But They’re Hard to Make!

Posted on 06 June 2017

We’ve mentioned several times how “tricky” it is to make our dividers. I imagine some of you find that odd (or maybe just whiny) - I understand. If I weren’t so immersed in making them, I’d be skeptical, too.

I mean, the tool has a total of four parts. (Five if you include the off-the-shelf washer – I don’t.) They are made using a single material (high-carbon steel) that isn’t even anodized, and there isn’t a single laser. Not one.

This is a world where you can buy a toaster oven with artificial intelligence, 12 kinds of safety lockouts and a Wi-Fi link to NASA for like $13 and free shipping. As I write this, some kid in Nebraska just made a full-scale model of Versailles or something with a 3D printer and dial-up Internet.

So what could possibly be so “difficult” about making two shapely sticks with a trumped-up dowel joint?

So first – the fine print. What we mean, really, is that they’re incredibly difficult to make within the confines of anything remotely resembling “affordability.”

Now just wait a second. Before you erupt all over the comment section about my use of the term “affordable,” know that I’ll talk more about why they cost what they do in the next entry. Until then, if we could just push “pause” on the whole pitchfork-gathering and effigy-torching thing, I’d be eternally grateful.

So let’s cover a couple of the first-order issues that make these difficult to produce.

First is just the overall shape. The dividers are curved on five out of their six exterior faces. We did sneak in about 2” of flat area at the top of each leg. Still, all that curvature creates significant workholding challenges, and a real deficiency of convenient reference surfaces for precisely putting parts in a CNC mill. No matter how the process is ordered, you’re going to have to grab some curved sections sooner or later and maintain some fairly tight repeatability tolerances while you do.

In practice, this adds up to the need for solid and creative fixturing to hold the parts at every stage. Or, for instance, at the very tip of each leg we’re talking about pieces of steel that have a cross section that’s 3/32” square and sticks out about 4” from the relative stability of the upper section, where the primary reference faces are. Add in the tapered chamfers on each face, you also have less than 1/16” of actual real estate (curved, of course) available for a clamping surface at those tips.

In short, these parts are long and thin, tough to hold, and susceptible to vibration and flexing.

The second issue is the number of setups these require on the mill. Ideally, you want to do everything in a single setup, because every time you remove and re-orient a part it adds (or multiplies) errors and inconsistencies. In practice, you rarely can make a tool in one setup, but by ordering things to work the most critical interdependencies together, things are usually manageable.

The dividers have rather a number of critical relationships like this. And to make things work properly, that means a lot of tradeoffs. In the end, we found we needed a minimum of three operations on the legs, and we have some pretty tough tolerances to hit across all the setup changes.

All of these things are doable. This is the sort of thing machinists, designers and manufacturers deal with every day. But every complication carries costs – in time, money, man-hours, fixturing and in how much error the process can tolerate.

Change out a cutter a bit too late, tighten clamps in the wrong order, or miss a metal shaving when cleaning up fixture plate – any of those errors cause problems. And those problems are cumulative. If the part isn’t secured perfectly, vibration increases. That makes cutters wear faster at best. More wear equals more vibration, and both add up to more force needed in each cut, and more force means more heat. More heat means more distortion of parts. More distortion leads to more vibration and higher forces and more heat. In other words: a vicious cycle.

How does all this play out? The dividers can absolutely be made. But it’s a procedure that’s sensitive to tiny errors. As long as the operator is competent and focused, things go fine. But it doesn’t take all that much distraction, lost sleep or overworked tooling to turn a batch of dividers into scrap. And quite possibly shred a few hundred or thousand dollars in tooling.

All these details can be hard to explain to someone who doesn’t do this sort of work. In most cases, it’s not worth explaining this in detail to customers.

In which case, it’s usually much easier to just say: It’s complicated.

— raney

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9 comments

  • jayedcoins: June 08, 2017

    Raney, thanks for the reply, it makes perfect sense and I can say that this series of posts you’ve done is accomplishing the goal, at least from where I stand. The insight is appreciated and it’s fun to read about.

