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Designing a Successful Tool: The Crucible Scraper

The most successful product we’ve produced at Crucible Tool is, hands down, our curved card scraper. In less than a year, we’ve sold thousands of these simple tools all over the world. And we’ve made a decent profit, too.

The tool isn’t a copy of anything that was commercially available before. It didn’t require any new materials or cutting-edge technology to manufacture. And it is aimed at furniture makers, a craft where the basic hand tools haven’t changed for thousands of years.

Was the idea for this tool just luck? I don’t think so. A flash of genius? Absolutely not. Instead, the scraper emerged from a mind warped in graduate school by Noam Chomsky and Edward S. Herman. Their theories changed the way I process everyday information and helped get this tool to market.

OK, we’re getting ahead of ourselves a bit. What the heck is a scraper?

Scraper 101

In the furniture trades, a card scraper is the weapon of last resort. If you cannot get a piece of wood to cut cleanly with a handplane, the scraper can fix the wood’s surface imperfections with just a few choice strokes.

Historically, card scrapers have been a rectangular piece of thin steel. The user creates a small “hook” on its edges, which does the cutting. Then the furniture maker flexes the tool slightly with his or her hands so that only a small area of steel contacts the wood. And then the scraping commences.

The downside to scrapers is the flexing. Using a rectangular scraper for more than a few minutes can be agony on the thumbs. And if you have arthritis, you might not be able to flex the scraper at all without loads of pain.

A New (to Me) Shape

In 2018, Welsh chairmaker Christopher Williams taught a class in our Kentucky workshop. While carving out the seat of a chair, Chris used a card scraper to finish up his work. When he laid the scraper down, I was struck by its shape.

Instead of being a neat rectangle like 99.9 percent of the scrapers in the world, Chris’s scraper was shaped more like a pill or lozenge. The main edges were curved. And the tool’s corners were curved even more. I asked Chris where the shape came from. He replied that someone in his training had one similar to it. Plus his chairmaking mentor (John Brown, from Wales) had a curved scraper. So Chris had ground one to a shape he thought would be nice.

It didn’t look commercially promising. It was a homemade scraper with a hand-ground, somewhat irregular shape. The students didn’t seem to think much of it. But it worked quite well. I traced its shape on a sheet of paper and set it aside.

Processing Weird Information

My graduate degree is in journalism. That program didn’t make me a better journalist, but it did force me to look at the way people process information. One of the lessons that stuck out was that we like our information to reinforce the way we see the world. We like to have a Left and a Right when we discuss politics. A Judge and a Criminal when we read about the law. A Correct Shape and an Incorrect Shape for a tool. We like to say there are two sides to every story.

But that’s crap. There are 100 sides to any story – you just don’t get to read about them all because of the way that modern media works.

Noam Chomsky, a noted (some would say notorious) anarchist, encourages people to look for information that doesn’t fit into the “two sides to every story” model. That odd information, he says, is what’s interesting.

That simple lesson now guides me as a designer, whether it’s a tool, a piece of furniture, a book or a website.

So when I picked up my tracing of Chris’s scraper several months later, I thought of Chomsky. I rooted through my tool chest. I found an old scraper. And I headed to the grinder.

About an hour later, I had a scraper that was similar to Chris’s. I sharpened it, put it to use and could immediately see its advantages.

You didn’t have to bend it to make a cut.

You didn’t have to wreck your thumbs.

You could easily use the entire cutting edge up before resharpening.

(Plus other geeky tool stuff I’ll omit here.)

Development

During the next couple months I tried different curves to find the one I preferred. Chris’s scraper actually had two slightly different curves, so I tried both of those. I ended up liking a slightly shallower curve overall. And I put a steeper curve on the corners of my final working prototype.

I drafted the tool’s final shape with trammel points and a compass on paper – old school. Then I drew it up in CAD to see how it would look when we entered the world of CAD/CAM.

Then I hit the history books. Surely we weren’t the first people ever to make a curved scraper. Why was this tool not already for sale?

When I research tools or furniture, I go back as far as I can. With scrapers, their history starts with the Paleolithic period – the Old Stone Age – with tools used for shaping wooden spears. Later scrapers in the Neolithic period were used for scraping animal hides clean, according to Kenneth P. Oakley’s “Man the Toolmaker” (British Museum). And both types of these scrapers had curved edges.

As for scrapers used in woodworking, I looked at tool catalogs, written accounts of shop practice and surviving examples. Sadly, scrapers don’t survive well because they usually were made from pieces of old handsaws and – at their best – look like a scrap of metal instead of a fine finishing tool. I suspect many of these scrapers were thrown away after the furniture maker died.

In old catalogs, scrapers are shown mostly as rectangles. There’s a radically curved “gooseneck” scraper that is used for mouldings, but nothing like the one from Chris’s tool kit.

