I am in the process of trying to drill off the head of a hardened steel cheesehead bolt on my car. I went out and bought an iron oxide bit. It started working fine but then wouldn't cut anything. I then went out and bought a titanium one. It didn't cut as long as the first one. Is there a technique to drilling metal. Should i not use a lot of pressure and should i use some type of lubricant?

 

Go and get a cobalt drill, slow rpms, about 500, enough pressure to keep it cutting. what diameter drill is it?

 

Most automotive grade bolts undergo metalurgical treatments that produce physical and mechanical properties for high tensile and yield strength, high levels of hardness and ductility, and excellent locking ability under high torque; all unique qualities usually exceeding the standards of the highest grade common bolt - but they are still no match for a good sharp, well lubricated drill bit that is run at the proper speed with the proper feed. Go slow and easy with lots of lubricant and don't push it too hard. Try a smaller sized bit first and work up to larger sizes. Should you plans include replacing the bolt it's very important to use the exact same kind. You may have, or may purchase a bolt that looks the same with a similar diameter and length, thread, and shank etc etc but that's where all similarities end. You need to get and use a bolt of the exact same strength.

 

I made the mistake of using a large bit, 1/2". I should have started smaller. What type of lubricant should i use.

 

I use Tap Magic, but any cutting fluid should do. You can find them at welding a metal supply stores.

 

I forgot, 30WT motor oil is better than nothing.