Printed object with deep stepped lines


#1

Hello,

I´ve been struggling with the new fep vat and decided to come back to the PDMS Vat. Recalibrated my Moai, ran the corner test (10.71,10.70, 10.67, 10.73), ran the cube calibration test (got 19.42 X and 19.36 Y). The cube surface was fine. Then, went back to my prototype, I already had printed it sucessufully once, but decided to print it again to replicate the procedure and may get a bit better object for sanding, priming and casting, but the printed object came out with very pronounced lines and I have no idea of what else to investigate, since the printer is calibrated and the temperature is controlled. Also checked screws (z rod, tilt system), but everything is well attached.

If anyone has any suggestions, I´d be really glad and thankful.

My complete setteings:

Settings:

Moai internal temperature: 30.6C

Firmware version: 1.18

System Setting is default per Peopoly recommendation? (Yes/No) Yes

Build plate type: (Standard 1-piece / easy to level): easy to level

Vat: (Silicon vat / FEP vat) : PDMS

Cura Version and Profiles: 3.4.1, 60nm August profiles

Infill %: default (70%)

Laser Power: 58

Z-reset position: 1880

PM Motor Speed: 15

Z Follow Speed: 10

What type of resin: blue resin

Leveling measurement: A 10.71,B 10.70, C 10.67, D 10.73

Model hollowed in meshmixer (2mm), two holes (1.5mm) in the models feet, supports in Asura and sliced in Cura (3.4.1, 60nm August profile)

!


Problems with hi-temp resin
#2

Hi @Ricardo_Rocha, i’m sorry your having trouble

Lets try and identify the issue.

I would say those lines are too perfect to be random… It looks like they are parallel to the buildplate and vat, correct?

Can you measure the distance between them (the lines)?

Do you also have a screenshot of the model in Cura with the supports?


#3

Sure, the lines closer to the model´s ear are about 2.5-2.6mm, but they get closer each other when near the base of the model. The spacing difference seems linear (it increases with the height of the model).

Attached images of Cura and Asura:


#4

would you try with the standard build plate instead the easy to level?

PS: very nice surface on that model! really great polygon distribution what did you use?


#5

Hi Matt,

I was affraid you’d suggest that :slight_smile:

I’ve done another full screw check (vat base/tilt, z axis) and galvo/laser status (to see if there is any debree). I’m recalibrating now with the normal plate, will re-print the model as soon as I get it under the 10.7~10.8 range.

About the model, it was originally done by a friend(and ex-partner) that works with game development. It was a low poly model originally, done in Blender. I got the model and did one more sudvidision in 3ds Max and did the booleans. The first version I printed was decimated in Zbrush, but I realized the original mesh wasn’t that heavy and decided to use it. I saw zero difference between them, I’ve got almost the same with my ecorche and found a good sweet spot between printed detail and mesh density, but realized that meshes with Very high frequency details hold better if decimated.


#6

Ok, testing it with the original buildplate is good to rule out any problems with the easy to level one.

But… did you noticed any movement of the plate (from the easy to level buildplate) when fully tightened? Did you check if the screws were able to be tight enough to actually be able to hold it in place when pulling the part from the PDMS/FEP?


#7

Yep, even removed the new plate and checked the screws. But also noted that one of the four screws is already worn out and the surface may don’t be perfectly flat, but I still need to check it with the proper equipment.

Anyway, almost done with the leveling of the normal plate, will start another test print as soon as my corners are ok.


#8

Ok, keep us posted!!!


#9

Had a light power failure in my region, but printed enough to check that the problem persists with the old build plate, exactly the same pattern. Printer well leveled, all screws checked and re-checked.

The only difference between prints is that the first one is 60nm and the second one is 80nm. Also, moved the second print to another area in the build plate, to see if it would make a difference (something VAT or build plate related, but I think it’s not).

It looks to me that I have a sort mechanical problem, maybe z-rod or z-motor? What else is possible to do? Is Moai prone to failure after only a few months of use? Really worried right now.



#10

is the vat firm in its stall? no wobbling?


#11

Nope, double tested it, it’s firm.

