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  #1  
Old 10-10-2018, 03:03 PM
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kbalch kbalch is offline
 
Join Date: Jan 2005
Location: Clermont, FL
Posts: 173
Default Counterbalance drilling

Maybe my memory has faded over the last 18+ years, but I don't remember the drilling of my -8's aileron counterbalances to be as challenging as I'm finding it to be for my -14A.

I've already broken one good cobalt drill bit and am probably on my way to losing at least another couple. I've been trying to keep the speed (both RPM and advance) slow and it's just occurred to me that using cutting fluid might be a good idea.

Any other suggestions on how to do this more efficiently/painlessly?
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RV-8 N118KB (sold)
RV-14A #140494 (Fuselage underway)
N114KB (reserved)
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  #2  
Old 10-10-2018, 05:11 PM
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RV-14E RV-14E is offline
 
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Location: Colorado
Posts: 154
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Greetings. You'll receive a lot of suggestions and they'll probably all be good ones. I'll share a technique I used which helped eliminate a drill bit that wants to take a walk.
  1. Cleco up the ailerons per plans.
  2. Use a center punch to locate the holes onto the stainless counterbalance.
  3. Remove counterbalance.
  4. Use a super tiny drill bit with lots of lubricating oil to drill at your punches (I used a #60). Use your drill press with a drill press jig. Keep extra bits on hand if they dull.
  5. Upsize the holes progressively with larger bits (I used #55, #50, #45 to #40). Be liberal with the oil.
  6. Cleco up ailerons again.
  7. Match drill with progressively larger drill bits to #30 (I used #37, #34 to #30).

Drill press jig:
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  #3  
Old 10-11-2018, 11:22 AM
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kbalch kbalch is offline
 
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Location: Clermont, FL
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Great idea; thanks. That worked a treat!
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Ken

RV-8 N118KB (sold)
RV-14A #140494 (Fuselage underway)
N114KB (reserved)
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  #4  
Old 10-11-2018, 01:51 PM
sblack sblack is offline
 
Join Date: Dec 2009
Location: Montreal
Posts: 1,295
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coolant or oil (they do similar things) is your friend. YOu don't want it too slow with the very small bits. Good firm pressure so that you make nice chips. Sharp bits. IF you don't get the drill to dig in it will just sit there and rub and dull and work harden the work piece. Drill bits most often break because the flutes get too full rather than because of firm pressure (within reason of course). Any old oil will do. Even bacon fat (is there anything that bacon doesn't improve????).
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RV 4, with an engine...and other stuff
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