Hardened bolt

[jetsam]

Somehow I sheared off the bolt that the muffler hangs on on my Dolmar 6400. It went clean at the heat shield.

I said, "Okay, I'll drill it out and extract it with a screw extractor", but I guess it was higher carbon steel, and due to its location now it's harder than the damn drillbits.

I don't have a diamond bit handy but I guess that would probably fix me up. I could probably do it by keeping at it and sharpening the drillbit 20 times too, eventually.

What's the best way? I'd like to avoid tapping it out and having a different size fastener if I don't have to.

It's part 61 (or 199 in my case) in this diagram.



Here's how she looks. You can see I did make a little progress, but that tiny divot took all the edge off my bit.

 

[Deets066]

Try a sharp left hand drill bit. Then all you need is for it to grab.

 

[Basher]

I place a nut over what is left of the screw shank, then hit it with a few pulses from my mig welder inside the nut to join it to the screw shank. Believe it or not most every screw backs out after, the weld won`t stick to the aluminum but it might lightly scorch it, buffs right out.

 

[jetsam]

No welding gear here, and I didn't want to wait for tools to arrive... I took an angle grinder to the heat shield and ground the face of the bolt nice and flush, worked off the heat shield, and had 1/32 or so of bolt to grab on to. Yay!

Thanks for the ideas!

 

[av8or3]

No welding gear here, and I didn't want to wait for tools to arrive... I took an angle grinder to the heat shield and ground the face of the bolt nice and flush, worked off the heat shield, and had 1/32 or so of bolt to grab on to. Yay!

Thanks for the ideas!

View attachment 286946

That’s what I’d call a happy ending.

 

[jetsam]

I also found a few more missing and broken bolts (one welded on nut busted out of the muffler, one missing bolt in the top cowl). So maybe it was time I took this saw apart and looked at it anyway, and maybe it's time I start tying my saws down better while we're in transit.

I also got some more insight into my original problem later on after it was fixed. I had a set of new super duper ultra cobalt titanium magic modern drillbits out for the stuck bolt, and so I figured the muffler was off anyway, let's open her up a little.

I broke three of those brand new bits, being more and more careful with each one, on the muffler. Then I went in the drawer and got out a can of old black steel drillbits from the 1960s. I sharpened one up and made my hole and put it back. And then I gave the remaining brand new titanium cobalt ultra steel drilling magic super bits my opinion of them.

So maybe I should have just drilled that bolt out with a real drillbit to start with and I wouldn't have had to go ask the internet how to drill a hole!

 

[Cooper264]

I do alot of heavy diesel mechanicing and drilling big bolts is a daily kind of thing in our shop. We usually always buy the cobalt bits but we buy them from 2 different ways. 1. Bulk packs of cheap bits from Sams club for the light duty work. 2. from the snap-on man. A GOOD set of cobalt bits will do better when drilling bolts. may cost a hundred or so but it's worth it when you need them. Cobalt is stronger and will cut harder metals but that also makes them brittler than the black oxides.

 

[jetsam]

I got mine from Home Depot, and brittle is what killed 'em. They're probably in your Sam's Club category.

I have actually drilled a fair bit of steel with those bits at work, and found them to be slightly brittle but overall pretty good. In spite of the fancy multi-angle factory grind, you can sharpen them up with a simple grind on both sides and it works well after. So I don't hate 'em, but I don't think I'll ever use one in an application where the bit is touching material on the way to the hole again.

What do you use when you have to drill a hardened bolt (maybe on a catalytic converter or something), a left hand cobalt bit?

Do you think a drill/dremel diamond burr plus a smaller left hand lag bolt would grab well? I was thinking of that earlier.

 

[huskihl]

I also found a few more missing and broken bolts (one welded on nut busted out of the muffler, one missing bolt in the top cowl). So maybe it was time I took this saw apart and looked at it anyway, and maybe it's time I start tying my saws down better while we're in transit.

I also got some more insight into my original problem later on after it was fixed. I had a set of new super duper ultra cobalt titanium magic modern drillbits out for the stuck bolt, and so I figured the muffler was off anyway, let's open her up a little.

