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

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.


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.


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!


tirsdag 23. juni 2015

3D print, railway model scenic grass and clear spray paint?

Inspired by Frits I bought some static model grass off ebay and tried it out on an old print from the shelf.

First I tried to use automotive spray glue, the kind you use when applying fabric to doors and such, but it was way, way to gooey and made a mess of the model. Since I didn't have any other spray glue, I tried applying a layer of clear spray paint and poured the grass over it. It stuck surprisingly well! I applied another layer of spray on top of the grass and poured even more grass over it, thus leaving it pretty well covered.

Here are a few pictures.

For a first test I'm very satisfied. It will be interesting to see how well it holds up, but it didn't fall off when touching, and the spray made it pretty static leaving an interesting looking effect.

The problem with a model this detailed is all the fine details is gone, this could be due to me applying several layers.

I will try with some landscape model printed in green plastic, to see how well it looks then.

Edit: I just tried rubbing it a bit, and it turned out most of the grass held on by surface tension. So the details wasn't that washed out, but also it was not very well covered after all,  and not handling safe in that state.

Thanks for reading!


fredag 12. juni 2015

How I broke a brand new E3D Lite6

Update 2015.06.23, E3D going above and beyond.

I messed up when trying to extract the nozzle, and the extractor broke off inside the block, making it near impossible to fix.
Driving out a drill bit with a drill bit
turned out to be difficult, as the softer
metal in the block gave away.

The issue with the nozzle breaking was due to me not following the nozzle swap procedure, which has to be done at 245C... As well as the liner compressing thus forming a plug.
I always ment to pay for new parts, but E3D actually gave me store credit to buy a new one(!) which was far beyond what I would have expected.

From E3D/Sanjay email: "The reasoning for me providing a replacement is that I think there could be an issue with the tube/lining coupling, and that there may be an issue on the internal bore which prevented you from inserting your liner fully. I am absolutely certain that the leaking you experienced is a result of the nozzle tightening procedure not quite being performed properly. You should be able to solve any leaking issues with a quick nip up and tighten of the nozzle when hot."

I'll report back with a new modified wades and my experiences with a more carefully assembled lite6.

Original post:

I just finished building a Mendel 90 sturdy for the school I work at, and started printing today together with my students. Everything worked pretty well and we did a few various prints, they really enjoyed this one. 

The extruder is the standard 3mm wades that comes with the Mendel 90 source, printed in ABS. I drilled out the filament path to fit the PTFE liner and just used it stock like that.

I had some issues dialling in the extruder settings though, and had to increase the extrusion multiplier to 1.1-1.2 to get acceptable solid prints, but there was still a lot of stringing. After a while I chose to remove the extruder idler to have a look inside, and I saw this.

The bottom PTFE liner should be flush with the plastic,
but it have moved quite a lot upwards.

The collet looks like to be in the right position.

I removed a good chunk of plastic to avoid moving the collet when inserting the hotend.

Teeth looks fine, and have not clogged.
Since this is the 3mm version, and the filament path hole is not moved, the idler does have to be tightened almost all the way, and the bearing does bend the filament slightly. But since there are no clogs, and it was easy to change out the filament, I reasoned it would be fine.

The nozzle is positioned correctly according to the assembly instructions.

I had to heat the hotend to 120C to unscrew the nozzle.
This is what it looked like.

The filament is pulled out and clearly shows the
PTFE liner was not completely flush with the nozzle.

Slight leaking from the top of the heat block.
After looking at it a bit and reinserting the PTFE liner a few times, I felt there was a tiny edge at the bottom of the heat sink, and you need to use quite some force to push the liner past it. I figured I rather push the liner through the heat sink and the heat block and then screw the nozzle into the heat block moving the liner upwards to make sure there is a tight fit.
Update: This was a terrible idea, the liner got compressed and probably had a lot to do with the nozzle breaking.

I started screwing in the nozzle with the liner like this. 

It was quite hard to screw the nozzle back on, possibly due to the plastic left in the threads, so I heated the hotend to 120C to make it soft and started out. Then...
Seems like I need a new nozzle, liner and heat block..

Any ideas to what could have caused this? I followed the instructions very carefully. The collet was properly secured, I could not move the PTFE liner up and down by hand. Thermistor settings were correct. I ran a M303 to ensure the temperature didn't overshoot, before heating to 245C and tightening the nozzle.

My guess is I only got the PTFE liner down to the small lip inside the heat sink opening, and there was a gap allowing the PTFE liner to move.

I'm in contact with E3D support already (they answered very fast), and wrote this post to better show my problem to them and to help others avoid the same mistake.

Thanks for reading!