I was talked into buying a set of left hand drill bits a few years ago by a tool salesman. He said they were the best thing since sliced bread to aid in removing broken bolts, so I bought them and stuck them away. They weren't too spendy, so figured I couldn't get taken too badly. Well today I was fixing a tranny leak on the TH350 in my Austin gasser. The "bullet" housing that the speedo screws into had a bad O ring, so I pulled the 1/4-20 bolt and removed it for a new O ring. While tightening the retainer bolt down the stupid bolt broke with little effort. After the initial reaction of total irritation, I pulled the tailhousing off and took it to the work bench. Used my Dremel with a tiny burr and ground the end of the broken bolt smooth with a small indent in the middle. I got out the left hand twist bit set and set the drill to CCW rotation and began to drill. To my amazement the tool guy was right! I barely got the drill bit cutting and it caught the bolt and turned it right out! I'm now officially a huge fan of left hand drill bits for removing stuck bolts!
A bolt that has bottomed out and broken or over torqued and broken is a different animal than one that has been in there for years,having been subjected to the elements and then broken while trying to remove. The LH bit will usually work for the former but not the latter. That has been my experience anyway.
Use that trick all the time ( will not work on anything that is bottomed out in the hole ) I have even reground some old bits to a left hand tip. ( I'm CHEAP!)
No, there are made for exclusive use south of the equator where even toilet water flows counter-clockwise.
LH drill bits are great if the bolt is free in the hole. They've helped me out a few times, although I did have to buy a reversible air drill.
I never even bother with them, in my world there's maybe a 1% chance that they'll be useful...I find if the bolt is sticking up, I use the next size larger nut and weld it to the bolt and use a wrench to unscrew the bolt, since the added heat from welding often helps shock it loose...otherwise I drill through and work my way up to the tap/drill size and just tap the old threads out...I've dealt with thousands of broken bolts working in the tool and die trade, and time is money...left hand drill bits are rarely worth my time...
Look up a product called "Kroil" on the internet and then pour some on the broken bolt that has been in the elements for years and wait a couple of days, then use the left hand drill bit. I assume we are talking about bolts that break off below the head surface.
Pick up a screw extractor set like a Williams No. EXS-206 . I have used them for over 40 years. Not sure if the company is still around. J.H.Williams & Co. 400 Vulcan St. Buffalo, N.Y. 14207. You just drill proper size hole in broken stem, insert correct size extractor, turn to left to remove screw. All info is listed on extractor case.
Removing broken bolts has always been one of my specialties. I use left hand drills very often. They are usually of the best quality steel and hold an edge very well. In any drilling project, it pays to buy good drill bits. I got started doing water pump/timing chain housing bolts on Ford engines where the bolts would break in the aluminum housing. I have a set of centering punches that I found at a flea market. The owner thought they were for driving roll pins because they were round with a flat tip and a raised point in the center. They work great for centering a drill on bolts broken inside an aluminum housing. I've also used brake lines or pieces of pipe to sleeve the hole so the drill doesn't bite into the aluminum. When people found out I was good at it I was called to remove bolts, fittings, spark plugs. I learned many tricks along the way. Patience is the most important.
In my bike shop I use these a LOT!! Many years ago I worked for a guy that told me "You are smarter than that broken bolt, you CAN get it out" peace
Snap-on tool co. Makes a real nice set of broken screw extractors and left hand drill bits. Expect to pay top dollar for a first class set of tools. In my mind worth everybit of money I spent.
Kano Kroil is one of my secret weapons...and those funny looking punches someone mentioned are called transfer punches, you use them to transfer the location of a hole to another piece of material you place below it...the punch slides into the hole and gives you a perfect centered spot to drill in the exact location of the part you're duplicating...
Next to drilling a water well I have found removing broken bolts/studs to be one of the biggest crap shoots going. x2 on Engine Man's advice, patience! That said, welding has worked for me with bigger stuff but I'm not that good a welder for the smaller sizes. If I have some time for the snake oils to work I let 'em, if not I give things a quick squirt and go right to the left hand bits - gotta drill for the easy out anyway - they have worked real well for me often spinning the offender right on out, wouldn't be without 'em. Next step easy outs, then heat as a last resort. YMMV. Ed
Ruiner Thanks for the transfer punch tip. I'll be adding that to my MO on anything broken below flush. Ed
KROIL...!!! Seriously, if I knew I could safely use that stuff during my late-night solo 'hand release' sessions, I would.... I put a squirt of Kroil on each of the screws that held the doors on my "A" since '29,, walked away for a cigarette, came back, and easily turned them all out with a regular flat tip screwdriver..... Considering that my "A" body is in several pieces, and the subrails and bottom few inches are completely rusted away, I was impressed... I only use "VD Blaster" or WD-40 when I don't want to waste my Kroil..... It also makes a hell of a bore cleaner for those of you out there that shoot old surplus rifles as well... For some reason, it is hard as hell to find... Cabella's has it in the old 'drip-tip' cans.... Aerosol units are exteremely difficult to track down.... My bedroom currently smells like Kroil and it makes me happy (cleaned up an old German gravity knife a few hours ago)....
ive got a set of lefty drills just incase they might come in handy the welding trick has worked best for me , weld on a washer , strike with a hammer , weld a nut onto the washer hit it again then unwind
They are used on screw machines and other high-production machinery for secondary operations where the spindle is not reversible. Bob
As "One Crusty One" said - the Snap On set works great. I use mine at least once or twice a week. Another nice feature - the Snap On dealer will replace the worn-out extractor and the dull left-hand drill bit at no charge. Expensive yes, but definitely worth it.
Yeah this one was broken off below the surface od the tail housing, so couldn't get on the stub at all. Kroil is great stuff too! I use it for many things around the shop and always go to it before anything else.
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