How To: Take Apart the V4 Hot End for Cold Cleaning

[Jules]

Know this is a repost, but danged if I can find it...it's buried somewhere in another discussion.

I've done the cold clean three times now, and so far, it's worked without having to resort to the torch.

First some don'ts:

1. Don't try to remove the screw-off nozzle while the hot-end is still in the seat. The neck of the hot-end is thin and can break if it is twisted.
2. Don't stick anything into the nozzle end to clean it while it is cold.
3. If you choose to poke a wire up into the nozzle to try to clear a clog while the nozzle is heated, use a short section of E-string (guitar) on the 0.35 mm nozzle, and a B-string on the 0.5 mm nozzle. (Not exactly recommended as the greatest method, but we're all guilty. ) Don't burn yourself, it ain't pleasant.

1. Heat the nozzle up and retract the filament completely.
2. Cut the power to the machine and let things cool down.
3. Disconnect the hot-end extruder wires and thermistor wire at the connectors near the motors.
4. Swing the fan up out of the way. Loosen the screw that holds the hot-end in place on the hot end mount under the fan assembly. Allow the cooled hot-end to drop down into your hand.

Mounting Screw for V4

5. Remove the black cloth cover.
6. Use two wrenches (adjustable and flat, or two adjustable wrenches) to just loosen the nozzle from the hot block. Grab the block near the nozzle, not near the neck. Do not twist the nozzle completely off, just loosen it so you can turn it by hand.

Loosen at the nozzle end of the block.

7. Gently twist the nozzle off by hand, back and forth to break the filament seal in the barrel, and pulling out away from the barrel to stretch the filament inside. Ideally, you want to loosen the filament in the barrel and pull it out in a long tube. It cleans the barrel (not necessary, but nice) and gives you a handle to work with for the nozzle cleaning.

The longer the tail, the better.

8. Firmly grasp the tail of the filament with a pair of needle nose pliers and gently roll it towards the side to pull the plug up out of the nozzle. Rock it a bit back and forth on all four sides to break the seal if you can. (Feel free to use your thumbs in the process, mine is holding the pliers in place so i can hold the camera in the other hand! ROFL!)

Roll against the edges.

9. When the filament plug lets go, it will pull out little bits of carbon that have been baked onto the nozzle. (Black specs in the plug.)

The plug from the nozzle.

10. Once you have removed the plug, hold the nozzle up to a light and see if you can see clear through the hole. If you can, great, put the nozzle back on, the clog is cleared.

11. If you break the plastic off in the nozzle, (no handle to grab), you can still use one of the other methods to clear the clog. (Propane torch, or solvents to dissolve the plastic over several hours.)
Or you might decide you want to clean off any carbonization inside the nozzle if there is heavy buildup.

PLA: solvent is any paint stripper containing methylene choride
ABS: acetone should work (unless it eats brass, and i have no idea if it does, so take that as flexible until someone who knows corrects me)
PETG: buy another nozzle or use a torch
Flex: No earthly idea. Since it's partially rubber, i would try freezing it out.

Anyway, it's always a good idea to have at least one spare nozzle on hand, so you can continue what you were doing while your clogged nozzle soaks.

[3dPrintingMD]

Great post.

I did have 2 instances where I had filament clog up inside the barrel. (Too much retraction, is my theory).

The first time I didn't really know what I was doing and just took it all apart, and got the piece out, but it was hell.

The second time, I put the nozzle to 250 and eventually it all cleared out.

[Jules]

Great post.

I did have 2 instances where I had filament clog up inside the barrel. (Too much retraction, is my theory).

The first time I didn't really know what I was doing and just took it all apart, and got the piece out, but it was hell.

The second time, I put the nozzle to 250 and eventually it all cleared out.

What kind of filament was it?
Reason I ask is - it's very chancy to take PLA up to 250C. The higher temps can bake it right onto the nozzle. (I did it once accidentally. Eventually it'll narrow the clearance and start affecting prints.)

That might indeed cause some jamming in the barrel if the filament can't get through. But usually jamming is caused by too tight of a Filament Drive screw tension, or trying to extrude too fast for that particular filament. (Anything other than PLA has to be extruded pretty slowly.)

I had the most trouble with that cleaning filament....stuff loves to jam!

[3dPrintingMD]

I've only used PLA.

Keep in mind the jam happened at normal operating temps. I've been experimenting with retraction, and it seems that when its at 2.00mm and doing constant retractions, there will be a jam.

I assume that is happening as the molten plastic is retracted too far into the nozzle and it cools, and jam.

I'll keep that in mind on the temps, I just used it to loosen up the filament that was jammed in the barrel, once it got hot a good amount of it extruded out, and the other I was able to pull out the top.

[Jules]

I've only used PLA.

Keep in mind the jam happened at normal operating temps. I've been experimenting with retraction, and it seems that when its at 2.00mm and doing constant retractions, there will be a jam.

I assume that is happening as the molten plastic is retracted too far into the nozzle and it cools, and jam.

I'll keep that in mind on the temps, I just used it to loosen up the filament that was jammed in the barrel, once it got hot a good amount of it extruded out, and the other I was able to pull out the top.

For PLA, leave the retraction at 1.0 mm or less. It's not a terribly oozy filament, so you could likely get by with even less than that.

[3dPrintingMD]

What I run into is that when it moves it seems to pull a trail of filament with it.

[Jules]

What I run into is that when it moves it seems to pull a trail of filament with it.

You're not talking about the "purge and wipe" routine that it does right before a print? (Nozzle moves off to the right of the bed, purges about 25 mm of filament to prime the nozzle, and then slowly drags itself across the plate to wipe the nozzle off before lifting and going to start the print.) It's supposed to do that to prime the nozzle and get it ready.

Is it dragging a trail of filament behind it during the print? If so, what temps are you using?

[3dPrintingMD]

Yes not the initial wipe purge.

I've varied the temps so hard to give a exact answer. I've also noticed it when it comes to an end point, even though I have it perform a wipe, if not enough is retracted, it will when it lifts to go to the next layer, form a small blob that over the course of the layers becomes noticeable.

[Jules]

Are you using S3D?

Try these settings for PLA:

(As opposed to typing all of this stuff up, i did screen caps.)

You need to change the settings highlighted in yellow to match the settings that you determined were correct based on your calibrations.
(Make note of the ones in pink and make sure they match.)

(Looks like the thumbnails are working insta!)

[3dPrintingMD]

Thanks, going to give these a try.