Best settings for support structures?

[CCA1 15]

I have been working with the experts at Ultimaker to find the best settings for the support structures when printing PLA (or anything for that matter) with the Ultimaker. I have yet to find an acceptable solution. (sigh)

I design parts for a living and decided that instead of sending all these parts out to Protolabs or places like that, I should buy a 3D printer and do them myself, thereby retaining that lost revenue. After much research, I settled on the Ultimaker based on the information available at that time. Since then I have been able to fine tune my prints so that anything that does not need support structures will print very nicely and be very presentable for the customer. However, anything that needs support structures will not turn out very nice.

 

   I have found that .7 for X and Y distance works very nice. No problem there. My issue is the Z distance. If I use .1 for that distance, the support is so hard to remove from the part that I end up destroying some of the part in the process of removal. I have had minimum success with this distance if I have a part that has supports that are easily reachable and not surrounded by the rest of the part. Problem is, I do mostly parts that are shelled out in the back and surrounded by material around the supports. If I go any further with the support structure in the Z than the material that is supposed to be supported by the support structure has too much room for creating a bad surface. And I mean bad enough surface to the point where it becomes un-presentable to my customer.

 I have tried different densities, patterns, support roof thicknesses, etc. The suggestion from Ultimaker (who is still helping me with this by the way. They haven't given up on me) was to pick the brain of the community. The problem is I can not share most of my projects because of NDA agreements.

So I am just asking if there is anyone else out there that has gone through this and found something that gives them a good starting point most of the time with changes here and there based on the part of course. (I realize one setting will never work for ALL parts)

Thank you,

Jason

O yea, I have the Ultimaker 2 Extended Plus.

Cura 2.3.0

Edited December 4, 2016 by Guest

[AreDigg 8]

Now I don't use cura but simplify3d (which I recommend to check out), but when the support of the slicer is limited, I also use Autodesk Print Studio which do supports in a very different way. But what about investing in a dual nozzle printer and use soluable material?

I understand you can't post pictures of your projects. But some example pictures of similar where your issue is shown would help.

[peggyb 170]

for the z distance I usually use the distance of one layer, so when you are printing in 0.1 layers, do a 0.1 distance. Than there is one layer not printed making it a weaker spot.

[CCA1 15]

Thank you for the responses so far.

"what about investing in a dual nozzle printer and use soluable material"

I would LOVE to be able to do that. Unfortunately my resources have fizzled out. I spent what I had on the 2+Extended before the 3 came out. (April 2016) Even if I could sell the 2+ Extended for say $2000.00 ($999 less than new) I would still need another $1500 for the 3 and $2300 for the 3 Extended. Since I have had very little work in the last quarter, this is an unattainable solution. Plus, I really don't want to take a thousand dollar bath on this thing. :angry:

"I usually use the distance of one layer"

This is the solution I found makes the best finish under the support structure. (Usually)

However, it also makes the supports extremely hard to remove. And impossible in small areas or where it is surrounded by "good" plastic.

[SandervG 1,521]

Just a wild idea that just appeared.. since you are modeling the models yourself. Have you considered modeling the support structures too? With some organic shapes you can make sure there is enough room for you to get in with some pliers, we use triangle shaped supports because they should be easiest to remove (like an accordion). As a rule of thumb you could maintain the 1-layer distance, create a small roof and some grips to grab the filament.  

What about that?

With automated generic support I always think it is good, but never perfect because it is never custom made for a certain model. It is like a one-size fits all solution. In your case, maybe a little bit less good than for others.

But if you have the skills, maybe you don't have to settle for (less than) good, but go for the perfect supports.

[geert_2 557]

If you design the models yourself, then also design the support structures. Think about these points:

- Design hooks, holes or other features into the support, so that you can pull them out with pliers, screw drivers, or other tools.

- Allow enough room for these tools.

- Allow enough room for a sharp knife or scalpel (surgical knife) to move in-between the supports and the model, so you can cut the supports loose from the model.

- In difficult to access areas, extend the support to outside of the model for easier access. So you can easily grip it from the outside with a plier.

- Between side walls and support, allow at least 0.5mm spacing, or better 1mm, so that supports don't stick to the walls.

- Between a model layer and the supports, I usually allow 0.5mm spacing.

- Between a support and bottom layer of overlaying object, I usually leave a gap of 0.2mm to 0.3mm.

Thus that gives: last layer of model below support, then 0.5mm gap, then solid (!) layer of 0.5mm as the base of the support, then the support scaffold, then a solid layer of 0.5mm which is still part of the support, then ribs of 0.5mm wide and 0.5mm high, then a gap of 0.2mm to 0.3mm, then the first layer of the model above the support.

