Tuesday, May 23, 2017

Lathe Machining 16" Diameter Wood


More detail not covered in the video:

It all started when the law of Scrap Alchemy provided me with a bunch of free wood to experiment with.


I first decided to test my 16" swing with a piece of plywood after running a 2" hole saw through the middle and rough cutting the outside with a saw.  For some reason, I chose a piece that wasn't large enough to get the whole circle.
This was the "machining plywood" mentioned in the video.  UUUUHHHHHHHHHHH!!!!!  I got impatient trying to reduce the diameter from the outside so I tried slicing a groove through the whole thing..... yeah, that didn't work.  The good news, however, was that the unfinished groove helped me align the 2X4 pieces in the next part.
So for this <secret project> I figured I could actually make the round contour needed by gluing a few 2X4 segments together, screwing them onto the board and turning them.  I used Gorilla Glue on the connection between each 2X4, and had screwed them together while the glue was setting.  The clamps ensured they were located correctly while setting, and later I screwed them onto the board to permit turning.
Trying to get the tool to reach the outside at first.  I had to adjust the compound at a funny angle and back it out all the way.  In the future, I will be using the boring head attachment shown below since this didn't give me much range.
The counterweight was just a scrap piece of 3/8" steel with 2 1/4"-20 holes already in it, so I just drilled 2 holes in the wood and attached with bolts and extra fender washers for weight.  In fact, this scrap piece is identical to the one I used for the bench grinder tool rest.
Starting the outside contour.
Finishing the outside contour.  Much more round than before.
This is the "I can't believe it took me this long to notice it looks like a happy face" picture.
Breaking through to the screws.  I didn't want to go much further or I might've compromised the attachment.
Starting the inside contour.
My fancy boring bar extension using an old Criterion 3/4" boring/grooving/facing head.
Inspecting the thickness. I was going for .335", but I figured I could finish the rest with a belt sander.  In fact, this whole project could've taken about 3 less hours if I had just cut it with a bandsaw with the table set at 3°.  I can already hear my shop instructor telling me "You know how a Polak would do it? like you just did."  But hey, that's not the point, the main objective was to try out the 16" lathe swing!
Actually, this contour isn't actually tapered the same direction on both sides.  On one side, the draft switches directions (reason will be revealed later!)
The end product thus far.  I'm very pleased that this actually worked.  The glass (or rather wood) ceiling has been broken!  Time to find massive tree limbs on the side of the street and make some bowls!

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