Broken bolt = square paperweight

[Vbb199]

I'd be thrilled if @Doppleganger could elaborate on what speeds and feeds he uses with his cordless drill.

Lol, the problem with power drills always is how steady your hand is, one wrong movement of the wrist and it blows up...

 

[RecklessWOT]

I find it usually breaks too.

carbide is very brittle so if pushed too far it explodes, but if used correctly they are the best tools out there. Basically all I use. Unless you're working with aluminum, that stuff likes to gall up and stick to the carbide and ruin your tools

 

[Doppleganger]

There is no exact feeds or speeds with a hand tool....too fast and you'll heat treat it (very bad). Too slow and you'll chip the cutter (thus why I like 4 flute BALL mills....2 flute break too easy, square ends will catch / chip). Kind of a feel for what you're drilling. Ball mills are like grinding something with your fist. 1/4 and 3/8 cover about any standard sized bolt. Its more like a medium speed - very intermitant cuts so no heat and firm/solid pressure but nothing that causes you to drift off center or break your cutter.

Take out the center then use a small cold chisel to break the side pieces up and out. Then after you make sure there is no pieces in the fugly threads, oil it up and run a tap through it gently - in-out every 1- 1 1/2 turns. Plan B if the threads are really fubar'd is a threaded insert.

Cant tell you how many times I used that setup on broken bolts or studs in engine blocks.

 

[Turbo4whl]

Feeds and speeds.

And cutting oil. Cools the drill bit.

I'd be thrilled if @Doppleganger could elaborate on what speeds and feeds he uses with his cordless drill.

Depends on what you are drilling, but here are ballpark numbers: 1/4" bit in cold steel, 500 RPM with coolant. Carbide drill bit, slower. Hardened bolt, little slower again. Jump in size to 1" drill bit, 40-60 RPM.*

Remember, the hardened bolt is only surface hardened. Start with a smaller pilot drill bit, the center of the bolt is softer. Then drill with the tap drill bit size.

* A machinist handbook can be very helpful

 

[hoagster]

just center punch it and drill it out, start small and drill all the way through the bolt

Use a left hand drill bit when it heats up it will probably pull it out!

 

[wanderinthru]

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I've been better.

Not really a hard fix. Center punch it as close as possible, then start with a 3/8 drill bit, cut it slow and "walk" the drill around unti you can see it is centered, Don't hurt if you cut a little of the manifold to get it centered. Then You can either start small, or just drill it out with a 5/16, get a 3/8 tap and clean her up.

Well ****.....now I'm sitting here wishing I could remember if they are 3/8 or 5/16 bolts....just changed one weekend before last.... Either size, start with the bolt size to get centered up, the go to tap drill size...

 

[Blue Ox]

This was what I was getting at:

Lol, the problem with power drills always is how steady your hand is, one wrong movement of the wrist and it blows up...

Carbide being so brittle, I find I have great results with the indexable tooling in the lathe, but drills will almost inevitably grab and shatter, especially when they break through.

 

[Ricko1966]

My first go to on that would be set an appropriate size flat washer around my broken stud mig it to the stud weld a nut to the washer and while everything s hot rub a crayon around the washer the wax wicks in like sweating pipe to lubricate the threads,and the heat helps a bunch too.Done it many times with good results.Oh yea don't try to come straight out with it out a little in a little out a little more in a little.

 

[Dave M]

Use an appropriate size pin punch and give what is left of the bolt an almighty hit with a hammer to jar the thread first, (I would have tried hitting the bolt head first ) then use the method as stated above by Ricko1966 . Can use candle wax also instead of crayon. https://www.gmsquarebody.com/members/ricko1966.13292/

 

[Vbb199]

carbide is very brittle so if pushed too far it explodes, but if used correctly they are the best tools out there. Basically all I use. Unless you're working with aluminum, that stuff likes to gall up and stick to the carbide and ruin your tools

2 flute for aluminummmmmm

 

[AuroraGirl]

how about the grade 10.9 bolt holding my sway bar bushing on my buick that sheared without budging (or visibly rusty) with a wrench?Oh, and its got 1 inch above it, but curves and frame lines make it hard to get on the bolt when it was good

 

[Vbb199]

The grade is irrelevant, you can drill welds out with carbide, you can drill ***** that's 62 Rc with carbide (tougher than any bolt, no matter the grade)
It's ALL in the speeds and feeds

Speeds and feeds Da MASTA!


Meant to add, case hardening of bolts definitely is tough. But still able to be cut into.

 

[AuroraGirl]

The grade is irrelevant, you can drill welds out with carbide, you can drill ***** that's 62 Rc with carbide (tougher than any bolt, no matter the grade)
It's ALL in the speeds and feeds

Speeds and feeds Da MASTA!

no im saying that ****** is stuck and i dont want to drop the engine cradle to get it out

because a grade 10.9 sheared without even slightl moving. just twisted right off. not rusty.

 

[Vbb199]

This was what I was getting at:



Carbide being so brittle, I find I have great results with the indexable tooling in the lathe, but drills will almost inevitably grab and shatter, especially when they break through.

The ball mill really is the best, or like in my line of work, when doing. High speed milling in something tougher like soft, annealed toolsteel, a 1/2" cutter with a .125 corner radius will really take a beating.


Sharp corners = breaks down faster.

 

[Blue Ox]

The ball mill really is the best, or like in my line of work, when doing. High speed milling in something tougher like soft, annealed toolsteel, a 1/2" cutter with a .125 corner radius will really take a beating.


Sharp corners = breaks down faster.

I do like the ball mill idea. I'll have to give it a try. But I still don't think I'll be using it in a hand drill.