Hello Everyone,
My name is Jordan and I'm a 17 year old student in the UK. Over the past Christmas holidays I put together my first RepRap. It took me a year to source the materials as I wanted to spread the cost a bit. I decided to start this thread to share my own experiences in putting together a Prusa Mendel i2 and the modifications I have made myself to it, in the hope that others can learn from my mistakes and that I can learn from other much more experienced people in the RepRap community.
I ordered the printed parts from ebay, which set me back around £55. This was one of the larger investments in the project. The parts came with Greg's Accessible Extruder, however I didn't like the bevelling on the edge of the gear as they didn't seem to mesh as well as I would've hoped, and I believe the Hot-End mount was designed for the Arcol Hot-End. I am using a J-Head MKVII which I also bought from eBay (I got pretty much everything from there) and found that the extruder would've needed a fair bit of modification and I really wanted something that would work out of the box. I opted to buy an extruder that would fit my Hot-End and also have nice deep teeth on the gears, the only drawback was that it is purple, and the rest of my printer is white. I am using the Sanguinololu 1.3a with StepStick drivers.
The entire build took about 3 days from beginning the build to getting a first print. The biggest issues along the way were that I ordered too few M3 screws, I ought to have ordered a wider variety and a larger quantity. If I were to assemble the printer again, I'd order 150 M3 screws of various lengths between 5mm and 70mm, as well as choosing machine allen heads over the weaker philips heads which easily strip, which is especially easy to do when working in more awkward positions. I was lucky enough to get access to a laser cutter in school and I cut my own bed out in school from acrylic. Unfortunately I laser cut the wrong mounting holes and therefore had to laser cut new bearing mounts, which were too short and therefore restrict my Y length. To get over this, I have printed out - but not yet fitted - 10mm spacers, which I'll use to raise the bed above the pulley, hopefully giving me a larger print area. The 3mm acrylic seems to be holding up well, however if I apply any pressure on the bed by hand, it bends very easily, making bed levelling that little bit more difficult.
![WH4WIhw.jpg]( "WH4WIhw.jpg")
I used the RepRap wiki and Gary Hodgeson's absolutely fantastic instructions to assist my building. However, I did find that the Prusa i2 build is nowhere near as well documented as the original and therefore I didn't buy the right length of bar and ended up with a Z axis that is too small. To compensate for this, I cut down some 8mm smooth rod and finished it off on a lathe, to allow it to fit into the modified piece that came with my printed parts. This is a temporary measure that desperately needs changing.
![JIppReY.jpg]( "JIppReY.jpg")
One thing that I really dislike about the Prusa i2 design is the floating Z axis, I encountered issues with it after less than 12 hours, I found that the self amalgamating tape I used to pack the couplings had slipped due to the weight of the entire X-Carriage and therefore ruined any calibration I'd attempted. I would like to try the aluminium flexible couplings from China, they seem quite sturdy and I doubt they would give the same issues.
![ykVQkCw.jpg]( "ykVQkCw.jpg")
Here's a coupling I printed next to another one being printed!
The final main issue I encountered was the stepper motor x end itself. There is a small bridge of plastic which puts a good amount of pressure on the part's weak spot and causes the layers to separate and for the pieces to split apart. I'd like to emphasise that this happened as soon as I screwed the motor on. I think this is probably both fault in the design and the printing.
![y1WCDJM.jpg]( "y1WCDJM.jpg")
![HFOkeoX.jpg]( "HFOkeoX.jpg")
Here's what happens when I undo the top screw into the stepper motor...
Apart from the above issues I mentioned, the printer is now running really well. I was originally running Slic3r and Printrun/Pronterface, but Slic3r has been giving me trouble through it's interface (changing values back to their previous setting, not changing print speed etc) so I gave repetier a go. Repetier seems like a very nice piece of software, however I ran into communication issues, which brought me onto Cura. Cura is a nice, user friendly way of printing. I didn't like the automated approach of controlling the heaters (I'd really like to keep control of them) but I did really like the ability to play about with the print speed. It's a good way to compare the print quality at different speeds. However, I've now run into communication issues with Cura and decided that perhaps Sprinter wasn't the best firmware to use. I've now swapped to Marlin and am still in the process of configuring it (my hot end is -32).
The only big problem that remains with the mechanics is the extruder. It is still rather hit and miss. Once it starts printing there is no issue at all, and once it has been running it performs perfectly, but when starting from the cold, the filament often jams and shreds of plastic get stuck in the hobbed bolt and cause it to lose grip on everything. I'm not sure how to fix this yet so if anybody has any potential solutions I'd love to hear your suggestions.
In terms of electronics, I ran into just two problems. One of them was the Heated Bed which drew far too much current through the MOSFET and through the board (which worried me), also the 7805 voltage regulator got very hot in the process. The other was in the initial 3 days, where the filament wasn't being extruded properly. The filament problem happened because the StepStick potentiometer was slightly too low, and it caused the extruder to only extrude very small amounts of plastic, which worked fine for very slow speeds but it failed at higher speeds. This is definitely something to watch out for as it took me a good couple of hours to figure. The other overheating problem was solved by hooking up the MOSFET source and drain to a relay coil and plonking two 12v wires from the ATX supply to one of the terminals. I connected the other end to the heated bed, and then the gnd on the heated bed to two gnd wires from the ATX. My problem has now been solved and it heats up in much less time.
![N4ZqXyx.jpg]( "N4ZqXyx.jpg")
At some point in the future I'm going to add a filament absence detector to pause the print when the filament runs out as well as hopefully adding an LCD with SD card reader. In terms of mechanics, I'd definitely like to add a bowden extruder to the Prusa and use a minimalist X carriage, with the possibility of turning it into a dual extuder as some point.
