Before buying a 3D printer I did a bit of research. For some printers, the build platform is quite small. The RepRap Prusa i3 kits I found would offer something like 20x20x20 cm, which sounded alright for me. Some parts I found on ‘Thingiverse’ would require a build platform of at least this size. Also the kits on Ebay were around 400 – 600 AUD, which was within my budget. As a complete noob in 3D printing, I did quite some research but was overwhelmed by the amount of information available.
At the end I decided to buy the ‘Sintron 3D Printer full Kit for Reprap Prisa i3‘.
The seller spent at least quite some effort to line up all the advantages of his kit and points out the different properties of his components. He also puts some emphasis on the quality of his kit, compared to others. But my experiences with Chinese sellers are that they rather work hard on improving their margin, instead of the quality. Later I came across some shortfalls in terms of quality which will be addressed in this review. For me it was at least clear here, that he is using the latest state of the art components. Other sellers left a lot to speculation. Another thing worth mentioning is, that the seller also provides some technical support.
So I decided to go with this Sintron Kit and spent a $AUD 499. It took almost exactly two weeks to arrive on my doorstep and it was shipped without any tracking information. It came in two boxes taped together. The power supply was in the small box and the rest of the kit in the larger one. Everything was wrapped well enough, nothing was broken or missing. Btw, towards the end of the item description at eBay, you might get the impression that the kit comes with a CD or something full of software, manuals, configuration files and a number of 3D objects for you to print – it doesn’t!
What followed was the adventure of assembling it – which turned out to be a lot more challenging than I expected. The technical support was helpful to a certain degree. But their responses were short and judging from the way they were written, the writer was struggling a bit with the English language.
The greatest puzzle ever
The RepRap Prusa in an Open Source 3D printer. The ‘i3′ in the name of the kit mentions, that this is the third (and latest) iteration of the Prusa. There are plenty of howtos and build manuals on the web. In fact, there are too many! The seller himself points towards the project website and not a single build manual linked there matches the components of the kit. You can search the web for more tutorials and information – but you will fail to find anything that matches in all (or close to) parts. Its not about the components being wrong, its more about how different the design of the hardware can be. But that makes it hard to get the kit together and thats the reason why some companies offering a Prusa kit, provide at least some instructions. With a few pictures of an assembled kit, things would have been so much easier. But you are left to scratch your head. Well I hope I can fill with this article at least a big part of this gap.
Assembly of the Y-Carriage
Here is a simple example. These kits come with a number of rods, some threaded and some not. They will be part of the mechanics or the frame. The first step is to put the Y-Carriage together. In this build instructions we need to have 4 threaded rods of the same length (like in most manuals you will find). But this kit comes with 3 rods of the same length (210 mm) and one a bit larger (275mm). I was also not able to find build instructions, having rods matching the lengths I got. It is simple, all rods are there, but which one goes where? After spending more than an hour researching that detail I found out, that the 275mm rods goes into the back of the Y carriage as shown in the image and that I was right about the other 3. Theses rods were indeed the ones for the Y carriage. The instructions in this excellent build manual fit better to the Sintron kit. But they are using a different extruder and also the Acrylic frame they use is different.
But with this picture, the first mystery of the build is solved for you. Unfortunately you will also notice the first quality issue with this kit at this early stage. The 4 corner pieces are of a bad quality print and will crack, once you install the smooth rods (use a rubber hammer). All Prusa kits you buy will come with a certain amount of 3D printed parts.
It is not the biggest draw back – you can print news corners with the printer once it works. But it worried me in the beginning of the assembly. I have not replaced them yet and it doesn’t seem to impact the performance of the printer. Most of t he 3D printed parts you get with this kit are having some issues. Keep your driller at hand, you will need it to make things fit.
Another part that was already broken and you will need a lot later in the assembly is the mounting bracket for the extruder. The quality of the print is again extremely bad. I printed a new one in this case, but an improved version I found on Thingiverse.
I will add a few more pictures of the assembled printer to this article, to provide some additional clues for assembly. There are two parts I replaced with better version from Thingiverse one was the already mentioned extruder mounting bracket and another one is an improved holder for the Y pulley, which can tension the belt.
The printer comes with 6 end switches and three 3D printed parts to mount them somehow on the printer. Another thing that was quite confusing. Well you only need 3 switches, forget about the extra 3. They are just in the box because these are really cheap and in theory you would be able to use six. The better question is, where to mount these switches. I can’t recommend the places where I have mouted them – thats something I will change soon. But I can show you where are the best places and why.
The seller mentions in the item description, that this kit randomly comes with either a left or right mounted extruder. The extruder has always a motor mounted to its side. In my case I got the extruder mounted to the right and therefore the motor is at the left side. I squezzed the X endswitch between extruder and the left end of the X axis. Tha’ts what I have seen in other builds – but they all got the extruder mounted to the left. When my extruder hits the endswitch in X-Min position its still about 1cm on the heated bed and not able to move further to the left. I am wasting a part of my range in X. If I would put the endswitch to the right in X-Max position instead, it would be a lot better fit and I would still be able to utilize the full 20cm on X. So depending on what extruder you get, make sure you put your endswitch in the best spot. I will rectify that in my build – but at the moment I am just happy that it works!
