I am a connoisseur of bit extenders. I have spent – easily – a couple hundred dollars on a wide variety of them, new and vintage.
Most bit extenders suffer from one of the following maladies:
- They don’t hold the bit and it falls out in use.
- They hold the bit but it wobbles in the extender, making a dog’s dinner of your work.
- The diameter of the extender (or its chuck) is so large that it’s ridiculous and unwieldy.
- They are not straight, and so the whole shebang wobbles like a one-legged pigeon on a bender.
I have not found the Bit Extender of the Gods as of yet. But I have found one that I like. The Bosch Daredevil DSBE1012 suffers from only one of the above defects. And it has a mild case of it.
First the good news. It’s cheap – about $7 – and is available at most good hardware stores and home centers. You won’t struggle to find one or to feed your family post-purchase.
It holds hex-shank tooling like the dickens, thanks to the two set screws in the chuck. The set screws are tightened and loosened with an Allen wrench (included and losable), which I keep rubber-banded to the tool when it’s put away. I have never had a bit fall out of the Bosch extender during the last few years I’ve had it.
The chuck is only .520” in diameter, making it the smallest I have used.
The bad news: The shaft is never straight enough for my taste. To be fair, the tool recommends you not exceed 600 rpm in use. And if you do obey that speed limit, the wobble is minimal. I’d rather use a faster rpm to help keep my holes cleaner, both going in and out. (So many jokes.)
I’d pay $14 (twice the price of the current tool) for a little more straightness, which I know I’ll never get.
It’s a good, simple and cheap tool in a world of garbage. Just don’t expect the world of it, and you’ll be happy.
— Christopher Schwarz
I think the problem with going faster is the centrifugal force generated at high rpm makes it wobble.
I used to do some high speed ( 10,000 rpm) machining with long shafts and we always had to use a sleeve to stabilize the shafts. In other words the shorter the extension the less wobble you will have.
A one-legged pidgeon on a bender walks into a bar……
Chris,
Have you ever tried any of the extensions made by Fisch? I think they do both hex shank and round shank ones (scroll down a bit on the linked pages to find the extensions).
I haven’t tried them myself (yet), so there’s no rhetorical element to my question. I have a number of Fisch Forstner bits in fairly large sizes (the biggest is 68 mm ≈ 2-11/16″) with which I’ve been very happy, and so I’ve been eying up their extensions as well. They’re a bit pricey, though, which is why I was wondering if you had ever come across them in your bit extension trials?
Mattias
I have not seen that particular extension in the United States. Though it may well be sold here and I don’t know it.
It works on the same principle as the Bosch, so I assume it holds the bit well.
I’ll be on the lookout for it. Thanks!
You’re welcome! I just remembered that TFWW carries certain Fisch bits – some Wavecutter Forstners and of course their Jennings Pattern Auger Bits for Braces, so maybe they would know or be able to find out more about extensions, too?
Mattias
On a tangent to boring round chair mortices, do you have a recommendation for a tool making tenons to mate that are longer than 1:5-2″ so I dont need to trim and lengthen them at the shoulder to get full penetration to flush trim on the seat?… Hand or powered.
There are lots of other ways to get there (including a vintage hollow auger).
If you wanna be extra cheap, you can use crescent wrenches as sizing tools. Just grind the top edge sharp.
Thanks, I think vintage is the simplest approach, although I haven’t held one in my hand for a long while. It seems from photos on the net that depth is longer than possible using the powered versions.
It occurs to me that one may be able to eliminate the wobble by tapping additional set screws at positions 120 degrees in either direction around the chuck.
That would work if the shaft were true.
I am using Jennings auger bits and a Stopford brace so I am limited on what I can use to extend the shaft. so I use a vintage 20″ extender. So the smallest hole I can do with the extender is a 10 ( 5/8) and my god it has never been anything close to straight, good thing I can’t get the RPM’s out of the brace or I would be in big trouble. When I do use power tools I do have one like you describe different brand but the set screw one is the best
Good suggestion. I’ve had the same one for years, using it for rough work when I was doing carpentry jobs, and now for furniture making. One must be careful to not leave the set screws too loose when you put it away, so that when you need it, they are not gone. It’s happened to me before, and that bit extender without the set screws, well, you know.
The best extension is a piece of drill rod and a coupler. They sell them in different diameters and many different length, or you can cut to size. They are very straight and also not too expensive.
The drill rod makes perfect sense. But I’m not aware of the couplers you are describing. Could you provide a link or two so I could investigate? Thank you!
Maybe you just answered your own question on which new tool for Crucible…….