How Long till the 3D Printing Revolution (Is Not a Revolution)?

http://solidsmack.com/fabrication/how-long-till-the-3d-printing-revolution-is-not-a-revolution/

Pushing the limits of the Ultimaker

After a long struggle with basic reliability, we are finally at the point where we can push the limits of the Ultimaker. We are interested in what it can do in a best-case scenario. How detailed can it print and how quickly? 

First task was to find and collect some complicated STL’s. Below is the printing of a circular chain which requires a significant level of machine tuning and general accuracy. Notice the rough edges as the Ultimaker struggles with a high-resolution object. For a print like this, I enabled a print option called ‘retract’ which is crucial for preventing bridges of filament between the individual links. Retract pulls the filament back a few centimetres microseconds before travelling over a gap. It worked fairly well in the example below. 

Despite the generally low quality of the print, it is still impressive that the Ultimaker was able to print thischain at all, considering the complexity required. Below is the finished chain.

After removing it from the bed, it took some massaging to remove the connecting supports. Still, despite the general crude appearance and sharp edges it is quite an impressive print!

Next I decided to step it up a notch and try something more difficult. I chose chainmail which requires a comparatively staggering level of accuracy. I was very surprised with the result. Doubting the Ultimaker could handle such detail, I was frankly surprised it managed to finish as successfully as it did. 

Prying the print off the bed was quite difficult, as each individual link had to be gently eased off, at the risk of breaking links (which happened anyway). All in all, I’d say 40% of the links worked properly, which is still quite amazing all things considered. I wouldn’t print chainmail again though, as the results aren’t ideal. This process might be more suitable for a DLP resin style printer like the newly released Form 1. 

These results are expected of a crude first-generation FDM machine like the Ultimaker, and I’m sure we’re going to see many improvements in the quality of prints which each new iteration. 

These chain experiments clearly show the quality limitations of the Ultimaker.

(Re)building the Extruder section

The last major fix in terms of reliability is the complete overhaul of the extruder section. It is responsible for keeping the filament flowing at a constant rate (ideally). The stock extruder suffers from many design flaws, the worst being the failure of the bowden clip support and the inability to apply constant pressure to the filament given subtle changes in its diameter. This is an unfortunate reality of PLA filament at the moment, but varies between manufacturers. 

In preparation for the overhaul of the extruder, I researched all the viable alternatives. Dozens of fixes have been suggested and posted in the Ultimaker forums, but I eventually settled on a modified version of the Taylor Greg-Wades extruder, pictured on Thingiverse below.

It utilises a larger gear wheel, a solid bowden clip support, a makerbot mk6 knurled bolt  and a variable spring-pressured filament clamp, which allows for even pressured stepping despite inconsistent filament diameter.

The benefits of this design include the utilisation of standard metric bolts and bearings, and an entirely printable frame. The challenge was to get un unreliable Utlimaker to print the parts at all of course, but with many failed attempts, and some luck – it worked. Below is the work in progress extruder, entirely printed with the Ultimaker, and standard bolts, springs and bearings from Bunnings and makergear. 

You can see here the bearing responsible for applying pressure to the filament. The springs, when fully screwed into the frame act as a sort of variable suspension.

Here is a picture of the finished gear wheel. This took a number of attempts to print, due to filament slippage and the complicated edges (speed adjustment was necessary).

Finally, after a few weeks of preparation, the new extruder is complete! Here it is installed on the Ultimaker.

I noticed immediate improvements in the quality of prints. The new extruder works as advertised and hasn’t slipped on the filament once. The results so far are very promising. I immediately set out to complete some of the more complicated / difficult to finish prints.

Here is the improved Ultimaker printing a cup.

And here it is printing a Yoda head, a surprisingly complicated print. Note the fine overhanging ears. 

Now onto some more complicated / technical prints.