A couple of nights ago I received a new Startt 3d printer for my daughters to play with. The kit includes a combination of acrylic and printed parts, and is very straight-forward in construction. I built it yesterday using the very helpful instructions from the imakr.com website. There were only a few issues with the build, but even with my level of experience building kits, it took nearly the full 5 hours they estimate. Listed below are some of my thoughts as I built the kit.
Toy Vanity Issue
To help beginner builders, Imakr puts together the more complex parts; x-carriage with hot end, bowden extruder, display panel, etc. That would be fine, except they did not remove the protective film from the acrylic. Wanting this printer to look “just so” as my wife often complains about the appearance of my original printer, I could not let this go. So, I had to take everything apart, remove the protective film, and put everything back together, without instructions as they had already done it for me.
X-Carriage Belt Tension
The method used to trap the belt in the x-carriage requires that you pass the belt through two holes and then wrap a zip tie around the doubled up belt to hold it in place. In addition, you need pretty good tension on this belt or it will get too loose or even pull free. I was able to get the necessary tension easily, although I was at first concerned about the strength of the printed parts. Unfortunately, when trying to adjust the bearing packs on the x-carriage so that they move smoothly on the rod, the belt worked loose, multiple times. I was finally able to get around this issue by adding a 2nd tie wrap to each side. In the future I will probably print a small retainer clip with a couple of m2 screws to hold this looped belt in place.
Rubbing things the wrong way
As I mentioned above, the printer comes with several printed parts, including the left and right ends for the x-axis. I put the x-axis gantry together as the pictures showed, but when I attempted my first print, I noticed that the belt was rubbing (and even flexing and twisting). The cause of this was that the space the belt goes through in the left x-axis end is close to the face of the motor, and the gear had been put on the motor shaft by imakr so that the groove was away from the motor. This puts the groove too far forward, so I tried to push it further down on the shaft, but then the gear rubs on the motor housing and tends to seize. To fix this problem, I had to remove the x-axis motor (which was under decent tension after my trick above) and put the gear on the motor backwards to allow the belt to track straight.
too small a space
This printer is advertised with printable dimensions of 120x140x130mm, which might be possible if you are willing to ignore, or work around, some issues. Realistically, the size is closer to 110x130x105mm. There are 3 main reasons for this; the print head is off the board at 112m on the x-axis, there are about 10mm that you cannot reach on the y-axis, and above 105mm the print head either pinches the display or clicks (and holds) buttons, plus it scrapes along both if printing at that height.
To simplify their design (also to make it cheaper), imakr uses m3x20mm screws almost exclusively in the main construction of the printer. This caused several issues including an unsightly screw sticking out in a place that can tear flesh. It also caused the command to home the printer to grind for 140mm of attempted belt movement on the Y-axis since I already had the print bed sitting at 0. Unless you pull the end stop as far forward as possible, it will never close and the automatic homing feature fails on the Y-axis. Instead, I replaced the two m3x20mm screws with two m3x16mm and pushed the end-stop further back. With such a limited printable space, 4mm here and there can be important.
Continuing on the space topic, make sure that you mount the print bed with the larger overhang towards the back of the printer. I had it turned the other way, which in my head looked like it would provide extra space, but real estate you can see on the print bed is not necessarily accessible to the printer, and space “inside” the machine is. Anyway, switching this around allowed me to add another 10mm to the printable space in my slicer settings.
Finally, imakr provides a fiberglass printing surface which measures 120x140mm as advertised. You can fasten this down to the acrylic print bed using binder clips, which they also provide. The binder clips occupy 15x10mm of printable space in each corner or side of the bed, and there is no slicer I know of that can be told to ignore them. Maybe if you put them in corners and describe it as an ellipse you could get close. Anyway, if you want that extra 600mm of printable space (really its 6000mm if you exclude the binder clip areas in your rectangle), you have to forgo using the fiberglass board and print directly to the acrylic bed (with a layer of tape of course). I have gotten around this by creating two profiles in Cura, “Startt 3D fiberglass bed” and “Startt 3d Acrylic Bed” with the appropriate sizes. I prefer to print on the fiberglass.
Conclusions
Overall, the printer seems to be exactly as advertised. A good beginner level printer. Construction is time consuming, but with their assembly guide it is not too difficult. I would definitely recommend it to friends interested in getting started with a 3D printer of their own. The only real negative is the limited print size, which (as with most printers I have researched) is overstated in the technical specifications.