Something new in my woodworking--I broke a chisel

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Forum topic by CharlesA posted 09-03-2015 01:55 AM 2172 views 0 times favorited 44 replies Add to Favorites Watch
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3322 posts in 1798 days

09-03-2015 01:55 AM

I’ve had a set of Irwin Marples Chisels for about 3 or 4 years. I was chopping some mortises in QSWO tonight, and all of a sudden, the blade was in two pieces, the break an almost perfect perpendicular. Any thoughts?

-- "Man is the only animal which devours his own, for I can apply no milder term to the general prey of the rich on the poor." ~Thomas Jefferson

44 replies so far

View BurlyBob's profile


5494 posts in 2266 days

#1 posted 09-03-2015 02:00 AM

Gotta be some kind of defect in the metal. Was it one of the new and improved chisels from China? Either way that really bites.

View TheFridge's profile


9482 posts in 1486 days

#2 posted 09-03-2015 02:18 AM

Sharpen it up and put it back to work.

-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

View Clarkie's profile


453 posts in 1841 days

#3 posted 09-03-2015 02:30 AM

Start using a mortise chisel. rut ro

View TheWoodenOyster's profile


1317 posts in 1935 days

#4 posted 09-03-2015 03:24 AM

My only thought is that is weird.

-- The Wood Is Your Oyster

View nailbanger2's profile


1041 posts in 3143 days

#5 posted 09-03-2015 04:37 AM

My thoughts are you were hitting that poor chisel too hard, Charles. I’m going to have to make some tips out of Charmin for mine, as I have the same kind.

-- Wish I were Norm's Nephew

View mahdee's profile


3883 posts in 1768 days

#6 posted 09-03-2015 11:03 AM

The mighty oak can do that.


View Redoak49's profile


3250 posts in 1989 days

#7 posted 09-03-2015 11:34 AM

I can guess at the cause if you give a good close up picture of the fracture surface. Also, were there any small nicks on the sides?

When trying to figure out why or how something fractured, a good picture of the fracture face is most important.

View bearkatwood's profile


1572 posts in 1012 days

#8 posted 09-03-2015 11:41 AM

You are becoming stronger grasshopper.

-- Brian Noel

View BubbaIBA's profile


387 posts in 2377 days

#9 posted 09-03-2015 12:24 PM

From the photos and where the break occurred I’m making an assumption that you were “levering” against the back not the bevel edge. I also expect there was a fault in the chisel but without a image of the fracture that is an assumption. Even with a robust mortise chisel like an English pig sticker the levering should use the bevel as the lever point. Using the back will put the stress point higher up the chisel resulting in a longer arm and greater stress at the lever point.

While bevel edge bench chisels can be used for mortices (I will on occasion) a better option is to use a mortice or sash mortice chisel. They have evolved over time for just that job. With a bench chisel you need to take smaller cuts than with a mortise chisel with more room to lever the waste


View CharlesA's profile


3322 posts in 1798 days

#10 posted 09-03-2015 12:31 PM

I was looking back on why I had decided I didn’t really need mortise chisels for my occasional mortise work and came upon an article by no less than Paul Sellers that suggested exactly that. I was cutting one far deeper than usual and started to really yank on that chisel. I finished up with an Aldi chisel I bought as a backup. I immediately noticed that the Aldo blade was thinner and bendier, so to speak.

I already figured it was mostly my fault, but I am surprised that it broke so cleanly.

-- "Man is the only animal which devours his own, for I can apply no milder term to the general prey of the rich on the poor." ~Thomas Jefferson

View boisdearc's profile


44 posts in 1336 days

#11 posted 09-03-2015 02:03 PM

I am sure Marples will warranty that…

View TheGreatJon's profile


337 posts in 1234 days

#12 posted 09-03-2015 02:08 PM

“Control, control, you must learn control!”

-- This is not the signature line you are looking for.

View HokieKen's profile


5017 posts in 1139 days

#13 posted 09-03-2015 02:21 PM

Look for beech marks on the fracture face. They’ll look kinda like growth rings in a tree. If they’re there, then there was a weak point in the steel that propogated out over time until the break occurred. If there are no beech marks, it was probably a brittle fracture that occurred suddenly. Either way, I’d think the manufacturer would cover it under warranty. But, if it was a fatigue fracture and has evident beech marks, it was a material flaw and they should most definitely replace it.

-- Kenny, SW VA, Go Hokies!!!

View Sylvain's profile


706 posts in 2499 days

#14 posted 09-03-2015 03:09 PM

It seems you first drilled a hole before using the chisel, something which is not part of the Paul Sellers method.
I have used the PS method to chop mortises 8 cm deep X 10 mm wide X 6 cm long (in fact 4cm because it was through and I flipped the board) with a no-name beveled chisel, bought a few Euro on a flea market, without any problem.
If you look carefully to the video where he does two mortises behind a glass, one with a mortise chisel and the other with a beveled chisel, you will see that the bevel of the chisel acts as a wedge, producing a shear force which split the wood along the mortise wall. Practically no leverage action is needed; except to clean the waste.
One has also to listen to the sound, the sound changes at the last tap before the next move, don’t make an extra whack.

-- Sylvain, Brussels, Belgium, Europe - The more I learn, the more there is to learn

View JohnChung's profile


408 posts in 2074 days

#15 posted 09-03-2015 03:41 PM

I would say that the chisel was faulty. If the chisel failed, there would at least be a bend on it first.

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