Help for printing overhangs!

[Viceman]

Ok, I have this issue when printing ABS parts (havent tried other materials yet). But when Im printin overhang, the part edges are much higher than extruder itself. And this is caused most probably (on my opinion) because the ABS shrinks and it is pulled toward the middle. Here's couple photos and video to show the problem:

https://vid.me/yH8Q

In the video you can see how the extruder actually pushes the part edges when printing. And this especially very bad problem when printing wider than 34mm parts because when the edges of the parts rise, the second extruder collides with the part.

What would be the best solution to solve this? Use support to prevent edges to rise? Can the supports in S3D be angled? So they don't come straing up? I have tried cooling to fix this but it didn't help as I hoped.

Is it good thing to add manual supports into my designed 3D part? See the attached picture. The blue part is meant to be support, and if I use circular patter to make those about 10 around the part?

[JoeJ]

Adding extra fan cooling and printing at smaller layer heights makes a big difference with overhangs. That has helped me a lot

[MikeO]

Adding supports will help a lot. That way the material can't sag, so it's not pushed out of the way and letting more plastic build up. You can experiment with support density, but it looks like you'll need supports all the way around, without gaps.

Cooling should help, just for grins you might try running a cooling fan, even on ABS -- if there's a fan on the print head -- at 100%, just to see what you can gain from that. I do that with some problematic ABS prints.

Another way is to print multiple copies at once, so the top layer on one copy has a chance to cool while the printer is doing the other one.

Also you might experiment with going to the Extruder tab, and setting in some "retraction vertical lift" -- so the heads will lift some during moves. 0.2 mm or more is a good place to start. Heck, tell it 1 mm lift just so you can see the biggest effect to see if it helps any.

[Viceman]

Well, I havent got much time to test these, but one thing I noticed about supports. I tried to print 3Dhubs Marvin, and i manually added supports under it and behind, but the behind supports leaves about 2-3mm space between the part. So whats the point using support if those does not touch the part? Or what I have done wrong?

edit:
I attached a screenshot from S3D. What I want, is a support that touches the part all the where it is made.

[dkightley]

Just as an exercise, turn off ooze control in your profile (temporarily) and take another look at the preview. The preview shows where extrusion takes place...and ooze control stops the extrusion short....and I think its that what you're seeing.

And don't forget to put ooze back on afterwards.

[Viceman]

Just as an exercise, turn off ooze control in your profile (temporarily) and take another look at the preview. The preview shows where extrusion takes place...and ooze control stops the extrusion short....and I think its that what you're seeing.

And don't forget to put ooze back on afterwards.

Well, turning the ooze controll off didn't do anything. I printed the part last night and supports didn't touch the part.

[dkightley]

Duh!! SIlly me. I must have thought you had added support as part of the model....something I was actually doing when I posted to try and cure an issue I'm having with support!

Have you checked what value you have for Horizontal offset for support? You may need to reduce it to get the support to hug closer.

[Viceman]

Duh!! SIlly me. I must have thought you had added support as part of the model....something I was actually doing when I posted to try and cure an issue I'm having with support!

Have you checked what value you have for Horizontal offset for support? You may need to reduce it to get the support to hug closer.

Uh, yeah.. it was a question in first post is it wise to do so. So mislead you a bit . I changed the horizontal offset from part to 0,00mm but it still doesn't touch the part? I also tried to set it to 1,00 but it doesn't change nothing in print preview.

[Rebekah_harper]

there is also a layer seperation from part. although it looks like about 2 to 3 layer seperation. this is a defferent setting from horizontal offset.

you could argue that the layer seperation is basically a vertical offset from part.

[Viceman]

Im crying out loud! I had 2 processes in this part, and I edited the top one Now that I changed the values in bottom process it touches the part. thanks guys.