Mortise Chisels verses standard

[Joe Cowan]

I just finished chopping out some through mortises on a table project. The legs were 2 7/8" thick. After using a router and jig to make the 7/8" X 2" mortise, I squared it up with regular chisels. Being new at this, I found it hard to hold the chisel square to the cut and it wanted to twist as I went down the cut. I do not own any mortise chisels but it had me wondering if that would work better? BTW, I did not have a 7/8" chisel, so had to do this with a 1/2" chisel. Any better way to square these up?

[David Weaver]

I would rather drill and pare a mortise that wide. There's just not a lot that's inviting about hogging out wood on mortises almost an inch wide where neatness on both sides of the joint counts.

[Richard Shaefer]

for a mortise that size, you either need to take smaller bites with a bevel edge bench chisel or look into a 'pigsticker' style mortise chisel, which you can get new or used on fleabay fairly readily.

[Jim Koepke]

The round cut left by the router may be what was causing the chisel to turn to the path of least resistance when it was time to clean up the cut.

There are so many ways to do this, there is a touch of trepidation in answering due to the likelihood of those posting after this telling me how wrong my methods may be.

So be warned. Then find what works best for you in your shop and don't mind all the profits of "one and only one way."

Once when using my router to cut a mortise, the tenons were rounded to fit the mortise as opposed to squaring up the mortise.

My preference now is to cut the mortise entirely with a chisel.

If you are using a router, it might be easy to cut a shallow mortise at the ends before proceeding with the router.

People drill out mortises and clean them with chisels so what you are doing is just a variation of this.

Of course there will be those who insist you need a corner chisel.

It is possible to cut mortises with a regular chisel. The main thing to remember is a bench chisel isn't designed to be whacked as hard as a mortise chisel.

One more thing to consider, the work goes easier when the tool fits the job or the job fits the tool.

jtk

[Chris Griggs]

I think he is talking about cleaning up the rounded ends guys. He cut the mortises with with a router. Honestly unless you regularly cutting tenons that size I wouldn't bother with a 7/8 mortise chisel, and I don't think a mortise chisel that is narrower than the mortise will stay any squarer since the sides of the mortise won't guide it anyway. A wider chisel may help. Do you have 3/4" chisel? I don't have a 7/8 bench chisel, so I would just use a 3/4".

Also, don't try to whack it all out in one bite. Pare down to your final mark with, well not light cuts, medium cuts I guess, and it will be a lot easier to control.

[Joe Cowan]

I think he is talking about cleaning up the rounded ends guys. He cut the mortises with with a router. Honestly unless you regularly cutting tenons that size I wouldn't bother with a 7/8 mortise chisel, and I don't think a mortise chisel that is narrower than the mortise will stay any squarer since the sides of the mortise won't guide it anyway. A wider chisel may help. Do you have 3/4" chisel? I don't have a 7/8 bench chisel, so I would just use a 3/4".

Also, don't try to whack it all out in one bite. Pare down to your final mark with, well not light cuts, medium cuts I guess, and it will be a lot easier to control.

Yes, I was speaking of squaring up the rounded corners left by the router. I had make a jig to clamp on the leg and cut one side, then flipped the leg over and cut the opposite face. Both lined up perfect. I just need to do a good job squaring up. The inside looks a little choppy, but I have one side that is perfect and that will be the exposed side, with the other side being hidden by the cheeks of the stretcher.

[bridger berdel]

a corner chisel *would* be a good way to square up those corners. rounding the tennons would probably be quicker, though.

[Jim Koepke]

I think he is talking about cleaning up the rounded ends guys.

This was my understanding.

It was also my feeling that this is not the last time Joe will make a mortise and tenon joint.

jtk

[Joe Cowan]

My big concern if the exit side and making sure it is true, as the tenons will be exposed and proud on this side.

[Chris Griggs]

My big concern if the exit side and making sure it is true, as the tenons will be exposed and proud on this side.

Mark both sides from the same reference face using the same marking gauge, so that you can cut into the mortise from both sides.

[Jason Coen]

Mark both sides from the same reference face using the same marking gauge, so that you can cut into the mortise from both sides.

Yep, scribed lines are your friend in this scenario.

[Jack Curtis]

One could argue that larger than 3/4" is not a mortise chisel, more of a timber framing/tataki chisel. I think this situation calls for a round loose tenon (dowel) and matching holes in leg and top. Another solution could be a multipart mortise, say two 1/2" vs one 7/8"

[Rodney Walker]

Through mortise and tenon joints where neatness counts because they're not hidden by the shoulder on the backside?
Are you building in the Arts&Crafts style and are you far enough along to take some pictures?

Scribe or mark your lines on both sides and use medium to light cuts as others have already said. A 3/4" chisel would also make it easier to keep your lines straight. Basically use the widest chisel that fits the space, at least to mark your cuts. It's easier to keep longer lines straight than it is to keep a series of short ones straight.

Don't worry too much about the scribed lines showing a bit when done or if the ends of the mortise aren't perfect. I have an LJ&G Stickley rocking chair (two of Gustav Stickley's brothers) where the scribed lines for the mortises are clearly visible. In this age of perfectly machined joints a little evidence of handwork happening isn't such a bad thing in my opinion.
Rodney

[Prashun Patel]

I make my mortises like you have. A mortise chisel works best for me because the sides are square. However, the real key is marking the square lines of the mortise with a knife and then paring down a little depth at a time. I chop down a little across the grain then pare down to that point with the grain then repeat.

[bridger berdel]

My big concern if the exit side and making sure it is true, as the tenons will be exposed and proud on this side.




in that case I wouldn't round the tenons, which would look, in my opinion, cheezy.

[Jim Neeley]

Another option for all-hand operation would be to use a 5/16" mortise chisel to cut two parallel mortises 2" long with the outside edges 7/8" apart and then chopping out the 1/4" of waste in between. If you felt brave, you could use a 3/8" chisel and have but 1/8" of waste to hog.

[Joe Cowan]

Through mortise and tenon joints where neatness counts because they're not hidden by the shoulder on the backside?
Are you building in the Arts&Crafts style and are you far enough along to take some pictures?

Scribe or mark your lines on both sides and use medium to light cuts as others have already said. A 3/4" chisel would also make it easier to keep your lines straight. