Expansive Bits


Adjustable auger

It’s certainly not an essential tool but if you ever come by an expansive auger it’s definitely worth grabbing as they’re a great get out of shite card in the workshop. I’ve had this one for years and its come in useful many times when drilling out for something a bit obscure. It goes right up to 3″ diameter which is a pretty big hole, and when you need a big hole you really do need one.
Fitting vices especially ones with large wooden screws tends to call for big drill bit sizes which you’ll rarely need for any other task, and when I look at the price of some of the larger¬†bits it’s easy to see it can get expensive fast, which is especially annoying if you’re only likely to use the bit once.

An expansive auger can be a fiddly thing to set up but being able to do right from the smaller 3/4″ (on this example) right up to 3″ you do have the ability to infinitely tune to any size you wish and there are times when you might want to choose a particular tolerance for a hole rather than being stuck to the common fixed diameters. The grace with fitting vices is that the large holes are usually just for clearance and so there’s no need to be too accurate with the precise diameter here.
Sharpening is easy enough and whilst an auger file is ideal for this a small saw file can also do the job if you’re struggling to find one.
Expansive augerI won’t pretend that drilling a hole in the 3″ diameter region is easy, or not by hand at least anyway. It’s bloody hard work pushing the brace round but these bits do cut fast and clear the waste out well. They have a tendency to break through if you let them and make a mess of your underside, so I like to stop just as the centre screw pokes through the bottom and then flip my work over and come back in from the other side.

I think these bits are easy enough to find second hand and probably not too expensive so if you’re ever in need of an awkwardly sized larger drill bit they could be worth a shot.Auger and brace for large hole drilling

15 Responses

    • Richard

      Hi Ken, nice to hear from you. Is it just me or is it every time I buy a second hand drill bit it’s as though the previous owner’s been drilling through bricks?!

      • Ken

        Not just you bud, I have the same luck. I was thinking they saved them just for me. ūüôā

      • Ed

        Wait…I’m NOT supposed to drill bricks with these? True, you have to pull them from the brace now and then and whap ’em with a sledge like a crows foot to get past tough places, but they eventually get through the brick or concrete. What’s the problem? They’re disposable, really, but you can offload ’em for a couple bucks at flea markets. ūüôā

  1. Dan Noall

    I have a couple untouched vintage Irwins’ that I know I’ll need soon enough.

    -Oh, and that’s some handsome mortise work there, Chief.

  2. david

    It’s not just the drill bits they used on bricks. Saws and chisels! Just what and how did someone ever use those things? You always hear about the fine craftsmen of yore but why is it every old tool you find is in horrible shape? Drills sharpened backwards, saw teeth that look like speed bumps, chisels with flat edges that are all chipped out? Stuff like that makes me think we are indeed in a New Golden Age of woodworking. 30 years ago it was almost impossible to buy any new decent hand tools. Today we have a bonanza of choices. Not the variety of the late 1800s/early 1900s but some great tools out there. I’ve pretty much given up on finding good condition old tools. If I can’t find it new I try to find another way to the job. If that fails it’s restoration time. I’d rather chop mortises.

  3. Steve Jones

    Agreed. I have a couple which I seldom use, but, as you said, when I need them, I need them. Now to the real reason for this reply: What is “shite card”? I assume one drops the “e”, but I still can’t parse it. Thanks.

    • Steve Symes

      In Monopoly, there is a “Get Out Of Jail Free” card hence a “Get Out of Shite Card” is a Device or Strategy for solving a sticky problem…

  4. Fred

    Bought one as in the picture in 1965 which has followed me around ever since. Used it 3-4 times, the last a month ago installing a new vise.
    They don’t weigh much or take up a lot of space. Wipe it after use and they’re good forever.

  5. fred

    Top man. Boring a hole with an expansion bit of this diameter and depth is good going. Good for building up your biceps! I must admit I would only use one for sheet material or thinner wood. Made me think twice about where I could use one. Top job.

  6. Joe Freeman

    I bought an Irwin No 1 (‚ÖĚ” to 1¬ĺ”) a few days ago and am really impressed with it.

    ToolStation have new ones for twelve quid but as well as wondering how the quality would compare to a vintage one they have round shanks.

  7. adrian

    I ended up with a need to drill 6 holes of varying size in the vicinity of 2.75″, and I was inspired by this post to give an expanding auger bit a try.

    However, I’m finding that I have a lot of trouble. My workpiece is 16mm thick and after I get about 5mm deep into the hole the hole for the lead screw is enlarged and the bit won’t stay centered any more, and I can’t continue cutting. Even getting that far seems to be a challenge.

    Do you have any advice on how to actually make one of these bits work?

  8. Mike murray

    That’s one thing about using a bit and brace that is or can be somewhat challenging. Several things come into play. How sharp the bit is, the hardness of the wood, the sweep of the brace and diameter of hole to be drilled, body positioning and strength. Also the thickness of the wood and the condition of the lead screw.
    If you position yourself so your chest is over the brace, then cup your hand over the knob and put down pressure on the brace as you drill with your upper torso, you may get it to continue. You can put another piece of wood under the piece you are drilling for the lead screw to grab into as you drill the hole on down. Good luck with it.

  9. adrian

    I have drilled many holes with a brace. My question is not how to use a brace, but how to use these adjustable bits. Note that even though the workpiece is only 5/8″ (16mm) thick the lead screw never makes it into the backer board I put there. (It put a little dent in the backer board but didn’t actually engage in the backer.)

    Once the small central hole is larger than the lead screw but without the larger (1″) central hole being well established, there’s no way to continue. There is nothing to keep the bit centered at that point.

    I’m also wary of applying too much force (to lever out a monster chip) because the workpiece can split.

    • Mike S.

      Have you taken a close look at the lead screw? It sounds like the threads could be dull or bent or otherwise defective. You can often clean them up with a three-cornered needle file.


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