intermittent overextrusion

Hello,


I understand this is probably a software issue. I'm a very novice user so I'm hoping for some tips. I've had an issue of blobbing and "zits" on my prints with ABS. I thought it was an issue of retraction. I've played with the setting from 1mm to 1.5mm retraction but here's where it got weird. I printed 3 copies of the same small item. About 30mm tall and maybe 18 wide. I only have this problem on the middle one though.


Maybe this is an issue of the retraction kicking in on the other 2 models based on a certain setting. I've tried this in cura, makerware, and Simplify3d. Same issue in all of them with varying retraction settings.


Qidi Tech 1 dual extruder
ABS 235
Bed 115
Print speeds 50-80mm/s (with slowdown on initial layers etc.)




Any ideas?

I can't seem to get the photo attachment, upload, or insert to work. Tried on mobile and PC. Maybe because I just registered? I will edit this post or add it in another post shortly when I am able to upload photos

When I view this thread on my mobile it's like 10 pages of blank. Maybe because I tried to attach my photo so many times? I see now that my ability to post attachments is turned off. Maybe because I'm a new user? If a mod sees this thread and it looks like a long blank post to you too please delete it.

edit: looks fine on PC. Maybe my phone is acting up.

Since I cannot post attachments I would like to add. The top of the models that looked great started to get this overextrusion as well. Maybe the last 10 layers or less.

Quote:

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Originally Posted by number40Fan

That is the weirdest thing I have seen. But, with the issues I had with mine, I wouldn't put it past the wiring that goes down to the carriage. Mine was rubbing at only certain parts/stretches of the print causing the temp reading to swing all over the place. Look carefully at the top-back screw that has the silver washer on it, that the cables are zip tied too. Check the wiring around it. Cut the zip tie off to relax the wiring and try printing that again.

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Interesting thought. Thank you for the idea. I hadn't considered a physical solution to the problem. I'll take a look at the wiring and how it's sitting shortly

Quote:

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Originally Posted by number40Fan

You could also try placing the print on a different spot of the build plate and see if the results replicate.

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I will also try this. The next thing I'm going to try is same orientation to the floor but turned 90 degrees so the wider sides will be closer together. These parts are small enough and they're a specific design to where I will need a decent amount of them so I don't mind reprinting these for testing.

Update: I checked the retractions. They're showing every layer, all parts, always on the left or right side (respective to the photos) I'll take a closer look at the parts but I'm starting to believe retraction is not my issue.

Maybe my Qidi bed is weird. Some quick info, the blue sticky layer popped today on one side in the middle of my first large print. I pushed it back down mid print and then pressed out any air bubbles when print was done. I don't think that's the issue since this is happening middle and not left or right but maybe my bed is an issue. I will level it again (I just trued both extruders last night. My left was lower by just a bit)

I will also check out the wire harness you mentioned.

Good call on checking the hardware. I was dead focused on a software solution (because I'm so new this software is very complicated)

Also, my first thread. I hope to be around here a lot. I run a very small ecommerce business, I survive on my research, and I am truly hoping to incorporate 3D printing into my business (probably not directly but as a completely new diversification of what I already do)

Quote:

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Originally Posted by number40Fan

If you haven't yet, print the following, in the order of importance.

https://www.thingiverse.com/thing:1463521 ABS

https://www.thingiverse.com/thing:409297 PLA

https://www.thingiverse.com/thing:1675208 ABS

Go the local parts store and get some 1/8" glass cut to 9 1/8" x 6 1/8". Grab some #4 machine screws with counter sunk heads, about an inch long and some wing nuts, 2 of each. Get some cheap Aqua Net hairspray. Print the first thingy, the corner clip holders in ABS. Once they are done, pull the bed out of the machine. Rip the blue pad off. Remove the front right and rear left screws and nuts on the aluminum plate. Replace with the new #4 screws and attach your corner clips with wing nuts. Spray down your glass with the hair spray and set it out in the sun for 30 minutes. Replace the bed plate and tighten down the wing nuts for the bed leveling quite a bit. Go into the bed level setting and grab your glass. With the carriage over the middle of the bed, with the bed raised up to begin leveling, see if you can sneak the glass in between the bed and the nozzles. If not, tighten the wing nut screws some more. Once you can get the glass in, cancel the leveling and push the bed down some. Tighten up your corner clips to hold the glass. Start pre-warmup of the bed. Once warmed up, go back into the bed leveling and do it properly. With the glass and NOT USING A Z AXIS SHIM, you'll have tighter springs.

