Pendulum Clocks
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AutoCAD, Plastic Mill Table Cover, Path Tracing Tool

CNC parts fabrication for Brian Law's Clock #19.
The plans includes .dxf  files. The workflow
uses: AutoCAD to isolate the single part to
be made (from the .dxf page of parts), mirror
the part if needed to get climb vs. conventional cuts,
offset the cutter radius on the correct sides, remove original
outlines, run AutoCAD to GCode (AC2GC) VBA macro with
the correct parameters to generate the gcode, test run by
tracing on paper, then plastic or metal cutting for the final part.

[archived]

AutoCAD

Original AutoCAD .dxf polylines
having joined segments (pedit).

For a 1mm diameter end mill,
0.5mm mill radius offsets drawn.

Original traces erased then mirrored to
yield offset tool path & climb cutting. 

AutoCAD to GCode (AC2GC) VBA macro screen.
G21 commands Mach3 run in metric.



Mach3 tool paths offset 0.5 mm radius.

Plastic Mill Table Cover



For tracing tool paths on larger (A4) pieces of paper
I made a clear, 1/8" thick acrylic top for the mill table. 

 
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Path Tracing Tool

Ink path tracing tool. I wanted the pen tip to
remain rigid as it moved through a 4mm range
so I made a second ink tracer using 5/16" OD &
1/4" ID brass tubing. The steel end plugs
are 1/4" OD with 2.5mm holes. The plugs are
pressed in. The hole in the top plug is to aid
 its removal. The pen cartridge tip was selected
for its uniform diameter instead of a taper.
A finer point & an improved design.
See original path tracing tool.

The steel plug's length is less than 2mm.

An AutoCAD .dxf file having end
mill radius offset paths & mirrored.
Back-plate layout. Paper tracing
helps me check the gcode & fixtures.




CNC milling of part using a 1mm,
2-flute, carbide end mill at 5665 RPM.
Here, climb cutting has the
end mill traveling clockwise.

Part cut completely through but
the double-sided tape is still intact.

Finished 10T gear & its blank.

A few assorted parts for the clock. Left to right:
one-way & standard 4mm ID bearings, 1mm
SS cable, M6-1 threaded rod, 4mm steel rod,
4 & 8mm reamers, & some CNC-cut gears.
The one-way bearings act in place of
a ratchet for winding the weight.

One-way bearing.

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Lazy Susan DIY Heavy Duty Ball Bearing.
6" (140mm),8" (200mm), 10" (250mm),
12" (300mm), 14" (350mm), 16" (400mm),
18" (448mm), 20" (490mm) sizes.

     
See Gears Section

 
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AutoCAD, Plastic Mill Table Cover, Path Tracing Tool