    The curves are great, and when I build a bigger bench you’ll have a holdfast customer, too. On dividers… I’m at that point where I’m not ready for my Last set quite yet, I’m a bit clumsy with them and still not using them to full potential. But hey, that’s the fun part, building skills.

    Good luck and I look forward to whatever Last tools you’re brewing up next.

  • raney: June 07, 2017

    Also – this is a funny spot for me to be in, but in defense of ‘people in general’ I feel like I should say that we’ve actually had very few people complaining all that much about the delays, or the price.

    I think that the blog posts Chris and now I have been putting up may seem as though we’re defending against unreasonable complaints, but I don’t think that’s a reflection of our inboxes or most of the comments.

    I think mostly we’re being so active about explaining because WE feel a bit displeased about the delays, and the fact that we keep plowing through inventory so quickly. It’s really not how we want to operate – and so we’ve felt somewhat obliged to explain it.

    Additionally, though, we’re also interested in teaching and explaining ABOUT our tools and what we do nearly as much as we are in making and selling them. Partly because we really do love woodworking, furniture-making, and craft in general. And partly because we feel that it’s important to explain why we make the choices we do in designing a tools – it helps sales I’m sure, but more importantly, it goes a long way to making sure the people who buy our tools know what they’re buying, and where we’re coming from.

    More blog soon.

  • jayedcoins: June 07, 2017

    It’s funny that people get so irritable about the availability (or lack thereof) of these dividers. There is not some massive national divider shortage. People, if you need dividers, go to a local consignment shop that sells tools, or check eBay. There are plenty of perfectly functional dividers available for a few dollars. Heck, there are functional ones available new.

    Don’t get me wrong. It’s pretty clear that the Crucible dividers have a level of refinement in them that most other new manufacture dividers have, let alone the sort of randomness you get with the used offerings. It also looks like the Crucible product has been designed to provide an easier feel in the hand for flipping and pivoting the tool while stepping out proportions or sketching, not having the large wing in the way and whatnot. So I don’t dispute WHY people want this product and the value that it adds.

    But really, the people whining could go buy a $3 set of used dividers from a flea market and use those for six months while the Crucible team finds a way to improve the volume of production. Easy solution to a minor problem.

  • Fairwoodworking: June 07, 2017

    “pitchfork-gathering and effigy-torching thing”. That sounds like Anarchy… over the “acquisition” of a divider. Who would have predicted that back in 2011?

    Perhaps anyone that is freaking out about how long this is taking should go back and re-read that book that started this all. You know, the one they freaked out about it taking so long to get printed?

    If there’s one thing we can learn from history…

    We’ll get there. We’ll be fine.

  • Raney: June 06, 2017

    Hi Nancy,

    Thanks… That’s what we’re hoping for.

  • Nancy: June 06, 2017

    It may not be worth explaining to most customers, but it is definitely worth explaining to your customers. I am sure that many others will be as interested in, and appreciative of, this insight into the world of making these dividers as I am.

  • Raney: June 06, 2017

    Well, I’ll probably get into this more down the road a bit (not hobie, but the other bits) but here’s a short answer to josh:

    We didn’t consider it much. Not really.

    well, actually we did toss casting around a bit, but I. The end we didn’t see it getting us the results we wanted.

    3D printing has its place. And that place (so far) is: not near me..

    Just kidding, of course. But not really.

  • mitch wilson: June 06, 2017

    I see that you have brought in Hobie Doyle to aid you here. No mirthful laughs for you.

  • Josh Cook: June 06, 2017

    I hear you, bro. We have to deal with this stuff every day — it’s a pain. And I’m just the guy that gets his sobriety questioned when he hands off his drawings to the machinists.

    Did you guys consider any type of casting or (gasp) metal 3D printing (now hear me out…wait come back!) and grinding of precision surfaces? The capital cost doesn’t have to be astronomical with those processes. I admit they probably wouldn’t look as sexy, though.

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