Stringing

[jdacal]

Hi everybody, could someone check this factory file and tell me what I'm doing wrong here. I've never had a print give me so much trouble.

This is like the 3rd time trying to print these rose stems and they keep snapping off.

What I've noticed initially was the filament would kind of curl coming out of the nozzle and bunch at the tip as I ran the extrude command. The PLA temperature on my 24 v M2 was set to 225 which is rsilvers default. Since I have had problems with white filament before I dropped it down to about 208 and that problem seemed to go away and flowed normally when I gave the extrude command.

The print started out fine with no stringing but after I just checked on it the stems continue to snap off and I'm guessing the filament extruding into the air is breaking the rest of them. My Z height had been a little off as I could feel some bumping as the head moved around on print one and two. But on this third one I re-leveled and set Z to .005" and seemed to be printing perfect. I don't print a lot of thin stuff like this, so I have no idea what I'm doing wrong. I did try raising the extraction another .02mm in the area of the settings that's supposed to help with stringing.

Oh, I also switched to another reel of white filament from other manufacturer with this last one. And replaced my heater and tip which I planned on doing anyway.

Factory file is too large to upload to the forum, here is a DropBox link to it:

https://www.dropbox.com/s/7codp1ny1ynk6 ... g.zip?dl=0

stringing.jpg (63.22 KiB) Viewed 10157 times

Thanks!

[jimc]

ok so i checked this out and nothing really jumps out at me. there are a couple things that might help here but not sure if its a cure or not. pla tends to not need alot of retraction. you have it set to 2mm which isnt over the top at all but coast is totally off. i remember with the v3b hot end that it was tough to control the blobs without the coast feature. it could be that you blobbing after the jump and the nozzle is hitting the blob on the next round and knocking off the stem. its kinda a long shot but i dont really see anything else. in any case i would try to relieve a little bit of the pressure in the hot end and divide the stringing control between the two features. this print has small features so i wouldnt go crazy with it. i would reduce my retraction to maybe 1.4 then turn coasting on to 1mm. also turn the wipe feature on. the wipe is great and adds a way to relieve a small amount of pressure without having any negative effects. default is 5mm. if the coast feature messes with those little tips on the leaves then do a dual process. first one with your current settings then after the leaves finish turn the coast on. mechanically, make sure your bed adjustment screws are as tight as you can get them while getting a level surface. looking closely at your picture though i see the stems arent straight. they are sort of wavy as they go up. i've printed these same roses a long time ago and i had the same issue with them. it was in abs though. usually when you see that on tall skinny objects i think that is due to the plastic cooling irregular and the part warps a little. your printing enough of these things for each layer to cool well. try turning the fan off once it reached the skinny section of the stem.

[jdacal]

Thank you Jim for taking the time to check it out. I will try your suggestions tonight.

I think the reason they show crooked at the top is a combination of the bed still moving and the lens on the netcam. It was still printing when I took that picture. I took a fresh one this morning with my phone which I'll upload this evening as well, should be much clearer.

[jsc]

Nothing really stands out for me. Long stalks will get broken off when the extruder contacts the print. Watch the tops of the stalks as they print, is any part of them sticking up too far? One thing I noticed is that you're printing with a 60% infill. That causes a very solid fill, which might contribute. This print could get away with a very low, even zero infill, you might consider trying that. Also, retraction with an oozy filament will sometimes suck up the end of the layer into a top zit. I've been getting away with zero retraction in PLA with no stringing, you might try that. You may have to dry out your filament, given your report of purge curling.

[jdacal]

Nothing really stands out for me. Long stalks will get broken off when the extruder contacts the print. Watch the tops of the stalks as they print, is any part of them sticking up too far? One thing I noticed is that you're printing with a 60% infill. That causes a very solid fill, which might contribute. This print could get away with a very low, even zero infill, you might consider trying that. Also, retraction with an oozy filament will sometimes suck up the end of the layer into a top zit. I've been getting away with zero retraction in PLA with no stringing, you might try that. You may have to dry out your filament, given your report of purge curling.

The white filament has always been troublesome for me for some reason. I did identify having to lower the temperature on it which helped. All my filament is stored in large containers with two huge cans of silica. The purge curling went away when I lowered the temperature. Also I tried it with a reel from MakerGear and a reel from Ultimachine.

I tried it with 0% infill, 20% and 60% with the same result. I'll play around with the retraction setting and along with Jim's suggestions will keep a closer eye on it tonight and report back. I suppose the nozzle hitting it could still be a possibility, but it didn't look like it after I re-leveled last night. May have to go with a higher than usual Z setting just due to the fragility of those stems I suppose. Is there a setting in S3D to temporarily up up the Z on a print without having to physically change the adjustment screw?

[jimc]

like jin said, i would assume that the nozzle is hitting the stems and breaking them off. your z lift amount should be fine really. make some adjustment there and just keep an eye on it. try and watch what its doing during the print. see if you can tell if there is any oozing causing zits, blobs or other strange behavior. tall skinny items like that are always tough to get a good clean print out of. if your printing a bunch of them again turn the bed fan off. if the stems are warping slightly then the nozzle can make contact and snap it off. take notice on the stems if the layers are all lining up evenly.

[jdacal]

Thanks guys. Will try it tomorrow, got side tracked making an airbrush holder.

[jdacal]

Ok, I was able to fix this. I changed some of the stringing settings based on a post jimc made to another user and everything cleared up. Thanks AGAIN Jim!

Specifically I made the following changes:

"for ooze control settings, try these: retraction 2mm, coast 2mm, wipe turn on to default of 5mm. this wont be perfect but should give you a little start on tuning. i think it was set right but also be sure you set the perimeter to print inside then outside."

The only exception was Retraction 2mm which I left at default since the stems were showing up with a gap in the S3D preview at the 2mm setting.

[Tim]

The only exception was Retraction 2mm which I left at default since the stems were showing up with a gap in the S3D preview at the 2mm setting.

But remember that the S3D previewer doesn't know anything about oozing. It's the ooze that fills in those gaps that you see in the previewer. The previewer just assumes that you have ideal conditions and draws it as if the filament stops and starts perfectly on cue.

[jdacal]

The only exception was Retraction 2mm which I left at default since the stems were showing up with a gap in the S3D preview at the 2mm setting.

But remember that the S3D previewer doesn't know anything about oozing. It's the ooze that fills in those gaps that you see in the previewer. The previewer just assumes that you have ideal conditions and draws it as if the filament stops and starts perfectly on cue.

Aaah! Good to know, thank you Tim, will give it a shot see it if improves further.