RE: [DML] Re: advice on stubborn bolt

["Joseph Kuchan" <josephkuchan@xxxxxxxxxxx>]

Building on what David recommends I would also recommend using a cobalt bit. 
The problem with Titanium bits is that they are Titanium coated whereas 
cobalt is the same alloy through and through. Thus when the titanium coating 
wears through (as it will when drilling somnething as hard as a broken 
extractor) the bit is not much better than a HSS (high speed steel) bit. A 
cobalt bit will retain its essential properties even as it dulls. Cobalt 
bits do have a coating, but it is really nothing more than a color coating 
to help you identify that the bit is a cobalt bit.


-Joe Kuchan

>From: "David Teitelbaum" <jtrealty@xxxxxxxxxxxxx>
>Reply-To: dmcnews@xxxxxxxxxxxxxxx
>To: dmcnews@xxxxxxxxxxxxxxx
>Subject: [DML] Re: advice on stubborn bolt
>Date: Wed, 01 Mar 2006 19:47:09 -0000
>
>Breaking off a drill, tap, or extractor is probably the worst thing
>you can do. With that being said there is still hope. Sometimes you
>can get lucky with a small hammer and centerpunch. Try working the
>extractor back and forth. If you can move it even a little then there
>is a good chance you can get it out. If it won't move at all then you
>have to try drilling it out. It is possible (with a lot of luck and
>experience) to drill it with a carbide bit like as used to drill
>concrete). You have to go a little at a time and constanly redress the
>tip. You can also buy a titanium drill bit, again very difficult to do
>and stay centered but will hold an edge longer but you need a special
>grinding wheel to redress it. Another option is to lay a washer over
>the mess and try to weld a nut to the broken bolt. Then, if all goes
>well, you just unscrew the whole mess right out! A lot depends on the
>skill of the person and his personal experience with each method. If
>you are a novice machinest maybe the thing to do is to have the car
>towed to the shop. Try to talk them into an "appointment" so it won't
>stay in their shop in their way. Do not be tempted to skip it and hope
>it won't leak much without the bolt. It will.
>David Teitelbaum
>vin 10757
>
>
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