EMC repstrap from old printers and scanners
November 14, 2011 12:29PM
Now that my extruder is reliable, my DIY mill is officially an EMC repstrap :


The extruder is supplied trough a tube to a spool dispenser in order to avoid parasite forces caused by the extruder pulling the filament.
Some successful prints :

The tape I print on is tesa N°4657 I borrowed from work, the PLA stick well to it but not too much, I can pull the printed part out without damaging it or the tape.


left : resolution = 0.3mm
right : skin enabled with a division of 3, so external resolution = 0,1mm
Printed at 30mm/s

STL from [www.thingiverse.com]

Max overhang = 30° with this setting.
Attachments:
open | download - EMC_repstrap.JPG (102.4 KB)
Re: EMC repstrap from old printers and scanners
November 14, 2011 01:10PM
Quote

The extruder is supplied trough a tube to a spool dispenser in order to avoid parasite forces caused by the extruder pulling the filament.

Good idea, what sort of tubing did you use?


[www.hydraraptor.blogspot.com]
Re: EMC repstrap from old printers and scanners
November 14, 2011 04:17PM
It was the insulation of a cable, not an ethernet cable but about the same diameter
Re: EMC repstrap from old printers and scanners
November 16, 2011 12:09PM
Support structure test :
After cleaning :
Not that bad.
I set the support flow rate ratio to 0.5 (less didn't work well)
I didn't found a box to change the support structure angle in skeinforge, so I had to rotate the part 45° and change the infill direction to get that result.
Re: EMC repstrap from old printers and scanners
November 19, 2011 08:53AM
vertical resolution test :

From left to right : 0.3mm, 0.2mm ant 0.1mm

Edited 1 time(s). Last edit at 11/19/2011 08:54AM by Petrus.
Re: EMC repstrap from old printers and scanners
November 21, 2011 08:13AM
Would you be able to give reference of the blue attachments for the cable?
Thanks
Re: EMC repstrap from old printers and scanners
November 24, 2011 02:49PM
Sorry, it was also salvaged so I don't know the reference, but they are not necessary in this configuration.
Re: EMC repstrap from old printers and scanners
November 26, 2011 01:05PM
Cooling improvement :

There is now only one powerful 40mm fan that cools the cold end and the print.
I found out the ventilation is very important for printing overhangs with 0.1mm layers.

The duct is drown with google sketchup and print in PLA with 0.3mm layers.
The wall at the right is wasted material like the support structure. I printed it to absorb the inertia of the extruder between the printing of support structures at half the flow rate and the rest of the print.

Some test prints after this modification :


layer height : 0.1mm
Support structure : Cross hatch enabled, flow ratio : 0.5


After removal of the support structure and cleaning with a file :
Re: EMC repstrap from old printers and scanners
December 04, 2011 02:18PM
I lighten the Y axis using 5mm MDF instead of the 8mm Plexiglas LCD screen light diffuser and replacing the glass with a failed PCB board, it's flat enough for small prints.
With theses modifications, I am able to multiply the acceleration and speed by 2.

I've also modified the raft plugin in skeinforge to add a "Support Feed Rate over Operating Feed Rate" setting.
my extruder tends to clog when extruding too slowly, with this modification I can print light, easily removable support structures that are printed faster and doesn't clog my extruder.

raft.py
If you want to use it it's at your own risk, it's the first time I modified a python script, I made it working using copy/paste and a lot of trial & error, I probably missed to do something.
Re: EMC repstrap from old printers and scanners
December 04, 2011 03:46PM
Petrus, your results look amazing!!!

Would you be able to show better how you use the fan to cool down? (especially if that's the trick!) Is the fan blowing to the metal parts of the extruder or to the deposited material?

Thanks for sharing this.
Syncra
Re: EMC repstrap from old printers and scanners
December 05, 2011 02:19PM
The fan cools down the cold end of the extruder and the printed part.
I made a picture from the part view :

The hot end is insulated by the inner section of the duct, so the air only cools the printed part.

I noticed that active cooling is important when printing overhangs but not much for other stuff, for example the 3 domes I printed to test resolution are printed with the previous version of the extruder where the cooling was quite inefficient:
extruder_V2

I noticed it when I printer this sphere :

The good bottom side was where the fan was, so I made a duct to cool all the sides of the part.
Re: EMC repstrap from old printers and scanners
December 12, 2011 04:47PM
A time-lapse of my last print :
[www.youtube.com]
Re: EMC repstrap from old printers and scanners
December 29, 2011 07:16PM
I made a small heated bed for printing with ABS :

It's a simple circuit board engraved by the printer with the spindle tool. I have to make an other one, The resistance is too high so it takes too long to heat up but I can get 100°C if I supply it with 12V continuously.
With this heated bed, I printed some clips to fix the new lighting system (fluorecent tubes from scanners):

The PLA clips I made first were too fragile.

[edit]
Here is the new lighting system made from scanners fluorescent tubes :


Edited 1 time(s). Last edit at 12/30/2011 03:08PM by Petrus.
Hey,
very cool. Where can I find the EMC RepStrap Software, which can control the Extruder? Please give me a advice.
Thank you.

regards
Re: EMC repstrap from old printers and scanners
February 25, 2012 12:38PM
I use the standard EMC2 software, you can download it on [www.linuxcnc.org]
The extruder stepper motor is controlled by the 4th axis (A axis) on EMC2.
Extruder and bed temperatures are controlled by a dedicated device I made : [forums.reprap.org]

Oh, and I made new time-lapses :
[youtu.be]
[youtu.be]
[youtu.be]

Edited 1 time(s). Last edit at 02/25/2012 12:41PM by Petrus.
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