Auger bits missing spurs
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- This topic has 4 replies, 4 voices, and was last updated 7 years, 9 months ago by lukedupont.
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Hi all,
I’ve just picked up a set of auger bits from a farm auction/sale and noticed that about half of the bits are missing the cutting spurs, some appear to have been ground off, but others don’t look as if they’ve ever had spurs. I’m wondering if there are different styles of auger bits that I’m not aware of, or if this is a fault of someone trying to sharpen them without understanding their functions? If it is a problem, is it fixable? The bits without spurs currently chip off lots of timber on their entrance into the wood.
Regards and help appreciated,
Liam24 June 2016 at 5:48 am #138068Nothing you can do to add spurs back to them. It’s possible that there are bits that don’t have spurs, but I don’t know of any. You really need the spurs to get a clean entry into the wood.
Seems like I saw something a while back about what you can use old or worn auger bits for. You might have to try that because they’re probably no good for boring holes.
I’d suggest searching the internet for different types of bits. Try looking at Bob Demers excellent blog at “http://thevalleywoodworker.blogspot.com/”. Look for the category of “Boring Tools”. He’s got some great information.
Sadly, without the cutting spur they’ll bore an extremely ragged hole, if they cut at all.
It is also most likely that the forces required to keep the drill on an even course will drag the screw out and prevent cutting.
The spur is essential for this type of bit which cuts by two simultaneous actions; the side-spur which rotates in front and scores the side grain and gives smooth sides to the hole, then the radial chisel that follows and removes the waste.
I don’t know what happened to them….. probably hit a nail in the past or been repeatedly sharpened until they disappear – it happens.
For the Auger bit to work properly, both need to be sharp and working in conjunction.
N.B. There are some types of auger bits that work without a spur (‘Gedge’ type bits for example) but they have a completely different geometry at the cutting end.
4 July 2016 at 7:35 pm #138239I have seen vintage bits that were not designed with spurs to begin with. So, in some cases it would seem to be by design.
I wonder if this isn’t akin to opening the mouth of a plane; a personal choice made by the craftsman to sacrifice fine finish work for easier rough work.
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