Odd "chirp" from extruder, excess stringing

[dramsey]

So after a tedious afternoon bed leveling after PEI installation, printing calibration blocks and computing the required Z offset, etc., I continued my project of printing more "Ford" logo key fobs for our upcoming car show.

The fobs have an almost comically excessive amount of stringing, even though my retraction settings haven't changed. Looks as if a small spider made some serious web-building effort here. As is the print is useless.

While the print is going on, the extruder motor frequently makes a little "chirp" noise. At the time this happens, I can see the filament feed tube pop up a millimeter or so, before it is sucked back down.

If I had to guess, I'd say the filament is somehow being occluded as the extruder motor tries to feed it through. I suppose this might also explain the excessive stringing.

Here's a photo:

[insta]

FYI, I'm willing to print these at-cost if you need to hit a certain number by a deadline. I can throw a lot of printers at it...

[dramsey]

Thanks, but I've got until June and I'd really rather do it myself. I've printed about 100 of these so far, and can crank out the next 200 before then, presumably.

(Really regretting the PEI installation now. I had things dialed in pretty well on bare glass. Oh well. Learning experience and all that.)

[Jules]

The chirping happens when the filament retracts....totally normal, but not a bad idea to check the Filament Drive Screw tension.

Try printing a few degrees lower with your extruder temp and your bed temp to reduce stringing. (PEI requires less bed heat to hold on to things, and if your filament is too hot, it will string more. I print PLA on PEI at 205/60.)

Or there is a setting on the Advanced tab for Ooze Control....uncheck Only Retract When Crossing Open Spaces, and check Force Retraction Between Layers.

On the Cooling Tab - reduce the Speed Overide to Allow Speed Reductions down to 4% instead of 20%. Gives those top small details more time to cool so the filament will be less inclined to thread when the nozzle moves.

Could be any combination of those - try changing one thing at a time until you get the threads knocked back to an acceptable level.

[PcS]

If this is pla ? I print pla at either 180 or 190 all day long. Try a slightly lower temp. Did these print flawlessly before the pei ?

[ednisley]

the extruder motor frequently makes a little "chirp" noise

Can it be that the extruder motor can't keep up with the retraction speed, for whatever reason, and the poor thing is skipping instead of retracting the full amount?

That would explain all the observed symptoms, except for "my retraction settings haven't changed". The strings generally come from inadequate retraction, but there's not enough of a mess to have no retraction.

I'd reduce the retraction speed by a factor of two, then see what changes.

[dramsey]

The chirping happens when the filament retracts....totally normal, but not a bad idea to check the Filament Drive Screw tension.

The thing is, the printer is sitting right here on the desk by my computer, and I've been enthusiastically printing for a month, and I don't recall hearing these sounds before...

Try printing a few degrees lower with your extruder temp and your bed temp to reduce stringing. (PEI requires less bed heat to hold on to things, and if your filament is too hot, it will string more. I print PLA on PEI at 205/60.)

Already done, as per your recommendations in an earlier "MY GOD I'M HAVING PROBLEMS WITH BED ADHESION" thread.

Or there is a setting on the Advanced tab for Ooze Control....uncheck Only Retract When Crossing Open Spaces, and check Force Retraction Between Layers.

Also already done. Figured that one out a few weeks ago. However, stringing wasn't this bad even with the box checked.

On the Cooling Tab - reduce the Speed Overide to Allow Speed Reductions down to 4% instead of 20%. Gives those top small details more time to cool so the filament will be less inclined to thread when the nozzle moves.

OK, this one's new. Giving it a try. Also, swapping out relatively pricey Makergear filament for leftover XYZPrinting filament until I get things running again (I know, I know...that's changing two things!)

[dramsey]

Well, that's interesting. Just finished a print with the XYZPrinting filament...and it's perfect. No visible stringing.

The difference was visually and audibly apparent very early in the print. With the failed prints with the Makergear filament, stringing was obvious even when printing the very first full layer: as the head finished the perimeter of the fob and zoomed over to outline the key ring hole, stringing was evident. As it was every time the print finished a perimeter and zoomed across the initial layers to another part of the print.

The "clicking" sounds occurred as the first layer was being laid down in the back-and-forth pattern to fill in the base of the fob, presumably where no retraction was occurring.

This morning, there was no visible stringing or audible clicking. I could hear and see retractions, but I'd describe the retract/extract noise as kind of a softer "zip-zip" noise rather than the harsher "click" I was hearing last night.

So: the changes:

1. Different filament. It's still 1.75mm PLA, so I'd guess that's not an issue. I've printed with both filaments before and haven't needed to change anything.

2. I did set "Allow Speed Reductions" down as Jules suggested. But I don't think this had an effect on the first layer stuff.

My guess at this point is that there was some sort of partial extruder jam or problem (yes, I checked the tooth pattern on the Makergear filament when I removed it, and it seemed normal to my untrained eyes), and that simply removing the old filament and purging with the new filament magically cured it. I suppose we'll see when I switch back to Makergear filament.

[dramsey]

OK, back to stringy prints. It was nice for about, oh, two prints.

Jules, this time I heard the "clicking" noise as the extruder was doing its initial purge off the edge of the bed. So, definitely not retraction noise!

Here's what my filament looks like when removed from the extruder:



Notice at the right of the image, things look great: the tooth marks are exactly as described in your how-to. Then they get weird. It looks to me as if...well, what does it look to you like?

Also, how difficult to turn should the filament tension adjustment screw be? Because I can easily turn it with my fingers.

[PcS]

how many hours are on the extruder ? A clicking noise could be a bad gear in the gear reduction portion. pla that sits out can absorb moisture and print terribly. when you extrude it does it steam and or pop coming out ?