Third party "Wavy" prints in vase mode

[triise 1]

Hi everyone,

 

I´m trying to print the forward part of a catamaran hull, and is doing it in vase mode on my printer.

However the print surface is becoming uneven and bulky. Any tips on settings in Cura?

Using a Creality CR-6 Max and PETG at 235 deg.

 

båt front v1.stl

[GregValiant 989]

I have printed a couple of boat hulls in PLA and they came out well.  None of that rippling that you have there.

Did that happen after the print had completed?  It would seem that if the condition was going on during the print that it would be a lot sloppier as one layer would be overhanging the previous layer.

Did you have the layer cooling fan running during that print?

[triise 1]

Hi,

 

It happened while the print was going on. I have the cooling fan running at 100%, but also 50 mm/s speed, så maybe its going to fast?

[glx 18]

Hello, 

 

That happens because straight thin flat surfaces have a very poor stability. You can bring some structure into your object that don't bend easily, so it can reinforce itself. You can see on your photo, that the curved area is nearly unaffected while the straight part is bent. Think of a sheet of paper, it bends right away, but if you have a wavy piece it can support loads pretty well.

When material cools down it shrinks a little, that introduces forces into your print (basically the same principle why prints tend to warp), if there's nothing that withstands these forces, the print bends and wrinkles up. 

[GregValiant 989]

Just for a comparison I print PETG at 35mm/sec with no fan unless there is an overhang that will develop a feather edge.  Typically when I print in spiralize mode I kick up the line width to 0.6 to make it stronger.  That would also increase the total heat that has to dissipate.  Spiralize usually drops the speed because the layers are quick and it bounces into Minimum Layer Time.  That boat is fair sized though so maybe you are hitting 50 going around.

I think you will have to experiment to find the sweet spot.  If you sink the model into the build plate you can print just a portion that is going bad.  When printing abort after 25 or 35mm.

Edited March 4, 2022 by GregValiant

[GregValiant 989]

Being an old RC guy I decided to take a stab at this with what was left of a roll of PETG.  Not good.  Using my regular PETG profile with .6 line width the part warped just as @triise's did.  Fan on, fan off no difference.  I think if you want to print this in PETG (and not move to adding bulkheads or stringers) then you might try putting a plastic garbage bag over the printer as a temporary enclosure.  I've had good luck doing that when I print with ABS.  You can hold the front open a bit to peek in.  I move the filament roll off the top of my printer when I do that.

 

I also had a couple almost empty rolls of PLA and so I used some up on this.  That print came out very well with no "oil can" warps like the PETG print has.  The print was a lot stiffer as well.  Unfortunately, if you leave a PLA hull in the car on a sunny day you may end up with a puddle of PLA in the trunk.

 

Here is the black PETG attempt with a severe oil can warp on both sides.  That was all the scrap PETG I had laying around so I couldn't take it any higher.

 

The PLA attempt looked pretty good.  You can tell where the ribs are in the STL file (although they don't print).  This is the top 250mm of the hull model.  (I keep thinking "Bismarck" when I look at it.)

 

 

 

 

[triise 1]

14 hours ago, GregValiant said:

Being an old RC guy I decided to take a stab at this with what was left of a roll of PETG.  Not good.  Using my regular PETG profile with .6 line width the part warped just as @triise's did.  Fan on, fan off no difference.  I think if you want to print this in PETG (and not move to adding bulkheads or stringers) then you might try putting a plastic garbage bag over the printer as a temporary enclosure.  I've had good luck doing that when I print with ABS.  You can hold the front open a bit to peek in.  I move the filament roll off the top of my printer when I do that.

 

I also had a couple almost empty rolls of PLA and so I used some up on this.  That print came out very well with no "oil can" warps like the PETG print has.  The print was a lot stiffer as well.  Unfortunately, if you leave a PLA hull in the car on a sunny day you may end up with a puddle of PLA in the trunk.

