3D Milling a Wooden Cup...

My local hardware store recently offered cheap spruce boards.
Well... most of the stuff was actually unusable but the price was too tempting and one of the boards showed a nice grain pattern. After sifting throug the rest of the pallet I finally found 3 boards I liked and decided to try a Finish "Kuksa"...

• The cup is modeled in Alibre Design. Quite simple and done in just a few minutes...
• If you like you can download the model and all other files in the "Projects" section at www.estlcam.com.

• To save material and cutting time I've decided to cut slightly oversized blanks rather than machining a rectangular block...
• The cup is about 85mm high so the best five 18mm blanks are selected and glued together...

• To make alignment easy the cups outline is cut into the spoil board...
• Then the whole block is glued to the spoild board with 5 minute expoxy resin...
  Bad Idea??? Well wait until later ;-)

• The tool I've used for roughing is acutally not long enough to cut down to the bottom.
  But it is long enough to clear the inside and reach a level deep enough to pass the largest dimensions in the X/Y plane so it doesn't matter because we can later flip the part and machine the rest from the other side...
• Finishing is done with a ball nose end mill...

• So how do we separate the cup from the spoil board?
  Well... many fast curing epoxy resins are heat sensitive and will get soft at temperatures above 100°C. If you put them into the oven and wait a few minutes the cup will just fall off... But check your resin first - I've used "Krick 5 Minuten Epoxy" and "Uhu Sofortfest" will also work but some will not...
• Another solution is non-waterproof wood glue...

• This time precise placement is absolutely crucial.
  If you're off by 0.1mm you'll have to sand a lot and if you're off by 1mm you can throw the part into the bin...
  So again I've cut a snugly fitting template to align the cup automatically with perfect precision...
• My template cut is 5mm deep. To get the correct shape I've just created a temporary cut view where the topmost 5mm are removed...

• Again a template is cut to align the handle perfectly...
• For the handle hole I've created a separate STL file showing just the hole and put the origin into its center...

• After machining the cup is sanded to remove the remaining glue and get a nice surface finish...
• Finally I've applied walnut oil to highlight the woods grain (use only walnut or linseed oil - most other vegetable oils will spoil)...