This is a log of my experiences in a first printer build. After looking at the various developments I settled on the Prusa i3 as a good starting point because:
- Simple, well tested design with active development
- Good build instructions
- Plenty of support & community knowledge
I did a lot of reading on the Wiki, Forums, GitHub and others before I made a choice. There is a lot of variation in designs so I wanted to ensure I chose something stable for my first build. I considered the timber frame initially and a possible repStrap pathway but I don't have a lot of timber working tools and needed a working printer as soon as possible and before I could get more adventurous so I chose the single aluminium frame Prusa i3 quite early on in my research
- The Prusa home page
- The incomplete reprap beginner's guide- A good starting point and a wealth of search /inks/terms to expand further
- EiNSTeiN variant - A nice build log that helped with selecting a suitable BOM
- [i3 build instructions] - Good build videos that are helped in seeing how the BOM goes together in sequence
- BOM and instructions - As the printed parts I purchased were based on this variant this helped in ensuring I did not have incompatible BOM parts
- Electronics variants - Ultimately selected the RAMPS_1.4 & Arduino_Mega combo as a robust solution
- A4988_vs_DRV8825_Chinese_Stepper_Driver_Boards - Electronics research around drive options. I went for the DRV8825 as they seemed a slightly better choice based on the comparison to A4988
I purposely selected the parts for my printer from the best buys I could find to compare the cost of a kit. All up I spent around AU$550 (although I have more parts than I require). There are some excellent kits for around that can match this price so this would be better value for money with less compatibility/quality issues if you purchase from a reputable dealer. However, if you wish to understand a lot more about the machine, like me, then go the hard road and use the mistakes as cheap training.
- How to get it? - Printable STL part files - Printed Parts from Lithuania through eBay AU$44 for the set. Not sure I would use this design again as I have a few concerns that I'll document along the way
- How to get it? - Laser/waterjet cut DXF files - I used the basic frame design and had 2 laser cut. AU$40 each. Not a good idea... see below
- NEMA 17 1.8° Stepper Motor, 2 Phase Bipolar - eBay purchase from USA. New & S/Hand for AU$6 each. OEM No: 42BYGH3903L-02. I purchased 6 to give me a spare
- Mk V J Head - Purchased from a local RepRapper who had upgraded to a 1.75mm Bowden Extruder. I also got his extruder parts & 3 rolls of 3mm filament
- PCB Heatbed MK2a - This was also purchased from my local RepRapper along with a Mk3 and a sheet of glass. In total he charged me AU$70 for this and the Nozzle etc
- I purchased a Chinese electronics kit for AU$69 that included: RAMPS 1.4, Mega 2560, 5x DRV8825 Driver Boards, 12864 Smart LCD Controller with SD slot, 3x Optical End-stops
- 12v 40A Strip Power Supply $70. I oversized this substantially to keep it running well within its range as the quality was dubious
- Other vitamins were mostly cheap Imported parts with rods purchased from a local supplier
The drives and printed parts were the first parts purchased.
The Y carriage assembles as expected. Things that could be pondered to improve the design:
- The spacing between the threaded rod could be increased by a few millimetres to allow access for a ring spanner
- There is a lot of movement, notably torsional that permits frame twist. With so many nuts there is also lots of variability in the structure. This increases the complexity of squaring/alignment for the inexperienced builder and will require maintenance to re-tension during operation.
The Y Belt tensioner
- Mine delaminated through the tension screw without a lot of torque applied. This is structurally quite a weak design
- The ridges on the inside of the bearing support do not appear to be parallel putting a small twist in the bearing. The original design that uses washers to create clearance and insure the clamping is on the bearings inner race is probably a simpler design
Overall, the Y belt tensioner... actually the whole drive leaves a lot to be desired as alignments are also very poor. It may be easier to use the 10mm threaded rod as the tensioning mechanism and perhaps make the tensioner similar in design to the drive end and mount across the two threaded rods. Even better would be to mount the bearing on the rod but this could further complicate the alignment issue for the belt as the increased bearing diameter would be substantial.
Linear Bearings I have more Z movement than I would like in the carriage linear bearings. That could be accounted for a lack of decent shafting and poor quality bearings. Belt alignment cause exasperate this issue