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toggle switch hole reamer?

bobnoffs

Well Known Member
hi all,
i have trouble making a large hole round with a twist drill. has anyone used a reamer to make holes cut for switches in the panel round? looks like .480 or .485 diameter. any experience would be appreciated.
 
I found a step drill (Unibit) worked well.

image_11761.jpg
 
Used a step drill for all switches on two panels. If you are drilling several holes in a line, a step drill in a hand drill can walk. Use drill press and clamp your panel!
 
Used a step drill for all switches on two panels. If you are drilling several holes in a line, a step drill in a hand drill can walk. Use drill press and clamp your panel!

A drill press is overkill, or at least a substitute for good workmanship, and nigh-on impossible to use unless the instrument panel is on the workbench and depopulated of components.

A better, more workable solution, especially for retrofit scenarios, is as follows.
1) Mark hole locations (I use blue masking tape on top of the instrument panel to lay out hole locations and to provide protection against tool marks)
2) Center punch hole locations
3) Drill through center punch marks with sharp/new 1/8" or similar twist drill
4) Use these holes as pilots for your step-drill/unibit

NOTE: when doing this kind of work in a retrofit with the panel in the airplane, aluminum chips are a problem. Save yourself some trouble by taking 2" blue masking tape, folding it along its length to form a 90 degree angle, like a piece of angle iron. Stick one side of this to the instrument panel below where you will drill a hole, leaving an inch or so lip of tape sticking out toward you, with the sticky side up toward the hole being drilled. Do this on the back side of the panel, too. You'll be amazed how much swarf will be captured in the glue of the blue tape. It also helps to have a vacuum cleaner nozzle over the back side of the hole being drilled to prevent swarf from spreading around on that invisible side of the instrument panel.

I've done hundreds of instrument panel holes this way with very good results.
 
thanks guys. i tried the step drill and it does work pretty good on aluminum. i am putting colored plastic over portions of my panel and then the plastic will be engraved for labeling.
bought a new, old 15/32 reamer on ebay for bout $6. just tried it out on the plastic . it makes a perfect cut in the relatively soft plastic and there is no chance of scratching the soft plastic. fwiw anyway.
 
When I would use my uni-bit step drills, I would drill a scrap piece of aluminum until I figured out where to stop drilling. I would then put some tape on the drill bit so I knew exactly where to stop. (Yes, I have ruined a part by drilling to far.)
 
'Cross hairs' extended well outside the final hole size can be used to keep a step drill centered if you're freehanding the hole.
 
I've had good results for panel holes in .032 and less with a step drill going one step undersized then tweaking the hole with a deburring tool. Couple swings round and I can get a nice tight fit for switches and such.
 
When I would use my uni-bit step drills, I would drill a scrap piece of aluminum until I figured out where to stop drilling. I would then put some tape on the drill bit so I knew exactly where to stop. (Yes, I have ruined a part by drilling to far.)

I do this too, but use a red sharpie to color the one step thats one too much......
 
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