can i drill out a broke bolt and tap it, with out moving up to the next thread size? would like to keep all bolts the same size.

 

Normally you drill a hole in the broken bolt and use an easy-out to remove it.

If you try to drill it to the size, you aren't likely to get it properly centered, nor to get the tap to start into the original threads.

You can drill it out and put in a helicoil, which will retain the original thread size.

 

If you center punch it first you can often drill very close to the same size and chase the threads with a tap. Worse case, you can helicoil it. I never use EZ outs as they often break in the hole and can't be drilled as they are the same grade steel as drill bits.

 

thanks 4 the info. one more question if i mess up, can i have the hole weldd up and drill out again to the same size?

 

Easier to use a helicoil.

 

If the bolt broke off flush with the surface or just a little under, weld a nut onto it and let it cool. The heat will loosen the remainder of the bolt and the nut welded on lets you remove it very easily. EZ-outs suck.

 

I recently got a broken off flush exhaust manifold out of my LS1 head. Didn't know when I started that the factory uses Loctite on them. I center punched it, drilled, used an easy-out, and got it out. Good thing, because even though I centered it as well as I could by sight with the center punch, it still wandered on me and was off-center by the time I was done drilling.

I understand about easy-outs - I broke one trying to get a broken-off license plate bolt out for my niece. And it was in a plastic nut! The good ol' Japanese engineers put the plastic nut in from the inside of a double wall trunk lid - thank you very much. Couldn't believe that plastic held that steel screw so tightly that it broke the easy-out.

 

Instead of easy outs, if you have access to a left hand thread tap and a left hand thread bolt, you can tap them that way and try to remove them with that. If you've only got right hand thread you can thread in a piece of threaded rod, jam a nut on it, and sometimes they come out when you go to loosen the nut.

 

Sometimes, just a left-hand drill will spin the broken piece out, provided the bolt isn't rusted into place.

Some PB Blaster will help.

 

While I have had problems breaking easy outs on really stubborn broken bolts, in general I've done pretty well using them. Of course you have to do a realistic appraisal going in. How corroded do things look? Things like stock exhaust manifold- to- Y pipe studs that have been heat/cool cycled for 20+ years and badly rusted to the point where the threads are deteriorating are probably not good candidate for an easy out!

One thing that helps in some situations is to CAREFULLY drill all of the way through the bolt, even though you may not be putting the easy out all of the way down in the hole. IF it is not already bottomed out. You can sometimes tell about the length of the bolt versus the depth of the hole by checking out the one next to it where you can remove the bolt and do a depth measurement. Also, try to use the biggest easy out that you can make a hole for without drilling into the hole's threads if you drift off to the side. I like to start with a punch mark and a small drill first to get the hole stated as straight as possible before moving up in drill size. You can actully carefully lean the bit to the side as your drilling to help get back to center in the very beginning.
Sometimes a very hard Carbide drill bit can work wonders when drilling into hard fasteners. Carbide drill bits are more expensive than regular tool steel bits and are hard and brittle and prone to breakage if they bind up from being pushed into a hole crooked. But sometimes they are a godsend.

The advice about left hand taps, welding, penetrating oil and heli-coiling are all great ideas as well. Good luck!

 

thanks 4 the help. My bro got the bolt out 4 me. he drilled and tapped it 4 me