My wife and I
visited some old friends of hers and as we entered their house, I couldn't help but notice
a great clock. It was 20 inches in diameter so it would have been hard to miss. I
thought it was just an "art" piece, but as the hands turned, I saw that it was a
real battery operated giant clock — and I had to make one. I took a couple of measurements.
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I think
making a copy is doable, but I either had to make a detailed paper copy or just get
to the shop and start dummy-ing it up.
I am using a 24" X 48" piece of MDF. The original is MDF painted
black. The outside diameter is 20", but I am going to cut the first circle at
22" diameter so that I have room outside the actual clock to screw down templates. I
start by drilling a 1/8" hole to hold the center pin.
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I have
mounted this circle jig (click
here for information) to the plunge base of my new PorterCable 890 series router. I
have inserted the pin at the 22" position (arrow).
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I am installing a 1/4" diameter up-spiral bit. I expect that this bit plus
the vacuum attachment will give me good clean cuts. By the way, this circle jig
dimensions are based on using a 1/4" cutter. If used with a larger diameter bit, you
adjust the dimension accordingly.
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I
have plunged the router so that the bit just touches the surface. That is
"zeroing" the router depth. Then I raise the plunge stop and set it to the
3/4" thickness of the MDF — and then I add a "skosh" to route a clean
break all the way through. Note that I have placed the workpiece on a piece of 1"
Styrofoam insulation board. I can route into this without any problems.
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With the
vacuum hose connected to the router base's port and the router, itself, plugged into the
vacuum, when I route, the dust and chips should be drawn out of the groove —
"should be" being the key words.
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With the router plunged abut 2/3 of the depth, it is
like cutting butter. The up-spiral bit cuts cleanly without any resistance. Furthermore,
the cut is clean and the groove is dust-free. The vacuum setup with this base is
perfect. Without this hook up, the groove would have had to be cleaned after each pass.
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Now I
have a very clean cut 22" diameter circle.
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I took
this picture to show you the foam insulation board that I have under the MDF. Cutting into
this board does not create a problem. It is a good way to keep the MDF off table tops that
could be ruined.
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