Makergear M2: Out of Box Experience

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.

M2 Electronics Case on chassis

M2 Electronics Case on chassis

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…

Makergear M2 3D Printer with cardboard protecting glass platform

Makergear M2 3D Printer with cardboard protecting glass platform

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  1. #1 by Jason Doege on 2013-04-05 - 08:24

    “…demagnetize the rotor…”

    Huh. Guess I shouldn’t have taken those steppers apart, years ago. ‘doh. Do you happen to know how that happens that the rotor loses magnetism?

    • #2 by Ed on 2013-04-05 - 08:57

      Well, now you know what’s inside a stepper; that’s not to be sniffed at!

      Maybe it’s something I know that isn’t so, but when the rotor smacks up against the stator and eliminates the air gap, the magnetic field increases to the point where it wipes out the adjacent poles. In the old days, they used to magnetize ’em in place after assembly, but nowadays I suspect the high-performance magnetic materials make that impossible… but I don’t know for sure.

      That FAQ discusses demagnetization, although for discrete magnets rather than rotors.

  2. #3 by Jetguy on 2013-04-05 - 09:07

    Only in this one case do I disagree. I have done everything you are not supposed to do with steppers and have not yet found one that lost torque from disasembly. This old habit might come from permanent magnet DC motors where the can was the field, but in this case, the rotor contains powerful rare earth magnets. For example, my new Y axis required a dual shaft motor which Kysan does not sell in NEMA17 form. Light Object does sell nice dual shaft NEMA17s, but then I found specific winding of those motors did not play nicely with gen4 stepper drivers and thus did a rotor swap into the Kysan body and windings. This motor cannot have any torque loss as it’s the Y axis swinging ~4 pounds of mass. It does it reliably at up to about 150mm/s, maybe faster but it begins to shake the machine so violently you tend to back off. The machine moves rather than the gantry…….

    Of course, I know you will test this with science rather than gut feel.

    • #4 by Brent Crosby on 2013-04-05 - 13:57

      On MiseryBot, one of the motors failed. I took it apart, found a broken wire (looked like a manufacturing defect) stripped and soldered it back, and the motor continued to work fine.

      I am pretty sure I was running MiseryBots motors about as hard as they could possibly be run, both before and after the repair.

      Maybe it applied to earlier motors but not to the modern ones,

      • #5 by Ed on 2013-04-05 - 22:14

        I’d love to be proven wrong!

    • #6 by Ed on 2013-04-05 - 22:12

      As the saying goes: one careful measurement trumps a kilo-opinion!
      Gotta measure the before and after torque, because half of too much may still be more than enough…
      In any event, swapping rotors probably invalidates any comparison, so you’d have to remove and install the same rotor. If I ever do a real Prony Brake, I promise to try it with a scrap motor…