Why We Don’t Sharpen the Dividers

Posted on 27 July 2017


We’ve had a few comments about the fact that our improved-pattern dividers arrive unsharpened. And while we understand how that might cause a wrinkled brow or two, there are good reasons we ship them that way.

As I see it, there are two questions I need to answer to explain our rationale.

Question No. 1: Don’t All Other Dividers Come Sharp?
Most of you probably think that dividers are supposed to come sharp. Every other new pair of these tools comes with the same shape tips: a slightly fatter-than-average sewing needle.

My contention is that this has little to do with what is best for the woodworker and has everything to do with what’s easy to manufacture.

(I’ve prepared a detailed exposition on the Industrial Revolution’s shift from single-source to multiple-source craftsmanship – and why that led to dividers being abandoned, while rulers and other standardized measurement devices took over. I also discuss the shift to engineering and draftsman pattern-dividers, and away from the more robust versions previously found in most shops. And if you aren’t good girls and boys, I might still run through that entire rant on this blog.)

So for now, keep in mind that just because you’ve never seen dividers sharpened (or shipped unsharpened), that doesn’t necessarily mean that’s for your benefit. In my experience, it’s usually not.

Question No. 2: Wait. Is There More Than One Way to Sharpen Dividers?
We think there are plenty of ways to sharpen them. There is a huge range of possibilities in sharpening and tuning up dividers for different styles of work, different purposes and even different materials.

Let’s start by discussing divider schizophrenia. In most shops, dividers do the work of at least two instruments, dividers and compass. But dividers and compasses are not the same things.

Dividers are fundamentally a measurement tool. Don’t be fooled by the total absence of laser-etched graduations and a certificate of calibration – they were the fundamental measurement tools for builders right up until the Industrial Revolution made “interchangeable measurement” and “universal standards” critically important. Before that, the measurements that mattered were “internal” to a piece of furniture.

Rulers tell you how long something is compared to the National Inch Standard measure. Dividers don’t measure in relation to anything external. They’re just tell you how big one thing is compared to another. They are also spectacular at taking a measurement and dividing it into any reasonable number of parts. They’re much better, in fact, at both those tasks than rulers (even rulers with lasers and a built-in calculator). The downside is that you can’t just can’t tell your Southeast Asian production shop some arbitrary number of dividers steps via Skype and have them reproduce that measurement – that measurement is only good for as long as the dividers are set that way. 

Compasses, on the other hand, aren’t for measuring at all (OK – oversimplification, but still mostly accurate). Compasses are for layout. A compass is for drawing circles and circular arcs. And that’s it.

In a shop, compasses don’t necessarily need a pencil on one end, though. Often, a scribing point is much better. Have you ever used your dividers to scribe a circle directly on a board? If not, give it a shot. Go ahead, I’ll wait.

Worked pretty well, no?

So here’s the first dip into alternate ideas for sharpening dividers: The tips for “walking off” distances are not necessarily the best tips for layout tasks. In fact, layout often works best with two different point-styles on the same pair of dividers.

In the next entry, I’ll discuss these different shapes for the points and how to create them.

— raney

More Posts


  • AAAndrew: October 13, 2017

    If I want a circled drawn with a compass that must be accurate and a fine line, I use ink. There used to be engineering compasses with ink pens built in. Nowadays you could make your own with one of the Micron .2mm pigment pens, if need be. I happen to have a school compass from the 1890’s that has a dip pen nib as an option on one side. I use iron gall ink and it draws a very fine and indelible line that sits on the surface but can’t be smudged off by accident. Not something you need all the time, but when you need it, it’s great to have. And the nib assembly comes out and fits into a larger shop compass’s pencil holder for larger circles and arcs.

  • Jason: September 29, 2017

    O.K., the idea of the rant is tantalizing, but what I’m really (and still) waiting for is the next blog post on the different shapes for the ends and how to create them. I had no idea the points would be anything but sharp points. Why something else??

  • Brad: September 05, 2017

    I’m looking forward to your thoughts on sharpening dividers. A friend just gave me two pairs of dividers that he inherited from his grandfather who was a pattern maker. They both have a point on one side and a curved blade with the flat to the inside ground on the other. I assume they are set up for marking circles.

  • Grigoor: August 15, 2017

    Will you ship to the UK please


  • John Tracz: August 09, 2017

    I know Chris recently made reference to an upcoming announcement concerning access to these tools for your long-suffering Canadian cousins… any update?

  • Patrick: August 03, 2017

    Um, another +1 on the rant. (Despite Justin’s warning) It does sound interesting and if it helps, I’m a baaaaaad boy.

  • Raney: August 02, 2017

    Hey Nathan,

    Not so much. I’m totally agnostic about metric, imperial, whatever. My rants tend more toward the ‘why efficiency is killing our souls’ and almost always center on who’s getting taken in the power shifts.

    I also don’t really adhere much to either harmonic proportions or whole-integer ratios. I prefer in all cases to work by eye.

    This might seem at odds with my core training, which was math and physics first and foremost. My greater concerns, though, are the way we are always prone to finding something that yields some good results (scientific method, master-based algorithmic structuring, and specialization) and then decide that it’s our new idol. Then we apply it to everything, absolutely everything undear the sun, and we get bit HARD by it.

    I get your drift, it’s just that for me addressing relative merits of metric/imperial/wavelength-based, or decay-rate-based systems of measurement is stopping to decide whether to take the left or right fork when your wrong turn was six hours earlier.

  • Nathan: August 01, 2017

    I’d be curious to see if your rant is in line with my theory about why the Imperial standard evolved directly from the craftsman/relative measurement era and why the metric system is a wholly modern, robotic product of the industrial revolution. “Everything divides by 10!” they say. “Who cares?” I say. The term 1/64" is a relative term in itself – 1 of 64. It at least gets us closer to using whole number ratios and harmonic proportions. Try getting that from the metric system.

  • Justin Leib: July 31, 2017

    I love you and truly respect you, Raney. But this needs to be said for everyone’s sake and safety.

    Please back away from the rant. Everyone please just turn away and go home. There is nothing to see here. Mr. Nelson can’t come out and play right now, he needs his rest. Please return to your homes. Oh look, there is a rainbow! A butterfly! A trainwreck! Anything! Just avert your attention elsewhere, please!

    Good work, Raney.

    P.S. I would kind of like to read it too.

  • raney: July 27, 2017

    I fear for you both. Maybe Chris or John should explain why the word ‘floodgate’ is so close at hand.

    I’ll give it some thought. Normally that’s the sort of stuff I only inflict on people at my daed blog, but you did ask for it. (they did John. You saw em.)

  • John: July 27, 2017

    +1 on interest in rants about the shift in craftsmanship

  • raney: July 27, 2017

    Oh man, you really don’t know what hornet’s nest you’re kicking there Shawn,

    It’s actually merely a side-note in the overall manifesto-rant of why exactly we’re in for no good given our current outlook – a crowd-pleaser at 30-40 intensely repetitive hours, coming to a traveling woodworking show near you anytime I can’t worm my way out of it.

    It’s actually a book I’m planning – but every time I mention it around Chris or John the response is a panicked ‘But that has nothing to do with the toolmaking book, right?’ which leads me to believe I may need to find an impressionable young publisher somewhere first…

  • Shawn Vincent: July 27, 2017

    Perhaps I’m odd, but I really want to hear your rant on the shift from single-source to multiple-source craftsmanship. :-) I hope you choose to run it.

Leave a comment

All blog comments are checked prior to publishing

Search our store