And the stepped pattern is exactly the same, same distance between the lines. I’ve checked everything within my reach, any ideas of what else to do? I’ve followed ALL these steps:

http://wiki.peopoly.net/doku.php?id=moai-checkup


#12

If its exactly the same its most likely a mechanical issue.

Moai has proven to be quite reliable according to some people i’ve heard. I’ve been printing non-stop with mine and aside from a few hiccups (that was actually me learning) the printer didnt fail any print and i dont have any problems whatsoever.

Could you shoot a video of the tilting action during a print? Is it smooth?

Aside from that i would say to check the build platform and Z-assembly screws… but it looks like you already done that.

Maybe shoot a video of the buildplate coming down and rising up… maybe we can spot something


#13

Here we go, videos of the plate going down at the beggining of the printing and vat tilt at layer 2.

Link for the vídeos:

photos.app.goo.gl/VB8ScZmvnCijcqNp8 —> just copy and paste the link into the browser

2 new photos by Ricardo Rocha

And again, checked all the screws and mechanisms, didn´t find anything loose (or bent) at all.
But, some screws are already worn out, even the ones below the VAT tilt bed, which I´d never had touched before this full check. Unfortunately, this doesn´t surprise me anymore.

How should I proceed from here, @peopoly ? I´d really need to have this printer working.


#14

Ok… vat tilting looks smooth. So does the buildplate going down. Does the top of the Z leadscrew wobble too much?

Did you build it yourself or pre-assembled?

I assembled mine and honestly i like to give the screws a good snug… i dont have one single stripped screw… maybe too much force was applied while building it?

If you can no longer tight some screws they might be
a bit loose and you wouldnt be able to tell unless they were completely loose.

Do you have any stripped screw on the Z assembly?


#15

Nope, it doesn´t seem to wobble much at all and is firm. And if it was wobbling, it wouldn´t have a linear stepped pattern I believe, but a more random behavior.

I assembled myself, I use to care a lot with pressure in the screws, since despite other things, I have a carbon bike and usually use a torque wrench, exactly because I know how bad can be a too tight screw :slight_smile:

Some screws were not manipulated by me until now (specially the tilt bed), but when I tryed to turn then, I felt they were already “soft”, which is very concerning. In my opinioin, this is one of the weakests points in Moai, really bad quality screws. I´d install new ones tomorrow, but will wait to see if my Moai is fixable at all.

And yes, I checked all the screws from Peopolýs checklist, despite of their bad state/quality, I was able to tight them.

And nope, no stripped screw in the Z assembly, these (the 6+2+2 in the z column) are ok.

Let´s assume the screws are tight, or better, I can assure you I´ve checked them many times through this weekend. What can I do now? Honestly, and as you can see in the videos, nothing seems to be loose at all.


Consistent layer shift
#16

It looks like another user is having the same problem:

The pattern seems really similar. Maybe a faulty galvo board?


#17

A bent leadscrew would result in artifacts always in the same spot…

But you were able to print without that issue before and i dont see how the leadscrew could be bent just like that…

I remember seeing a user that had a faulty galvo board, the issue doesnt look like yours, it looked more random (look here: Inconsistency with layer shifts is really starting to bug me)

Could you try printing another file…? Something like the cylinders but a bit higher to see if you get the same pattern?


#18

Sure, I´ll do that.

And yes, a bent leadscrew in the same spot would produce an artifact, but my regular step/shift pattern is something that repeats itself along one axis, moving the model´s layers along Z from a certain N distance.

If it were mechanical, there should bs some sort of loopable step, but the tilt mecanism simply rotates the tilt bed in one axis, no position shift at all. And the Z axis has a linear movement, which would imply in something repeatable along it´s own axis.


#19

Test prepared, what do you think?

Created a mix of half a cilinder, half a box, spikes at 10mm distance each, hollowed (2mm) up and down.


#20

Check the Z axis linear rail to make sure its not loose. The lines looks like Z wobble which will show up in the print every full rotation of the threaded rod. If its tight, then it could be the galvos. Do the circle test like when you first put the pinter together and make sure can do a perfect circle. If that’s also fine…then check the tray holder that tilts and make sure everything is tight, since using the FEP puts a lot of strain on everything in the peeling process. Good luck and keep us posted!