Double Helix / Week of July 31 to Aug 6 - 2012

I haven't heard from Greg, so I'm going to go ahead and post another competition here to get things going again.

I made this a while ago, and it is both cool to have lying around and a challenge for bridging! Good luck!

[www.thingiverse.com]

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www.Fablicator.com

I keep meaning to get around to printing a competition piece, but I never do. I will have to this time. Need to switch colors though, the silver PLA I have sags really badly on bridges.

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I'm having a go at this as well although I'm having a problem. One of the Helix has excess plastic like a fungus on one face. The other helix looks good and the bridges between the helices are well formed. I'm using lift and retraction. Looking closely, the overhangs are not very tidy. I'm using a 2 hour old 0.8.5 dev of slic3r from the master branch.

Printing with 0.1mm layers 50%infill every 2 layers 185 degrees in PLA.

Anyone got any good ideas?

Bad boy helix
Good boy helix

Edited 1 time(s). Last edit at 07/31/2012 05:07PM by MotoBarsteward.

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Using ABSPrusa Mendel Zaphod with Pronterface and slic3r 1.3.0. Printing well with 3mm PLA and ABS through 2 x J Head Mk IV b and Wade Geared Exruders. Controlled using RAMPS1.4 board running Marlin_v1.1.9

Do you have a fan blowing from one side only?

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Yes.

Bleeding obvious really. Should have thought of this myself.

Time to wheel out the old desk fan, me thinks.

Sublime Wrote:
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> Do you have a fan blowing from one side only?

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Using ABSPrusa Mendel Zaphod with Pronterface and slic3r 1.3.0. Printing well with 3mm PLA and ABS through 2 x J Head Mk IV b and Wade Geared Exruders. Controlled using RAMPS1.4 board running Marlin_v1.1.9

You could try printing 2 at once

Tried the desk fan. Didn't make much difference but screwed up the cross bars. The over-hanging side of the helix is pretty atrocious. I have just started using a brand new 100mm hank of Faberdashary Earl Grey 3mm PLA having used prety well every other colour in their range to print angry birds. I'm going to re-calibrate and check my machine as the print quality is off from what it used to be.

Bruce, those look of exceptional quality. Want to let us know how you printed them (PLA/ABS? slicer/skeinforge? setting files?)

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Using ABSPrusa Mendel Zaphod with Pronterface and slic3r 1.3.0. Printing well with 3mm PLA and ABS through 2 x J Head Mk IV b and Wade Geared Exruders. Controlled using RAMPS1.4 board running Marlin_v1.1.9

I'm having strange slicing issues on this model... it prints great, but when it gets to the bridge, it tries to start in the middle of the object (in free air) and draw outward toward each tower. It does that a couple times, and then it makes a figure eight shaped outline which bridges from tower to tower a couple times, and those bridge quite well. Then it does a couple more start in the center and work outward bridges, which work ok because they're depositing on top of the central full-span bridges.

I thought that it might be nyquist aliasing causing the problem, and I turned my layer size down from 0.3mm to 0.15mm. That made my rounded edges on the base look awesome, but didn't solve the bridging issue.

I'm using slic3r 0.8.5-dev.

It was printed from a sample spool of ABS from a new supplier, it seems to stick a bit better than what we have been using so far.
The nozzle used is a .4.

This is the Slic3r settings.

; generated by Slic3r 0.8.4 on 2012-08-01 at 13:09:38

; layer_height = 0.2
; perimeters = 2
; solid_layers = 3
; fill_density = 0.26
; nozzle_diameter = 0.38
; filament_diameter = 2.89
; extrusion_multiplier = 0.9
; perimeter_speed = 48
; infill_speed = 60
; travel_speed = 160
; scale = 1
; single wall width = 0.40mm

M190 S133 ; wait for bed temperature to be reached
M104 S224 ; set temperature
G28 ; home all axes
M109 S224 ; wait for temperature to be reached
G90 ; use absolute coordinates
G21 ; set units to millimeters
G92 E0 ; reset extrusion distance
M82 ; use absolute distances for extrusion

We are pretty new to Slis3r so we are still fiddling with it.

Although the nozzle temp says 224 it reads 232 with a probe, which is as cool as we could go without having extrusion problems.
The bed temp is also out of whack, in case you are wondering: Why so hot? We really should tune in our thermistor tables.
There was a problem with bridges sagging on the first attempt with the extrusion_multiplier set to 1 so I dropped it to .9..... and I used a fan.

Just in time, here's my effort for this week.
My first attempt was pretty awful - just demonstrates the importance of a fan. I didn't have one for the Mendel90.
So, I then spent most of the weekend (when I wasn't watching the Olympics) designing prototype fan ducts. Finally, this evening I managed to make one that worked and fitted onto the printer.
And the acid test ...



I sliced the model using slic3r 0.8.3 and there is a problem with the gcode because the nozzle frequently doubled back on the bridges before it had reached the other side. To be a fair test of the fan, I decided to use the same file again.



There is a dramatic improvement in the vertical spirals, but still the same problem (nor surprising really) with some of the bridges. I cleaned these up and the resulting print is really quite acceptable now.



richgain

Printed on Prusa using UltiMachine silver and .35mm nozzle
Sliced with KISSlicer at .2mm layer height

2bad this topic is bleeding to death.....

i love to check this thread seeing the nice things ppl make

Bah! Sorry I forgot to check up on this!

Bruce is the official winner with excellent bridging and quality, and simple no-hardware-required solution to the layer cooling.

Congratulations!

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www.Fablicator.com

Oh..... Thank you Andrew, didn't realize I had actually entered the contest.

hahahahaha well posting a picture with an extra post for all the settings makes it a little .......... (pls fill in the blanks)

maybe next time in front of the post this line

I am entering the contest with this:



for now you will have to get next object as i can understand why he chosen you as the winner :-)

If you don't have an idea I suggest an ABS adhesion to bed challenge : the ball and socket part of [www.thingiverse.com] (BallSocketSR.stl) has such a little bed contact that I had to resort modifying the model and using kapton to have it printed - no way to do this on heated glass only, even with a brim, an "abs glue" attempt etc.

I'd like to see what people come up with to have it adhere to their bed (besides kapton).

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Most of my technical comments should be correct, but is THIS one ?
Anyway, as a rule of thumb, always double check what people write.

W need a "if you post here you are implying participation" disclaimer

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www.Fablicator.com

To the winner go the spoils. You get....... To make a mew competition! This is beginning to sound like work, lol.

I already had a print in mind DeuxVis. However, if you win the competition you can create it yourself. I thought it only fitting that since the validity of my hobbed bolt design was brought into question on another thread that I would post something with lots of retractions.