T-Rex
Posts: 4
Joined: Mon Aug 06, 2018 1:39 pm

Perimeter bumps only on curves

Tue Aug 07, 2018 10:14 am

Hello. I'm having issues w/ my MakerGear M2 using MH 1.75 Pro-ABS. I'm getting zits/blobs, but only on curved surfaces. Every other facet of the print is coming out great, straight sections, rafts, supports, etc, all good. I've done close to 3 dozen prints (only doing a small section which contains all the curves) and I can't get it clean. Here's a shot of the best print thus far.

I've messed with speed, layers, extrusion, nothing makes as big a difference as retraction. However, I can't get retraction narrowed down enough for a perfect print.

No usual indicators to suspect this is from humidity in filament, especially since it's isolated to curves.

Image

T-Rex
Posts: 4
Joined: Mon Aug 06, 2018 1:39 pm

Re: Perimeter bumps only on curves

Mon Aug 13, 2018 2:07 pm

Yet to receive a reply, not too sure if this means no one has a clue. But, I figure I'll share some more info. I was watching the machine print and noticed it stopping, for a fraction of a second, during the curves and it seemed to be still extruding. Even though I knew all was ok with the model, I went ahead and redesigned the .stp file from the ground-up. The new file is still producing the same results.

I can print a regular cylinder w/o the machine producing the same blemishes.

Anyone???

S3D-Chris
Posts: 27
Joined: Wed Jun 20, 2018 11:52 am

Re: Perimeter bumps only on curves

Wed Aug 15, 2018 2:03 pm

Hey T-Rex,

Welcome to the Simplify3D forum! Try checking out our Print Quality Guide - Blobs and Zits section for tips and tricks to reduce blobs.

https://www.simplify3d.com/support/prin ... s-and-zits

arhi
Posts: 345
Joined: Thu Oct 06, 2016 4:13 pm

Re: Perimeter bumps only on curves

Wed Aug 15, 2018 2:47 pm

T-Rex wrote:
Mon Aug 13, 2018 2:07 pm
Yet to receive a reply, not too sure if this means no one has a clue.
if you uploaded the G-Code file it would be much easier for us to help you.

are you using 4.0.1? if you are using 3.x this was because you have a STL that's too detailed so S3D produces a GCODE that's toooooooooo detailed and you have many small moves that
- your firmware ignores but slows you down in the path and you get accumulation of filament
- your electronics can't handle the speed of g-code (can't pass enough g-code trough serial port / can't parse enough g-code in time) so you have stops and slowdowns and you develop blobs

4.x mostly solves this problem as it ignores "too precise" stl's and creates less moves but it's not ideal so it can still have this issue on some STL's. If you are not on 4.x move to 4.x, if you still have a problem, use some STL editing/modifying software to "optimize" your STL and reduce triangle count. For e.g. you can safely optimize the STL to 0.1mm "error" it will significantly reduce triangle number and will create STL that will slice faster and not produce this blobs.

Do a simple test to prove that's a problem; create a curved object and export it into STL with low poly count and super high poly count, then print them both and compare results :)
gcodestat integrates with Simplify3D and allow you to
Calculate print time accurately (acceleration, max speed, junction deviation all taken into consideration)
Embed M117 codes into G-Code
Upload your G-Code directly to Octoprint
open source and unlicence

airscapes
Posts: 233
Joined: Tue Mar 06, 2018 10:35 am
Location: Philadelphia PA Area

Re: Perimeter bumps only on curves

Wed Aug 15, 2018 2:59 pm

Set up your print as you have it and go to File > save Factory File as> and save it to a name of your choice. Then attache it. This will let me see all your settings and the model. I have the M2 as well and there will always be bump where the layer changes. I have yet to eliminate it but you can sort of control where it happens.

If you have a small part that suffers do the factory file on that and I will print it on my machine to see what it looks like with your settings.

