Funbie Studios
4 stars based on
78 reviews
So you are considering buying a Makerbot Replicator 3D printer to help you in your engineering work? I will tell you why here.
Before we start I would like to stress that I am not advocating against 3D printing in general but only sharing my experience with Makerbot Replicator printers.
Also, I would like to focus here on engineering models which bring some more complex issues compared to household or creative 3D printing. For example, can you make a valve with a 3D printer?
How do you accurately assemble models together? Can you use 3D printing to replace expensive laboratory parts such as opto-mechanical devices? It is for these precise reasons that I bought a 3D printer and I was quite enthusiast at that time I pre-ordered my Makerbot Replicator Mini months before its release and was one of the very first to receive it.
So if you are thinking about buying a Makerbot Replicator 3D printer for engineering purposes, please read this carefully before settling your choice. One of the most disappointing things about the Makerbot Replicator 5 th generation is their so-called smart extruder.
The extruder is the part of the FDM printer that actually takes the filament, pushes it into an heating chamber before letting it go through the extruder nozzle which create the very thin filament used for printing. Because fused deposition modelling involves melting a polymer and extruding it through a very small orifice, it will clog after some time. And when it does, you basically have to do some maintenance on your printer. The very problem with the Makerbot smart extruder is that it was not designed for maintenance but rather for easy replacement.
Obviously, Makerbot will not tell you that when you are buying the printer — they leave you the surprise for later. And when your extruder will clog for the first time, you will discover a whole new world of troubles when searching on the Internet. A lot of people are complaining about how frequent their smart extruder clogs. In my experience, it is much less than that and was about only hours of working.
I would also like to comment here that this is only an average based on personal experience and that it is not a guarantee that your smart extruder will last for at least hours. For instance, I have bought a replacement extruder from Makerbot which clogged after printing only 10 grams of PLA! Hopefully, Makerbot accepted to exchange the extruder for a new one due to EU warranty. To give you an order of magnitude, my models are relatively small and take from 2 to 4 hours to print so that makes only 25 to 50 small 3D parts per extruder.
Yes, you read it correct: Hopefully, you can find similar extruder at 3 EUR on e-bay and they really look the same. So I tried the whole procedure which worked fine at first and I managed to print one model. But when I tried to print a second one, the extruder clogged again.
So I tried the cleaning procedure one more time but the extruder now clogged in the middle of the printing. As a consequence, I would not be so confident about the smart extruder clogging issues having a definitive solution.
Fitting is, in my experience, the most frequent cause of having to discard correctly printed models. When designing your part, you specify some width and height for the features of your model that are relatively precise. When working in a mechanical shop, this is usually machined using a reamer which will ensure, when properly used, that the hole will satisfy the tolerance.
So, when inserting, say, a 3h7 pin whose diameter is toleranced between 2. This will always be the case, even if your part is produced in the USA, China or in Japan by different operators. But things do not work like that when printing 3D parts.
When printing, you first produce a 3D model usually a stereolithography. With Makerbot, this transformation occurs in the Makerbot Desktop program.
The problem is that Makerbot Desktop does not, at the moment of this writing, take into account any analysis of the shape of the elements to ensure fitting and tolerances. The question is by how much? And there is no simple answer to that. Depending on the software which transformed your design file into machine instructions, your hole will not be of the same size. And even worse, I have experienced that different version of the Makerbot Desktop software will not print models the same way!
The consequence is that you have to include some knowledge of how your printer actually does its job when designing your parts. At occasions, such as when updating the Makerbot Desktop software, I print the calibration file and try to fit some 3h7 pins into the holes. That way, I know by how much I have to increase the size of the features in my design. The final consequence is that you cannot exchange 3D models that easily with other people. Depending on the printer, your features may show too much clearance or too much interference.
Obviously, what is true for holes is also true for any kind of feature. I had to print my cuvette holder 5 times before getting it right! And it gets really frustrating when you try to print older models which used to work and now do not fit the same way anymore. Also, I have noticed some odd things with the quality of larger models.
