Steep Overhangs - advice and help?

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stratogavster
Posts: 120
Joined: Tue Jul 17, 2012 9:04 pm
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Steep Overhangs - advice and help?

Post by stratogavster »

Hi All,

I'm trying to print parts with what could be classified as steep overhangs (45 degrees or so). I'm not getting good results and i'm having threads fall away from the part as there is not sufficient support material to hold it in place.

Having not messed with the profiles supplied on the Felix website I was wondering where I should focus my attention within SFACT to improve the overhang printing output?

Thanks :)

Kjetilei
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Post by Kjetilei »

Hi stratogavster,

45 degrees shouldn't be a problem. What layer height/profile are you using? Could you provide photos?

stratogavster
Posts: 120
Joined: Tue Jul 17, 2012 9:04 pm
Location: United Kingdom

Post by stratogavster »

Hi there....

Production full support is the profile....it seems to not get support material close enough to the steep feature hence I get dangling threads :(

Layer height I understand is 0.25mm by default? though I have a print running now at 0.2mm...that is if the settings have 'stuck'.

The overhang i'm trying to print is around 45 degrees though only spans around 4 or 5mm....see pics

In general the support sucks...it sticks too well to the part and renders the surface unusable!!! :( (this is my first DIY 3D printer....used to have access to a pro Dimension FDM machine with dual extruder based support which came off beautifully and printed good parts....though not much better than a Felix or any other Reprap for that matter.....didn't justify the £30k price!!! :P)
IMG_8398.JPG
IMG_8400.JPG

Kjetilei
Posts: 334
Joined: Fri Mar 16, 2012 8:26 pm
Location: Stavanger, Norway

Post by Kjetilei »

The way I see the photo, this is a problem more about bridging than overhang (?)

Using support can be a pain in the %$&. You could try to adjust the support settings to see if you get the needed improvements. I've had success with that for some of the parts I have printed.

Another possible solution could be to "embed" support structures in the model (which can be time consuming and hit and miss since you normally want as little as possible support material for easier cleaning up).

stratogavster
Posts: 120
Joined: Tue Jul 17, 2012 9:04 pm
Location: United Kingdom

Post by stratogavster »

Actually forgot to mention...the odd thing is this part is rectangular and has the chamfered edge all the way around, yet the support didn't generate in one section along one edge :?

Hence the confusion...certain its managable but the overwhelming interface of SFACT and the learning curve has given me cause to ask for help :D

Kjetilei
Posts: 334
Joined: Fri Mar 16, 2012 8:26 pm
Location: Stavanger, Norway

Post by Kjetilei »

One quick way of getting different support (without messing with the settings) would be to rotate the part, e.g. 45 degrees, in Repetier and see if the generated support covers the chamfered edges better.

satoer
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Post by satoer »

Have you tried to use a layer height of 0,2mm (Carve button) and a activated skin (Skin button) with horizontal infil of 2, horizontal perimeter division of 1 and vertical divisions of 3?
This way the outside layer hight is 0,06 mm high so there's more flesh to bond under the layer below.
skin.jpg
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stratogavster
Posts: 120
Joined: Tue Jul 17, 2012 9:04 pm
Location: United Kingdom

Post by stratogavster »

not tried that....and from the diagram makes perfect sense and seems to be exactly the solution in theory!...will give it a try! though i'm not sure if this is already enabled in the standard Felix profiles?

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gfeliksdal
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Post by gfeliksdal »

@ satour: To my knowledge the skin plugin works differently. It divides the outer perimeter in smaller layers stacked vertically on top of eachother. For vertical walls this gives very nice results, but for angled walls you will still see the large steps of the un-skinned layers.
My best practice to get good overhang performance is this:
- As low as possible temp
- slow perimeter printing
- the lower the layerheight the better. 0.1 in my experience gives better overhang performance than 0.2mm layerheight.

@: For the object you've shown, you could better use the "enclosure" profile as a starting point. I've tuned that specifically for your requested sample a while ago. It gives relatively easy to remove support material and still enough support for the low layerheight.

Kjetilei
Posts: 334
Joined: Fri Mar 16, 2012 8:26 pm
Location: Stavanger, Norway

Post by Kjetilei »

I also believe skeinforge stacks the half height layers directly above each other. But I seem to remember having read somewhere that Slic3r (or some other slicer) actually supports double skin resolution - something that should work the way satoer visualized. If so it is a great trick I have never thought of.

Satoer: If you're the originator of this idea you should claim ownership to it and demand a hefty royalty ;) Great idea!

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