Do you get these with PLA? ABS is pron to absorb moisture and I have seen blobs like this when my spool needed to be sent though the dryer.
attached is a picture of 3 or 4 layers of MakerGear ABS that was a bit too wet.. When looking at the moisture bumps with a magnifying loop, you could see a hole in the center of some where the moisture (steam) had blown out like a volcano, and others were just bubbles.
Get the factory file attached and I will see what I can see..
bumps.jpg

T-Rex
Posts: 4
Joined: Mon Aug 06, 2018 1:39 pm

Re: Perimeter bumps only on curves

Wed Aug 15, 2018 8:20 pm

I've been in the field, the passed couple days, but thanks for the replies.

I've definitely read through all the "tips & tricks". Very helpful and did solve many issues over my course of learning.

Definitely not moisture. The printer is in a closet under the stairs and stays above the dew point and kept dry. Also, you can see from the print, the blobs are kept to curves and none of the straight sections share the imperfections.

My version of S3D is up to date and my stl file is approx. 750kb. I use Inventor for all my stl file creations and typically use high precision settings. I've printed extremely complex models and never had trouble. However, I see your point. This one is a doozy and throwing me a curve.

I'll get the g-code when I'm back in the office, friday.

SWCNT
Posts: 26
Joined: Mon Jul 16, 2018 8:51 am

Re: Perimeter bumps only on curves

Sat Aug 18, 2018 11:36 am

From what ARHI said, "- your electronics can't handle the speed of g-code (can't pass enough g-code trough serial port / can't parse enough g-code in time) so you have stops and slowdowns and you develop blobs"
I would agree with that if you have the newest S3D already.

Are you printing via SD or USB? I've had issues with some parts where my printer would slow down on curves with USB printing but not with SD. I've seen in on my CR-10, MonoPrice Ultimate, and TEVO builds. I've never seen it on my Smoothieboard builds, so I've attributed it to the control boards for those other prints not being able to handle the gcode at the rates needed.

T-Rex
Posts: 4
Joined: Mon Aug 06, 2018 1:39 pm

Re: Perimeter bumps only on curves

Mon Aug 20, 2018 12:31 pm

It was because of printing over USB. Same setting done via SD card and print came out beautifully.

Where is the line drawn as to whether to print over USB vs SD? I prefer USB, due to the ease of being able to VPN at night, from home, and having the part ready the next morning. I can't see it being file size as I've done larger files via USB and had them come out fine. Do I look at the model and determine its complexity?

Thank you all.

SWCNT
Posts: 26
Joined: Mon Jul 16, 2018 8:51 am

Re: Perimeter bumps only on curves

Mon Aug 20, 2018 2:21 pm

Correct, it's not the size that matters, but the complexity and speed of the movements needed. The more complicated the motion profile is, the greater the chance you will have issues, which may be layer shifts, blobs, zits, etc from incorrect movement and/or extruder issues. It's difficult to say exactly when X with print fine via USB, and Y won't, because besides the print itself, the control board and computer play a roll. One thing you can do is slow the print down a bit, which might be an option for you since it sounds like you are running things overnight. At slower print speeds you may notice the lag goes away, besides that, it's experience that you need to go by.
"I prefer USB, due to the ease of being able to VPN at night, from home, and having the part ready the next morning."
Why not transfer via USB to the internal SD card and then print from the SD? The transfer will take awhile, but you don't have to physically be there to print.

arhi
Posts: 345
Joined: Thu Oct 06, 2016 4:13 pm

Re: Perimeter bumps only on curves

Mon Aug 20, 2018 6:00 pm

T-Rex wrote:
Mon Aug 20, 2018 12:31 pm
It was because of printing over USB. Same setting done via SD card and print came out beautifully.
so too many too short moves, it's a problem s3d is yet to fully solve but as a temp. solution export your parts at lower resolution as you are obviously exporting stl at higher resolution than your printer really have :)
gcodestat integrates with Simplify3D and allow you to
Calculate print time accurately (acceleration, max speed, junction deviation all taken into consideration)
Embed M117 codes into G-Code
Upload your G-Code directly to Octoprint
open source and unlicence

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