Chris Schwarz's Blog

In Praise of the Engineer’s Hammer (aka a Lump Hammer)

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While I was at David Savage’s workshop I was delighted and surprised to see he used a “lump hammer” for assembling casework.

David brought the hammer to my workbench when he helped me knock together my dovetailed tool chest carcase for a class. And when he saw me smile hugely at the lump hammer (instead of recoiling in horror, which is what I think he was expecting), he told me something I didn’t know.

The lump hammer was one of Alan Peters’s favorite tools, as well.

I’ve carried one of these heavy hammers or one with wood faces (which I call “Mongo”) to classes where beatings were required, usually classes in tool chests or workbenches. Lump hammers look like they would destroy a carcase, but quite the opposite is true. They are gentle giants.

David and I are not alone. Richard Maguire, the English Woodworker, has written about his love affair with “Lumpy” on his blog here. Same with James Watriss. Now before you go looking for a “lump hammer,” read on.

Here in North America, it’s called a sledge, blacksmith or engineer’s double-face hammer. But none of those names does the tool justice quite like “lump hammer.”

I like one with a head that weighs between 2 lbs. and 2-1/2 lbs. (in metric land, look for a 1,000-gram head) with the tool’s total length about 10-1/2”. You might have to cut down the handle; this will improve its balance and finesse.

And here’s the good news: These sledgehammers are incredibly plentiful and cheap. Check out what’s on eBay today here.

I have an old Japanese one, and I recently gave it the “Seth Gould” treatment – charring the handle with a torch. You can read more on this technique in the April 2015 issue of Popular Woodworking Magazine.

Next time you see one of these tools at a flea market or used tool sale, pick it up and see how it feels in your hands. You just might just want to take one home.

— Christopher Schwarz

10 thoughts on “In Praise of the Engineer’s Hammer (aka a Lump Hammer)

  1. JWatriss

    It’s a bit much to be mentioned side by side with someone like Richard… I’m humbled.

    Thanks, Chris

  2. Derrick

    I am having trouble understanding the gentle giants part of this. How are they employed without damaging the work? Just something as simple as wooden pads, or am I missing something else?

    1. JWatriss

      Simple math… but not obvious math.

      The amount of force a hammer imparts to the receiving object derives from two things: how much mass the hammer has, and how much oomph you put behind the swing. (mass times acceleration, for you physics students)

      Put another way, to apply equivalent forces, you can either swing a very light hammer really recklessly hard, or give a much slower nudge with a lump hammer.

      Here’s the other side of the math: Pressure is a measure of force applied over how much area. As a result, small hammers actually impart much more pressure at the point of impact, due to the smaller face. PSI: Pounds per Square Inch: P/SI: Larger hammer face means larger value for SI means a lower amount of pressure applied…

      and that lower amount of pressure is applied more slowly.

      If you were swinging the lump hammer like you would a wooden mallet, of course you’d make an unholy mess. If you swing it intelligently, it’ll treat your work more gently.

  3. Jolar

    Just want to point out that Richard Maguire from the English Woodworker blog has evolved and found an even better hammer – the one that Paul Sellers have been recommending for years, the Thor/Thorex 712 hammer.

  4. landrover224

    I got a very nice Lump hammer out of the old Wheeling Wv. LaBell Cut Nail Factory not to mention a very large amount of Stainless cut nails. I think that Labelle is the only ones to have made stainless Cuts. They were made for decks and docks but I bet they would look nice for other projects..

    1. john2t

      I was just looking for La Belle. It looks like they had an auction in September. Must be closing the factory.
      Anyone who knows this company well, please advise if this is correct.

  5. Sawdust

    Chris –
    Why would you use such as these beast on wood when a non-marring shot & oil-filled mallet would do the same with less of a chance of damaging a surface?

  6. Alex

    I just started using one of these to assemble my French style bench. It now lives under that bench for those moment when it is needed.

  7. BLZeebub

    I have what could be called a small lumpy. Found it years ago at a flea market and was smitten. It is a slender girl meaning it is more elongated than most sledges, weighs in just under two pounds and already has a shorter than normal handle. It is never far away from my hand. I also have my father’s three pound cross peen which will put a serious beat-down on anything needing one. It stands ready like a harem guard for the time it’s special qualities are called for.

  8. Jim McCoy

    I’ve had mine since 1975. I found the head lying on the side of the road on my way to work. I stopped and picked it up and took it home and cleaned the rust and dirt off it and put a new handle on it. I’ve been using it ever since for everything from splitting logs to banging together stubborn joints. I always called it my single jack but now I know it’s real name. Thanks.

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