Hacker News new | past | comments | ask | show | jobs | submit login

This is better because it has uniform extrudate geometry. That is, portions of past planar layers are omitted and then the nonplanar layer is of uniform thickness.



Intuition tells me variable extrusion generally should yield stronger parts. Adhesion between stair-stepped and non-planar layers in this method is probably subpar (with the emergence of new gaps). With variable extrusion, as long as the variability isn't too large layer adhesion should be kept fairly unchanged, maybe even stronger if there's a certain waviness (the waves increasing surface area).

Actually I wonder if internal waviness could be a useful method to add strength in general (area should be increased as ~1/cos(angle), or ~(1+angle/29) for very small angles, i.e. about 3% per degree).


What I'm saying is that the first variable layer is of relatively constant thickness, compared to previous approaches which attempt to taper layer thickness to slowly introduce curvature.

The problem that results is the actual dynamics of the extrudate varies a lot, going through a fixed size nozzle: there's a relatively limited range of shapes that do not excessively impede flow (and risk jamming/clinging to nozzle/dragging) and are sufficiently smashed into the previous layer. So if you have layer thickness varying a bunch over an otherwise continuous layer, pretty easy to have poor adhesion in many places or pressure building and later overextrusion.

Also there's a fair bit of lag-- often hundreds of milliseconds- between extruder movement, pressure change, and extrudate geometry changes. When you're moving the nozzle at, say, 100mm/s over the surface, the uncertainty of this lag translates to a big uncertainty of where on the part extrusion thickness changes.




Guidelines | FAQ | Support | API | Security | Lists | Bookmarklet | Legal | Apply to YC | Contact

Search: