Vibrating attachment for Dremel / Bosch GRO (Hitachi clone)

I was looking for an attachment that could help eliminate voids when filling 3D prints with concrete. I cloned the mechanism of Hitachis implementation of this tool from photos found online. 

Required hardware

• 4 x DIN 934 M3 Nut

• 4 x DIN 912 M3x8 Bolt

• 2 x M8 Nut (as weight)

• 1 x DIN 912 M4x40 Bolt

• 2 x 634Z Bearing

Printing the head

• Both pieces can be printed with no or minimal support

• Experiment with infill to calibrate strength of vibration

• Pause at layer to insert nuts

Printing the imbalance

• Print with axis normal to print bed

• Use support distance = 0 and pause at layer to paint support interface with permanent marker as release layer

• Insert between 0-2 hex nuts to calibrate vibrations

Printing the coupling

• Use TPU

• Use small line widths (0.32 mm on 0.4 mm nozzle) and Arachne

• Pause at layer on male coupling to insert nut

Printing the vibration dampener 

• Use TPU 

• Use Height range modifier on non threaded section (13 mm - 33 mm): Zero walls

• Use high infill ratio (15% - 25%)

Assembly

• M4 bolt is used as axle, test fit according to photo and shorten bolt (oversized bolt is specified for a longer non-threaded section)

• Ensure M8 nut weight faces coupling side

• Using the modelled hole in the imbalance either:

• a. apply CA glue to bond bolt to axle

• b. drill 1.75 mm hole through bolt and pin imbalance to axle with a filament cutoff

• Place assembly in head, close head with M3 bolts

• Thread vibration dampener to head

• Thread female coupling to rotary tool (about halfway)

• Connect attachment and rotary tool

Notes on usage

• Turn the attachment over manually first and listen for scraping sounds before using on a rotary tool

• Use lower rotation speeds ('1' - '2')

• This is not intended for use on humans and it may not be safe to use it for this purpose