Hi,

I am sure this has been covered before but I cannot find reference to it anywhere. I am removing the last two studs from my TF035 exhaust side housing and have an issue with steel hardness.

The studs would not unscrew so I am drilling them out, which I am okay to do BUT, I have just stuft two nice drill bits on the first stud as for some reason it appears to be harder than the drills and they are good quality HSS ones.

Does this happen on turbo bolts where the hardness of the bolt increases dur to the temperature cycles that it goes through? If so how do I either revers the hardness or what type of drills can someone recommend that will cut through these puppies.

Cheers

 

tungsten carbide bits. Expensive, but, if they dont work, you're screwed. ID take it to a machine shop and have them take care of it. Rapid cooling from high temps will harden steel, and, will REALLY harden cast iron.

 

+1 it's amazing what heat cycles do to fastiners... I'm a fan of carbide but you can't turn them fast and they have the nerve to just break off when they want. LOL

 

I went by a tool shop at lunch time and got an 8mm ARTU/RIMET drill bit that looks like a masonry bit type end but it’s sharp like a normal HSS bit. The package says it can cut through springs and Hardened Steel so it may be Tungsten, although it does not explicitly say so. At $16 it had better do the job! (Just cut nice and Slowwwwww was the instruction)

Cheers

 

I hope that does the trick for you...

 

hhmm

 

good luck

 

yeah good luck.

to soften it wouldnt you want to superheat it and then dump cold water on it until it stops sizzling. but then you might hurt other things around it too.

 

The 8mm bit will probably not like anything more than 700 - 800 RPM's when drilling into steel that hard and I consider lube a must. Even 800 RPM's is on the high side of my scale. Slow and steady wins the race when ever you are machining metal!

 

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