Perimeters being unsupported

[JD95]

When I get parts that have broad curves on the underside, Simplify doesn't put support under perimeters, so the perimeters just fall away, don't attach to anything unless it's wrapping itself around something it shouldn't. This is even with layers of gap set to zero and a narrow horizontal distance from support. I've had a few parts this causes serious problems with, and workarounds meant reorientation such that it needs a lot more support material and run time to finish the part.

[dkightley]

A brief description of the issue you have is not really sufficient for anyone to be able to suggest how you can resolve the issue....and it would be almost impossible for the S3D development team to identify if there is an issue in the software that needs resolving.

Can you please supply a factory file for an example of where you are having this issue. File menu.....Save factory.

[JD95]

OK, you're right. I've attached something that illustrates the problem.

The model files in question weren't mine to post but I've made a quick test model to illustrate the problem.

On the second layer, the two inner perimeters on the second layer won't attach to anything and just fall away for about 40mm spans. I suspect the problem will propagate a few layers, leaving a mess. The machine in question is occupied for another day so I can't test print and post photos but I think inspecting the g code preview should be enough.

I use HIPS as a snap-away support so I turn off separation layers (set to zero). The second material is not reflected in the included.factory file but the support geometry would be the same.

[dkightley]

I would have taken a look at the profile settings and possibly suggested some changes to make......but you attached the stl file and not the factory file....so the only suggestion I can make is to ensure you have at least 4 perimeter shells and ensure the outline direction is set inside-out.

[JD95]

sorry about that

I am inside-out.

More perimeters won't help because there's nothing below it to keep it up. On an inside curve the bead will tend to pull away from existing part.

[dkightley]

For very shallow curves like this, you need to improve the adhesion of the outermost perimeter to the perimeter immediately inside it. There are a few things you can try to do this....

Firstly, ensure you have a filament cooling fan fitted and its ducting pointed to maximise airflow onto the just-extruded filament. Set the fan at 100% (you have it at 60%..not sure if all cooling fans allow fine speed control). You want to hit the filament with as much cool air as possible to harden it to stop it wilting!

Secondly, slow the perimeter printing down ( say to 40%) and increase the extrusion multiplier. I'd consider using a second process for this....set the extrusion width to manual and wind the multiplier up to say 1.00. This will push more plastic out without the extruded lines being shifted further apart...this should force better adhesion.

Thirdly, I'd try thinner layers...again possibly in a separate process. This will reduce the overhang slightly.

Finally, despite your doubts, I'd add an extra perimeter....just to give a little more support.

Of course, one thing I can't do and have no experience of using is a dissolvable support material.....but I imagine if using , you simply get support gaps and separation to zero.....and don't end up with unsupported extrusions.