Layer lines, again

#1

I’ve been getting layer lines on my prints with flat surfaces, here’s all the stuff I’ve tried to fix it.

I’m using the Moai 130 with the FEP vat and the “Recommended Moai with FEP vat Firmware setting” from http://wiki.peopoly.net/doku.php?id=moai:firmware

All prints are done at 40u with the moai_calib_2 profile with the Peopoly heater turned on.

In this thread @ad_fontec links to his diagnosis of problems with layer lines. TLDR: the heater turns on and off which messes the print up. It’s warm here at the moment so I thought I’d try running a print without the heater turned on:

Lines are present.

I’ve modded the Moai with Project Tripod, though I may have messed it up which could cause the lines, so I detached the build plate arm from the cross-beam & ziptied the beam to the top of the printer so the z-axis can move without the tripod, just in case it’s causing a wobble:

Lines are present.

I read more about the various settings, so though maybe turning off z-follow might help as this is a small model without much suction so why would you move the z-axis more than you have to?:

This looks a little better IRL, but lines are still present.

This is not my first resin printer. With previous ones I noticed horizontal banding caused by errors in the model. This model is clean but has been hollowed in Mesh Mixer with drainage holes placed manually in Blender, which might have created some crazy geometry, so I printed it without the hollowing:

The print still has lines.

It’s been noted elsewhere that the vat can move around in it’s holder - mine’s tight vertically but can shift horizontally with a bit of force - I shimmed the vat in place by sticking a 2mm allen key between it and the frame and printed again:

Still got lines.

At this point I noticed I’d actually been using some of the settings for the PDMS vat (with the exception of Z Reset Position and PM Reset Position), so reset them all to be for the FEP vat:

Nope, still has lines, though looks a little better.

I turned off z-follow again but kept all the other FEP settings:

Lines, everywhere.

Someone on the FB group mentioned that lines seem worse on faces towards the door/back of the machine, and the face in all the photos is indeed pointing towards the door, so I tried rotating it by 45 degrees so the side photographed faces the front right corner:

Nopenopenope, seems to have made it worse.

Aside from that nothing I’ve tried seems to have made much of a difference.

@peopoly @peopolysupport @Peopoly_Support_2 got any ideas? And why do you have so many accounts on here?!

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#2

Hey @achingbrain ! You have done some extensive testing I see. Glad you tried to self help and find advice on other platforms. The first question I want to ask is: Are you using Asura 2.2.3? I saw you said you were using Meshmixer and blender which could generate more risk in getting a faulty model (not saying that’s the issue).

Also, check to see if there is any dust on the Acrylic cover over the galvo. Check the rail, make sure there is no buildup on it (because that does happen with any mechanically moving parts) could have dust/grease build up and if you are a cat or fluffy pet owner that stuff magically goes everywhere. So check those also.

I will do some more analysis of your photos and get back with you (thank you for all the photos and details). That first picture was with the heater off? Did you do a print with the heater on?

As for the accounts, I am the fun one. Just pure unadulterated fun and I will get you your answers. :blush:

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#3

I do modelling in Blender, add supports in PrusaSlicer (because it’s got great support tools and all Asura mesh manipulation tools are currently unusable on Mac OS X) then finally generate gcode in Asura.

v2.2.2 because you only released the Mac version of v2.2.3 a few hours ago.

All prints other than the first one have the heater turned on with the resin left in the vat to warm up for 20-30 minutes before printing.

No pets here, but I’ll check the galvo cover, rail, etc for debris.

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#4

those lines are (or at least seem) caused by the slicer not the moai. we extensively talked about it here Weird striping effect

bottom line there’s very little you can do about it. you may try to print it flat on a raft of supports instead of at 45°

there are also some Cura (not asura) settings that you can try to apply but it won’t go completely away.

that is the major issue of the Moai especially with geometric models.

you may also try to remesh the model, can you post a detailed wireframe?

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#5

There are numerous reasons you get layer lines on the Moai. 1. Heater banding. 2. Peel lines. 3. Vat shifts. 4. Galvo backlash. 5. Inconsistent support. Your lines are a combination of vat shift, galvo backlash, and peel lines. You can reduce the vat shift with new vat flange brackets, check the FB group for my downloadable .STL for those. For the galvo backlash, you can reduce it by orienting your model to 20 degrees from flat. This is an area I wish Peopoly would pay some attention to. For the peel lines, reduce the pm motor speed to 12, and orient the model so the highest point is away from the hinge.

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#6

@matt3o I tried printing horizontally, lines were still present:

Ignore the soggy looking supports, I was trying out Asura’s auto-generation on that print.

This is the wireframe of the .stl used in Asura imported into Blender so has all the triangles:

@briggsmodels pm motor speed is already at 12 as Peopoly recommend.

