Head Broke Off Bolt...Please Help!!

[Scotty370]

Chilly- My only thought are A) I've never tryed to 'plunge' arc a weld, through a nut, and into a hole, and don't feel I be willing to try. and, B) I think that the broken drill bit is the most problematic part of this attempted fix! Once the drill piece is out, drilling can resume, thread-picking can happen, and worst case, oversize drill it, tap it, and insert a Heli-Coil. But the broken drill is the killer! ~S

PS Interesting idea Dave!

 

[Prodirt6000]

Yes the drill bit is the major problem here. If I knew of the best way to get that bit out of there, I could go on with my usual way of getting these bolts out. Just that bit is killing me.

And dave, will that still work even though the bolt is upside down?

 

[CurlyDave]

The wax trick will work with the bolt upside down. Capillary action "pulls" the molten wax into small cracks, and it will travel up the threads of the bolt.

If you only need to get the drill bit out, get a grade 8 bolt of the same size as the drill bit. A long one, only threaded on the end, you want the head and a smooth round shaft.

Now, using a dremel tool, cut the long bolt to the shortest practical length and cut two "nubs" on it that will engage the flutes of the drill bit. This will be a time-consuming pain in the rear, but you may be able to push these nubs into the flutes on the drill and back it out.

Start by cutting a slot, sort of like a screwdriver slot, in the shank of the bolt, and have a drill bit of the right size next to you so you can shape the nubs properly, lube it all up, heat it a little and give it a try. This won't screw anything up any further, and all it will really cost is a lot of your time.

 

[Egon]

This may sound weird but can you use a hole saw to remove the mess and then retapp the new hole ???

 

[dex3361]

What size is the bolt? I didn't see it mentioned.

 

[Egon]

Randall:

I have a bolt probably around 3/8 inch I think that the head broke off of it in the casting.

 

[Kernopelli]

Turn your welder up some more and bury the rod in to the stud through the nut. I use 7018 rod. 3/32 would be a good size. I think 6011 is too brittle and 6013 not strong enough. The weld will not stick to the cast very well so don't let that scare you. Let it cool till the weld chills but don't let it cool off to the touch.

Did the original bolt break off or twist off while being removed. If you twisted it off you may not get it out. Can the casting be removed and taken to a machine shop?

Dan

I have a good friend that is not only the best machinist and welder I've ever known but one of the most particular guys on the planet....."do it right or don't do it at all" would be a good summation of his work ethic and how he approaches everything in life. He swears by this method of removing broken bolts in blind holes. Instead of 7018 rods, he uses stainless rods though. We talked about this just recently and he said he has used this method tens of times and never had it fail. He says the stainless rod will penetrate the nut and bolt but not the cast iron or steel it is threaded into. If I didn't know the man so well I may doubt this line of thought but he went as far as bringing me some stainless rods for this very purpose, in case I needed them in the future. I will see him tonight and ask him for further information about this technique and post tomorrow morning what he says.

 

[dex3361]

Randall:

As usual I miss the important stuff. Thanks.

 

[BXpanded]

Do I understand the bolt went in from the bottom so you are working overhead?

Also, did the bolt break in use or did it break as you were tightening or loosening it?

That info might all be here but I don't have time to read the whole thread right now.

 

[mostly_gas]

I have had luck with using a center drill to drill out drill bit if I can't easily EDM it out.