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Chopping Mortises Mangles Chisel?

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Forum topic by DrPuk2U posted 08-27-2012 03:12 PM 1574 views 0 times favorited 22 replies Add to Favorites Watch
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DrPuk2U

49 posts in 1047 days


08-27-2012 03:12 PM

Topic tags/keywords: chisel mortises mangled

I am working on a big Holtzapffel style workbench made of Southern Yellow Pine. I finally at the point of chopping out the big mortises for the legs (2.5×5”). I drilled them out with a Forster bits, the chopped out the waste with a 1” chisel. The result was a reasonable mortise, but my chisel ended up mangled. It was very sharp to start with (I have Work-Sharp system). Check out these photos after chopping one mortise:

Admittedly, I was chopping with a mallet through end grain but it was SYP, not hard maple. Is this to be expected? Or does this suggest I should pay more than $10 for a chisel? :-) They are “Buck” chisels from Home Despot.

-- Ric, N. Illinois "Design thrice, measure twice, cut once... slap forehead, start over"


22 replies so far

View Bertha's profile

Bertha

12951 posts in 1448 days


#1 posted 08-27-2012 03:15 PM

I’m sad to say, but it’s the chisel quality. Good mortise chisels are expensive but they excel for chopping. Start saving, brother;)

-- My dad and I built a 65 chev pick up.I killed trannys in that thing for some reason-Hog

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Brandon

4145 posts in 1706 days


#2 posted 08-27-2012 03:17 PM

I’d get new chisels! I’ve never had that problem, especially in SYP. For pretty cheap, you can get the Narex mortise chisels that work very well for this operation. I used a pair of 1/4” and 1/2” for my mortises in beech, which is much harder than SYP.

-- "hold fast to that which is good"

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carguy460

784 posts in 1090 days


#3 posted 08-27-2012 03:18 PM

Wow…after one mortice?? I’ve got a set of cheap chisels and am getting ready to start on a bench build…I wonder if this will happen to me too??

-- Jason K

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rwyoung

369 posts in 2226 days


#4 posted 08-27-2012 03:20 PM

Regrind the bevel at a steeper angle, try 35 to 37 degrees. Leave the primary bevel at around 25 degrees.

Hollow grinding the primary on a bench grinder will be MUCH faster than trying to use the WS3000 to reform the primary. Pay attention to the metal temperature and quench often. Should take less about 5 minutes or so to reform.

Bench chisels aren’t the best choice for chopping mortises. Pairing to clean a side wall, OK but not so much with the wailing and hammering. Narex branded mortise chisels are good, new chisels at reasonable prices. If you expect to make a lot of M&T joinery by hand in the future and expect to be working in smaller dimentions, say 3/8”, 5/16”, 1/4” mortises, and want new, invest in the LN brand mortise chisels. For a one-off, big-honkin’ mortise job like your bench, the Narex are fine. Go with a 35 or slightly higher secondary bevel on the mortise chisels too.

And if you go for vintage, look for the “pig sticker” type and not sash mortise chisels. Socket or tang (pig stickers are tang) construction is fine.

-- Don't sweat the petty things and don't pet the sweaty things.

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Bertha

12951 posts in 1448 days


#5 posted 08-27-2012 03:35 PM

Pigstickers, baby. Check out the Iles chisels too. Vintage pigstickers have gotten ridiculous ($) lately. I collect W. Butchers and consider them clearly my favorite. The steeper bevel angle is very good advice.

-- My dad and I built a 65 chev pick up.I killed trannys in that thing for some reason-Hog

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Jorge G.

1526 posts in 1230 days


#6 posted 08-27-2012 03:50 PM

but it’s the chisel quality.

I agree with Al about the quality of the steel, but disagree on grinding to a 35º or more. I have Ray Iles mortise chisels and they come ground at 35º with a 20º base grind. It takes forever to chop a mortise this way. The primary bevel compresses the wood too much and you can only reach about the depth of the primary bevel. We are talking about 1/4” or so…. I re ground my chisels to 25º and they are a joy to use, you can make an 1 1/2” mortise in a few minutes. Of course the quality of the steel on the RI chisels is great, so that helps.