I’ve reorientated the print to 20 degrees & angled the high point so it’s away from the hinge, will take a photo when it’s done.

I tried shimming the vat previously but it didn’t make any difference. I’ve also tried printing with the heater on & off and that didn’t change anything either.

Thanks for sharing that .stl of the vat flange brackets - I’m printing them right now and will give them a go tomorrow. Do you have a photo of them installed in your Moai so I get them in right?

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#7

Shimming the vat as the machine comes won’t help these lines because the sprung posts allow it to move. If your lines are aligned with the edges or corners of features that’s galvo backlash. The vat brackets only fit one way. You also need a 5mm drill bit, 4x 4mm x 150mm bolts, 4x 4mmhex nuts, and 6x 3mm hex nuts to complete the install. Screw the brackets in place, mark the top hole locations, drill the top flanges on the tilt table, then screw it all together. I removed the tilt table from my machines to do it. I also don’t like the Peopoly fep, I think it’s too thin, and allows too much peel instead of pop. I am replacing mine with .15mm fep as soon as it arrives.

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#8

Hmm, that definitely sounds like a measure twice, cut once kind of situation, I’d love to see a picture.

If your lines are aligned with the edges or corners of features that’s galvo backlash

@Peopoly_Support_2 do you have any thoughts on this before I start drilling holes in things?

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#9

Here’s a junky photo. It shows how the bolts have to go through the top flange. It’s not a critical hole as long as the bolt can go through

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#10

by rotating the model you can see that the lines follow some of the edges they do not go through the whole layer. it’s not an issue with the vat or interference (as peopoly/support will try to tell you) or dust or loose screws. it’s a slicer issue combined with the mesh topology. The post I sent you covers the issue in great details, I suggest you to read the entirety of it (it’s very long I know).

you may try to remesh your model, possibly also increasing the polygon count. You’ll probably see that the defects will change based on how the polygons are distributed.

the bottom line is that you can lower the effect, but you can’t completely get rid of it. I said this one million times, the moai is not great for geometric stuff.

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#11

@briggsmodels: For the galvo backlash, you can reduce it by orienting your model to 20 degrees from flat

This didn’t seem to make any difference:

I’m going to try the vat shim though, pretty much every other resin printer on the market lets you screw the vat down, it seems a curious omission from the Moai 130. Even the 200 has it.

Perhaps @peopoly could release a screw-down FEP vat as the next upgrade?

@matt3o: it’s a slicer issue combined with the mesh topology.

To test this out I switched up the model for a plain 1cm cube so no fancy geometry and it’s printed pretty much without layer lines (ignore the sagging under the cube, not enough supports there):

I don’t think this is the sort of thing we can fix with homebrew hardware mods.

Any thoughts @Peopoly_Support_2?

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#12

I told you so :slight_smile: We’ve been fighting with this issue since day-1. peopoly is well aware of the problem but they simply don’t have the resources for a dedicated slicer (actually path-generation).

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#13

Would using the Formware slicer make a difference or does it do the same thing?

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#14

every slicer I tested presents that kind of issue, but all slicers are basically FDM optimized.

I haven’t tested formware with the moai long enough, but it’s likely they are using some common library to create the toolpath, if that is the case very little would change. If they actually developed a proper toolpath generator, it might actually work. rather easy to test anyway.

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#15

What is your laser power at?

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#16

I know the developer of Formware is trying to support as many SLA style printers as possible. Its probably worth a test to see if it clears up the problem with this print. If it doesn’t, it may be worth looping him in to the discussion and see if we can narrow down where this problem occurs and possibly fix it.

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#17

These are my settings:

X Size 900
Y Size 900
X deviation 100
Y deviation 100
Smooth 50
Z moto speed 2
PM moto speed 12
Laser Power 58
XY Speed Set 4
Z Reset Position 1816
PM Reset Position 60
Z Follows 10
CompensateX 100
CompensateY 200
Z Initial Speed 2
PM Initial Speed 10

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#18

Would using the Formware slicer make a difference or does it do the same thing?

I don’t think there’s a Mac version available so it’s not really an option for me.

Doesn’t look like they’re in much of a rush to produce one either: http://forum.formware.co/t/low-priority-port-to-os-x/35/2

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#19

if you can share the model I can slice it for you on formware just to see how good of a toolpath generator it is

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#20

@achingbrain

sorry to hear about your issues.

what cura version are you using for OSX?

and can you run a small print this way?

some of your layer lines are some what random so I want to make sure everything is securde well

  • check to see if z-axis lead screw is stable and the arm does not shift left and right very easily
    to print
  • set heater is off
  • make sure environment is not under 20C, perhap print during a day

and see how the print turns out

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