Heavy duty rock tumbler / barrel rumbler
Polish rocks or metal 3D printed parts!
This design uses a mains powered AC synchronous geared motor which runs quietly and reliably for long durations.
The barrel is made from cheap, durable PVC plumbing components and can be optionally lined with rubber or a printed insert. Mine is lined with checkerplate rubber sheet.
Note that I am in Australia. Barrel parts are available from Bunnings 'Holman' brand. Electrical parts from Jaycar. The motor and rubber mounts are from eBay and the O-rings came from a kit from Aldi.
Bill of materials
- 6 parts, CNC cut from 18mm plywood
- Cover plate, from thin acrylic / aluminium etc (I used 2mm clear acrylic).
- 10 x 10G x 30mm wood screws
- 4 x small self tapping screws approx 3mm x 10mm long for cover plate
- 4 x drive wheels
- 1 x motor pulley
- 2 x shaft pulleys
- plug to cover motor shaft hole
(STL is included with all parts for printing)
Hardware - barrel:
- 2 x 100mm PVC threaded access coupling (105mm long overall)
- 2 x 100mm PVC screw on cap
- Short length of 100mm PVC pipe
- PVC glue / primer
Hardware - mechanism:
- Motor - AC Synchronous geared 100RPM 60mm x 60mm
- 4 x M4 15mm x 15mm rubber mounts, Male - Female threads
- 4 x M4 x 25mm machine screws
- 4 x M4 nyloc nuts and washers
- 1 x M3 grub screw + nut (for motor pulley)
- 2 x 300mm lengths of M8 threaded rod
- 20 x M8 nuts, 13mm hex (I used 8 x nylocs and 12 x plain nuts)
- 4 x 608ZZ (skateboard) bearings
- 2 x O-rings 50mm ID x 3.55mm for drive bands
- 4 x O-rings 28mm ID x 3.55mm for drive wheel tyres
Hardware - electrical:
- IEC power socket + fuse + switch (optional)
- Mains power cable
- Wire, lugs, solder, heatshrink etc.
- Measure the distance inside the threaded access coupling up to the ridge, from the non-threaded end.
- Cut a length of 100mm PVC pipe just shorter than twice this distance.
- Assemble the 2 couplings to each other with the pipe, using PVC glue (primer optional).
- Screw on the end caps.
- Cut all 6 parts from 18mm Plywood
- Contersink screw holes if preferred
- Assemble frame with screws
- Rout a rebate around the inside of the underneath of the motor box, to fit the cover plate. I used a 9.5mm rebate bit, 30mm diameter, 5mm deep using a hand router.
- It is easier to take the outer ends and lid back off the frame for the remainder of the assembly.
- All cuts can be made with a 6mm tool except for the 4 x motor mount holes which are 4mm diameter.
- Outer pockets for 608 bearings are 7mm deep
- Outer pocket for IEC power socket + fuse + switch is 16.5~17mm deep, allowing the clips to hold on the thin ridge left.
NOTE: This design uses mains voltage, which is dangerous! It may be illegal in your country to wire this yourself. Do not attempt to wire this unless you know what you are doing!
Fit the rest of the frame plus the cover plate with 4 x small self tapping screws before operating.
Frame CNC cut from 18mm film-faced 'form ply' plywood using 3.175mm and 6.0mm tools on Chinese 6090 router.
This was my inspiration for the barrel design, threaded rod shafts and drive wheels: http://www.thingiverse.com/thing:935252
Given that I have a CNC router I decided to design it from plywood rather than printed brackets.
I also found a suitable AC geared motor and opted for belt drive instead of gears for quietness, since this needs to run for weeks at a time!
This was designed in Solidworks then exported to Slic3r for 3D printed parts and ArtCam Express for CNC parts.