The Awesome Power of the Chain Mortiser

Mafell Chain Mortiser. Dang.

 In Chris Schwarz Blog, Power Tools, Schwarz on Workbenches, Tools, Woodworking Blogs, Workbenches

My least-favorite joint to cut by hand is – hands down – a deep mortise.

But when you build a French-style workbench, you need to make about a dozen of them. And if you do it by hand, you are talking about a lot of boring, chopping, paring and sweating. When I mentioned this to Peter Lanz at Dictum GmbH, where I am teaching a bench class this week, he had an idea.

The Mafell chain mortiser. If you aren’t familiar with Mafell, don’t feel bad. I wasn’t either. Mafell is a professional line in Germany and is not frequently used by home woodworkers, according to the folks at Dictum. The tools are available in the United States; if you’d like to take a look, click here.

I’ve never used a chain mortiser, which is a handy tool when building a timber-frame house, so I was eager to get the thing set up and running on Tuesday. Peter built a jig to guide the machine to make all the mortises for the bases of the 13 workbenches. We got a little instruction from a timber-framer. And then we fired it up.

The thing is loud – about 97 dB to the manual. But it has every right to yell because it dove into this material (heavy Scots pine) like it was yellow pudding. I cut about 50 mortises with the machine, and I don’t think I’ve ever seen a method that is as fast or clean for gigantic mortises. (Confession: I’ve not used a slot mortiser.)

It feels like a giant plunge router as you drive it down into the work and produces a surprisingly tidy pile of dust to one side. Plunging to its maximum depth took about 15 seconds. Incredible.

Of course, we had to cut all the tenons for these mortises today. So we sawed all those (by hand) and everyone finished up their work by the end of the day Tuesday. The workbench bases will go together on Wednesday. Then we have another two days to get the glued-up tops attached to the base and finish work on the leg vises.

— Christopher Schwarz

This is the second day of this workbench class. If you’d like to see the video from the first day, click here.

For more on workbenches, check out “Workbenches: From Design & Theory to Construction & Use” in our store.

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Showing 7 comments
  • utensilegno

    Actually there are a lot of portable machines doing this job for large and deep mortises, produced by Mafell, Hema, Protool, Makita, Haffner, Holzher, Bruhwiler, …
    The spare tools (chains, guide bars, sprockets, greasers …) can also be bought directly from the european quality mortising tools producers you can find on the web, mainly from Germany and Italy.

  • tunznath

    Here in Portugal chain mortisers are common, there is a very old manufacturer MIDA, that made machinery for carpenters – big heavy cast iron machines – not portable though.

  • Niels

    Time to call mom, I think I am in love!

  • John Cashman

    A Mafell mortiser? How about a Ma Deuce mortiser? That would be cool.

    • Jon

      that might leave a little bit of tear-out on the back side.

      I see you can buy these in the USA – only $3000! and then another $1500 for the stand. So where can I rent one?

      the ma duece might almost be cheaper.

  • Wilbur

    Very impressive. How was the surface on the opposite side? Was there much blowout as the chain mortiser cut through the other side?

    • utensilegno

      actually the result depends a lot from the kind of wood.
      To avoid breaking the wood surface around the mortise on the outcoming side, for fine works, you can
      – use a couple of small metal plates fixed (nailed) to the wood piece on each side of the future mortise place
      – use smaller pitch chains

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