About to try sacrificing a goat


#41

okay so, the mesh looks fine even though not perfect for Cura but I understand that retopology takes a lot of time.

I see an issue with her teeth that would be printed mid-air, so the tip of her teeth won’t probably come out leaving residue on the vat and causing problems on anything printed above that.

You definitely have some useless supports and you could get rid of them. The model basically holds itself up by itself, you probably just need supports for the arm, I don’t think the breasts need supports at all but I’d need to check the model to be sure, those are definitely huge boobs so… probably just the left one.

For such a big model I would probably use fewer bigger supports.

That being said I don’t see anything stopping you from getting a great print there.


#42

cheers @matt3o and @teivion On a previous attempt I did end up missing a piece just below the breast but I think I could probably do with remove a few of those judging from the last as it came out nicely on the most recent attempt.

The teeth actually worked out quite well, they’re supported from behind by an inner mouth piece I inserted behind them in zbrush as I couldn’t get any supports tiny enough to fit in there so had to come up with that method of fixing them.

Looking at the latest attempt it’s not actually that bad and would be pretty much what I’m after it wasn’t for the layer shifts in the face. I could fix a lot by giving a gentle sand with some high grit paper, but I know this printer is capable of more impressive results after seeing what you guys have achieved.

I think I’m going to try it with fewer but thicker supports. I’ve also upped the laser power and changed the z reset to 1877 as per the guidelines so hopefully the pressure won’t be so high on the PDMS and I’ll get a stronger cure as I noticed some of the internal supports I pulled out earlier were a bit on the flimsy side.

I’ll get back with some results in about 24 hours or so


#43

Yet more failure

https://drive.google.com/drive/folders/1J5qA7Paau70-_i_HGAU0LpnlAwoufJeO?usp=sharing


#44

@bendouglas86 @peopoly @peopolysupport

Maybe you are printing too high a temp?


#45

Id ask @peopolysupport @peopoly about the heigth as it seems worse in the last few inches which may be a height related problem etc ( so support and orientation issue)
Id be interested to know whats causing the weird artefacts up the back, at the side of her- I get that sometimes with my FDm printer where the print head stops/starts a line too often in the same place…
Ij guessing the printer is securely mounted against vibration/ knocks etc.

Have you another print to try just to compare ? Mine is sat here at the mo so I can possibly try a print for you just for the hell of it


#46

one thing @peopolysupport
I have always found it odd that the Z-axis screw thread is open / unfixed at the top. This allows for a lot of wobble…
Mines all over the place when its in full motion dropping or raising the plate.
The guide rail I am presuming is also un lubricated.
Has anyone tried to put a skate bearing in the top of the z axis screw to fix it to the guide rail mount?
Or used any lubrication on the rails ?
A slighty sticking guide rail/ wobbly z screw might be whats causing a lot of these issues esp as most of them seem to be height related


#47

Have you tried printing another model? I know it can be frustrating when the same thing fails over and over, but theres a few variables that can be ruled out if you try a model that is known to print.

The ring is an ok test, but its quiet small and IMO doesnt reflect what can happen when printing ‘big’ which is mostly why we got the moai in the first place.

I would have split the head and arms off as there are already natural seams, getting it to fit in perfectly after print is another topic. but I think you will have a better time with it.

I have a few things on thingiverse with SLA support already baked in if you wanted to try.

Might be worth testing.

Latest is this skull

PS: great looking model btw :slight_smile:


#48

@teivion Cheers dude. I’m currently using the Moai heater which should turn off at the 35 degree mark according to the product page, but i’ve also got a wireless thermostat kit that I’ve got set at 31 so the resin temp is unlikely to be higher than that, maybe a bit lower (I’ve got an IR heat sensor arriving tomorrow so I’ll know the correct temperature offset soon).

I’m actually pretty confident in other prints working, some of my other smaller models (10cm tall) have come out very well but they were quite simple with few internal cavities as they were pretty much just monster heads.
I believe the major issue I was having with my previous layer shifts was interference from the jury rigged heater (a dodgy thing off ebay) as after shielding it off with foil the issues stopped.

