onsdag 24. juni 2015

3D Printing and spray painting large multi-part model.


I've always wanted to do a huge print of a statue of some sort on my printer, and I finally decided to print the famous beautiful owl statue by cushwa.


Here's the finished project.


Preparing the model for printing

Picture from thingiverse

I used netfabb Basic to cut the model into slices. I originally wanted the owl to be closer to 50 cm tall, but since the base of the owl is approximately square I would have had to print a lot more parts (as in ~16) to get finished. I therefore scaled it up to fit my 20x20 platform and cut it in three pieces to print.

I sliced it with Slic3r it with several perimeters and very low infill, to save time and plastic. I could have gone with even more perimeters and ever lesser infill on the centre parts instead, the result was more than rigid enough.


Printing the middle part on my trusty Mendel90
sturdy.

I printed with scraps of remaining plastic, which was a bit of a bad idea.

Here is the finished print before any painting is done.

Assembly

In total it was printed in four parts due to the filament clogging up a few times, so I had to measure and cut it several times in netfabb Basic. Notice the visible seam on the very top with the ears, and how they disappear later.

Attaching a model like this together was a bit tricky at first. I tried to heat the centre of the print to make it stick to the previous part, but it was impossible to heat a area that large fast enough and attach it together before if cooled of. So I ended up attaching using a soldering iron along the edge only, and it held up very well.

First I ran the iron through both parts, leaving some ugly but strong anchor points. Then I ran the soldering iron along the edge smoothing it as best as possible.

Painting

First I tried some plastic primer, but it reacted with the PLA in some way, and made it all soft. Instead I started out with this spray filler from Jula (norway/sweden). It was not as thick as I expected so it needed several layers with sanding in between, but it is very nice to work with.


First layers of spray filler.
Notice the visible lines in the eye sockets.
The spray filler was not thick enough to remove the larger seams,
so I added some wood filler. It all bonded surprisingly well.

I also had to sand it several times between spray filler and wood filler to make it smooth.


I really liked the colours in this shot.


I do believe this was the final sanding stage.


The back is feeling real smooth now.
The top still have a few layers of sanding and smoothing left,
but it looked real good with the soft shine and reflections. 

I was considering painting with a gloss paint at this stage instead.


From the front, all shiny.

 Granite effect

I used this granite effect spray. It was very different to work with than regular spray and had to be painted on in very short bursts to avoid running. Luckily it dries very slowly (as in days) and you have plenty of time to wipe off and redo any mistakes.

For being handling safe it needs to be painted over with some kind of clear spray.


First test with the granite effect spray resulted in horrible running.

The granite effect hid the seams and lines extremely good.

After days of very thin layers of granite effect,
 I gave it several (can't recall exactly how many, but at least 5)
layers of  clear glossy paint.






Painting with the object laying like this was the only way to paint under
the feathers of the body, as the granite spray really doesn't like to be applied sideways.




Final result 

Here are a few shots of the final result.

All the equipment used.












Thank you for reading, I do hope this inspired you to print something huge on your own RepRap. :)
Feel free to ask any questions about the process!


-Peter