Gaps in solid layers, why?

General discussion topics
User avatar
Expresso
Posts: 26
Joined: Fri Dec 30, 2016 2:25 am
Location: Dallas, TX

Gaps in solid layers, why?

Post by Expresso » Tue Mar 28, 2017 2:59 pm

Hello,

Looking at the attached picture, is it possible for someone to tell me what may be going on with the printer to cause the gaps between the plastic strings?

Thanks.
Attachments
PatternGap.jpg

3dPrintingMD
Posts: 277
Joined: Fri Oct 02, 2015 5:37 am

Re: Gaps in solid layers, why?

Post by 3dPrintingMD » Tue Mar 28, 2017 3:45 pm

What slicer are you using?

If S3D, on the advance tab, what is your setting for thin wall behavior?
M2 - V4, MIC-6 Build Plate, Astrosyn Damper's(X/Y), Rev. E, Geeetech LCD

S3D - FFF Settings https://forum.simplify3d.com/viewtopic.php?f=8&t=2367
Print Quality Troubleshooting https://www.simplify3d.com/support/prin ... eshooting/

User avatar
Expresso
Posts: 26
Joined: Fri Dec 30, 2016 2:25 am
Location: Dallas, TX

Re: Gaps in solid layers, why?

Post by Expresso » Tue Mar 28, 2017 3:56 pm

Sorry, I should have included that information with the original post.

I am using S3D with the default MakerGear profile that comes built in with the software, in my case the built in profile is called "MakerGear M2 (24V V4 hotend)". When I printed the piece shown in the attachment, I used the profile default values.

To answer your specific question, I have selected "Allow gap fill when necessary" together with "Allowed perimeter overlap 10%".

Thanks.

User avatar
sthone
Posts: 883
Joined: Tue Jul 08, 2014 8:25 pm
Location: Connecticut
Contact:

Re: Gaps in solid layers, why?

Post by sthone » Tue Mar 28, 2017 4:46 pm

Is that the bottom of your first layer? If so your z-height needs to be lowered. (less gap)
____________________________________________________
See my projects at https://www.theneverendingprojectslist.com

ksevcik
Posts: 56
Joined: Fri Oct 21, 2016 1:07 am
Location: Houston, TX

Re: Gaps in solid layers, why?

Post by ksevcik » Tue Mar 28, 2017 5:51 pm

If you're doing standard 45,-45 infill and your concern is the part you have circled there, that's almost certainly backlash. Both axes change directions on the alternating lines there, and any backlash means X or Y doesn't move the full distance on a direction change. For instance, if there's 0.1mm backlash in X, you can think of it as lines moving X+ being shifted 0.05mm to X-, and lines moving X- being shifted 0.05mm X+. And voila, you get lines that are alternately too close and too far apart.

Typical sources of backlash are loose belts, loose screws holding motors, belt clamps, or anything else that moves. A loose glass plate would also look like backlash on fast infill, since the plate would keep sliding after the axis stopped. More rare is a belt clamp that's a loose fit for the belt, which can be fixed by putting a shim behind the belt to shove the teeth more into the grooves on the belt clamp.

User avatar
Expresso
Posts: 26
Joined: Fri Dec 30, 2016 2:25 am
Location: Dallas, TX

Re: Gaps in solid layers, why?

Post by Expresso » Tue Mar 28, 2017 9:40 pm

ksevcik wrote:If you're doing standard 45,-45 infill and your concern is the part you have circled there, that's almost certainly backlash.
I decided to experiment a little more by printing two small squares, in one of the square I set the "External Fill Patter" to "Rectilinear" and the other square to "Concentric". I then printed the first layer and looked at the results. Turns out that the square with the rectilinear pattern (45 / -45 angle) had the issue with the gaps while the square with the concentric pattern was pretty much perfect.

Based on those findings, your backlash theory (something loose) makes scenes (at least it makes scene to me at the moment). The problem now is going to be figuring out what is loose, everything seems to be nice and tight but its impossible to tell by feel (given the tolerances we are talking about here) if something is loose or not.

The printer is brand new by the way (two months old) and only two spools of PLA under its belt so wear and tear should be out of the question. Are there any video / instructions on how to reset the printer belts / steppers etc?

UPDATE: See attached Rectilinear and Concentric photos.

Thanks.
Attachments
Rectilinear.jpg
Rectilinear
Concentric.jpg
Concentric

User avatar
PcS
Posts: 667
Joined: Mon Mar 09, 2015 12:19 pm
Location: Michigan

Re: Gaps in solid layers, why?

Post by PcS » Thu Mar 30, 2017 1:02 am

sthone wrote:Is that the bottom of your first layer? If so your z-height needs to be lowered. (less gap)
plus 1

User avatar
Jules
Posts: 3144
Joined: Wed Jan 21, 2015 1:36 am

Re: Gaps in solid layers, why?

Post by Jules » Thu Mar 30, 2017 5:31 am

PcS wrote:
sthone wrote:Is that the bottom of your first layer? If so your z-height needs to be lowered. (less gap)
plus 1
plus 2

User avatar
Expresso
Posts: 26
Joined: Fri Dec 30, 2016 2:25 am
Location: Dallas, TX

Re: Gaps in solid layers, why?

Post by Expresso » Thu Mar 30, 2017 7:21 pm

Jules wrote:
PcS wrote:
sthone wrote:Is that the bottom of your first layer? If so your z-height needs to be lowered. (less gap)
plus 1
plus 2
Thank you, sounds good, however, just a couple of quick questions if you guys don't mind:

1) How will lowering the z-height address the funky layer pattern? If you notice in the picture from my first post, the pattern goes something like "filament line" -> "filament line" -> "gap" -> "filament line" -> "filament line" -> "gap". Is this really the type of pattern that you would expect to get from an incorrect z-height?

2) In a different post, I show the exact same object first layer printed with concentric and rectilinear patters, if this was a z-height issue, why would one pattern display the issue while the other does not?

3) How do I lower the z-height so I can test the theory?

Thanks.

M3Jim
Posts: 19
Joined: Sat Jun 13, 2015 2:16 pm
Location: FL

Re: Gaps in solid layers, why?

Post by M3Jim » Thu Mar 30, 2017 9:31 pm

I would use S3D to decrease the z-height. Under the G-Code tab is a box called Global G-Code Offsets. Decrease the Z-Axis to some negative value to start printing with the extruder closer to the bed.

Jim

Post Reply