- Make a test print with different sizes of gaps, and try which works best for your material, sizes and temperatures. Bigger models require bigger gaps between model and support. Higher accuracy and smaller models need smaller gaps.

Have a look at this image to illustrate the gaps and ribs:

Here too I can cut the supports loose with a scalpel, and pull them out with a plier.

Edit: the ribs at the bottom of the support can help but are not really necessary in my experience. The ones above the support are. And they should be 90° rotated to the direction of the infill of the bottom layer of the part above the support.

Edited December 7, 2016 by Guest

[geert_2 557]

Forgot to say:

Another method that sometimes works, depending on the model is this:

- at the bottom touching the glass plate: a solid layer of 0.5mm thick.

- then a gap of 0.5mm

- solid layer of 0.4mm

- gap of 0.5mm

- solid layer of 0.4mm

- gap of 0.5mm

- and so on...

- solid layer of 0.4mm

- ribs of 0.5mm wide, 90° rotated to the direction of the fill-in of the bottom layer of the model, as shown in the pic above.

- gap of 0.2mm to 0.3mm

- rest of the model above the support

So the support structure consists of separate layers above each other, all "floating" in the air. Due to the sagging of the first layer, they will bond very weakly to the layer below, so they break off easily. So you get a very stable support that is not knocked over, but you can easily peel it off layer by layer afterwards.

It all depends on the model, and it may require some prototyping.

Edited December 7, 2016 by Guest

[CCA1 15]

Just a wild idea that just appeared.. since you are modeling the models yourself. Have you considered modeling the support structures too?

What about that?

 

Good advice.

And yes, I have considered this. It would be fairly easy in most cases for me to do this. The only thing missing is "what do I draw?"

As you know, Sander, I have been printing many of the same parts with different settings to try and find that "ideal" setting for most of the supports. (I say most because we all know "one size fits all" doesn't apply here ) I think once I find those settings, I may have to resort to designing my own supports, using them, to obtain the best results.

 

- Design hooks, holes or other features into the support, so that you can pull them out with pliers, screw drivers, or other tools.

 

Excellent idea. I will incorporate that when I do manual supports.

 

- In difficult to access areas, extend the support to outside of the model for easier access. So you can easily grip it from the outside with a plier.

 

Unfortunately, most of my problem areas are from "trapped" supports under the part with no way to extend them.

 

- Between a support and bottom layer of overlaying object, I usually leave a gap of 0.2mm to 0.3mm.

 

Don't you find that this leaves an unacceptable surface? (I'm curious becaus in my experience, anything over .1 or .15 leaves a surface I can not send to my customer.)

I love the image explanation and am anxious to try just that. Thank you!

Also liked the method suggested in the "Forgot to mention" post. I will be trying that too.

Thanks for all the help guys!

[peggyb 170]

You can also try to let Meshmixer generate the supports for you (look for tutorials)

The generated supports can be partially deleted or added to your liking. When satisfied, export the whole thing and load into Cura to print.

[geert_2 557]

Hello again,

I have tried smaller gaps than 0.2mm too, but that did not work well with my filament (Ultimaker PLA and colorFabb PLA/PHA) and my models.

If the gap is too narrow, the bottom layer of the model sticks too hard to the support. When trying to remove it, this severely damaged the bottom layer of my models.

With a gap of 0.2mm or 0.3mm, and the ribs rotated 90° as shown (very important), this gave the best balance between an acceptable bottom layer, and ease of removal of the support. At least for my relatively small models.

For bigger models, I might try a bigger gap of 0.4 to 0.5mm. And I would print the model in such a way that the support is located somewhere where surface quality is not too important.

The effect of the ribs is double:

- They cause the support to not stick too hard to the model, so you can easily remove it. It only sticks on the ribs, not in the gaps in-between.

- The ribs prevent sagging of the first layer.

- They cause the first layer of the model to be 90° rotated compared to the direction of the ribs. At least in my version of Cura, 14.09. I don't know about earlier or later Cura-versions. This also helps in creating a nicer bottom layer.

Of course, the bottom layer is always much uglier than top layers, due to the 0.2mm sagging, but in most cases it is still acceptable, especially for technical models. Not for juwelry of course.

I have tried different shapes of ribs, but a rib of 0.5mm wide, with a gap of 0.5 to 1mm seems to work best for me. And it is easy to create on a 0.5mm grid in my editing program (DesignSpark Mechanical), also important.

The solid layer in the supports, on which the ribs are modeled, is ment to create a more stable and equal base plate for the ribs. This also improves the quality of the first model layer above the support. The support itself must be very stable.

