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Separate suports on object  

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ben.g16
(@ben-g16)
Estimable Member
Separate suports on object

I am having trouble getting supports to work properly on an object.  Specifically, I need the direction of the support layer to be perpendicular to the object to get a good bottom surface and to be able to remove the support.  I can see the direction of the layer scan using the Preview command.

My problem is I have multiple layer heights that need support.  One layer prints with a scan angle of 0º, and another prints at a scan angle of 90º.  When the support structure scan is parallel to the object scan and the support fails.  The object sufrace is rough and almost impossible to remove.  The picture shows the problem.

Item 1 is a lower view of a test piec eshowing three levels

Item 2 shows the support structure direction

Item 3 shows the first object interface, which is perpendicular to the support structure (no interface layers)

Item 4 shows the second object layer, which is parallel to the support structure. It fails.

If I turn the support structur 90º to make it peperpendicular to the second layer, th result is shown in Item 5.  The third layer is the narrow strip to the right in 5.

Using interface layers gives the same results.  The problem staye the same.

I tried turning the supports to 45º, but that is very hard to remove, and not really a good fix.

I want to find a way to have the support structure be perpendicular to the different object layers.  

Is there a way to divide the supports and turn them separately to the correct angle?  I am thinking I may have to draw my own support structures oriented the correct way and add them to the slicer.

Posted : 28/04/2020 3:05 pm
Area51
(@area51)
Member
RE: Separate suports on object

Judging from the image, there is less support needed if the part is flipped top/bottom (as shown on picture 5) before printing.

There is properly a good reason for not doing that, but it is not obvious from the images.

Have a look at my models on Printables.com 😉

Posted : 28/04/2020 10:51 pm
ben.g16
(@ben-g16)
Estimable Member
Topic starter answered:
RE: Separate suports on object

I may not have been clear.  Pic #1 is the upright orientation looking from the lower left.  Pic # 5 is upside down to show the bottom patterns.

This test object is a portion of a real object that is ~ 55mm x155mm.

My original goal was to have all support filaments perpendicular to the object filaments.  I couldn't find a way to make separate support structures inside PruserSlicer, and I decided to give up trying that route.

However, when I post something, a number of ideas always come to mind, so I did more research and printed 5 more variations.  One turned out to work pretty well, so I think I will focus on it.

First, under Print Settings, I increased the number of Perimeters to 4.  This strengthens the wall and helps removal of the support.

Second, under Support Material, I made 2 interface layers with 0 mm spacing, effectively making a solid surface just below the object surface.  This effectively eliminates having a support surface with filament direction parallel to the object filament, which causes a mess.  

I had created solid surfaces before and put them just below the object surfaces, but I found out you can do the same thing in PreserSlicer.  I decided on 2 interface surfaces, so they would be flexible, which I hoped would aid removal.  Not sure if this matters, but it worked.

Then I increased the XY wall separation to 75% (of the wall thickness). I have found a tight wall separation distance makes removal harder.

I reduced the Contact Z Distance to 0.15 mm.  This was risky.  Whenever I have gone below 0.2 mm in the past, the support stuck to the object so bad I had to scrap some parts.  I hoped the solid but flexible interface layers would come loose without all the previous hassles.

Finally, I widened the support Pattern Spacing to 4.5 mm.  With the solid interface layers, I figured the vertical supports could be fewer, and give less resistence to removal.

The final result is shown in the Pic below (bottom view).  The right end is on the print plate.  The middle section and left end are the surfaces needing support.  While it is not perfect, is is a lot better than I have gotten before.  I used a sharp knife to slice between the support and the object, then twisting it to pop the support off.  This worked much better than grabbing the support walls and pulling away from the object.

Posted : 29/04/2020 4:23 pm
Area51
(@area51)
Member
RE: Separate suports on object

That is a very nice result 🙂 

Have a look at my models on Printables.com 😉

Posted : 30/04/2020 9:20 am
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