Why does PVA place support structures in different areas on the same part as PLA support structures?

[RGordon87 0]

Ok. I will try and word this the best that I can. I have a straight pipe. I need PVA support structures because I have a cone with several throughholes inside the straight pipe. However, the PVA not only places itself in my overhangs on the inside of the pipe but for some reason PVA wraps itself completely around the outside of the pipe as if there was an overhang at the top of the pipe but there's not. This is a complete waste of PVA material.

The kicker is, if I change the support structure material to PLA, there are no support structures on the outside of the pipe. I've attached the two pictures of one using PVA support and the other using PLA support so you can see what I'm talking about.

Thanks,

Rachel G.

[ultiarjan 1,081]

I think it's because for pva there's a bigger default ' horizontal expansion' setting. This is an attempt to connect different spots where pva needs to be printed and avoid isolated spots of pva printed on top of pla. This because pva attaches poorly on top of pla. If this is not needed for this model you can lower the amount.

[RGordon87 0]

Thank you for your response. However, the horizontal expansion setting is already at 0. It cannot go any lower. Also, when I looked up what that setting actually did, it says that is allows the user to adjust the size of your 3D print in the X/Y dimension to compensate for the change in size that happens when the plastic shrinks as it cools. I don't think it has anything to do with the PVA material supporting the PLA material around the outside of the part. Am I reading that right?

[ahoeben 425]

There's a similarly named setting called "Support Horizontal Expansion", which acts on the generated supports.