The more I study the models the more I think what I’m seeing here is solely down to the suction force being applied due to complicated cavities and large cross sections being in contact with the PDMS at any one time.

Looking at the internals of the model it’s quite clear that while the vent holes in the arm and base of the body might be ok for that section I don’t think they’re enough further up when the augmented arm and the hair are involved.

I do agree about the Zscrew though, it’s always looked like a significant weak spot to me without something securing it at the top end despite the rail and the build plate running up it.

@johnchen cheers bud, I’ll be attempting something else in the meantime while I work on chopping this mesh into pieces. The difficult part is the parts that need chopping are also the highest detailed parts, so it’s a bit tricky.

With regards to the supports in your hawk skull model, what software did you use to create them? they’re rather nice!

Overall I think I’m quite happy with the setup of the printer itself. I’ve never had it quite so accurately calibrated until now, so I’m very sure the issue lies with the model itself and my limited experience of dealing with complex shapes in prints.

Hopefully I’ll be posting something nice soon, I just need to re-evaluate this model overall.

I really appreciate any and all advice guys, it’s a big help and tbh the community here is probably the only reason I’ve lasted this long with the Moai.


#49

Your evaluation of the model in reply to teivion is spot on, on the right track to get her to print nicely, unlike other LCD / FDM printers, the Z rails doesnt actually do that much work, only moving up ever so slightly after the peel, its the vat tilting assembly that does most of the heavy lifting / peeling. ( PM Motor)
You have probably checked it already but there shouldnt be any movement of the z rail if you shake it slightly.

Also the way you installed the PM motor / bracket should be checked against the manual.

A light oil and clean of the rails is also a good idea to remove any debri, on both the z and pm rails.
I used ChiTuBox for supports on that example.


#50


These steps and the few above are critical to get your vat tilting smoothly.

I had to readjust the two silver brackets holding the other side of the vat so the riser rod was moving the black vat frame as vertically linear as possible without any horizontal obstructions.

This was one of the trickier part of the build I must say.

If you want to take a clear photo / video of your PM motor assembly that might help. it tilts during the start up sequence.


#51

do the layer shifts happens always at the same spot? or do they vary? If the former it’s either a problem with the mesh or the supports or some kind of issue with the moai main board. If it’s the former it could be a mechanical problem.


#52

the screw on top of the z axis is not meant to be secured, it’s just there as an emergency stop in case the end-stop sensor doesn’t work


#53

@johnchen just a heads up, the STL you linked, there are some parts of the supports that go below the rest and so It failed to stick to the build plate. Correcting it now though.

Image from Gyazo

Hope you don’t mind but I fixed it up in Meshmixer, you can find it here:
https://drive.google.com/open?id=1-kfyFndTtcA8DVgJSlluk-ml4fIZuU_N

@matt3o I’ve already had a replacement main board so I think that can be ruled out. I think it’s mostly just the model now. I’m working on cutting it into pieces in a way that it should fit back together again (hopefully). In the meantime I’ll be trying other models - like the one jonchen posted above.


#54

getting a lot of thunking while printing the skull, hopefully it’ll come out alright


#55

I can check the 3d model if you can share it


#56

thanks Ben, thats a bit embarrassing, and will definately cause a problem if you have auto centre on.
Thanks for that,

How is the print looking?,


#57

looks like it’s going well @johnchen think the thunking was due to the start of the back of the skull - it’s all quiet now and the supports are holding well.

@matt3o I’ll upload it and send you a link :slight_smile:


#58

The skull came out quite nicely @johnchen There is a lot of banding around the back of the skull which, incidentally, is the part that was printing when there was a lot of thunking sounds I mentioned above.

I think I may need to lower my laser power too as some of the supports on the internals were fused to the rest of the model so I’m guessing it’s overcuring a bit (makes sense since I’m moving over to grey resin now, having ran out of black).

https://drive.google.com/drive/folders/1O5aJ99Wnur0cbazjvqmbUUhaKeFvQs2q?usp=sharing


#59

I think I needed to move the vent hole a lower to the bottom, lines would have been caused by suction.
Its amazing how much little suction will throw off the print.
Glad it came out ok.

Moving forward feel free to post up screenshots of your supports on your new split up model, happy to lend you my eyes.