What causes chisels to twist when chopping mortises?

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    Joe Beazelman

    I chopped 8 mortises for a workbench and it was quite frustrating. I was using a Neiko 9 piece chisel set I purchased from Amazon. There were numerous times when the chisel started twisting on me as I chopped the mortise. At one point, I stopped and switched to my beater chisels from Harbor Freight and it worked better, but I still had a hard time fighting the “twists.”

    What makes it even more frustrating is that there isn’t an established reason for why the phenomenon happens. When I tried to research it by conducting internet searches, reading magazine articles, etc., there were tons of differing opinions and many contradicted each other. Consensus among the traditionalists claim that bevel chisels are just not up to task and appear to disagree with squarely with Paul. Here’s some examples:

    Hand Cutting Mortise and Tenons

    “A non-square chisel will twist as you drive it. You cannot stop the twist! Levering out waste with a twisted chisel will make a mortise wider than the chisel.”

    “When driving a bench chisel with a mallet to square the end of the mortise, the chisel tends to twist. That’s because the blade is relatively thin and the edges are beveled, so there is little side support.”

    Moreover, in one of Paul’s Workbench build video’s he said to “take control” of your chisel to keep it from twisting. I tried to fight the chisel and it always won. Interestingly, his chisels had squarer sides than mine and he wasn’t using a joiner’s mallet. In a past blog, he says that a joiner’s mallet isn’t up for the task because of the COP. Could this be the culprit?


    Perhaps it may be the reason, but as I was writing this, I discovered

    I am confused about the whole matter. Sadly, I think hand mortising is certainly more fun and less noisy than the power tool route, but there are times when you just want to pull out the Bosch 1617 and be done with it.


    FYI: Before you blame it on a cheap chisel set, let me tell you that I can’t tell the difference between these chisels and the far more expensive Irwin/Marples set. They look nearly identical minus the color. I am almost certain it came out of the same factory. They are also very highly rated on Amazon. You’ll be hard pressed to find a level-headed bad rating on it.

    Salko Safic

    I had that very same issue when I firt started so long ago but it didn’t take me long to ffigure out a neat little trick. Knife line it and sit the chisel in the line, that will get you started then stand in front of the chisel not on the side to keep it vertical and straight. Try that a few hundred befre you develop that muscle memory. I also like Pauls’s jig as well.

    Hope this helped.

    The Lost Scrolls of HANDWORK
    (Hand tool only woodworking magazine)


    I think it’s due to the growth rings of the wood more than it is chisels. The same thing happens with my mortice chisels. The mortice chisels help because of the large handles with which you can get a good hold on and resist. Smaller handled chisels may prove more difficult in this respect.

    Take smaller cuts and the problem should go away.


    Salko Safic

    True David they do play a significant role but smaller bites and a good ffirm grip should help, he just can’t give up on it and resort to using a router that defeats the purpose of attaining true skill. I have to get back to work and start getting ready to put things up online for the first time. It’s nerve racking cause I never did sell online before, it was so much easier when someone rings up or walks in and say’s hey you made this for my friend can you make one for me. Atleast I know I had a sale and never a stock build up. Wish me luck I hope it turns out to be fruitful.

    The Lost Scrolls of HANDWORK
    (Hand tool only woodworking magazine)


    I am in agreememt that the smaller bites you take helps. Some wood types, growth rings, dense areas, knots, etc can be troublesome.
    I have a set of narex bevel edge with very slim tapers, i also have lee valley set with a more squared edge. Same twist for both if they are not very sharp and i try too take too much.

    Ontario, Canada

    Greg Merritt

    There are a few factors at play. Like has been stated above, size of the bite taken, force of the mallet blow and growth rings. Another factor is hand strength. All chisels will try to twist. Like Paul has said you need to “take control.” As you build hand strength you will find it much easier to take control. Its a matter of practice and developing a feel for it. Once you have the feel for it you will recognize when the chisel is beginning to twist and react immediately to prevent it.


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