If you have any questions or tips or anything I'd love to hear from you :)
Jordan
My name is Jordan and I'm a 17 year old student in the UK. Over the past Christmas holidays I put together my first RepRap. It took me a year to source the materials as I wanted to spread the cost a bit. I decided to start this thread to share my own experiences in putting together a Prusa Mendel i2 and the modifications I have made myself to it, in the hope that others can learn from my mistakes and that I can learn from other much more experienced people in the RepRap community.
I ordered the printed parts from ebay, which set me back around £55. This was one of the larger investments in the project. The parts came with Greg's Accessible Extruder, however I didn't like the bevelling on the edge of the gear as they didn't seem to mesh as well as I would've hoped, and I believe the Hot-End mount was designed for the Arcol Hot-End. I am using a J-Head MKVII which I also bought from eBay (I got pretty much everything from there) and found that the extruder would've needed a fair bit of modification and I really wanted something that would work out of the box. I opted to buy an extruder that would fit my Hot-End and also have nice deep teeth on the gears, the only drawback was that it is purple, and the rest of my printer is white. I am using the Sanguinololu 1.3a with StepStick drivers.
The entire build took about 3 days from beginning the build to getting a first print. The biggest issues along the way were that I ordered too few M3 screws, I ought to have ordered a wider variety and a larger quantity. If I were to assemble the printer again, I'd order 150 M3 screws of various lengths between 5mm and 70mm, as well as choosing machine allen heads over the weaker philips heads which easily strip, which is especially easy to do when working in more awkward positions. I was lucky enough to get access to a laser cutter in school and I cut my own bed out in school from acrylic. Unfortunately I laser cut the wrong mounting holes and therefore had to laser cut new bearing mounts, which were too short and therefore restrict my Y length. To get over this, I have printed out - but not yet fitted - 10mm spacers, which I'll use to raise the bed above the pulley, hopefully giving me a larger print area. The 3mm acrylic seems to be holding up well, however if I apply any pressure on the bed by hand, it bends very easily, making bed levelling that little bit more difficult.
I used the RepRap wiki and Gary Hodgeson's absolutely fantastic instructions to assist my building. However, I did find that the Prusa i2 build is nowhere near as well documented as the original and therefore I didn't buy the right length of bar and ended up with a Z axis that is too small. To compensate for this, I cut down some 8mm smooth rod and finished it off on a lathe, to allow it to fit into the modified piece that came with my printed parts. This is a temporary measure that desperately needs changing.
One thing that I really dislike about the Prusa i2 design is the floating Z axis, I encountered issues with it after less than 12 hours, I found that the self amalgamating tape I used to pack the couplings had slipped due to the weight of the entire X-Carriage and therefore ruined any calibration I'd attempted. I would like to try the aluminium flexible couplings from China, they seem quite sturdy and I doubt they would give the same issues.
Here's a coupling I printed next to another one being printed!
The final main issue I encountered was the stepper motor x end itself. There is a small bridge of plastic which puts a good amount of pressure on the part's weak spot and causes the layers to separate and for the pieces to split apart. I'd like to emphasise that this happened as soon as I screwed the motor on. I think this is probably both fault in the design and the printing.
Here's what happens when I undo the top screw into the stepper motor...
Apart from the above issues I mentioned, the printer is now running really well. I was originally running Slic3r and Printrun/Pronterface, but Slic3r has been giving me trouble through it's interface (changing values back to their previous setting, not changing print speed etc) so I gave repetier a go. Repetier seems like a very nice piece of software, however I ran into communication issues, which brought me onto Cura. Cura is a nice, user friendly way of printing. I didn't like the automated approach of controlling the heaters (I'd really like to keep control of them) but I did really like the ability to play about with the print speed. It's a good way to compare the print quality at different speeds. However, I've now run into communication issues with Cura and decided that perhaps Sprinter wasn't the best firmware to use. I've now swapped to Marlin and am still in the process of configuring it (my hot end is -32).
The only big problem that remains with the mechanics is the extruder. It is still rather hit and miss. Once it starts printing there is no issue at all, and once it has been running it performs perfectly, but when starting from the cold, the filament often jams and shreds of plastic get stuck in the hobbed bolt and cause it to lose grip on everything. I'm not sure how to fix this yet so if anybody has any potential solutions I'd love to hear your suggestions.
In terms of electronics, I ran into just two problems. One of them was the Heated Bed which drew far too much current through the MOSFET and through the board (which worried me), also the 7805 voltage regulator got very hot in the process. The other was in the initial 3 days, where the filament wasn't being extruded properly. The filament problem happened because the StepStick potentiometer was slightly too low, and it caused the extruder to only extrude very small amounts of plastic, which worked fine for very slow speeds but it failed at higher speeds. This is definitely something to watch out for as it took me a good couple of hours to figure. The other overheating problem was solved by hooking up the MOSFET source and drain to a relay coil and plonking two 12v wires from the ATX supply to one of the terminals. I connected the other end to the heated bed, and then the gnd on the heated bed to two gnd wires from the ATX. My problem has now been solved and it heats up in much less time.
At some point in the future I'm going to add a filament absence detector to pause the print when the filament runs out as well as hopefully adding an LCD with SD card reader. In terms of mechanics, I'd definitely like to add a bowden extruder to the Prusa and use a minimalist X carriage, with the possibility of turning it into a dual extuder as some point.
If you have any questions or tips or anything I'd love to hear from you :)
Jordan