The first written evidence I could find for a scraper with a gently curved cutting edge turned out to be a magazine I had stared at for a decade. Charles Hayward was the editor of The Woodworker Magazine in Britain from 1939-1967 and has been my guide since I first learned about him in the 1990s. I collected every issue of The Woodworker while he was editor, and he wrote two articles about sharpening a scraper that shows a clearly curved edge.

He exaggerated the curve in his drawing, but said the curve should be about 1/32" over 5". That’s not much of a curve at all, but I was glad to see his description of how to use the scraper: “There is no need to bend it unduly as the edge is already bowed. The corners will not dig in.”

All my research (about 50 hours in all) led me to an important conclusion: There is so little written on scrapers, and they are such a nondescript tool, that really almost anything is possible. Perhaps people added a curve to their scrapers the same way they add a curve to the cutting edge on a handplane. It’s such an obvious modification that it doesn’t bear much discussion.

But somehow, that common knowledge became uncommon when the world became full of power sanders and scrapers were (for a time) a rare sight in a workshop.

How to Manufacture One (or 1,000)

Manufacturing a curved scraper turned out to be mostly straightforward. Scrapers are typically made from the spring steel used in handsaws. It’s fairly soft steel (softer than a chisel, for example) which makes the steel easy to sharpen. Some modern makers make super hard scrapers, which are difficult to sharpen but hold their edge longer. I’m not a fan of super hard scrapers so we stuck with the traditional spring steel.

How do we make it curved? My first instinct was to try laser cutting. But the heat from the laser can change the hardness of the steel. So despite the tempting low cost of laser cutting, I decided to use a waterjet to cut the scraper to shape instead.

Waterjet doesn’t heat up the steel and it is very precise, but it is messy and it doesn’t produce a beautiful resulting surface, either. It looks like someone has bombarded the edge with tiny rocks (because that is exactly what has happened). So we had to find a way to clean up the edge so that it would be easy to sharpen.

Most scrapers come from the factory with an edge that has been coarsely ground or cut. You have to polish out the coarse scratches, and this can take 15 to 20 minutes. Could we come up with a way to polish the edge at the factory so the scraper was almost effortless to sharpen?

I started experimenting on our belt grinder – basically a horizontal sanding belt – that I loaded with a variety of 3M Trizact abrasives. This worked. But even with a jig, it required skill to do the job. And it was pure drudgery. I couldn’t ask anyone to grind 3,000 of these tools.

One of the machinists who does work for us came up with a jig that we could use in a milling machine. Slap the scraper in, press a button and the robot mills the edge to a perfect mirror every time in just a few seconds. (This was the only pure stroke of genius in this project – thanks Craig.)

The last hurdle turned out to be a problem with the supply chain for the steel. We wanted to use polished spring steel that was bright and silvery – just like everyone else. Our supplier could only get us polished spring steel that was blued for rust protection.

We tried removing the bluing with a variety of processes. Then finally someone said: Why not just keep the bluing? It doesn’t hurt anything, it helps protect the scraper from rust and the blue looks different than other scrapers.

Duh. Sold.

Pricing

A high-quality card scraper costs about $7-$10. There was no way we could get our scraper near that price and make it in the United States. We had three operations – cutting it to a rectangle, cutting it to a curve and then milling the edge – where most scrapers are made in one or two cutting operations.

Plus, we’re a tiny company and can’t buy steel by the container-load.

So we decided to instead add some niceties – a printed storage envelope for the scraper and a nice magnet that sticks to the tool (the magnet absorbs some of the heat generated while scraping). And we put the price at $20 – far above everyone else. But we figured hey, it’s still just a $20 bill for a scraper that’s easy to sharpen and doesn’t hurt your hands. (And $20 is an important psychological price point in my experience.)

And then we did one more thing. When the scraper first went on sale, we sold out of the first 1,000 in a few hours. So we gave everyone a pattern and instructions for how to make their own from an existing card scraper. We figured that people could easily make one based on our photos of the product. Why don’t we show them how to do it correctly?

This (unintentionally) muted a lot of criticism of the $20 price. If you couldn’t (or wouldn’t) spend $20, you could make one at home with our pattern and a scrap of steel. Price $0.

Honestly, giving away the pattern wasn’t a calculated move. But I’m glad we did it.

Looking to the Future: Ripoffs

I feel pretty certain we’ll get ripped off and someone will make a similar scraper (perhaps overseas) for a lower retail price. It’s a common occurrence in the woodworking tool industry (and no, patents are not the answer for tiny businesses without a legal department).

When that day comes, I know we’ll suffer quite a bit in sales, but we’ll keep making our tool regardless. Because while they’ll be able to make the tool for less money, they won’t be able to make it any better than we can. And that’s some high ground that’s worth defending.