Why is filament building up on the nozzle during a print?  

RE: Why is filament building up on the nozzle during a print?

Posted by: @chocki

Coppaslip can be used on the nozzle threads, but only a tiny amount and you have to place a paper towel underneath when you first heat the nozzle as the grease component will run out leaving the copper behind in the threads.

So I decided to purchase a new nozzle. Ordered the E3D Nozzle X, because I read that it prevents buildup of PLA on the threads and head. Will get it in few days and will continue build from there.

RE: Why is filament building up on the nozzle during a print?

also make sure the end of your heatbreak is clean, yours looks suspect as if there is burned plastic around the edges, and try to get the heater module into the heat block, so that an equal amount sticks out each side

Gap between nozzle and heatsinkHeater sticking out both sidesHeatbreak end clean

Regards Joan

RE: Why is filament building up on the nozzle during a print?

What is the best method for cleaning the heatblock and threads in the heatsink of the burnt plastic?

I have tried using a soldering iron (without any solder, just the heating tip) to just heat up those pieces and remove them with pliers and a brass brush. It has of course not worked that well, what else can I try?

RE: Why is filament building up on the nozzle during a print?

A soldering iron wont put out enough heat as that big a mass of metal is designed as a heat sink and it does that job really well.  You could use a butane torch or similar to heat it up while in a vice and then go to work on it with the brass brush.  

Oh and if you cant really separate the heatbreak from the heatsink then don't forget to remove the ptfe tube before heating that whole assembly up to avoid any possibility of damage to it.

RE: Why is filament building up on the nozzle during a print?

Ok, quick update. Finally got my new nozzle in the mail today, but leaving the entire extruder open for the last week was a mistake, and I saw today that the thermister wires got pulled off from the heater block.

Is replacing the heater block the only option here? What is the best place to order it from (in the US), MK3s printer? Or can heater block still be fixed.

RE: Why is filament building up on the nozzle during a print?

Thermistor is the broken part. When you buy a replacement - buy a couple. They are fragile and almost expendable.

There are a bunch of suppliers. One reputable one is:

https://www.printedsolid.com/products/prusa-mk2-mk3-thermistor-cartridge?variant=12645439144021&utm_medium=cpc&utm_source=google&utm_campaign=Google%20Shopping&gclid=Cj0KCQjw84XtBRDWARIsAAU1aM28iXxeWAeE4JAdb_suSOPLtufCrcPi5QrOKGH9v8NFZVMpbQOeW58aAt1fEALw_wcB

Amazon is another choice - but lowest price option is rarely the best one.

RE: Why is filament building up on the nozzle during a print?

Looking at that it looks like the heater cartridge and not the thermistor.  Both can be bought separately and fitted to the block and the wires on both are rather fragile so spares are a good idea.

RE: Why is filament building up on the nozzle during a print?

Posted by: @ravish-c

[...] Is replacing the heater block the only option here? What is the best place to order it from (in the US), MK3s printer? Or can heater block still be fixed.

You might be able to recover the block, but be prepared for the worst. It's not unusual for the block, heat cartridge and thermistor plus the heatbreak to be very difficult to remove once they've been used for any length of time. I'd suggest keeping spares of each handy. Use a silicone sock to reduce build-up around these pieces for next time.

I ordered my parts from Filastruder in the US. MatterHackers and PrintedSolid also carry some of the parts.

RE: Why is filament building up on the nozzle during a print?

I mis-spoke on my reply. Definitely the heater cartridge.

Rest of my comment still applies...

RE: Why is filament building up on the nozzle during a print?

Posted by: @bobstro

Posted by: @ravish-c

[...] Is replacing the heater block the only option here? What is the best place to order it from (in the US), MK3s printer? Or can heater block still be fixed.

You might be able to recover the block, but be prepared for the worst. It's not unusual for the block, heat cartridge and thermistor plus the heatbreak to be very difficult to remove once they've been used for any length of time. I'd suggest keeping spares of each handy. Use a silicone sock to reduce build-up around these pieces for next time.

I ordered my parts from Filastruder in the US. MatterHackers and PrintedSolid also carry some of the parts.

That is the problem I realized as soon as I tried to open out the thermistor. Because it is so cold now, the nozzle is entirely stuck enside the heater block, and the thermistor cartridge is also going to be almost impossible to remove. 