 

Here is the black PETG attempt with a severe oil can warp on both sides.  That was all the scrap PETG I had laying around so I couldn't take it any higher.

 

 

The PLA attempt looked pretty good.  You can tell where the ribs are in the STL file (although they don't print).  This is the top 250mm of the hull model.  (I keep thinking "Bismarck" when I look at it.)

 

 

 

 

 

 

Hi, and thank you very much for a very detailed explanation and you even tried to print it 🙂

 

I think maybe I'll have to do this without the spiralize-mode in Cura. It was just a way to make this go a bit faster. I'll have to print 2 of theese and 4 more uniform length pieces to go behind it.

It'll probalbly be better with a more thicker wall. And the normal print procedure.

I have made a plexiglass casing for the printer, to keep the temperature, but havent used it yet. Maybe a good time to try it.

[GregValiant 989]

Looking at the little black print I did - there is a lot of stress in the areas of the warps.  I'm thinking the outside cooled faster and there was some shrinkage that was different on the outside than on the inside.  Printing in an enclosure may be the answer.

Too bad the model didn't come with the inside hollowed out leaving something like a 5mm thick hull and deck.

Hang on...

Try this...Bring the model into Cura.  Add another instance.  Scale model 2 uniformly at 90%.  Move it to 0,0,+5 so it is exactly inside of the real model but 5mm off the build plate.

With model 2 selected select Per Model Settings, Modify Settings for Overlaps, Cutting Mesh - and select Wall Count, Top Surfaces, Bottom Surfaces, Infill Density and set them all to 0.  It's still a very long print but it won't require infill throughout the whole structure.

Here you can just make out the shadow outline of model 2 inside the real model.  A spiralized model would be pretty delicate and this one could hit the dock and be OK.

Edited March 5, 2022 by GregValiant

[triise 1]

On 3/5/2022 at 11:11 PM, GregValiant said:

Looking at the little black print I did - there is a lot of stress in the areas of the warps.  I'm thinking the outside cooled faster and there was some shrinkage that was different on the outside than on the inside.  Printing in an enclosure may be the answer.

Too bad the model didn't come with the inside hollowed out leaving something like a 5mm thick hull and deck.

Hang on...

Try this...Bring the model into Cura.  Add another instance.  Scale model 2 uniformly at 90%.  Move it to 0,0,+5 so it is exactly inside of the real model but 5mm off the build plate.

With model 2 selected select Per Model Settings, Modify Settings for Overlaps, Cutting Mesh - and select Wall Count, Top Surfaces, Bottom Surfaces, Infill Density and set them all to 0.  It's still a very long print but it won't require infill throughout the whole structure.

Here you can just make out the shadow outline of model 2 inside the real model.  A spiralized model would be pretty delicate and this one could hit the dock and be OK.

Did now try your approach to the printing. Went very well!

 

[GregValiant 989]

Well congratulations.  That looks pretty good and it will be a lot stronger as well.

 

I haven't had any luck keeping spiral vases waterproof and so the wife just uses them for dry flowers.  That thicker hull has a much better chance at keeping dry on the inside.  I suppose if you paint it that would help as well.

 

 

[triise 1]

22 hours ago, GregValiant said:

Well congratulations.  That looks pretty good and it will be a lot stronger as well.

 

I haven't had any luck keeping spiral vases waterproof and so the wife just uses them for dry flowers.  That thicker hull has a much better chance at keeping dry on the inside.  I suppose if you paint it that would help as well.

 

 

I wasn't plannig on painting, but it might be a good idea. The print looks very tight and I assume it's watertight. But a bit of paint won't hurt, so thanks for the advice. Second print is now in the works (second front part). I'll have to do some design changes on the 2nd and 3rd aft parts, as I now have decided to have the batteries (custom made Li-ion) inside the potons instead of on top.

The plan is to use two underwater thruster motors mounted on each poton, and steer the boat with differential thrust using a Pixhawk and Ardurover software.