Thread: Spurs or no spurs

As you say, MA, there is plenty of opinion & anecdote wrt to the spurs but very little original informatin from manufacturers o what they thought they were providing. We were taught that the spurs were for softwoods (as in conifers) & the plain bits were for hardwoods. I later came to doubt that & formed the opinion that the spurs are simply to make cleaner holes and the plain bits for rougher work. In many instances I find the holes they make aren't any rougher than I get with spurred bits & they are are easier to maintain so I don't find an overwhelming difference.

Your information leans me to a new opinion, that the spurs are of best use when drilling into side grain & the plain bits for end-grain. It makes sense to me, because I can see how severing fibres helps when boring side-grain, & that spurs don't do anything useful when boring end-grain since the fibres are vertical & all have to be severed by the cutting edge of the bit. Since softwoods generally have longer fibres than hardwoods, I guess the two ideas are not incompatible.

All of which is simply more anecdote & opinion, of course......

Cheers,

Ian has accurately identified the "received wisdom"on spurs or no spurs. I must say that I have never found the soft/hard distinction very convincing in practice. Nor have I found the clean/rough distinction helpful - my holes with spurless bits have been so rough as to be unusable, but that may just be my bad technique or that I am doing furniture work, not house building or fencing!
The idea that the spurless are for use on end grain is interesting and I may give it a go, since otherwise my spurless bits are , frankly, just taking up room in my toolbox.

A discussion on spurs and no spurs here, Leo is a superb craftsman and definitely know what he is talkng about. His large joinery work is an art form I reckon. Go to 11 minutes in, The URL for that won't capture.

Plenty of explanation re Spurs here.
What are the different auger bit patterns? - Wonkee Donkee Tools

MA, is there any other branding on your bits other than mainbor and endbor? Without having any examples I'd assume they're made by the same outfit and the brands allude to the manufacturers purpose of the bit. Ian and jmk89 have covered it pretty well, my opinion is the hard/soft wood is USA and British terminology and has little relevance on many of our Aus' timbers.
The wonkee donkee site is aptly named, their item on the Cook pattern and mention of Gedge as an American term is back to front. Cook was the original USA patentee (17th June 1851 Pat No 8162) Gedge was an agent in Britain who patented it there on Cooks behalf. Therefore "Cook" in USA and "Gedge" in UK.
Cheers,
Geoff.

Hi all. Geoff, bits have "Irwin" inside a rectangle and "USA" on them. Ian, I tried using the spurred version on end grain (because it was the only type in the size required and it required a bit of pressure to keep it moving. Jeremy, I am hoping this means the spurless bits were not a waste of money also. Ian, the accumulated experience on this forum is why I spend so much time on it. And it's always nice to post a thread that generates interest from others.

Hi Chris. I had a look at the video but couldn't find the discussion regarding spurs/no spurs?

Originally Posted by Mountain Ash

Hi Chris. I had a look at the video but couldn't find the discussion regarding spurs/no spurs?

I didn't see any explanation of the reasons/principals involved either. I only started viewing just before the time Chris suggested, where he takes the lead-screw & spur(s) off a long bit, and altered the cutters. He mentions a couple of times afterwards that it made it easier to keep the bit running true, but gave no explanation of why. He was boring cross-grain, which is where I would have expected the spurs to be mot useful, but I got the impression that his primary concern was keeping the hole straight rather than neat.

From the smatterings I've read over the years, drill bit design is a rather arcane science & much of it seems counter-intuitive to my simple brain. I would have expected the modified bit in the video to be a beast of a thing to keep going in a straight line across the grain, but it appeared to do the job nicely. So-called "D-bits" are another example; used for boring & reaming very accurate holes in metal. They look like they'd go every which way but straight, but clearly don't. And the "spoon bits" used by chair makers - I couldn't have dreamed up one of those in several lifetimes!!

Cheers,

I will go along with what Ian has said, simply because he is usually right!

There was also a cost element involved - spurs were more difficult (read expensive) to produce.

And I will add a caveat if you buy used bits. Beware of bits where someone has "sharpened" the wrong side of the spur. Spurs should only be sharpened on the inside radius.

Leo probably could have got away with filing three sides of the lead screw to leave a more or less threadless point, which would still give him a centre point but virtually nil aggression.
The result he referred to as a "barefoot" bit is listed in both Mathiesons 1933 and James Swan 1920 catalogues as " ship" augers. Swan offered them both with and without a lead screw.
I've been told that it was usual practice to chop a pilot hole with a chisel to start the screwless version.
Cheers,
Geoff.