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M5Duo

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firepick1 (localhost) edited this page Aug 20, 2016 · 12 revisions

FireBolt™ M5Duo synchronous drive

M5Duo (see video). is a dual-bolt synchronous drive that uses a 3D-printed (3DP) herringbone gear train.

Applications for M5Duo include:

  • Z-lift
  • syringe pump

Required Parts

Electrical: The choice of stepper motor and driver is critical. They all work to some extent, but the documented configuration works much better than a random setup:

Mechanical:

  • Misumi 20x40 extrusion 180-300mm (1)
  • 5x10x4mm deep groove sealed bearing (4)
  • Teflon tape used for plumbing
  • Grease for lubrication

Fasteners:

  • M5 hex cap fully threaded bolts ≥50mm (2)
  • M5 hex nuts, preferably thin (4)
  • M5x10mm screw (4)
  • M5 extrusion nuts (4)
  • M5 washers for bearings (4)
  • M3 set screw (1)
  • M3 hex nut (3)
  • M3x15mm screw for limit switch (2)
  • M3x10mm screw for stepper motor (4)

3D-printed:

Assembly

  1. Assemble GH17 pinion gear by adding M3 nut and set screw
  2. Push assembled GH17 pinion gear firmly onto stepper shaft with gear-side away from stepper motor. Leave about 1mm space between gear base and stepper. Do not tighten set screw.
  3. Anneal GH17 gear and stepper assembly for 50 minutes at 160°F/71°C. Cool.
  4. Attach stepper to stepper bracket with four M3 screws
  5. Attach stepper bracket to 20x40mm extrusion using two M5x10mm screws
  6. Wrap both M5 bolts with enough Teflon tape to ensure a snug fit with bearings and herringbone gear
  7. Thread each M5 bolt through GH21M5 herringbone gear, M5 washer and one 5x10x4mm bearing
  8. Insert M5 bolts into X40D21B510 bearing block
  9. Slide one 5x10x4mm bearing onto each M5 bolt
  10. Thread two M5 thin nuts onto each M5 bolt. Do not tighten
  11. Attach X40D21B510 bearing block to 20x40mm extrusion with two M5 screws and two M5 extrusion nuts. Do not tighten.
  12. Slide X40D21B510 bearing block along extrusion so that GH21M5 herringbone gears mesh properly with GH17 pinion gear.
  13. Tighten M5 thin nuts finger tight to hold bearings in place. If you overtighten, the drive will jam.
  14. Attach limit switch to X40D21B510 bearing block with two M3x15mm screws and two M3 hex nuts.

Drive Alignment

A properly aligned FireBolt™ drive will function smoothly and quietly. However, a mis-aligned drive may slip gears or not even turn. Alignment is conducted in two phases:

  1. Low-speed alignment uses low speed and high torque to mesh gears properly
  2. High-speed alignment uses drive vibrations to "rattle things into place"

During alighment, keep the M5 thin nuts loose to allow all the various parts to align themselves in use. After alignment and lubrication, tighten screws to support axial thrust load. Do not overtighten the M5 bolt thin nuts or the drive will jam.

Low Speed Alignment

A newly assembled M5Duo drive needs to be aligned before production use. Align the parts by running the drive at low speed (30-60rpm) and use the high torque of the lower speed to align the parts. Herringbone gears are self-aligning, and we simply allow them to find their correct position by loosening the X40D21B510 bearing block fasteners.

For example, if you are using FireStep, you would start with low speed, high-torque alignment:

{"tstph":{"tv":0.1,"mv":1000,"pu":6400}}

As low speed alignment proceeds, the drive will gradually become slightly quieter as the gears mesh better.

High Speed Alignment

After the gears are properly meshed by low-speed alignment, you will need to attach a light load to the M5Duo for high speed alignment. The load is required to align the M5 bolts to the thrust axis. You should therefore only tighten the M5 thin nuts with a load in place.

For high speed alignment using FireStep:

  1. Home: {"homx":""}
  2. High speed alignment: {"tstph":{"tv":0.2,"mv":8000,"pu":32000}}

After the gears settle in, grease the bolts and gears as they turn. Once the M5Duo is running smoothly, tighten remaining screws for thrust load.

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