Previous: Part 5 - Grip Assembly
- Hand Drill Motor
- 9/64" Drill
- 7/64" Drill or 6-32 tap drill to suit material
- 6-32 Tap
- 10-24 Tap
- Tap Handle
- Mini Grinder/zip wheel
- Soldering Iron
- T19 Drive Housing
- T19 Drive Spacer
- T19 Drive Cover
- T19 Bolt
- T19 Crank
- T19 Crank Pin Bushing
- 6-32 1.5" or 1.75" SHCS x 6; or 4 x 2" length and 2 x 1.75" (max) length (drivetrain upper stack bolts)
- 10-24 x 3/8" or 1/4" headless cup point set screw (crank to bolt motor shaft)
- 6-32 x 5/8" SHCS (recommended) or use 1/2" length (crank pin bushing to crank)
- OSM 17HS16-2004S1 x 1 (bolt motor)
- M3 x 6mm length FHCS (bolt motor to drive housing)
- Leadfree Solder
- 1/8" Heat Shrink Tubing
- 0.1" male breakaway header, 7 pins required total (4 and 3 pin segments)
- Subminiature microswitch, roller lever or simulated roller lever actuator (bolt limit switch)
- M2 x 20mm length button head machine screw x 2 (Limit switch mounting screws)
- M2 washer x 2 (above)
- M2 nut x 2 (above)
Part prep time ...again. Is this fastener prep business getting old yet? Well, get your sore wrists ready for a drill and tap-a-thon, because this is your exit exam on that subject with some of the most important threads in the blaster! GO SLOW, back off and clear chips often, don't let that PETG get hot and gummy (and possibly strip) by hurrying, and good luck!
2 front grip base bolt holes - drill and tap for 6-32, about 15mm deep.
4 rear grip base bolt holes - through to top side. Drill and tap for 6-32 on BOTH sides.
4 controller board mounting holes - leave alone. We will install self-tapping screws in those later on.
4 bolt motor mounting holes (NEMA 17 pattern) - clean out to 3mm, should NOT be required with proper prints.
Stock mounting flange: Tap 4 10-24 bolt holes. Holes print at tappable dimension.
Drive housing to breech: Drill and tap 6-32 through flange
Drive spacer and cover: Clean out 6 6-32 through holes (9/64" drill) per part.
Drive cover to breech: Drill and tap 6-32 to exist hole depth in part
Rear top rail mounting hole: Tap 10-24. Hole prints at tappable dimension.
Drive housing front upper bolt holes - drill and tap 6-32 to exist depth. Note, these threads break through on the wiring slots in the housing. This is normal. Keep tap straight when cutting this area.
Crank assembly time:
Crank pin hole: Tap 6-32 thread.
Setscrew hole: Tap 10-24 thread. Hole prints at tappable dimension.
Deburr the crank pin bushing if required.
Bolt it on. Use the longest screw possible for max strength - if thread protrudes as here with a 5/8" length fastener, zip that off flush. Or, use a shorter fastener if you wish to not do that.
N.B.: The top side of the crank has a fillet and is a top layer. The bottom side has a chamfer and is a bottom layer. Does it matter if someone reverses it? No, technically.
Thread the setscrew in.
Motor shaft shortening:
Install the motor into the drive housing.
Bolt on temporarily - ensure seated fully.
Slip the crank onto the shaft. Set the crank with about 1mm or less clearance to the drive housing surface. Check for daylight as so:
Place the drive spacer and bolt on as shown and check for nonzero clearance between bolt and crank surface. (This is not a FDL or Rapidstrike, we don't design things that way at DZ Industries. The bolt MUST NOT touch the crank web.)
Adjust the crank around until both requirements are satisfied and both clearances are even.
Use the crank and a marker to mark the motor shaft length required - use a good sharp tipped marker to get an accurate mark position.
Use tape or a rag to shield the motor bearing from grinding debris and zip the shaft to length with a cutoff wheel. Deburr/break edges slightly.
Cut motor phase wires to about 5", and terminate with a 4 pin 0.1" male connector. Keep stock connector pinout ("Blue Red Green Black") or refer to DRV8825 datasheet and 17HS16-2004S1 datasheet for phase wire colors and proper winding connections to driver
Permanent install, bolt on with 4 M3 x 6mm length flathead cap screws, torque evenly
Mount crank - double check drivetrain clearances and shaft end NON-protrusion, grind a bit if necessary. Torque setscrew.
Bolt limit switch prep:
Wire and terminate the submini switch with a ~3" 2 wire cable - common and NO terminals. Use 3 pin male connector, connect outside pins only.
N.B.: 3 pin connector is used for mechanical security. 2 pin 0.1" header connectors can come loose too easily. Clip the wire-side end of the center pin off if you want but leave the pin in the housing, that's key.
Use M2 switch mounting hardware to mount the limit switch onto the drive spacer using the screw slots.
Don't torque it down yet.
Fit the spacer and bolt to the housing. Start 2 drive stack bolts in place to locate the spacer.
Adjust the switch position for consistent actuation at bottom dead center (note crank angle in the image), WITHOUT the bolt bottoming the switch out. IOW, move the switch as close to the motor shaft as possible without anything interfering/binding/having excessive friction.
Where in the slot travel YOUR switch is, will vary. The slot length is intended to accommodate different switch brands, models and actuator types. You shouldn't need to grind or shim anything to make nearly any lever-equipped submini switch work here.
Once satisfied, be careful not to disturb the switch position and torque the M2 hardware down solidly. Recheck free drivetrain rotation and switch actuation (CLICK!) at BDC.
Next: Part 7 - Blaster Controller