Cutting a Circular Window: Part Deux

Posted 10/20/2007 at 3:04pm | by

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Last week I made a pattern for installing a circular window in a side panel and started the cutting. I used a Dremel Stylus with a fiberglass reinforced cutoff wheel to make a first pass. Eventually, the completed mod will be a “window in window” side panel for project Nautilus. This was also a good opportunity to put the Stylus through some hard core testing.

As I mentioned last week, it would take multiple passes to complete the window cutting. The key is to be patient. The less metal you take off during a pass, the better the final result – but the longer it will take. As you get to the last couple passes, you will see the metal begin to blister on the back side of the panel. Resist the urge to just “go for it” – let the tool do the cutting – don’t force it. A few passes later, and the cut will be complete.

For me, this cut took 10 passes with the Stylus. I originally started with a setting of 6.5, but ramped that up to 8 after the second pass. I figure that’s about 18,000 RPM, and it cuts much better. It seemed like I would never get through, but on the tenth pass the center finally gave way.

The Stylus worked great and is perfect for someone new to rotary tools. It has lower torque than AC powered models which makes it easier to control. At a setting of 8, I could only get one or two passes before I needed to let it cool or dock it for a recharge (about 10-15 minutes running time) and the cuts were not as deep as what you would get from a corded model. The result is forced patience on to the user and slower, better cuts - perfect for a first timer.

With the cut finished, I switched to a bonded grinding nib. I used this to quickly go over the back edge of the cut at about 45 degrees. The idea here is to remove the “flash” (metal flakes) left from making the cut. Then I switch to 200-300 grit sandpaper to clean up the edge. Be careful here – a small burr could go right through the sandpaper into a finger. I didn’t have any areas to “tune up”, but if you do, try the sand paper first, and if that will not work, go back to the rotary tool with the grinding nib.