I decided to order a new hotend, and will try to do this part of the build from start, using the guide. The parts I ordered are https://www.amazon.com/Genuine-E3D-All-Metal-Universal-V6-175-B/dp/B00NAK9L6Q/ref=sr_1_8?crid=QOEQI276XQCA&keywords=e3d+v6&qid=1570912678&sprefix=e3d%2Caps%2C147&sr=8-8

It also has a silicone sock, which is good.

RE: Why is filament building up on the nozzle during a print?

Posted by: @chocki

Coppaslip can be used on the nozzle threads, but only a tiny amount and you have to place a paper towel underneath when you first heat the nozzle as the grease component will run out leaving the copper behind in the threads.

You could also use Boron Nitride Paste (like Slice Engineering recommends it for the mosquito) as it is heat resistant enough but given the low thermal conductivity of boron nitride I doubt it is really beneficial.

RE: Why is filament building up on the nozzle during a print?

Time for a new hot end from someone -- Prusa if you want a direct replacement: E3D if you can handle adding/extending the wire set. With the E3D version, you get the better heat break and lower shipping costs (order from Amazon).

RE: Why is filament building up on the nozzle during a print?

Has anyone documented adding connectors to the current wire set for use with the E3D hot end?

I sure like connectors better than messing with a cable bundle - if they are satisfactory.

RE: Why is filament building up on the nozzle during a print?

Posted by: @robert-rmm200

Has anyone documented adding connectors to the current wire set for use with the E3D hot end?

I sure like connectors better than messing with a cable bundle - if they are satisfactory.

I'd sure appreciate knowing what connectors to use for the standard E3D parts! Dealing with the wrap is annoying.

I'm a little jealous of some of the newer designs that route all the cables parallel with the X carriage using a ribbon cable and modular connector. Less twisting and side-to-side movement seems like a smart move.

RE: Why is filament building up on the nozzle during a print?

I finally got all the parts today, and followed the E3D Guide for assembling the hotend.

So far, everything looks good, but before I put in any filament into the Extruder, I need an opinion on whether this is assembled correctly, as some of the instructions were a little unclear to me.

What I am worried about is the distances between the nozzle and heat block, and the gap between the heatblock and heatbreak. The instructions said to "untwist" it one full turn, which is how much I did. For the heatbreak, it said to make it "flush" with the heatblock, which is also what I did. But I am worried that the nozzle is protruding too much outside the heatblock. Is that wrong?

The nozzle used here is the "Nozzle X" from E3D. I also ran a quick self-test, and it passed. No filament inserted yet, and no calibration done yet.

RE: Why is filament building up on the nozzle during a print?

Don't go just on my input - but I would screw the nozzle all the way into the heat block. Use any recommended thread compound.

Unscrew it one turn.

Screw the heatbreak into the heatblock until it is snug against the nozzle. How much of the heat break sticks out does not matter.

Bring the hot end up to recommended temperature.

Tighten the nozzle fully.

Now get input from someone that knows - like Tim.

RE: Why is filament building up on the nozzle during a print?

Posted by: @ravish-c

[...] What I am worried about is the distances between the nozzle and heat block, and the gap between the heatblock and heatbreak. The instructions said to "untwist" it one full turn, which is how much I did. For the heatbreak, it said to make it "flush" with the heatblock, which is also what I did. But I am worried that the nozzle is protruding too much outside the heatblock. Is that wrong?

That definitely looks like too much of a gap between the nozzle and heat block. This is one of those times where you want to focus on the intent of the instructions and not specific measurements. The goal is to ensure you have a good seal between the nozzle and heatbreak. The heat block is just a glorified nut that is used to screw them together. The idea is that:

1. You tighten the nozzle into the heat block and leave a bit of a gap. This is to allow room to further tighten the nozzle to the heatbreak at the end. About 1mm is usually sufficient.
2. You screw the heatbreak into the heat block until it hits the nozzle. Don't get hung up on how deeply it goes into or protrudes out of the heat block. What is important is that it make contact with the nozzle. This is more of a feel thing than a look thing. How it looks isn't as important as making a good seal with the nozzle. If it's not tight, you won't have a good seal and a mess will ensue.
3. When you heat everything up, brace the heatblock and tighten the nozzle, you are taking advantage of that small gap between the nozzle and block to tighten things a bit more while everything is hot and fully expanded. This finalizes the seal and avoids the leak.