For example, check these two gears below. They have the same tooth size 2 mm but different diameter. Notice the details in the tooth for the larger model. My advice is then to avoid very large models and to keep the details on the order of the millimetre. DO NOT try to make very small details like small threading for fasteners and such. If you need thinner details, use a mix of 3D printing and hardware parts bolts, nuts… glued on the model.
Models printed with the FDM technology will present a rough surface finish. In the past, with ABS, it was possible to post-process the models with acetone to actually dissolve the plastic to make it flat and shiny.
With PLA, this is not possible anymore. Surface roughness can be important for engineering parts that slide on each other or that may accept mechanical sliding parts such as guide rods.
I have spent numerous trials at filing models to get a better finish but without success. During some time, I used heat the model with a lighter to melt the PLA and remove small filament hairs coming out of the model. However, this caused much problem such as complete melting or even burning!
I do not recommend it anymore. I would not recommend this approach because it may increase the size of the model which might be a problem in engineering and is also not applicable for inner features such as holes for guide tubes.
When you print a file, the design you sent to the software is first transformed into extruder movements operations, the g-code. With Makerbot, this occurs in the Makerbot Desktop software. The problem is that we have very little control on constraints applied to the algorithm.
This may look like a small issue but is actually quite boring when it happens in high precision models. Let us take, for instance, the holes calibration model:. The black lines represent the movement of the extruder head. You can see on the picture that the extruder head passes several times inside the holes. As a consequence, you will have some filament in your calibrated holes which is quite difficult to remove without damaging the actual and precise dimensions of our features.
In the case of the calibration model, this results in slightly obtruded holes that will not accept the pin. And this is the price you have to pay with all-in-one commercial solutions like the Makerbot Replicator: Because the models are made of plastic and may have an hollow structure due to the infill ratio, they do not have the stiffness or strength of metal parts.
Also, by the very inherent process of deposition modelling, the parts are very brittle in their axial dimension and you can break them very easily. I broke a few parts that were designed to be screwed into each other using large threads. About half of the models that I printed where designed to replace Thorlabs opto-mechanical components but due to the very low rigidity of the plastic, they never performed well at all and caught a lot of vibration.
The same was also true for microscopy application. This is a large issue for 3D printing because, in my experience, it is totally useless for optics; even when used as a base support for stiffer elements made in aluminium. On the picture below, a lot of wasted trials as reproducing opto-mechanical parts…. Almost immediately, I realized that the parts where absolutely not airtight and there was a lot of leakage inside the main body. I was able to fix this with tons of silicon and Teflon but still, I was not able to get more than 50 mbar pressure which is quite low.
I had to pour the solution after placing the stir bar and every time the stir bar lost the magnetic coupling, it went back on top of the solution. This is not too much of a problem as you can increase the infill ratio to have a bulk density close to 1. The real problem was that, after a while, the model started soaking in water. And this is much more problematic if you are using the stir bar for sensitive application such as stirring solution of yeasts because you would have to discard in a properly sealed container the stir bar immediately after usage.
The conclusion to these two experiments is that the models printed by the Makerbot Replicator or any other FDM technique are not airtight nor watertight and if you are planning to do so, you will have to use SLS printing technology with a post-processing such as a sealant.
One of the biggest errors that you can make with a successfully printed 3D model is to try to drill holes into it or to rectify it with any conventional machining techniques. I once tried to enlarge a hole due to a tolerance mistake with a drill bit.
This was an horrible mistake as the PLA melted almost instantaneously with the friction of the tool! The part was ruined and I had to spent hours to clean my drill bit. The only solution I found was to actually burn the PLA to remove it. So never, never, try drilling into a PLA model! If you need to add fasteners, do not use a tap but rather create an hexagonal hole in your model to support a nut and fix it with a small point of epoxy glue see image below.
Still, if you want to fasten anything into your SLS printed model, you should use metal inserts in the tapped hole to prevent destroy it, even with very light torque.
Price of printed models is usually the largest misunderstanding about 3D printing. Let me tell you this:
