Monday, April 1, 2013

Build Log #18 (running out of titles to use)

Finally finished designing a simple, adjustable Z end-stop for my mutant bot. I didn't have any M3 bolts long enough for the assembly so I had to use a #4-40 bolt instead. I also had a bunch of unused wing-nuts to boot so it worked out fine, just looks a bit bulky.
Printed and installed. 

Since I'm almost done finalizing the 2nd iteration, I went ahead and printed out the small parts, two pulleys and two Z rod holders. 

The prints came out nice but I couldn't figure out what was causing these tiny blobs to form. I thought it had something to do with the retraction but after going through a series of retraction settings, I had a feeling something else was in the mix. After inspecting them under a magnifying glass, I noticed there was this wavy pattern running along the X and Y path. I remember reading about this problem somewhere on the reprap forum. Basically it's the result of the belt's teeth bouncing along the "flat" pulley. I didn't think GT2 belts would be affected by this but I guess I was wrong. 

Y Pulley belt flip
Solution: Flip the belt around!

X Pulley belt flip
Minimalistic Endstop
Fired up another print and boom, barely a blob in sight. 

Comparison shot1

Comparison shot2

Slic3r 0.9.9 just came out and I wanted to tackle that torture test print again since I was pretty disappointed on how it came out....I know it can perform better than that. For this print, I'll be using three of these:
  1. Hairspray + Elmers stick glue on the HBP, no kapton tape
  2. Belt flip trick
  3. Slic3r 0.9.9
; generated by Slic3r 0.9.9-dev on 2013-04-01 at 16:25:21

; layer_height = .1905
; perimeters = 3
; top_solid_layers = 3
; bottom_solid_layers = 3
; fill_density = .3
; perimeter_speed = 50
; infill_speed = 100
; travel_speed = 195
; nozzle_diameter = .35
; filament_diameter = 1.63
; extrusion_multiplier = .89695
; perimeters extrusion width = 0.55mm
; infill extrusion width = 0.70mm
; solid infill extrusion width = 0.55mm
; top infill extrusion width = 0.55mm
; support material extrusion width = 0.70mm
; first layer extrusion width = 0.70mm

left: Old, Right: New
The belt trick and the new slic3r's new "avoid crossing perimter" option made a very clean print.  

 The cylinder parts still give off some artifacts. It happens most of the time when it finishes it's final perimeter run and slingshots straight to the center for the infill. I think lowering the acceleration might help.

The Hairspray + Elmers Glue combo worked out really well. I don't have to worry about ripping the kapton tape since I'm not using any at all anymore. After waiting for a few minutes to cool down, I laid out some water around the brim to loosen up the adhesion. The moment I loosen the brim with my tweezers, the part literally popped off the glass.