Vacuum Adapter Finally Made!!
I have been away from the lathe for several months and I finally got to the turn a bowl in early May for a wedding gift in June. I picked up a vacuum pump in January, but never got around to using it. When I turned the bowl for the wedding I wanted to add some details to the bottom, so I finally went to work on the vacuum pump.
I have a small metal lathe, so I chucked up a piece of aluminum rod and turned it to fit in the opening in the headstock spindle. I added two grooves for some o-rings to seal the adapter in the spindle. I happened to have a sealed bearing in the hardware drawer, so I just bored the other end of the rod to fit the OD of the bearing. I then bored a center hole through the adapter for the vacuum.
After cleaning up the adapter I epoxied the bearing in place. I had to run to the hardware store to find a brass fitting that was just bigger than the id of the bearing. I then chucked the brass fitting in the metal lathe and turned the threads down until it fit in the bearing. Again I used the epoxy to fix the fitting into the bearing. I threaded a couple of additional fittings on and gave it a test run.
I needed to get the bottom of the bowl done fast, so I grabbed some MDF and closed cell foam and made a simple flat vacuum chuck to turn this bowl. I still need to make some kind of mount for the vacuum and filters, but it works great!!
I put the bowl up against the chuck and turned on the vacuum, there was only 15 inches of Hg, but with such a large surface area, I couldn’t break the vacuum no matter how hard I tried. I forgot how porous MDF really is, I will have to work on doing something different for the chuck.
Here is a close-up of the detail rings I added. I will put my signature in the center, the bowl number in the middle ring, and wood species in the outer ring.
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