Tuesday, January 08, 2008

Daily Grind

The demise of the Marples sash chisel has provoked a flurry of interest in the comments box. I was indeed a Bad Woodworker and levered when I should not have, but the more I think about it the more I feel the chisel was an equally Bad Chisel and gave up the struggle with rather disappointing ease. The irony is that as a side issue I was hoping to prove that you don't actually need an Oval Bolstered Mortise Chisel to successfully mortise. Hmm, maybe you don't, but old ham-fists here probably does...

Anyway that chisel isn't escaping that easily, and a lengthy spell on the hand grinder creating a fresh bevel on what is now a considerably chunkier cross-section seemed penance enough for me. (Tapered blade, see? So now it's not only shorter but a bit sturdier too.) At about halfway I was already flagging...

... but I persevered and got there in the end. Naturally I had to do further back polishing; when I did it originally I'd allowed enough up the blade to last my lifetime, which is now to be found on the shortest mortise chisel blade in the Western World. D'oh. Oh well, I'm not so sure I don't slightly prefer the shorter tool to be honest. No, not that really short 1" one - this shorter one!

Thus, albeit a trifle gingerly in comparison with my earlier cavalier attitude, I finished the mortises. Now I'm worrying whether I should have a centre rail too...

And finally a few pics to better clarify my brief comments box description of my mortising method. I'm not exactly sure why I settled on this particular one over the many others out there, but it's the one I tend to gravitate to every time. An alternative or variation is to bore the relief "cut", sometimes called the "Maynard" method after an article in The Woodworker, popularised by first Jeff Gorman and then Chris Schwarz in Woodworking magazine (Spring 2007 issue - excellent mortise & tenon-centric issue btw). The idea is to give somewhere for the waste to go. If you bore you can, of course, go full depth and subsequently chop full depth too. Or in my case break through the side of the stile due to my usually reliably unreliable hole boring... Chopping, Alf-stylee, goes more like this:

The intrepid woodworker is standing to the left, looking down the length of the stile so as to facilitate keeping the chisel, and thus the mortise, at 90°. First cut is with the bevel facing you, slightly "in" from the eventual end of the mortise (this allows for the "crush zone" where the chisel is inevitably levered against the end of the mortise and would ruin the end otherwise). One brisk tap.

Hell's bells, that looks deep; it's not really, just the wood is soft-ish. See where the area from the cut to the real end of the mortise has broken off slightly when the chisel was removed? S'one reason why you want knife or gauge marks. If that was just a pencil line then the wood would likely have splintered off beyond the finishing point; not a disaster in this case, but not neat and not good practice. In this case, because the end mark is at the bottom of the groove, I used the chisel itself to mark the line.

Now the chisel is turned round with the bevel facing away and slightly angled to cut towards the hole.

And the result; a v-shaped hole, into which subsequent waste can go.

All the subsequent cuts are bevel facing away, gradually getting deeper.

About two thirds done now, and you might be able to make out the changes of depth. By the time I got to the end I was chopping full depth. Then it's just a matter of turning the chisel round so the bevel's facing again and chopping your way back to the other end again. A paring chop (maybe two, depending on how generous you needed to be with your "crush zone") at each end on the knife line to finish up and 'tis done.

S'not probably the best way or the easiest way, but (thus far) it works for me so I'm not about to fix it :-)  No doubt the more knowledgeable will point out all the places I'm going wrong despite all I can do to stop them...  ;-)


  1. Alf,

    Thank you for the very thorough follow-up post. In my opinion, you are using a well-trusted method and that chisel should not have fractured.

    As an aside, do you happen to know what happened to the bulk of information that used to reside on Mr. Gorman's website? Perhaps a better question would be "why".

    Also, I am envious of your vintage handscrews. Very nice.

  2. I use the same method for chopping out mortises, and have used a cheap bevel edged chisel many times to do it (including 1" wide ones in douglas fir for my bench). Never broken one yet, but I try not to lever.

    Amusingly enough, the gentleman who taught me that technique was also British.

    mark (msweig)

  3. Thanks for the great explanation. It strikes me that your method is classic and the tool god simply knew you would benefit from the shorter chisel...and your audience from the more detailed lesson on mortising it's failure caused. Wise, the old hand tool gods...

  4. Jeff, as far as I know all that nourishing, good stuff on Mr Gorman's site was removed after Good Woodworking magazine changed owners. I presume they aren't so accommodating as the old.

    Anon, the hand tool gods may be wise, I couldn't say, but they certainly do seem to believe in the old adage "those whom the gods wish to destroy, they first make mad"!

  5. Good technique, Alf. I think of it as the Robert Wearing method - no predrilling, all cuts to be made across the grain and the commandment "Thou shall not niibble the sides of thy mortise"!


  6. Wot I'd do is this:
    Cut mortices before any rebates, slots, mouldings etc.
    Always have the chisel vertically - absolutely no levering required, the waste gets compacted and generally flies out under it's own steam.
    Do not hold in cramps - they'd have to be very tight to hold when you are whacking a chisel as hard as you can, and will mark the workpiece.
    Have the workpieces loose over a pair of bench hooks - this enables waste to fall out without it getting trapped underneath and you can pick up and tap (to loosen waste) or turn over to work from the other side.
    Don't bother about waste left in the hole - it'll get pushed out when you try the tenon - or you can make up a loose tenon sized piece from hardwood to clean up the holes, which is a good idea anyway as a trial fit.
    A sash chisel is only for small cross section mortices such as are found on sashes where the glazing bars go. These are also the deepest mortices and may be half inch square but 3" long through a bottom rail. You can use it for larger mortices, but a big OBM will do it better and neater.
    Work on the corner of the bench so that you can move easily to sight down the length or across the width.


  7. Oh and PS - I just spotted that yours are stopped mortices. Proceed as above but get a straight mortice bottom by applying a wide as possible chisel to the sides - then the bottom comes out with a bit of a scrape - still with no serious levering.
    So if it's a 2" long mortice use a 2" bevel edge chisel for the bottom edges
    You could mark the face of the chisel with the depth, if you want to be very neat

  8. PPS sorry to keep psing!
    The other important reason for not holding down your workpiece is that it makes it easier to extract a stuck chisel: you pick up chisel with workpiece and tap the end of the workpiece (ideally on a horn - that's what horns are for amongst other things) with your mallet, to loosen it from the chisel.


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