Polishing Your Noz

[nick-foley 4]

After some of my bad firmware decisionmaking caused the printer to repeatedly hulk-smash its build platform into its hotend while it was moving around, I got worried that some elements of my printhead were knocked out of alignment. While I was inspecting all of that (turns out everything was mostly ok) , I noticed that the tip on my nozzle wasn't as perfectly smooth as it could be... and it got me thinking about what I could to to change that.

Conveniently enough, the XY gantry on a printer is pretty much identical to a precision surface grinding setup in miniature... so I taped some ultra-fine grit (5 micron and then 0.3 micron) sandpaper to the bed, moved the z platform up so that it was just barely touching the nozzle, and moved the printhead back and forth several dozen times. The end result was a mirror polished nozzle tip, which is (in theory) perfectly parallel to the build platform.

This has made a noticeable difference in my extrusion quality while printing. Previously, I could see a slight asymmetry to the lines being put down by the printer when doing infill, as the uneven finish of the nozzle dragged more in some areas than others. Now the lines go down perfectly uniform, with a clean, smooth surface. I don't know if this will have a noticeable impact on overall print quality, but I'm sure it can't hurt.

This is the paper that I used:

http://www.toolsforworkingwood.com/store/dept/THS/item/ST-MAF.XX

And the whole operation took less than a minute.

This may be particularly useful for those using old or off-brand nozzles with less than perfect surface finishes. This is probably not something to attempt if you do not have sandpaper adequately fine enough to complete the polish.

 

[valcrow 144]

I had a similar experience with my busted nozzle.

I ground it down as shown:

and I polished the edges and tip to a mirror finish with similar sandpaper you had mentioned and then knife sharpening abrasive compound. (it's like a super fine paste)

(the one on the left)

The result is an ever so slight increase in quality. (the right one is the polished, note the cheek fins)

I'm gonna try this with one of illuminarti's nozzles and do some direct comparisons once i have some time over the break, since I got 2, and one of them has a little bit of a nick on the printing end of the nozzle.

 

[Dim3nsioneer 447]

Interesting. Are you not afraid of getting a burr on the nozzle inside?

 

[nick-foley 4]

Not really - 0.3 micron sandpaper is approx. equivalent to 50,000 grit sandpaper - and so it isn't really producing a burr.

Another perk of doing this polishing (and the way I know that there is no burr in the nozzle) is that now, when I aggressively extrude hot filament through the nozzle by hand in thin air, instead of squirting out in a spiral or a curve, it shoots perfectly downwards.