Folding chisel edge?
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14 June 2018 at 1:50 pm #548539
I’ve stated work on a new workbench. I’ve sharpened my chisel, started the mortise in one of the legs but before the end of my first pass my chisel was dull. It looked and felt like a burr on the edge, almost like the edge folded over. This happened to my Aldi chisel as well as my Ashley Iles chisel (which I bought because I thought the problem was the Aldi chisel quality). Sometimes it can be fixed with the strop alone, mostly with the fine stone (1200 diamond) and the strop.
I’m sharpening as per Pauls example, at about 25-30 degrees, don’t hit it harder than Paul does (I don’t think), and am working on simple 3 x 3 pine. I got really annoyed when I found that “Paul cut all the mortises without re-sharpening his chisel.” (from the wrokbechn FAQ).
Any idea what could cause this? What could I be doing wrong?
Mic
14 June 2018 at 2:07 pm #548540are you sure about the angle? you can go further and see if it helps while mortising.
14 June 2018 at 2:40 pm #548544Sometimes the surface layer of new chisels is not tempered optimally as part of production methods. Sometimes the edge is a bit brittle and chips, other times it seems a bit soft and the edge forms a burr or buckles. Try sharpening again on both the flat and bevel sides to get to fresh steel. For edges that buckle, try a secondary bevel at a slightly steeper angle or using Paul’s convex bevel sharpening method. Either will work.
That often solves the problem with new chisels.https://paulsellers.com/2012/04/questions-answered-chisels-and-quality/
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You must be logged in to view attached files.14 June 2018 at 2:50 pm #548546Is it possible that the cutting edge is actually fracturing? I would be surprised if the edge is rolled. That hard steel wants to break, not bend. I have some of my chisels sharpened at 25 degrees just for soft wood dovetail work and such but I remember once going a little too deep in a mortise and levering and the very end of the edge broke. That’s when I stopped using 25 degree chisels to chop mortises. It’s easy to chop pretty deep in pine, but then when you go to lever, a deep chop puts a lot of stress on the tip of the chisel because those bottom fibers aren’t severed yet. I would do three things. First, be sure that you’re not shallower than 25 degrees – more toward the thirty degree mark for chopping mortises. Secondly, don’t advance more than 1/8″ (3mm) on each successive chop, and finally, as soon as you hear that “dit” sound Paul talks about so often, stop! As you lever, it really shouldn’t take much pull on the chisel and if it does, you’re most likely in too deep so pull the chisel out and go again. Hope that helps.
14 June 2018 at 2:54 pm #548547Are you sure you are sharpening the tool enough.? You should have a burr on the back to start on the rough stone then by the time you are on the fine stone the burr should fall off. You have taken the bevel all the way to the flat.
I find tiny parts of steel on my fine stone from the bevel.
If you look at the bevel’s edge when you are done you should not see any edge if you see any hint of a strip of light the edge is not sharp yet.
When you say the strop helps that kinda sounds like you havent quite got the burr off15 June 2018 at 3:01 am #548553I’ve had the same issue, I bought a set of very expensive Lie Nielsen chisels thinking it was a chisel quality issue and still had the same problem. It was only after I ground down to the “good steel” when the problem disappeared. What I found was on the Lie Nielsen website where sometimes the metal does not get hardened to the tip. In the same article from Lie Nielsen they mention the difficulty of making sure the steel is uniform throughout the manufacturing process. They don’t make a paring chisel because of the difficulties of producing a long chisel. ( especially a narrow chisel) that is uniform in hardness. That’s why I went to Narex for my paring chisels. The price is very reasonable, they know what they are doing! The handles need tuning (for me) but that’s easy to do.
15 June 2018 at 1:41 pm #548555All,
Thanks for your thoughts.
I’ve been following Paul for a while and I recognise what yous say. I sharpen them freehand, creating a slight convex bevel and a flattened face, both buffed on the strop/wood. I don’t get them as sharp as Paul does yet (slicing into the edge of paper when presented at 1 degree) though sometimes by accident I do – I’m guessing I need to refine by buffing skills. They slice paper readily, just not as readily as Pauls example (in one of his Q&A videos he shows this).
What I’ll do is try the steeper bevel as suggested by Larry above. I didn’t think it would help as I’m only chopping a bit of pine, I could be wrong here.
Will let you know how I fare.
Mic
Mic,
Sorry for being a bit late on this topic but I think that the manufacturers are perhaps machining too close to net shape before hardening and not grinding sufficient off afterwards to get through any potentially decarburised layer on the surface of the steel from the hardenening process. Remember that these chisels are done as batches, not hardened individually. Not all in a batch will come out the same. I hope that you have overcome the issue by now Mic! But the steeper bevel will strengthen the edge for morticing.Cheers
Mark -
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