Crucible Lump Hammer: Specifications
Posted on 22 November 2017
Manufacturing a lump hammer was one of the dozen or so things we wanted to make before we even incorporated Crucible Tool. It’s a tool I’ve been experimenting with in my personal shop for years by modifying vintage hammers to get the balance and feel that I wanted.
Before I discuss the specifications of the lump hammer, however, let me first answer a question several customers have asked: What in the tarnation is a lump hammer?
In the United States, it’s typically called an engineer’s hammer or a small sledge, and it comes in a variety of configurations – different head weights and different handle lengths. In the United Kingdom, the tool is sometimes called a lump hammer and is a tool that shows up in the kit of many 20th century woodworkers, including Alan Peters and David Savage.
The lump hammer is used for everything that a wooden mallet is used for – mortising, assembly, disassembly, chopping dovetails, setting holdfasts, persuading stuck joints. It’s advantage (in my opinion) is it has a lot more punch in a small package. And a lot of woodworking operations can be done without swinging the tool. You merely lift it and drop it – gravity and mass does the work instead of your arms.
During my tests, I worked with a variety of weights, handle sizes and metals to find a lump hammer that was balanced, durable and something I reached for at every opportunity. I am not a fan of cast iron heads, which are common, so we settled on a steel head that is milled directly from a 4140 QT steel (usually called 4140 prehard) that's prehardened to about Rc 28-35. The head is 1,000 grams.
The handle is just as important as the head. Ours is octagonal in section, made from hickory and is 9-1/2” long under the head. During the last year, I think we’ve fussed over the handle more than any other aspect of the tool. The handle has a charred black finish and is coated in soft wax.
The tool will be $85 and made entirely in the United States from domestic materials.
I know that several commenters have noted they can go to Harbor Freight and purchase a similar-looking drilling hammer for $5.99. Is our hammer 14.91 times better than the Harbor Freight hammer? Of course not. It’s 15 times better.
As always, we make these tools for ourselves and our use in the shop – not to a price point. We think the price is incredibly fair for what the hammer is, but if you don’t get that, we don’t seek to change your mind.
The lump hammer is coming soon, just as soon as we can afford the bill for the steel.
— Christopher Schwarz