Mortising, To pry or not to pry?

[Lasse Hilbrandt]

That is the question

Im a rookie and usually overthink things. When I the other day chopped my first mortise I notised that there was quite a wear bevel on the back of the mortise chisel. It made it hard to flatten while I sharpened it. I think the wear comes from the prying action and I decided not to pry, and instead remove the waste with another chisel once and a while. It works, but I find it a bit slow.
whats your experience ?

[chris carter]

Here’s what I do to protect the edge of my mortise chisel:
- My primary bevel is 25 degrees, but I rounded the tip over gradually so the tip is probably 30 – 35 degrees (I never bothered to measure). I just kept rounding it until it was durable enough for my taste. A straight up secondary bevel would work as well I imagine.
- I don’t try to space my chops too far apart. In really soft wood, I’ll take chops spaced further apart. The harder the wood, the tighter I space them. Same goes for depth of chop. If I’m prying hard, then I tried to take too much wood.
- Instead of prying by pulling straight back towards me, I will give it a gentle pry pushing forward first (toward the back of the chisel), then I’ll pry back like normal (opposite direction when you turn around going the other way). This dramatically reduces the amount of force needed to prey the waste out.
- I keep the mortise chisel really sharp. I keep my strop on my bench and I’ll give a few strops BEFORE I think it’s needed. For some big mortises in hard wood I might strop several times during the same mortise (it’s only 20 seconds wasted so no biggie). The duller your edge, the more prone it is to damage.

Eventually you learn through trial and error how aggressive you can be chopping and prying waste. But it takes a little bit of guess, check, and refine at first.

[Lasse Hilbrandt]

Here’s what I do to protect the edge of my mortise chisel:
- My primary bevel is 25 degrees, but I rounded the tip over gradually so the tip is probably 30 – 35 degrees (I never bothered to measure). I just kept rounding it until it was durable enough for my taste. A straight up secondary bevel would work as well I imagine.
- I don’t try to space my chops too far apart. In really soft wood, I’ll take chops spaced further apart. The harder the wood, the tighter I space them. Same goes for depth of chop. If I’m prying hard, then I tried to take too much wood.
- Instead of prying by pulling straight back towards me, I will give it a gentle pry pushing forward first (toward the back of the chisel), then I’ll pry back like normal (opposite direction when you turn around going the other way). This dramatically reduces the amount of force needed to prey the waste out.
- I keep the mortise chisel really sharp. I keep my strop on my bench and I’ll give a few strops BEFORE I think it’s needed. For some big mortises in hard wood I might strop several times during the same mortise (it’s only 20 seconds wasted so no biggie). The duller your edge, the more prone it is to damage.

Eventually you learn through trial and error how aggressive you can be chopping and prying waste. But it takes a little bit of guess, check, and refine at first.

Does this mean that you chop with the bevel towards the waste side ? Then I guess prying is of no concern to the back.
Im chopping with the back towards my self and the waste side, so if I pry its the back that is getting the wear.

[steven c newman]

Single 25 degree bevel on mine. Usually one whack, wiggle a bit, move a bit, repeat. Gets to be too many chips? I have a special shaped tool ( old brake drum adjuster, reshaped into a chisel) that has a curved end to it, and let it pop the chips out. It will also clean the bottoms of the mortises out.

One could use a Lock Mortise chisel for chip removal.....

[Prashun Patel]

I was taught not to pry - even though it's hard to resist the urge.

I will flip the bevel and chop the waste pieces. That usually breaks them up enough to blow, pick, or (best) vacuum out.

If the mortise is long enough, I will try to plane the bottom with the chisel bevel down or a router plane.

But I try not to pry, only to scoop loose chips.

[Robert Engel]

I don't think that's wear pressure, I think you're bending the chisel. How much pressure are you exerting?

I haven't chopped 10,000 mortises but I've done my share & a pry a little but, but I've never seen anything phenomenon like this.

What brand of chisel is this?

[Lasse Hilbrandt]

I don't think that's wear pressure, I think you're bending the chisel. How much pressure are you exerting?

I haven't chopped 10,000 mortises but I've done my share & a pry a little but, but I've never seen anything phenomenon like this.

What brand of chisel is this?

Its a vintage Berg 3/4" and I dont think its bend.

[James Pallas]

I don’t pry. I chop with the bevel facing the waste. I think this may be the arguable point, ride the bevel or not. I chop straight down and listen for that telltale solid hit and then move back for the next chop. The chips are loose then and will scoop out. If I want to speed up the process and not concerned about straight sides as much or have many to do it may be worth the effort to set up the drill press or a hollow chisel Mortiser if you have one. I also have a swan neck chisel for deep mortise scooping out.

[ken hatch]

First you must have some place for the waste wood to go, then tap, tap riding the bevel, lever the broken chips into the open area, repeat until everything that does not look like a mortise hole is gone. With mortises it is back to the go light and slow to go fast. Going Conan on the chisel just slows things down and quickly ruins the cutting edge.

ken

[Thomas McCurnin]

I’m no expert but .....

I just finished a week long school on chiseling in Waco, and we used the Paul Sellers method—make a knife wall, lead with the bevel, chisel at 60 degrees away from you, take 16th of an inch cuts and pry out the waste, building a 60 degree ramp inside the mortise. Finish the mortise with a smaller size to twist out stubborn chips then final finish on the walls and bottom with original chisel. No aggressive pounding or prying necessary if one builds that ramp and takes 16ths of bites. No sharpening, just a very quick honing every morning.

It took us about two days of chopping mortises 8 hours a day on test pieces before the body mechanics set in and the whole class started really whipping out accurate mortises out in no time.

When I got back, I watched a Paul Sellers video on mortising, and his way was the way we learned how to do it—to a “T.” Our instructors even used a piece of plate glass for one side of the mortise to demonstrate the angle and ramp—Mr. Sellers’ video uses the same glass teaching method.

I was stunned how fast and accurate one could chop out a mortise once that technique is mastered with very little wear on the chisel edge.