Fast, simple, and beautiful: MendelMax 2.0
The new MendelMax 2.0 is a complete reinvention of the MendelMax. It makes the MendelMax faster to build, easier to source and even better looking than before.
When I designed the original MendelMax, I had no intention of selling kits, so I put little thought into the manufacturability. Once I started selling kits, it rapidly became apparent that printed parts are great for small scale production, but became a limiting factor as demand grows.
To address that, I wanted to consider other ways of producing that parts; however, I was not willing to go the way that other RepRap sellers are by moving to closed or pseudo-open source (open, but using proprietary parts). My goal was to design a 3D printer that was easy to manufacture in large quantities and still fully printable (though the exact details may vary between the printed and non-printed versions).
While bouncing ideas around, I looked at a variety of ideas like bent sheet metal before deciding to use flat aluminum plates. The beauty of this design is that not only are the plates printable and machinable, but you can also make the parts at home with readily available home-shop tools, no CNC equipment required.
Ease of Assembly
While ease of manufacturing was a prime motivator, it was not the sole goal. I also wanted a design that lowered the barriers of entry as much as possible. After supporting the MendelMax for a year, I’ve identified several of the hard parts people face in getting their printer up and running. Throughout the design process, I tried to keep those lessons in mind and designed for ease of assembly.
Some examples of how the MendelMax 2.0 makes things easy:
- Inexpensive, easily sourced linear rails on the x and y-axes
- Easy to use belt tensioners on the x and y-axes
- Wherever possible, tapped holes in the aluminum, rather than nuts
- Machined parts eliminate warped, cracked parts and incorrectly sized holes; and assure proper alignment and squareness
The frame: New upright, open design
The MendelMax 2.0 includes a completely redesigned frame, made from aluminum extrusions and primarily flat plates. These plates can be cut from aluminum, printed, laser cut from plastic, or hand cut with a scroll saw or a coping saw (making this arguably the most accessible DIY reprap ever). Unlike previous “RepStraps”, when made with care, a hand cut MendelMax 2.0 will virtually function identically to a custom machined one. There is no longer a reason to see your hand built machine as merely a means to an end.
For those of you who have a printer, the design remains fully printable, though a few parts need to be modified for printability due to strength and rigidity requirements (in particular the x ends). I hope to have printable parts available by the time I release the sources. The base ends are not printable, but you can substitute the lower base corners from the MendelMax 1.5 and use 340 mm extrusions to get a printable equivalent.
Triangles are a smart choice for the gantry, both functionally and aesthetically. From a design standpoint, I wanted the MendelMax to still be visibly a Mendel descendent, while not letting the shape get in the way of improvements. By switching to a right-triangle design, the MendelMax 2.0 gains ~50mm more z-axis movement (the exact amount will depend on your extruder choice). The new design results in a very open, unobstructed print area.
The z-axis stepper motors and lead screws have been moved to the inside of the frame, while the efficiency of printer footprint to print volume has significantly improved. This change looks great and results in a larger build volume relative to the overall footprint of the bot.
The power supply and electronics are mounted within the frame, under the printbed.
Linear rail X&Y, new y bed frame, and new carriage
The new MendelMax 2.0 now has a linear rail-based axes for both the x and y. This makes movements smooth and quiet, requires less maintenance, and makes assembly even simpler. Traditional linear shafting is one of the biggest sources of problems on home built 3D printers: the shafts need to be perfectly straight, perfectly aligned and extremely consistent in diameter. Even the slightest variation can cause binding or increased friction. Switching to rails adds a bit to the upfront cost, but it saves significantly in the end, both through faster assembly and configuration times, and with faster print times due to the lower friction.
For the x-axis, a key design goal was maintaining backwards compatibility with older extruder designs. Most linear rail x-axis designs switch to a vertical layout, which limits the extruders you can use, or they sacrifice y-axis build area by mounting the extruder off center. By carefully choosing the correct rail for the job, the MendelMax 2.0 maintains a horizontal x-axis design that still allows use of almost any extruder and hot end design.
The y-axis features a new rail when compared to the 1.5+; it is cheaper, lighter and has an adjustable car system. It also features a new three-point bed leveling system, making for easier bed leveling. The print bed utilizes a heater, heat spreader, and glass with a larger print area than the MendelMax 1.5+, as well as most other RepRaps.
Of course like all MendelMax versions, my version is not intended to be the only variant. If you prefer linear shafting or you want to experiment with some other design for the x and y-axes, I encourage you to experiment!
When is it coming?
The MendelMax 2.0 was developed with the intention of it being both an Open Source project and a product sold by my new company Maker’s Tool Works. The current plan to do a batch of beta kits to work out any bugs, and then release the sources when version 2.0 is released, probably in Early February. The exact OS license is to be determined, but it will likely be CC-BY-SA. Sources will remain closed during the beta phase, but I am happy to work with adventurous DIYers who don’t mind being on the cutting edge. Just contact maxbots for more information.
I greatly appreciate the community that has supported this project over the last year. It has been an eventful year, for myself, for the community, and for 3D printing in general. Without your contributions to previous versions, requests for features, and ideas shared with me through our Google Group, Wiki, and FreeNode IRC chatroom, the MendelMax would not be the printer it is today. I look forward to working with the community as the design is tested, finalized, and released.
Happy holidays to everyone!
More photos are available on Flickr.