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Great tip about the glass setup. I had some pretty bad PLA deformation on the right side so I printed a dual fan duct right away. Really helped. I'll work on that glass upgrade. I've got a menards and lowes here and even window shops but I haven't ever seeked out glass cut to my specs. Hope one of them will do it for me. Do you think getting tempered glass from one of these places is truly comparable to the borosilicate upgrades sold online?

Since I'm starting to figure out this is more of an issue of hardware instead of software I should also ask about upgrading the hot end. Obviously during searches I am consistently running into the Micro Swiss upgrade. How worth it is it and is there comparable stuff out there or should I go with Micro Swiss?

Good to know. I won't worry so much about extruder upgrade then.

UPDATE:

I believe I have solved this issue. It looks like it was a combination of software and hardware. It seems to have been directly related to acceleration and jerk settings as well as good bed leveling.

I started by removing the zip tie holding the wires down to the hotend as well as changing the orientation of the parts. I was still seeing the issue on one part more than the others. After watching closely I realized that using simplify3d my priming line up front primes the extruder then at the end of the line moves another 10-20mm or so VERY slowly with no extrusion. I don't know if this is a retraction setting, a wipe setting, or what. Having come up short there I solved this issue by printing a 3 line skirt around my parts.

What was happening was that last movement on the priming line was doing something to take pressure out of the extruder (please help me if you know what is causing this slow movement with no extrusion). The first part wouldn't get but a little bit of filament laid down. Basically was a layer skip that caused the rest of that middle part to look crappy. After adding the skirt I was getting solid application and a solid part.

After doing that I still saw some really ugly parts. I went down to two parts and both were coming out pretty gnarly but at least they looked the same. It was basically "ringing" that I was getting. It just looked way worse on that part with the missed layer.

Since Simplify3d does not have acceleration and jerk settings and I could only find an Mcode script for acceleration but NOT jerk settings I did some further research and loaded up ReplicatorG. I connected ReplicatorG to my QIDI Tech 1 and looked at the acceleration settings (had to learn to open the makerware program and turn off background service so that RepG could connect). I changed them to the recommend 800/8 and wrote those setting changes to my printer.

After doing those things (some small changes but mostly adding a skirt, a fresh bed level, and changing accel/jerk settings) I'm watching a fresh set of 2 print and they're looking better than ever. However, I'm going ALL the way back to looking at retraction settings now because the only noticeable issues are falling in line with where S3D is showing the retractions. I'm going to start by turning off retraction and then move on to negative priming after retraction.

Once again if anyone knows what that movement is at the end of my priming line please tell me. Wipe and coast are not turned on but in the advanced tab there are some options ticked such as wiping for outside perimeters. Those shouldn't do anything if wiping is turned off though I would think

Found it. Here is a section of my starting script in my Qidi profile in S3D. I'll assume the "fast wipe" or the "wait for ooze" is what is causing my priming issue. I received the full script from someone and I honestly don't know what is "safe" to remove from it. Any tips?


G1 X90 Y-68 E24 F2000 ; Extrude a line of filament across the front edge of the bed
G1 X100 Y-68 F180 ; Wait for ooze
G1 X110 Y-68 F5000 ; Fast wipe
G1 Z1 F100 ; Lift
G92 A0 B0 ; Zero extruders
M73 P1 ;@body (notify GPX body has started)

Line 2-5 I'd like to remove completely but I don't really understand anything but the wait command

Triple post I know. New info, I've got a good amount of stringing on one of the pieces since the slowdown. It is where the retractions are showing on the print preview where the head crosses to the second part. Based on S3D's troubleshooting page and my recent changes I'm going to try and figure out if it is a retraction distance, restraction speed, or maybe I can change an acceleration/jerk setting that only relates to when the head is not extruding (because I haven't had this kind of string before) or a combination of these.

on the gcode side of things.
comment out the lines you want to remove and see what happens.
to commen out - just put a ';' at the start of the line and s3d will ignore it.
This way you keep the gcode in case it's needed and just ignore the bits you want to check. :-)

so:
G1 X100 Y-68 F180 ; Wait for ooze
G1 X110 Y-68 F5000 ; Fast wipe
G1 Z1 F100 ; Lift

becomes:
; G1 X100 Y-68 F180 ; Wait for ooze
; G1 X110 Y-68 F5000 ; Fast wipe
; G1 Z1 F100 ; Lift