This is the best how to sharpen a drill bit video Ive ever seen. He breaks down how drill bits are made and how to sharpen them to make them cut. Its kinda a long video, but definitely worth the time to watch all of it.
If you have a hard bolt to try to drill out, anneal it first. Heat it up with a torch until it's cherry red then back the torch off slowly to allow it to cool slowly over several minutes.
I hope the guy(s) that invented "keyless chucks", "Astro Ventilation" (no vent windows), and "compact spare tires" have to live with trying to use their inventions throughout eternity.
Over the years I have purchased thousands of drill bits. Twenty years ago when E bay was fun, I would buy used drill bits for pennies on the dollar. Seems like some people had access to quality factory production drill bits, and the folks using them would just replace the bit instead of sharpening. Bought several batches of various sizes of 500 for $10/12. Also bought a lot of large bits( up to 2 1/2 or so ) on Ebay back in the day for pennies, seems like back then no one wanted them.I buy at swap meets if the bits look like they are quality ones. I have purchased several quality 1/64 to 1/2 inch sets and letter and number sets along the way. One thing I have learned is there is a difference in drill bits, sometimes you can tell by looking at them, sometimes not. Just got another nice set for Christmas! I guess I’m a drill bit junkie! Bones
For smaller drills (under 3/8") I use cobalt screw machine drills. Very short and stubby, less likely to walk than a longer drill. I've used them in my shop forever. I like the TiN coated ones if I'm working in stainless or steel. For production work I figure in buying drills and either toss them at the end of the job or I sharpen them.
My brother bought a nice looking set at a garage sale years ago. Not expensive and not brand name. The first try was on a race car chassis... freaking drill bit BENT before it could take a bite. We were getting rid of our machine shop at work... so a TON of stuff was on the scrap pile. I had to have grabbed 75 lbs of drill bits alone, most new and some exotic stuff like carbide circuit board drills. Reamers, taps, dies, holders... sick stuff. I have lots of end mills too, slitting saws to fit my arbors.
One thing I like about variable speed drills is that you find the sweet spot that every drill bit has and drill the best. Sent from my iPhone using The H.A.M.B. mobile app
With all of our manufacturing going overseas, the tooling and machines are going to the auction block or scrap yard. There’s a local shop, here that has buckets of tooling, so much a pound. Probably a nickel on the dollar. I’ve got a Cincinnati Radial Arm Drill, in good condition, can’t sell it! Bones
Hi Tubman, I was following up on your advice but I find with rare exception none of the cobalt bits on amazon give the spacific grade of the bits. Has this changed since your initial posting?
On the set I purchased, it was listed in "Answers" in the "Questions" section". I checked, and it's still there.
i used to be one of those guys that just reached in, grab the bit the was the right size, & went at it. Now, i religiously follow the "start out small, & work my way up" mentality.
As an old tool and die maker, I can positively tell you that the only drill bit you need will be plain old, uncoated, 82 degree, high speed steel, twist drills made by Precision, Cleveland or latrobe. Nitride coating or gold color plating is basically worthless. Special tip grindings other than the tried and true 82 degree cutting edge are going to lessen the life span of the bit. Cobalt is going to chip or break easier than HSS in the homeowner or garage use. Standard HSS twist drills are the only way to go. You will never find these in the big box or hardware stores. You need to go to an industrial supply or online to get them. Fork out the money for a fractional drill index. You won't regret it.
I own a set of Drill Hog bits also, and they're amazing quality. But I was told whether they got dull or broke the warranty would replace them. I broke two smaller bits, and when I contacted the company I couldn't even get them to reply to me. Can you tell me how you got them to replace yours?| As for the OP's 5/8" holes. I've had much better luck drilling large holes over 1/2" using good quality holesaws with lots of cutting fluid instead of drill bits. Holesaws like Milwaukie, Lennox, Greenlee are all excellent quality, and drill large holes faster and easier than fighting big drill bits.
