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  #1  
Old 12-31-2018, 02:34 PM
Thunderpig Thunderpig is offline
 
Join Date: May 2017
Location: Titusville
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Default Countersink bit tip broke of in longeron

With 7 holes left to countersink, the tip of the bit broke off and is now stuck in the hole. Tried to drill it out gently, but to no avail...anyone ever have this problem and what a solution might look like. I've already broken two 1/4" titanium bits trying to get an in with a # 40. Considered drilling up to a #30 and putting in a 4-5 rivet but the tip seems to be laughing at the bits.
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  #2  
Old 12-31-2018, 03:01 PM
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BrianDC BrianDC is offline
 
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Can you drive it out with a 3/32 pin punch from the non counter sink side?
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Old 12-31-2018, 03:01 PM
Kyle Boatright Kyle Boatright is online now
 
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Can you accurately drill in from the back of the longeron and use a drift or punch from that side to drive out the countersink?

That, or a drill bit remover...
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  #4  
Old 12-31-2018, 03:11 PM
rv7charlie rv7charlie is offline
 
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Default

Can you get to it with your rivet squeezer? If so, you might be able to push it free from the back side (same idea as the punch, but with a bit more control). With a little work at tool making, you can make your own punch to fit the squeezer and an oversize female die for the other side of the squeezer jaw.

Charlie
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  #5  
Old 12-31-2018, 03:33 PM
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wirejock wirejock is offline
 
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Default Punch

Quote:
Originally Posted by BrianDC View Post
Can you drive it out with a 3/32 pin punch from the non counter sink side?
Take a step back. Don't drill. Punch from he back side with a helper holding a bar with a hole in it over the pin hole. It will come out. I had the same problem.
Every hole gets a little buzz with a reamer now. All it takes is a tiny burr to snag a pilot and snap it.
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  #6  
Old 12-31-2018, 03:39 PM
rvbuilder2002 rvbuilder2002 is offline
 
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The countersink cutter is made of highly hardened tool steel.
You will not be able to drill it.
Breakage is usually caused by the hole not actually being the proper diam., and being a tight fit for the cutter pilot).

I have pressed thing out of holes by making a small tool to put in a hand rivet squeezer.
Drill the center of a short AN3 bolt for a tight fit on a 3/32 drill bit. Cut the smooth portion off of a drill bit and press it into the hole in the bolt. Use the pin to press out the pilot, using a rivet squeezer.
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  #7  
Old 12-31-2018, 03:53 PM
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Mike S Mike S is offline
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Default Something to try....

Different expansion rates might turn out to be your friend here, try applying a bit of heat.

Also, when hot, rub a candle on the broken stub, let the wax melt into the interface area.

Use a heat gun, not a gas fired torch.

Try pushing/punching the broken stub out while still hot.

A bit of lube on the pilot when countersinking thick stock is helpful. Bees wax or Boelube are good.
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  #8  
Old 12-31-2018, 04:04 PM
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wirejock wirejock is offline
 
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Default Pin punch

Quote:
Originally Posted by rvbuilder2002 View Post
The countersink cutter is made of highly hardened tool steel.
You will not be able to drill it.
Breakage is usually caused by the hole not actually being the proper diam., and being a tight fit for the cutter pilot).

I have pressed thing out of holes by making a small tool to put in a hand rivet squeezer.
Drill the center of a short AN3 bolt for a tight fit on a 3/32 drill bit. Cut the smooth portion off of a drill bit and press it into the hole in the bolt. Use the pin to press out the pilot, using a rivet squeezer.
That is a cool idea. Logging that one for future use.
I have a rivet gun set drilled 3/16" for pin punch use. I have pin punches milled down to 3/16". I never shared the idea because it's kinda tricky to use. Have to dial down the pressure and feather the trigger. Works when there's no one around to help. One hand on the gun, one with bar. Also have a set of bars with 3/16" holes for shop heads or rivet sets.
https://drive.google.com/open?id=0B7...md0cEtqaW1NMWc
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Larry Larson
Estes Park, CO
http://wirejockrv7a.blogspot.com
wirejock at yahoo dot com
Donated 12/27/2018. Plus a little extra.
RV-7A #73391, N511RV reserved (2,000+ hours)
HS SB, empennage, tanks, wings, fuse, working finishing kit
Disclaimer
I cannot be, nor will I be, held responsible if you try to do the same things I do and it does not work and/or causes you loss, injury, or even death in the process.
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  #9  
Old 12-31-2018, 07:50 PM
Thunderpig Thunderpig is offline
 
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Location: Titusville
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Default

3 hardware stores, no punches...ended up cutting the end off a #40 12" bit...ironically, I had just ordered a replacement bit. Had tried an old bit, but the temp was an issue initially, thanks guys.
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