NylonX - over-extrusion at the start of each layer only on OD of part?

[jirodriguez72 19]

So we are printing a part that is basically a cylinder at the beginning and noticed the only on the OD of the part we are getting lines on the OD where each layer starts, then about 1/4 of the way around the part they blend back into the part. On the same part the ID looks fantastic! It's super noticeable on the first few layers as well. I have it set to randomize the layer starts, and I printed one with the layer starts lined up and it was really obvious to see. We love how strong the NylonX is, I just need to figure out how to get it to not over-extrude at the start of each layer. Any suggestions would be appreciated!

 

 

 

[geert_2 558]

I am going to do some wild guessing: could this be a result of high pressure in the nozzle, after printing infill at high speed and temp, and then suddenly slowing down to the outer layer. Thus the built-up pressure and temperature has to leak away, sort of? Or a result of a move through the air, where it temporary stops extruding, with the same effect? Or both together?

 

If the first, then setting all speeds and temps equal should minimise this effect. If the second, printing slower and cooler should minimise it (but printing cooler of course might reduce layer bonding).

 

But as said, this is guessing.

 

[jirodriguez72 19]

Thanks I will look into that. I was also guessing was something along those lines, but wasn't sure where to begin.... there are so many different settings that could tie into that. We definitely need the high layer adhesion these will be working parts that we hope to spin at 3600 RPM.