Droopy Bridges with PLA Help

[Brian]

Hi guys,

I need some tips for getting better bridging with PLA prints. I have a cylindrical object with a couple of diameter changes in the outside that I am having problems with. The shoulders are about 2mm wide, and when the printer prints the first layer of the overhang, it kind of prints it along the side of the previous layer and it sags and droops randomly making a horrible looking worm of filament where there would be a shoulder.

I've played around with turning on support material, but that resulted in my entire part being encased with a support shell that is stuck to it so tightly I couldn't cut it off (there's probably settings I need to make this less dense) but I would think that there must be something I can do to make this work without support because I have seen some models others have made here that have a lot larger undercuts and they print fine.

One thing I tries was to fillet my overhangs or make them 45 degrees instead of 90. The angled ones came out better, but the layering there looks wavy and blobby, so I think I must need to make some adjustments to get it better. I also tried printing the fan shroud, because it has some bridges, and it was really saggy there too. The ABS fans I did on my first print were better.

Are there any tips or suggestions I can try to improve the undercuts?

Thanks!
Brian

[RAMTechRob]

I found that 30 degrees was a good starting point for my overhangs.

[Brian]

I can certainly try that. It makes sense that it should keep some material under the new layer that way. Thanks.

Another question I have is if the print speed or temperature would have an effect? It may be hotter is worse because the material sags, or perhaps hotter is better because the material is more fluid and has less force on the layers below. I don't know which way to go. The same thing for print speed. I can think of reason why slower would be better and other reasons wh faster would be better, so I don't know what to try first.

[Holy1]

you might want to try this >>http://forum.seemecnc.com/viewtopic.php?f=35&t=5632 .<< to get more air on the PLA.