Bannister back chair – getting to the center of things

centers

After cutting the rear post from the stock, it became clear that we were dealing with a little bit of warp. We determined the position of the “centers” of the cylindrical section to be turned, prior to attaching the counterweight.  The illustration above shows the centers on one plane (the next centers were marked on the adjacent plane or 90 degrees from the first).  Then the lines were projected to find the “true” centers.

The first task was to create a “roller path” for the wheels of the steady rest to ride on.  This needs to be done carefully, as significant deflection will be encountered.  After the steady rest was mounted, we found that deflection was nearly eliminated.  The “working length” of the workpiece was shortened from 41″ to 24″, stiffening it considerably.  Our effective diameter is approximately 8″.  (Several posts back I indicated that the effective diameter was 16″.  My mistake.  Old age setting in…)  So we’ll be turning the details at approximately 1000 rpm.  Note that we’ve attached the counterweights with screws, backed up by several layers of duct tape, just in case…

Advertisements
Explore posts in the same categories: Uncategorized

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s


%d bloggers like this: