Micro lathe for coloring spinning tops

Context:

My woodturning club does fundraisers for charity several times a year where we demonstrate turning and decorating wooden spinning tops. We also sell a lot of beautifully decorated spinning tops.

The kids that come to the fundraisers think the coloring process is amazing. It wouldn't be safe to let them try coloring a top on the big lathe, so to let them do it themselves safely, I came up with this micro lathe. 

With this lathe, we can mount plain wooden tops and let the kids have fun coloring them. The kids love it, the parents love taking picture of it, and it helps us raise money for our local children's hospital.

You could adapt this for coloring eggs or other small objects.

Parts:

3d Prints: There are 10 3d printed parts. All of them except the lid print and work well in PLA. A couple pieces need supports I print the lid using TPU in order to dampen the sound generated by the motor, but you can print it with PLA as well. The tailstock bolt head back, tailstock bolt retainer, and live center bearing holder all print with supports. Everything else prints without.

Laser Cuts: There are 5 laser cut parts. You could in theory 3d print a base, but it would be a heck of a lot of plastic. I print 2 copies of the “lathe base” out of ¼" birch plywood, and 4 copies of each of the legs. I glue the bases together with wood glue and glue in the legs at the same time to ensure alignment. I paint the whole thing with latex.

Purchased parts and materials:

• 1x 2.5" 3/8 hex bolt - I use a zinc hex bolt from the big box store.
• 1x 3/8 hex nut - Same deal as the bolt.
• 3x 20mm m3 button head bolt
• 6x m3 washer
• 4x 10mm m3 button head bolt
• 7x m3 nut
• 8x 25mm m4 button head bolt
• 8x m4 washer
• 8x m4 nut
• A high-quality 608 bearing - don't use super cheap ones, 9 out of 10 wobble.
• DC geared motor: I use this one from Amazon, the lathe is designed around it. You can use a different motor, but you'll need to redesign the mount plate.
• PWM motor controller: I designed the lathe for a different, now discontinued controller, but you can use this one, also from Amazon.
• You'll need a way to power it. You could use the combination of these three items to make a pretty polished product:
  • A 12V power supply
  • A threaded barrel jack
  • An inline power switch
• A machine lubricant
• E-6000 or another glue that works well for 3d-printed parts - you could use ethyl acetate or something to weld PLA, or acetone to weld ABS.

Part Prep:

The parts are designed to have a tight fit. If your printer makes an elephant foot where the part meets the bed, trim that off all of the pieces.

You'll need to file down the bar along the top of the tailstock quill, as well as the matching channel in the roof of the tailstock body. You should also file down the whole inside of the tailstock body with a fine cylindrical file or you could also use sandpaper wrapped around a split dowel held in a hand drill to sand down the inside.

The screw holes in the top of the motor housing may need to be reamed out with a 1/8" drill bit. The captive nut holes might need a bit of scraping out as well.

You'll need to turn two precision parts on the lathe - it's explained in the video. But the “chuck” that attaches to the motor spindle as well as the “cup center" that goes in the tailstock bearing both can be turned from any hard smooth grained wood. The motor spindle is 6mm, so I use a 6mm steel bar held in a jacobs chuck to turn that piece, and then drill and tap a m3 size hold so I can add a m3 bolt to act as a set screw to hold it on the spindle. 

Solder wires onto the motor connectors or otherwise securely connect them.

Assembly:

My friend Bob put together an assembly video with me, check that out: 

• The tailstock bolt retainer is separated from the tailstock body by pairs of m3 washers, and is attached using the 3 20mm m3 bolts.
• The motor control board can be hot glued in, or it can just sit in there. I find it doesn't really need to be that secure.