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206mm print of the Michelangelo David

Posted: Tue Feb 26, 2013 11:49 pm
by WalterMo
This David statue was printed with my self-built printer called WIZARD1. The hollowed out print consists of 1967 layers à 105 µm.
The 5.17 m tall original was scanned in Florence in 1999 by a team of 22 people from the Stanford University:

Situation during printing:


206mm print of the Michelangelo David

Posted: Wed Feb 27, 2013 4:06 pm
by behold3d
great work Walter

206mm print of the Michelangelo David

Posted: Thu Feb 28, 2013 3:50 am
by WalterMo
Thanks behold3d.

And now for comparison the scan and the print. Latter was illuminated for a better visibility of the details by diffuse light of a green and blue LED array.

206mm print of the Michelangelo David

Posted: Sat Mar 02, 2013 3:56 pm
by b26354
Walter, that looks amazing. Can you tell us a little about your printer? What it your build table made from - since you don't seem to be having any trouble keeping the resin stuck to the build table. How fast does the vat slide left/right and what exposure times are you using?

206mm print of the Michelangelo David

Posted: Sat Mar 02, 2013 9:00 pm
by WalterMo
My machine is working on the same principle as the B9C. There are some little differences:
1. The whole print process is controlled by an Arduino Uno, not by a pc. Only the single slices, stored as BMP images, are saved on a pc and are waiting for its retrieval.
2. I am using another projector, an InFocus 3118HD. At present at „only“ 1366 x 768 pixels. No internal modification of the lens barrel was made, an additional lens (f=300mm) is mounted in front of the projector.
3. The horizontal table is guided by 4 linear ball bearings. Its drive is not a DC motor with gear but a stepping motor with a planetary gear. So no incremental sensor was needed for the servo mode and no photoelectric barrier. The same crank drive principle as for the B9C was used. Advantage: The speed of movement of the table is sinusoidal, means low acceleration for the start phase and then for deceleration.
4. The beam of the projector must be blocked (e.g. during movement of the vat) by a two-winged shutter, rotated by a stepping motor. This is necessary because the projector cannot project in between a "black image".
5. The vertical Z-axis has a ball screw. 3 mm thread pitch.
6. The build table is a 5 mm thick PVC plate. Its edges are rounded to avoid any damage of the PDMS during sliding. The plate is adjustable for a perfect parallel position to the vat's bottom by a spherical joint from a tripod. After the vat was moved to the right side, away from the higher platform, the build table is moved up for 3mm and goes down again when the table is in its exposure position. So another sliding over the PDMS can be avoided. I think the B9 works in the same manner. You call it overlift (?).
7. The zero Z-position is found in this way: The current of the Z-stepper motor is switched off and by means of a button on the second shaft end of the stepper the build table is carefully (!) lift down onto the PDMS.
8. The (first) prints directly stuck to the PVC plate. I am not using a printed base plate in between. The surface of the plate is roughened by sandpaper before, then coated by a thin layer of resin which is cured by UV light from a sunlamp. Exposure times: The first two layers are 75 µm thick and exposed for 50 seconds each. The „normal“ layers are 105 µm thick and exposed for 25 seconds. Of course "normal" 75 µm layers are also possible to print.

The WIZARD 1 is still under development. If you like to see my progress (over months), it was posted here on the DAVID-Laserscanner forums:

And in general for 3D printing:

And now here the white-sprayed statue:

Edit: In the meantime I am using the full HD resolution of the projector, 1920x1080 pixels.

206mm print of the Michelangelo David

Posted: Fri Nov 22, 2013 2:32 pm
by printer_kid
Walter, nice print! I have a question though - is hollowing your models affecting them in any way? If not, and you are still hollowing them, what is your recommended wall thickness? I figured I could use Magics to hollow and save some material but I wasn't sure how it would affect the final prints. Your input is appreciated. :)

206mm print of the Michelangelo David

Posted: Fri Nov 22, 2013 8:55 pm
by WalterMo
Nearly all my prints of sculptures and statues that I printed with the B9-red resin are hollowed. Wall thickness is about 3-4 mm. Because I already have the DAVID software I do the hollowing in this way:

Using the example of the Morpheus bust you can see that layers often have deep incisions from outside. At this areas the hollowing software sometimes fails to enable a constant wall thickness. So it is necessary to scroll through all the layers in the B9C software and to rework this critical parts by the white pencil tool.
As long as I used B9-red I never had the case that a hollowed object broke. And I have printed several!
Recently I tried the Spot-A-HT resin. I mixed it with the rest of the B9-red, ratio 1:1. But the Spot-HT resin is more brittle and the 2.6 mm thick cannon tube bursted after two days:

I could repair it:

In the meantime I have printed two other objects with the Spot-HT without to hollow them:
The 201 mm Japanese doll Mikoto Misako:

….and the 120 mm tall US infantry man:

Because of the incident of the burst cannon tube I am a bit afraid to hollow objects which shall be printed with the Spot-HT material.