Filament not extruding consistently

Hey everyone,

So I’ve checked all the usual suspects (blocked bowden tube, blocked nozzle, plug formed between nozzle and bowden tube, leveling the bed) and I’m at a loss for what could be causing issues.

I have my slicer set to make my printer do a “test line” before the raft is even printed, and it mostly comes out okay. Fairly consistent. Once it gets to the object raft and the object itself though, it stops extruding correctly. I get dotted lines and parts where it doesn’t extrude at all. I can’t even get a main layer consistently. The filament that does extrude ends up flaking at times, getting caught on the nozzle as it passes over causing more interference with the nozzle.

What else should I be looking at? I recently switched to a brand new nozzle that shouldn’t be having any problems.

Just to be clear: are you talking about not extruding consistently or failing to adhere to the bed?

Have you checked the tension on the extruder to verify that it isn’t slipping?

As for the bed, if it’s not flat (ie. wavy) you can get periods in a line where there is enough clearance to extrude filament but then a high portion comes along and cuts off the flow. But I suspect you already knew that.

One test I use is to lightly hold the filament as it’s entering the extruder with my fingers touching the extruder to feel if the filament is moving consistently. I do this while keeping an eye on my extruder wheel. Obviously, if the extruder wheel is turning steadily but the filament is jerking, the extruder is slipping.

If it’s an older printer (I don’t know how old is reasonable for this to start) you can have the extruder gear starting to get worn down in the same way that brass nozzles wear down. The gear may start to develop areas where the teeth are going flat. Take the extruder apart and check.

are you talking about not extruding consistently or failing to adhere to the bed

Both, in parts
It’s brand new printer (bought this year) so there shouldn’t be an issue? but I’ll double check the extruder gear. I’ll report back.

Unfortunately I don’t know of a way to measure extruder tension. You kind of have to judge by its performance.

One thing you can do, I suppose, is to try to print a large square across the majority of the build plate. If the first layer appears to be skipping sections, hold the extruder open and push the filament manually. that way you know continuous pressure is being applied. If continuous pressure solves it then you have an extruder grip problem. If continuous pressure still results in the filament skipping sections then it’s something else, but then you’ve already checked the nozzle, heat break and bowden tubes for clogs.

Can I assume you’ve also verified that the end of your bowden tube is cut square and smooth and that it’s pushed all the way down until it contacts the top of the nozzle (so as not to provide any opportunity for leaks and clogs to develope)?

I’ve made sure the cut on the end of the bowden tube is square and smooth and pushed all the way down. I haven’t a chance to take a look at the extruder gear. I just remembered I do have the all metal extruder mechanism (in cherry red!), maybe now is a good time to replace the stock part?

Ah! you have the plastic extruder. I recently saw a post on Facebook by someone who was having extrusion issues. It turned out that the plastic extruder had cracked. It hadn’t fallen apart so it wasn’t obvious, but there was a hairline crack that meant the extruder could no longer apply the pressure it was supposed to.

Hmm might be time to do an upgrade!

When you change the extruder, give the plastic one a good inspection. I’d be interested to know if it has any cracks.

Did you print the calibration patch (large square or multiple squares) yet? before you swap parts about look at this post a pic if you want. It sounds to me like the nozzle might be too close or the bed is not level or is warped. Lego suggested this and to me it is the most obvious. I am unclear if it was explored.

Printers can be a pain, new doesn’t mean much they can come with a gamete of issues. The danger is to start replacing parts and not really improving it just changing it. One thing at a time most likely to least.

Nozzle distance
bed level
bed warp
extruder arm…

On a new machine there is a point, of contact tech support and have them replace parts that you don’t pay for. My cheap printer ended up costing more than my Prusa and is still not even close it its quality.

Hecker, it was cracked!

I have the new metal one almost fully installed, but where I’m supposed to put the coupler in for the bowden tube, there’s nothing to screw into? What am I missing?

For all that are following this, this has been moved to a new thread. I’ve answered it there.