Another decision has to be made on the Z-Endswitch. I placed mine into Z-Max position, which is the top of the printer. That turned out to be a bad decision as well. Before you print, your Prusa will try to hit all endswichtes in all axis’. From there he knows how far he can travel in each directions (something you secify in the configuration of the printer software). In other words, before I can print my printer moves his head away from the bed to the top of the device. Movement on the Z axis is slow – going first all up and then down to the bed probably takes 3 – 4 minutes. My recommendation is to better put the Z-Endswitch into Z-Min position at the bottom of the printer, close to the bed. That will save you a lot of waiting time.
Harder to mount than the switches are the RAMPS controller board and the power supply. The already drilled holes in the Acrylic frame do not match with either one. Most people would say that you can’t drill into Acrylic – it would split. But well… you can. Just take it slowly with a hand driller. I mounted the RAMPS to the left and the power supply to the right. Two mounting point would do the job already. The power supply also has a quality issue, the fan started to make terrible noise after 5 days already. Thats a record!
I decided to mount the display on top of the printer. The two connection cables are not long enough to mount e.g. at the front of the printer. People are selling longer ones on ebay. I found two simple parts on Thingiverse, that makes it easy to put in on the top of the printer. I went with the simple display, but you can also go with the (better) graphic display. Setup is as easy, as the other one.
A big lapse is that there is no heat resistant tape included in the kit. You need at least a small strip of it, to attach the thermistor to the bottom of the heated bed. Many seller include a small roll of Kapton tape for that purpose. Something you can hardly buy in the hardware shop around the corner. You might find yourself stuck here, waiting for a roll of Kapton tape to arrive – which is not cheap. I found some aluminium tape in the hardware store, which turned out to be cheap and able to do the job. Just make sure that you don’t create a short between both legs of the thermistor. The cable included in the kit for the bed itself is unfortunately quite stiff. I replaced it with some silicon speaker cable.
What you can see all over the web, is people covering their heated bed in blue painters tape, Kapton tape or using a glass plate on top of it. You don’t need that. The prints do stick on your bed alright and come off easily once the bed has cooled down. But to improve the stickiness of your bed I would buy some PVA wood glue (you can get it everywhere) and mix it with water. Its usually 1 part glue and 10 parts water. Mix it well and keep it in an old coke bottle or whatever. Apply a thin layer with a paper towel and let it dry. Believe me, it does wonders – prints stick incredibly well. Once the bed is cool you can still remove them easily.
In the package are the standard alloy pulleys, belts and bearings the X and Y axis will slide one. There are two additional bearings in the kit. The quality of these Chinese bearings is not the greatest, as you can read on the net. Check how smooth the bearings are, if one feels rough – you have two spare! Rest of t he parts are all state of the art and I also want to mention that you will get a generous amount of nuts and bolts. Whats really bad is the quality of the M5 threaded rods the Z axis moves on. These rods are not even close to be straight! That impacts the accuracy of the printer when it moves up and down. They are bent so bad, that it has an impact on the extruder position in all directions’. I created two plastic caps to be placed on the top end of the rods (STL and SCAD file attached), to have them wiggle around only half a mm instead of 5mm. But the only solution is to replace these rods with better ones!
To get you going, I have attached my Marlin configuration file. As long as you put your end switches in the same (stupid) positions like I did, it should work out of the box. If you have questions, just leave a comment.
Shortfalls of this kit
- Some of the included 3D printed parts are of bad quality.
- The M5 threaded rods are bent for the Z axis.
- Power supply quality seems poor – the fan makes noise after days already.
- One of the polulu stepper drivers had a short. The heatsink touched a part on the PCB. Check the heatsinks to be in the right spot.
- No thermo resistant tape (e.g. Kapton) to mount the thermistor on the heated bed.
- Not even basic instructions or pictures to ease the build.
- No sample configuration for Marlin firmware and Slic3r.
A positive aspect is certainly the technical support the seller provides! I asked the support for a sample configuration, but they just provided some clues instead. If you run into issues don’t count that much on it, I recommend to go into the #RepRap IRC channel on freenode. Not at every possible time someone has the breath there to help a noob (which I found understandable), but there are awesome peoplewho got the answers you are looking for.
Thats it about the build. At the bottom a few more pictures as promised, also of some prints! The Prusa i3 is able to deliver great results, once its well calibrated.
This is the configuration.h for Marlin - the Prusa firmware. Make sure endstop configuration matches your setup.
|Date:||May 5, 2015|
This is the black cap you can see in one of the pictures to limit the movement of the threaded rod. I creaded it in OpenScad.
|Date:||May 5, 2015|