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Broken drill bit - Extraction

P

Pbr47906

Well Known Member
What I feared just happened. I got the first main gear leg drilled, and was working on the second leg when the bit broke. How do you extract a broken bit?

Thanks,
Paul
LAF
N277PM
 
The through bolt that attaches the leg to the mount at the upper part of the leg. The bit is snapped down in the hole.
 
I don't know if the RV-7 leg is similiar to the RV-10? With the 10 gear leg, the gear is predrilled. The mount has one hole drilled just undersized. If you made it through the undersized hole and were drilling the opposite side and the bit broke as it was breaking through, try a small punch from the breaking through side to punch the piece of the bit back out. If it was not about to break through, you could try drilling a very small hole (sized for a small punch) as centered a possible to where the hole should be and punching the bit out through that hole. If you broke the bit in the undersized hole , any chance you could punch it into the gear tube, then remove the leg to get the bit out?
Ron
 
I broke mine too. Used needle nose pliers to grab the remnant and "unscrewed" it.


Edit; my break was at lower part the method may not work on upper part.
 
Last edited:
OK, easy. Drill a small hole from the other side and use a punch to drive it out. I'd use a carbide drill so you can drill up to the broken drill.
 
My legs were also pre-drilled but are called to be drilled to .311 or 5/16s by the plans.

Paul
N277PM
LAF
Stuck.
 
If you decide to use a carbide drill, be very careful they will break pretty easy. I've broken more carbide drills than high speed steel drills. Carbide is made to
drill into tuff material but the are brittle.
 
Thanks for the suggestions on getting that drill bit out of the gear leg; they all helped including Smidler's suggestion of "get a bigger hammer".

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Me too

I'm not brave enough to hold the punch for Paul either that's why "I" have the hammer and he has to hold his own punch.:)
 
Pbr47906 said:
My legs were also pre-drilled but are called to be drilled to .311 or 5/16s by the plans.

Paul
N277PM
LAF
Stuck.
Click to expand...

The legs need to be reamed for a very snug bolt fit...not drilled. I recommend you search the archives on this one as there has been plenty of comments on exactly this topic.

Vans written building instructions call for drilling but it is bad advice (and if you ring them they'll probably admit it). Many builders who follow Vans instructions and drill these holes end up with a sloppy bolt fit. The subsequent hole elongation caused by dynamic landing loads results in permanent undesirable gear leg movement. That can be very problematic and difficult to reinstate in the future.

I recommend you use an adjustable hand reamer for final sizing and bring up the hole a couple of thou at a time until the bolt is a very snug tap-in fit.
 
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