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Zen and the Art of 3D Printing

  In a nutshell, think twice before buy the Replicator 2. At last not until MakerBot has fixed the issue with the extruder. Chances are high that you happily print for a few days until you get air-prints and then you start to spent endless hours trying to get that dammed thing printing again.
  But it won't. Because MakerBot made you believing that with this machine you just can print 3D objects without understanding what you are doing and so you bought it. Which is true until you get the first failure and you have no idea how to fix it. Then you painfully start to realize that you are staying at the very bottom of a steep learning curve.
  Which you have to climb alone, because MakerBots support turns out not to be really useful. On average we got an answer every 10 days. Which just contained only common information anyway. That said, things are slowly improving, just it takes time and patience.

Feb 2013

It seems 3D printing even for hobbyist becomes very popular. There are a lot of various low cost 3D printers out there, but we feel that most need some involvement to get that thing properly running. Since we are running a little bit short in time with all our ongoing projects, we decided to pay a little bit more and get a Replicator 2 which promises to be plug&play.

A bit of History

Our Replicator 2 has arrived!


From unpacking to installation to the first print it took us only 15 minutes. From the hardware side they kept their promises and we are very excited. Next step is to to dig into the MakerWare 1.1 software and generate our first file to print. 3D geometry (as .obj) we can get from all our 3D programs like modo, Z-Brush, SektchUp or whatever we have. For technical parts we will try the free Autodesk Inventor Fusion.


The free Autodesk Inventor Fusion does not seem to be a really useful tool - to complicated to learn, it is probably more a toy. So we bought the ViaCAS 2D3D 8. We do not need a full flagged CAD software, just a tool which allows us to quickly produce precise mechanical models. After a few hours of learning curve we get decent results out of it. And it seems to be a good companion for modo.


Due to a loose Kapton tape which holds the ceramic isolation of the extruder we had to dismount the whole thing and after placing the new tape and assembling everything back we can not properly print any more. Even after endless hours of trying and lots of lost PLA we still can not properly print any more.

Reading through the posts of the support forum from MakerBot we have to come to the conclusion that we suffer of common problems with many others: a badly designed plunger mechanics. And maybe we have an issue with the temperature control or settings of the extruder.

There is no short-cut in low-cost 3D printing. It needs time and patience to get familiar with the technic, the materials, the machine and the software. Probably we just bought that machine to early and now have to act as beta-tester. No plug&play so far, but we really should know it from the beginning.


As we are waiting to get our support ticket answered from MakerBot, we have time to inspect this machine in deeper detail.

There is not much electronics needed for such a printer: an ATmega1280 processor, four stepper motor drivers and some circuits for the heater. Not too much electronics, but nicely done.

What probably makes the difference to self-made printers is the MakerWare for the PCs which slices the 3D models and generates the commands for the printer. You are not confronted with a myriad of slicing parameters, one can easily start with the default settings.


The more we google about "Extruder problems Replicator 2" the more bizarre the situation becomes. Here a very informative text we found in Google Groups from pfinuncan, and it seems to describe our situation quite well:

From my experience, knowing only the temperature that someone was successful at doesn't help much.  That is because the volumetric rate of plastic they are melting is very important. So you also need to know the flow rate, and layer height.  With the MK8 extruder your print can fail because you are printing too fast, or too slow. Or another way to look at this is you are printing too hot or too cold

If you are running at a high feedrate, say 80 mm/s and a large layer height like 0.3mm, you are melting a lot of plastic quickly. In this case if you temperature is too low your extruder will not be able to melt the plastic fast enough. This will cause the motor to start skipping, (the click noise) or for the drive gear to strip the plastic filament. If you see the motor click a couple of times but then continue, it is likely that you are running too cold. The skipping gave the hotend a chance to catch up.You can't see the gear strip the filament, the extruder will just slow and stop.

