Archive for April 5th, 2013
It didn’t take long to realize that Makergear doesn’t actually have any assembly instructions that convert an array of parts bags into a working M2 printer. The box contained a set of subassembly drawings, their internal BOM checklist, and an orange sheet with cautionary notes. So I figured I’d build enough subassemblies to reduce the clutter, then put them together into the chassis while working on Phil’s card table.
Unfortunately, the BOM on each drawing may not match the drawing, the drawings don’t quite match what’s currently shipped, neither of those match the instructions on the website, the assembly videos / animations aren’t particularly useful (at least to me; I don’t need animated trajectories for nuts and bolts after the first one), not all hardware has a corresponding drawing, and nowhere will you find enough information to actually put the thing together on the first try. Makergear is obviously running as fast as they can, making improvements as they go, and, while the task isn’t impossible, if you’re not pretty good at mechanical assembly, building an M2 from scratch won’t be a pleasant experience.
A thread on the Makergear Google Group suggests there’s an unofficial “Heathkit style” manual in the offing, which will be a major improvement over the status quo. The catch will be updating the instructions in pace with production improvements, while not losing previous owners along the way. The Google Group has pointers to some good build logs; I regret I can’t contribute anything of the same scale.
Some assembly notes that don’t fit anywhere else…
The chassis arrived with the Y axis slide, Z axis stage, and Z axis stepper motor preassembled and aligned in the chassis. Given that’s the part of the process requiring, by their own admission and video example, some finesse, I think they found it impossible for newbies lacking experience.
CAUTION! If you must assemble the Z axis or modify it, you must remove all four screws from the stepper motor’s case to get it in or out of the chassis. Do not let the motor endcaps fall off or become misaligned, because that will demagnetize the rotor and drastically reduce the available torque. Perhaps wrapping some tape around the sides of the motor to secure the endcaps will prevent disaster. As I’ll describe later, the Z axis motor has barely enough torque for its job and any loss will render it useless.
Use the shortest possible screws in the two huge rubber feet on the X+ side of the chassis, because the electronics case must fit flush to the chassis just above them. The recommended screws protrude too far through the chassis plate, which is perfectly fine on the X- side.
Secure the electronics case to the chassis side using M3 screws, instead of the M4 screws that fit the threaded holes, with three M3 washers between the case and the chassis. Put Nylock nuts on the outside of the chassis. You’ll understand why when you get there.
Tape the picture of the power supply plugs behind the electronics case where you won’t mislay it, because inadvertently swapping the power connectors will not go well.
Believe it or not, that giant lump of wire on the end of the harness actually fits inside the electronics case. Take it slow and it’ll be all good.
Cut a cardboard cover (I harvested a shoe box) to fit the build platform and clip it in place whenever you’re not actually building something. You will drop tools on that lovely glass platform…
I’ll be volunteering at the TCHFFRC this weekend, so if you happen to be near Hartford CT, drop in to see some high-pressure robot debugging.
You’ll find me behind the Robot Inspection Table, making sure everybody’s building robots that meet the same specifications. That’s a step up from a few years ago, when I got to dress the Granny Doll used in the RoboWaiter Contest…