Archive for March 7th, 2010

Sherline: Milling the Ends of Too-long Acrylic Panels

Having flycut the acrylic panels to the proper width, I had to cut them to the proper length, too. This picture shows the lashup I used to hold them down during the operation…

Clock top panel fixture

Clock top panel fixture

The brown bar sticking out to the left is one of the bookshelf struts that held the toolmaker’s vises down during the flycutting; it’s now secured to the Sherline table with a T-nut. A vise clamped to the bar serves as an end stop for the panels.

Brass tubing locating posts

Brass tubing locating posts

A pair of brass tubes around studs serve as locating pins. To get the things lined up:

  • Loosely clamp a panel down atop a spacing plate
  • Push it back against the loose tubes: crudely parallel to X axis
  • Snug the clamps
  • Align the panel to the X axis using the laser
  • Push the tubes against the panel
  • Tighten their nuts
Top panel end trimming detail

Top panel end trimming detail

Crude, but good enough for this purpose.

Then a bit of manual CNC to shave off the end. Half-inch mill, 1500 rpm, 150 mm/min, more-or-less 0.5 mm cuts. The panels don’t have to be any exact length, as long as the clock circuit boards fit inside, but the ends must be perpendicular and smooth for good gluing.

The exact part will come when I rabbet the side panels…

The side panel setup was much simpler: same brass posts, same spacer, no need for the long bar hanging off to the left.

Side panel fixturing

Side panel fixturing

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