Now, say you got the printer to work great at 0.3 mm layer height and now go down to 0.10 mm at the same temperature. The rate the plastic is flowing into the extruder is now reduced by a square root.  Now you are melting the plastic way to fast. With PLA this cause the end of the filament to mushroom out, and melt further up the stainless steel tube. Once it has mushroomed out, it will not fit into the nozzle anymore and will stall the extruder. If you remove the filament you can see the mushroomed filament tip.

The tricky part is knowing which problem you have. If you are running too cold, and the extruder jams, the filament will sit in the hotend. If you wait too long the filament sitting in the hotend will have time to over melt and mushroom out. So even though you print failed because your temperature is too low, it will look like it was too high, if you find it later. So if you are having trouble, try to notice right when it fails.

On another note, retractions are also a problem area. I would suggest turning it was down like 0.1mm or off if you are having jamming issues to rule that out.

But it also could be the software for slicing. Or manufacturing tolerance with the PLA. Or it is full moon.

Oh men, it seems we still have a steep learning curve in front of us...


Every day a few more lost souls join the support forum. Best of today: Terribly disappointed. My spouse has insisted the machine leave our home because of the tension it has created.

Yes, we can confirm, regardless how peacefully you approach this issue, at a certain point it gets emotionally.


The Scientific Approach

But having a scientific education we will try to leave the emotional path and do a series of experiments (instead of happily printing), because we already know that we do not deal with a single problem, there are several of then.

Here is our setup. We added an extra thermocouple to actually measure the temperature.

Now it just sticks under the ceramic isolation, next time we open the extruder we will place better.

So far the temperature is stable, but about 10 -15 lower then what the Replicator shows.

We use MakerWare V and the firmware V7.0

First, before starting a new print, we adjusted the plunger properly and leveled the build plate, extruded about half a meter with the Load function to be sure the extruder works properly - still without success. Even a well adjusted or even mechanically improved plunger does not solve all the troubles. It is only one step.


Since printing failed after 15-30 minutes and we measure lower temperatures and do not know anything about PLA we had the idea to increase the temperature, not knowing about the mushroom problem (see reference above).

Now we start to decrease the temperature and see how long it takes until the clicking starts.

This are prints with 0.1mm layer height which seems to be more critical then the default 0.27mm.


Once we have to abort the print, we unload the PLA and have a look.

And indeed, for the times with failure we find the mushrooms (red circles).

More technical information about Polylactic acid (PLA) can be found here.


These are only preliminary results, more experiments have be done (since MakerBot does not publish anything else then success stories).

Next time we run the machine, we will reduce the temperature even more until the extrusion fails again due to too low temperature.

Probably there are software issues as well, because the failure rate also depends on the model and the settings for the slicing.


Not sure if our theory is right since we get this mushrooms at any temperature of 210/220/230 C.

At last things are moving, in the meantime we got informed from MakerBot that we will get the parts for the spring loaded plunger free of charge and there is also a new MakerWare and firmware available, so we will continue our journey when we have all new parts together.


Today we got informed from MakeBots support that our upgrade parts are on the way and we are choose to be among the beta-testers. That is good news because it tells that they are aware of the troubles a lot of users have and try to solve it.


Still being unsuccessful with the Replicator 2, we backed a Kickstarter: the Bukito Portable 3D printer. We just want to see how others are doing. The machine should arrive in spring 2014.


MakerBot merges with Stratasys. Means they joined the big players in 3D printing with IP and corporate muscle. Business wise that certainly makes sense because there is an endless number companies producing low cost 3D printers. Not happy that we have invested our money in this company.


And here we go: Stratasys announced  that it has brought suit for patent infringement against Afinia, a small but successful 3D printer company.


Somehow we are back on track. We got the extruder upgrade from MakerBot which certainly helped to eliminate a factor of uncertainty. But still we got to many failures, regardless what Voodoo or science we applied. So we lost interest and let the machine sit there for more then a half year.

What finally made the biggest positive impact was the software update of the Makerware 2.4. Right now we think that the most critical part of 3D printing is the slicer. It will fail only eventually with small or critical parts but slowly we get back some confidence in the machine. We print again!