Your gap for the nozzle looks a bit excessive, so you're likely having to screw the heatbreak further into the heat block. I'd back up and not leave as much of a gap between the nozzle and block. Usually around 1mm is plenty.

Note that there are differences with some nozzles (non-E3D branded). Some might be a bit shorter, and require that you adjust accordingly. Also note that having filament accumulated on the nozzle and/or in the heater block can throw you off. If you are hitting resistance screwing the nozzle into the block at the level shown in your pic when cold, see if there's excess filament blocking the threads in the block. If so, heat it up to 285C and run the heatbreak all the way through a few times to clear it. Just don't lose track of which bits are hot while doing so.

Having done this a few times, I worry more about the feel than the look. If the nozzle and heatbreak aren't firmly together (avoiding stripping things out), check to see if there's anything gumming up the threads and try again. It's a lot easier to get this right with everything disassembled, so spend a bit of extra time.

RE: Why is filament building up on the nozzle during a print?

Posted by: @bobstro

Posted by: @ravish-c

[...] What I am worried about is the distances between the nozzle and heat block, and the gap between the heatblock and heatbreak. The instructions said to "untwist" it one full turn, which is how much I did. For the heatbreak, it said to make it "flush" with the heatblock, which is also what I did. But I am worried that the nozzle is protruding too much outside the heatblock. Is that wrong?

That definitely looks like too much of a gap between the nozzle and heat block. This is one of those times where you want to focus on the intent of the instructions and not specific measurements. The goal is to ensure you have a good seal between the nozzle and heatbreak. The heat block is just a glorified nut that is used to screw them together. The idea is that:

1. You tighten the nozzle into the heat block and leave a bit of a gap. This is to allow room to further tighten the nozzle to the heatbreak at the end. About 1mm is usually sufficient.
2. You screw the heatbreak into the heat block until it hits the nozzle. Don't get hung up on how deeply it goes into or protrudes out of the heat block. What is important is that it make contact with the nozzle. This is more of a feel thing than a look thing. How it looks isn't as important as making a good seal with the nozzle. If it's not tight, you won't have a good seal and a mess will ensue.
3. When you heat everything up, brace the heatblock and tighten the nozzle, you are taking advantage of that small gap between the nozzle and block to tighten things a bit more while everything is hot and fully expanded. This finalizes the seal and avoids the leak.

Your gap for the nozzle looks a bit excessive, so you're likely having to screw the heatbreak further into the heat block. I'd back up and not leave as much of a gap between the nozzle and block. Usually around 1mm is plenty.

Note that there are differences with some nozzles (non-E3D branded). Some might be a bit shorter, and require that you adjust accordingly. Also note that having filament accumulated on the nozzle and/or in the heater block can throw you off. If you are hitting resistance screwing the nozzle into the block at the level shown in your pic when cold, see if there's excess filament blocking the threads in the block. If so, heat it up to 285C and run the heatbreak all the way through a few times to clear it. Just don't lose track of which bits are hot while doing so.

Having done this a few times, I worry more about the feel than the look. If the nozzle and heatbreak aren't firmly together (avoiding stripping things out), check to see if there's anything gumming up the threads and try again. It's a lot easier to get this right with everything disassembled, so spend a bit of extra time.

 

That was very useful. I followed the steps, and was able to get the nozzle to be much closer to the heatblock. Then I heated it up to 285 and was able to get it to turn a little more as well.

The image above is before I put the heatbreak back into the Extruder.

This image is after I heated it to 285 and turned the nozzle a little more. Is this a sufficient distance, or is it supposed to be even closer than in the images? 

RE: Why is filament building up on the nozzle during a print?

Posted by: @ravish-c

[...] image is after I heated it to 285 and turned the nozzle a little more. Is this a sufficient distance, or is it supposed to be even closer than in the images? 

That looks fine visually, at least from what I can make out. What's important is the seal. Keep an eye on it as you print and watch for any discolored filament or odd drips on the heat block. It may take a few prints for the leak to occur, so just check regularly until you're confident of it.

RE: Why is filament building up on the nozzle during a print?

Thank you for all the help!

Printed a Benchy, and it turned out to be perfect. And No visible PLA is stuck at all anywhere on the Heat Block now like it used to before. Going to try printing out some more complicated materials as well.