In the image above, I designed the holes in the support at the sides, in which I can insert pliers or tools. In some other models, I did design the holes at the bottom, so I could pull the supports out from the bottom.

As you also see in the image, I have cut these supports in four separate parts. Not only because of the different heights in this test, but more important because those separate pieces make it much easier to remove the support. Especially in difficult to access areas. You can easily wiggle each separate part loose. This is not possible if the support is in one big piece.

A thing to watch out for, is that you do not get a massive, solid brick of support that you can not wiggle loose, can not access with tools, and can not get out of the holes. Don't ask me how I know.

Although in some other occasions, a solid support worked best: for example if I need a deep, small square hole in the model, then a solid support block that extends way out of the hole worked best: so I could easily grab that extension, and wiggle it and pull very hard, without breaking the support itself. It only would break between support and model. Otherwise it would not have been possible to get the support out of the small hole.

Sometimes it took me more time to (re)design the supports than the model itself.

I would suggest that you design a couple of similar support structures that fit your particular models, and try which gaps and designs work best for you. It depends very much on the model, and on how you are going to remove the support. The support is an integral part of the design.

Also forgot to say: if you print cooler, the bonding between support and model will be less strong, and the bottom model layer will sag less onto the support. So this gives a nicer bottom layer of the model too, and makes the support easier to remove.

For high quality, a temp of 190°C and slow speed of 20mm/s would usually work better than the defaults for PLA (210°C - 50mm/s) in most cases.

In some cases, for very accurate prototyping and complex surfaces, the use of supports was not acceptable at all, or required too much cleaning work. Then the solution was to split the model in several parts that I could all print on a flat side, and then glue these parts together with cyanoacrylate glue. Roughening the surface with a file, and wiping it with an activator before glueing, gives very strong bonds. I haven't had a faillure yet.

Or in other prototypes, I just mounted the separate parts together with a few M4 nylon screws and nuts. This is also an option, especially suitable for technical models.

Using snap-ins to click parts together is not recommended for PLA: it is too stiff and too brittle. And the layers in Z-direction cause high stresses on the snap-in clips, so they easily break off.

If I don't forget, I will try to find a few more images of supports next week.

[geert_2 557]

Here are a few pics of support-concepts that do work well for my designs. These are just things I learned the hard way; I am in no way a "support design specialist".

In all these pics, the ribs on top of the supports are 0.5mm wide, and the horizontal gaps between the ribs are 1.0mm. Usually the vertical gap between ribs and the bottom layer of the model above the support is 0.2mm.

Pictures:

Bottom left: floating supports: each solid layer and each gap are 0.5mm high. The bottom layer of the supports is sitting on the glass plate, to create a good stable base. The other supports are just floating above it, without connection. This gives a very weak bonding, so the layers can be peeled off. Spacing between the ribs and bottom layer of the model is 0.2mm.

Top left, center left: these supports do extend from the model, so I can grip them with pliers and wiggle them loose. Otherwise they are very hard to remove. The width of these supports is only 5.5mm, height is even less. These are too small to get in with a knife. The yellow block is a bit more than 1 cm wide.

Top right: side view of a support test model, with different gap heights between supports and model, to try which worked best. The separate blocks make it much easier to remove these supports than if they would have been in one block. Small electronic or dental pliers do fit around the center Y-column of the supports, to pull them out.

Center right: in this example one support block is extended, so you can easily grip it with pliers, or with your bare hands, and wiggle it loose. Or you can move a tool into the hole to pull. This is just to show the concept.

Bottom right: slanting the support and extending it a bit like this, greatly improves the quality of the first layer of the model above the supports, near the edges. Otherwise that first layer outline sometimes falls off the supports, which these extensions do prevent.

In this cyan test block it took a lot more effort to design the supports than it took to make the block itself.

These are concepts that a standard automatic support generator obvious would have trouble to do. So for difficult models (small, critical dimensions, hard to access) it may be best to design the supports manually.

Edited December 12, 2016 by Guest

[CCA1 15]

Geert_2,

Awesome information! Thanks for taking the time to do that extensive response with images. This will help a lot in my future attempts. I have run short of funds and short of filament so my testing days have been over for a while. Hopefully work picks up soon and I can get back into the swing of things.

Thanks for everyone's responses.

JB

[AreDigg 8]

Another thing to think about is to go down on nozzle size, removing support printed with 0.25 size is markedly better than I.e. 0.40 mm.

[CCA1 15]

Thank you AreDigg. I will consider that as well on some of my smaller prints. (otherwise it takes too long sometimes)