1Ton is exactly right. That being said, I can see buying a set of HF "Cobalt" drills because it gives you every size up to 1/2 inch and can get you through a lot of projects where you might need specific sizes for tapping a hole. I have been thinking lately though that I often use odd sizes simply to open up holes a little before finish drilling them to the size I need. I had to ask myself, what are all these sizes actually for? What seems logical to me is that most of the time I need bits that will drill the size needed to use a tap or the size needed to put a bolt thru something. So having a Cobalt set to use for everything and then HSS drills for tapped holes and bolt holes pretty well covers everything, especially as the sizes get larger. I watch on line for people selling HSS drills in bulk and take what I can get, but like I said....many of them just get used for enlarging something before finish drilling. It might be better to stock up on the "necessary" sizes for tapping and bolt holes and use all the other odd sizes for resharpening for roughing out.
I'm pretty sure the standard drill tip angle is 118 degrees. I was taught as an apprentice that it's bad practice to drill a hole by pecking at it with ever increasing drill sizes. Just drill the full size, and if the finished size needs to be precise, use a reamer after drilling 1/64" undersize. If the hole is big, like 5/8" or more, predrill with a drill the same size as the web of the big drill. This is industrial practice, it's different when you are trying to fix up old machinery. Sneaking up on the finished drill size in several steps is often useful when drilling out broken bolts or studs, or bleeder screws.
Beanscoot is right. The included angle of the standard drill bit is 118 degrees. I got it mixed up with the chamfer angle for flat head bolts. Which is 82 degrees. If you look at a decimal equivalent-tap drill size chart, you will find that drill bits come in three basic groups. Fractional, letter, and number. For all practical purpose, a fractional drill index, which is drill sizes from 1/16" to 1/2" in 1/64" increments is all you would ever need. Huot is also a very good brand of drill bits.
Speaking of chamfers, it is nice to have a couple sizes of chamfer tools on hand to clean up the burr on drilled holes. The handled one is really handy, the unhandled one is for your drill press or electric hand drill.
Yep, too fast, overheated the bit. Think of a metal drill press speed, and watch your chips. Plenty of lube and run slow.
I've been meaning to buy a decent set of cobalt bits for a while, and this thread is useful. Tubman's suggestion (from some time back) of Chicago Latrobe makes sense. I think he might have typo'd the numbers though, as the steel grades are M35 and M42 (not M32 and M45). https://en.wikipedia.org/wiki/High-speed_steel I try to buy Aussie when I can, but the local manufacturer (Suttons) only does the M35 bits. If I can't buy Aussie, I try to buy US. I can't manage to lay my hands on a Chicago Latrobe catalogue, and the info from their distributors is patchy. Any ideas on how to tell which of their cobalt bits are M42 grade? Cheers, Harv
And now for something completely different: I recognize this thread is about drills and which ones to use to drill out studs. But I have discovered that a MIG welder may work far easier than drilling. Welding a nut on a broken stud and backing it out often works. Sometimes several tries are needed. The heating / cooling cycling of the welder acts to break the seized stud loose from the surrounding metal. My BBC RV snapped off two exhaust manifold studs a half inch below the casting surface. Drilling out the stud would have been a bear without the drill wandering into the threads of the head casting, even if I had had enough room to get a drill motor between the head and the chassis, which I didn't. I built up little "ice cream cones" of MIG wire and welded a nut on them. After several tries the studs broke free and backed out. Saved me a cylinder head R&R in a motor home chassis.
Harv, I have some Australian made drills and taps here in Canada, I believe P&N or P&C and maybe some others. Nice quality pieces.
Yep, P&N (Patience and Nicholson) is an Aussie company that dates back to 1921. They were bought out by Suttons in 2001. They still manufacture locally, and next door in New Zealand. They make good gear. Cheers, Harv
All good - you taught me something today about high speed steels, which is appreciated. ... now if could only learn to centre-punch on-centre, I'd be a happy man Cheers, Harv
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