I broke three of those brand new bits, being more and more careful with each one, on the muffler. Then I went in the drawer and got out a can of old black steel drillbits from the 1960s. I sharpened one up and made my hole and put it back. And then I gave the remaining brand new titanium cobalt ultra steel drilling magic super bits my opinion of them.

So maybe I should have just drilled that bolt out with a real drillbit to start with and I wouldn't have had to go ask the internet how to drill a hole!

Old skool American steel > today’s Chinese steel

 

[Cooper264]

I got mine from Home Depot, and brittle is what killed 'em. They're probably in your Sam's Club category.

I have actually drilled a fair bit of steel with those bits at work, and found them to be slightly brittle but overall pretty good. In spite of the fancy multi-angle factory grind, you can sharpen them up with a simple grind on both sides and it works well after. So I don't hate 'em, but I don't think I'll ever use one in an application where the bit is touching material on the way to the hole again.

What do you use when you have to drill a hardened bolt (maybe on a catalytic converter or something), a left hand cobalt bit?

Depends. Most of the stuff usually gets drilled the whole way out and tapped again. Like an exhaust manifold bolt that is practically welded to the head. Those just get a big cobalt bit and a size up on the bolt. Something like a valve cover bolt that doesnt see THAT much heat usually gets a left handed cobalt bit. On the newer Cummins that we work on, the jake heads that the covers bolt to are alot harder than that of like a c15 cat. The Cummins usually need a small hole and an extractor while the soft cats get away with a left handed bit.

 

[jetsam]

Old skool American steel > today’s Chinese steel

These boys have been around the block.



I did order some left hand bits. Have to go dust off an old corded drill to use 'em, I can't see one of those new finger tight chucks being much good for that.

 

[Cooper264]

Old skool American steel > today’s Chinese steel

Exactly. $15 ebay bit set vs $300 snap-on set. Not too hard to see what the outcome will be

 

[Lightning Performance]

Buy your drill bits at old tool sales and odd places with used old stuff.

A diamond burr will remove anything even a broken tap but it takes patients.

 

[huskyhank]

Another thing to try is to cut a slot in the broken off bolt using a Dremel cut-off wheel. This does two things. First it makes a slot for a straight blade screwdriver. Second the heat and vibration of grinding the slot helps to loosen the broken stud or bolt. For small screws, use an almost worn out cut-off wheel. With a small enough diameter wheel you can cut a slot in #6, maybe #4 and get them out.

 

[Nutball]

Another thing to try is to cut a slot in the broken off bolt using a Dremel cut-off wheel. This does two things. First it makes a slot for a straight blade screwdriver. Second the heat and vibration of grinding the slot helps to loosen the broken stud or bolt. For small screws, use an almost worn out cut-off wheel. With a small enough diameter wheel you can cut a slot in #6, maybe #4 and get them out.

I had the same idea. Maybe even cut a + in it and try going at it with a screw extractor.

 

[Al Smith]

Old tool makers trick .Take a small drill bit and grind a point about like an awl and "peck it out " Meaning using a small hammer and trying to strike around the edge to back it out .An old drill bit is hard material and nearly everybody has a few .To actually "drill" a hard steel bolt takes a carbide drill bit .FWIW I've drilled grade 8 bolts used on a brush chipper that are 3/4" bolts because nobody was bright enough to use never seeze on the threads and they wallow the socket heads out trying to remove them . I scold them about it .

 

[Al Smith]

Now if you have to drill it out chances are you'll get into the aluminum .Simple enough fix, tap it out to the next size,M5 becomes M6 and drill the muffler mounting hole out to match .Never seeze the danged screw now .

 

[Redfin]

Or build a fixture smaller than the bolt diameter to guide bit. Did this to retrieve a broken ex bolt on a 2100 recently.

 

[Philbert]

Reassembling with anti-sieze compound?

Philbert

 

[kanscruzer]

My newest favorite trick, Buy some pickling spice ( ALUM ) off Ebay in bulk ( I bought 5 lbs) mix heavy. 1 cup on the alum with regular water 1/2 cup just enough to absorb the alum. Mix & place in a small crockpot , Behind your wife's back is best. Don't let it come in contact with anything steel/iron that you want to keep. Keep warm for a day or two . it will eat the steel leave aluminum alone . Worked great on a 056 with a busted case bolt . Do a search on YouTube