insertion of PTFE whatsoever. i.e: the hole was too small.

[printbus]

Reaping miner, I'm still not sure what you have for a hot end. The Orballo website only shows one printer - is that the one you have? The description doesn't say anything about using an E3D-brand hot end (did I miss it?), and it describes the hot end as generically being a "V5". You say you can't fit a PTFE liner in your heatsink, but all E3D v6 hot ends for 1.75mm filament have a PTFE liner that passes through the heatsink and into the top end of the heat break. Assuming you might have an E3D v5, I believe even those had a PTFE liner that went partway into the heatsink. So, without more pictures it's impossible to understand what you have.

EDIT: Bowden extruders use the PTFE tube in a different way. The extruder motor is located a ways from the extruder, typically mounted on the fixed frame of the printer. Having a short section of PTFE tubing in the hot end anywhere does NOT mean you have a Bowden extruder. This does confuse people, especially since the same material used for a Bowden tube is typically used for the PTFE liner.

Regardless... If the heat break tube is now stuck in the heatsink, you possibly had melted filament get way up in the heatsink where it shouldn't have been and melted filament got into the threads between the heat break and the heat sink. This could happen if you let the printer sit at too high of a temperature for too long, and/or have inadequate cooling airflow for the hot end heatsink. If so, you likely now have a partially clogged heat break tube (and possibly heatsink) that occasionally binds with the filament, leading to what you are seeing.

[noiseboy72]

Info on correct assembly here: http://wiki.e3d-online.com/wiki/E3D-v6_Assembly

Explains it better than I can!!

[Reaping miner]

Info on correct assembly here: http://wiki.e3d-online.com/wiki/E3D-v6_Assembly

Explains it better than I can!!

It is not possible to insert PTFE tubing in the heatsink.
I do have PTFE tubing between the hobbed bolt and the top of the heatsink (pictured) though. To be extra clear, i mean that i pictured the top of the heatsink, not the PTFE tubing. (I thought it might be unclear when i read my own message.)

[printbus]

Yeah, that led to some confusion on my part. I should have paid more attention to the user name. Thanks for clarifying.

[Alibert]

You have a full-metal hotend. These are notoriously finnicky to the temperature transition zone between cooling body and heating block, most especially for PLA of all plastics. A simple way to see if this is your problem, you can replace the existing heatbreak (the part that connects the cooling body to the heating block) by a ptfe lined one. They cost very little. If that solves your problem you know it is this issue and then you can concentrate on solving it and returning to the full-metal heatbreak.

Another possibility is too fast extruding, that is the heating block/nozzle can not melt the plastic fast enough. As raising the temp did not solve your problem, I suspect this is not the case, but I would to see what all your print speeds are.

[Reaping miner]

Accidentally deleted message so i will keep it short.

Tried printing between 20-70 mm/s.
Most, if not all prints shown are at 30 mm/s.

Unfortunately barrel is stuck in heatsink. If i remove it i am afraid i might break something. Ironically i got the full-metal barrel for the versatility and robustness. (Less likely to damage).

Edit:
I will try this
https://forum.e3d-online.com/index.p...-heatsink.341/

[printbus]

Never seen or heard of an E3D v6 hot end for 1.75mm that doesn't have a PTFE liner in the heatsink. Is this some form of E3D knock off? Where was it purchased?

Have you tried another roll of filament, preferably from a different source? "...hear a popping sound..." could be excessive moisture in the filament.

What is happening with the Wades gears when you run into one of the extrusion gaps? Do the gears keep rotating through it all as they should?

Are retractions enabled? A single width wall shouldn't be applying retractions anywhere but possibly the layer shift point. If retractions are occurring (look at the gcode layer by layer in a viewer like gcode.ws if necessary to verify), it could be that you're retracting way too much.