New support material method.

[coen 11]

Happy New Year!

 

While the fireworks was going off outside my Ultimaker was happily printing away at the parts I was having trouble with, downgraded to 13.06. One of them failed, of which I will post a separate topic. However, the parts are illustrative of problems of the new support method, so lets investigate:

First of all the parts to be printed:

I'm printing them for a client, and they are apparently prusa parts: https://www.thingiverse.com/thing:119616 (xEndidler and xEndMotorV2).

As you can see these are quite complicated engineering parts. Horizontal areas spanning some 6-8cm won't be printed decently with just bridging alone (at least not with my current configuration), so I need supports for these parts.

I tried some different orientations to print them but in the end, keeping them as is seemed to me the best orientation:

 

• The large open hole keeps the best shape (no overhangs or support in it)
  
• Only one dimension with possible shrinking issues
  
• All orientations would need support material 'everywhere', so no significant difference in support volume for different orientations
  

Supports generated in 13.11 (no upgrade to 13.12 yet due to failing to do a firmware upgrade last time, and the difficulty to track settings and quality impact of settings while continuously changing SW):

As you can see, this support block will be locked in by the part itself, making it impossible to get it out:

 

• It is surrounded by the part itself, even with corners and ends locking it against rotation
  
• the support consist of a 'closed box' making it rigid and stiff
  

 

This is wat 13.06 creates:

 

This is a flexible and open support structure, which can easily be removed.

 

By the way: compare the amounts of support material cura calculates: 84gr for the old method, and 82gr for the new.

 

This leads me to think: 'if it ain't broken, don't fix it'.

 

So, that gives us the first question to discuss: what exactly is broken in the old implementation?

 

I'll try my 2 cents:

 

• Creating a 'cube' of material instead of a shape that starts small and increases to the right size is a waste of material
  
• Starting supports on the object itself instead of on the build platform damages its quality
  

With an extra step in the workflow both of these problems can be currently fixed by using Meshmixer. Thanks for the great tip illuminarti!

What needs fixing in the new implementation IMO:

 

• closed method can only be used for 'convex' support parts: concave polygons needs to be broken up in multiple convex support parts (some explanation here: http://www.rustycode.com/tutorials/convex.html)
  
• Special treatment for difficult shapes: for instance a blind hole or hollow cube with one opening: how to remove the support?
  

 

[Daid 306]

Interesting case, I did not think about this case when doing the new support material. It is clearly a problem for break-away support in some cases.

Note, the old method was broken in many ways, many ways that do not impact you. But it has quite some issues.

While there have been complains on the support material (as with every change) this is the first time someone makes a real case. So I'm planning to do something about it. I might be adding an option for the "wavy walls" support. As cutting the concave polygon into multiple convex polygons sounds easy but is difficult to do for all cases in a good way.

Note, the new support material is awesome with water-soluble support material.

Finally, most reprap parts are designed so they are printable without support material. I would rotate the X-END-MOTOR by 90 degs so it's flat on the biggest area. Bridges should be able to take care of all the overhangs then for both objects.

 

[coen 11]

Thanks for your reply and your great work on Cura Daid. Great that you'll take the feedback to work.

Attached you'll find some pictures of the final print, with meshmixer supports included. I'm really,really fond of these after this first print: They're very easy to break off, don't take much time/material to print, and do provide adequate support. As with the concave parts, these also are probaby more difficult to generate, as the topology of the object also plays a role. If you're going to spend serious time rewriting the support this might be the way to go (please add a function to bring the supports to the outside of the part on the buildplate then).

(first pic shows two failed attempts: 1st one with 'wavy' supports had material feed problems, the 2nd one was with fix horrible B, while I should've chosen A).

As for bridging: I'll do some experiments just like gr5 did, I think my fan is very off-ideal at the moment to do this well (one blade has broken off and I'm waiting for the replacement from Ultimaker Central.

And well... dual head, water soluable supports: :wub: ... however no extra money atm... first for a sabbatical (and afterwards a heated bed).

 

[3dcase 37]

@Daid,

Morning..

 

While there have been complains on the support material (as with every change) this is the first time someone makes a real case. So I'm planning to do something about it. I might be adding an option for the "wavy walls" support. As cutting the concave polygon into multiple convex polygons sounds easy but is difficult to do for all cases in a good way.

 

When planning to make some changes to the support.

Please take a look at the support distance settings. Perhaps I think the other way around as You do.

But decreasing the distance between support and mainpart, should (imho) result in more support. Since V13.10 I have to use a higher distance to get it closer to the part.

http://umforum.ultimaker.com/index.php?/topic/3472-cura-1311-support-lost-direction/

Regards Kees

 

[drblackadder 0]

I'm looking forward to being able to choose the wavy support again. The new support is great in many ways that the wavy support was deficient, but in some instances I need to go back to cura 13.06 to use the wavy support, as the new support proves problematic.

Keep up the good work!

 

[parabolic 0]

Finally, most reprap parts are designed so they are printable without support material. I would rotate the X-END-MOTOR by 90 degs so it's flat on the biggest area. Bridges should be able to take care of all the overhangs then for both objects.

 

Daid,

Im not sure about the OP, but when I print some of my Prusa derived bearing holders I WANT to print them perpendicular to the linear bearings. The style he has shown (what I like to use) is kinda a tensioned friction holder for the bearings. If printed another way the "grain" of the print creates a weak spot and may break easier.

I am hoping that you will add a sort of selectable support system in the future. some areas that print fine without support are a pain in the ass to remove when printed with support (i.e. bolt through holes). I may look into meshmixer, however I LOVE the fact that Cura is a "one stop shop" for printing an stl. Id hate to have to implement another program to do this function.

In any case - THANKS for the program!

 

[marshal433 0]

Hi I am having issues where on the first layer it will print the model well, however when going over to do the support it rushes it and the plastic dose not even touch the build plate and get carried away with the print head, I'm using the UM2 with PLA normal quality speed as when I use my own settings it never works . Dose anyone have any tips to help it stick or make it do the support slower?

When I do normal prints with no support it works perfectly.