-- To surrender a dream leaves life as it is — and not as it could be.

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Ripthorn

800 posts in 1739 days


#7 posted 08-27-2012 03:54 PM

I had this same problem chopping the mortises for my bench in doug fir. What I did was buy the 7 piece wood handled chisel set from Harbor Freight. I flattened them really well and sharpened them up using the method that (some popular UK woodworker who’s name I don’t remember right now) showed in a youtube video. It is free hand sharpening where you lift the handle up more as you end the sharpening stroke. This creates almost a domed surface instead of a flat bevel. This creates a higher angle at the tip while reducing the amount of material you actually have to take off. This worked phenomenally for a few reasons: 1) the softer steel did not chip, 2) they sharpened quickly, 3) I could bash on them all I wanted without worrying about hurting anything, 4) the set comes with a 1 1/2” chisel which is great for those big mortises. Now, I’m not saying you have to do it this way, but it worked very well for me, and let me save my nicer chisels for more delicate work.

-- Brian T. - Exact science is not an exact science

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DrPuk2U

49 posts in 1047 days


#8 posted 08-27-2012 03:55 PM

Thanks folks. Good info. My biggest problem is that I am impatient, Nobody around here (northern Illinois) carries mortise chisels so I’ll have to order them online then wait. So I’ll probably do that and, in the meantime, re-grind the mangled chisel (at 35 degrees) and try to get the other mortises done.

-- Ric, N. Illinois "Design thrice, measure twice, cut once... slap forehead, start over"

View Loren's profile

Loren

7832 posts in 2402 days


#9 posted 08-27-2012 05:00 PM

Sometimes there is some better steel 1/8” or so back from the
edge of a new chisel.

-- http://lawoodworking.com

View Bertha's profile

Bertha

12951 posts in 1448 days


#10 posted 08-27-2012 05:05 PM

^is that right, Loren? I would have never thought about that. Maybe JGM’s right about the bevel angle. I have the Iles too. I liked them pretty well out of the box, but I like them better at 28 degrees. I prefer my Butcher pigstickers at the same angle.

-- My dad and I built a 65 chev pick up.I killed trannys in that thing for some reason-Hog

View Brett's profile

Brett

636 posts in 1437 days


#11 posted 08-27-2012 05:20 PM

I used my 1” Stanley FatMax chisel last weekend to do the exact same thing (chopping mortises, except on a SYP Roubo bench). The steel strike plate stood up just fine to my 20-oz framing hammer, and the chisel showed no damage—on either end. Resharpened nicely, too. I think I bought it at Lowes for $10 or $12.

-- More tools, fewer machines.

View Mosquito's profile

Mosquito

5195 posts in 1047 days


#12 posted 08-27-2012 05:23 PM

I used a new Stanley Bailey chisel to chop mortises in oak, and didn’t have this issue. And (sad to admit) I didn’t even sharpen it before I used it… Yeah…

Mortise chisels are on my want list though…

-- Mos - Twin Cities, MN -- Stanley #45 Evangelist - www.youtube.com/MosquitoMods

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chrisstef

11489 posts in 1761 days


#13 posted 08-27-2012 05:23 PM

Hmm. It looks like its just the corners of the chisel effected. Ill assume that youre getting into the rounded corners and the only portion of the chisel doing any work is the very edge. Maybe try squaring up the corners of the mortise with a 1/4” chisel then paring away with the larger 1”.

-- "there aren’t many hand tools as awe-inspiring as the #8 jointer. I mean, it just reeks of cast iron heft and hubris" - Smitty

View Loren's profile

Loren

7832 posts in 2402 days


#14 posted 08-27-2012 05:27 PM

@Bertha, I’ve just read that, perhaps in reference to
Japan chisels but I think also there’s this idea that this
occurs with English chisels like Sorbys too.

-- http://lawoodworking.com

View Bertha's profile

Bertha

12951 posts in 1448 days


#15 posted 08-27-2012 05:55 PM

^learn something every day:)

-- My dad and I built a 65 chev pick up.I killed trannys in that thing for some reason-Hog

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