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Counter Sinking w/o a Micro-stop

kjowen

Well Known Member
In several areas while working on my -8 empennage the plans call for counter sinking spars inside the flanges. Some of the holes called out are a nonissue since they are away from the sides, but some are very close to the flange. In some posts, it has been suggested to cut off 1/2 of the countersink so access can be obtained. That was not my 1st choice, so I disassembled a rivet removal tool and inserted the counter sink bit in place of the drill bit (fits perfectly) and used my drill press slowly to remove material until the proper depth was obtained. This produced a much better result, I feel, than free-handing with a 1/2 cut countersink. This can also be accomplished by inserting the counter sink bit directly in the key chuck of the drill press, the threads can take a little pressure without flattening out and making it unusable in the micro-stop.
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Adapter

A drill adapter is readily available to do just that...

I think most of the countersink bits use 1/4-28 threads...
 
Good job identifying a problem and exhibiting Man?s separation from most animals. We can make tools!
 
Most difficult access countersinking in 3/32 or 1/8" can be neatly done with a hand held deburrer. Practise, practise, practise on scrap and you quickly get the feel. if you have good access at the back, deburr onto your finger as a very accurate depth stop ! No, it doesn't hurt ;)
 
Most difficult access countersinking in 3/32 or 1/8" can be neatly done with a hand held deburrer. Practise, practise, practise on scrap and you quickly get the feel. if you have good access at the back, deburr onto your finger as a very accurate depth stop ! No, it doesn't hurt ;)




+1.



Especially when using the NAS 1097(?) oops rivets. The 3/32 body dia ones with the "1/16" rivet heads. If memory serves it was 2 or 3 turns with the tool to get the correct depth.
 
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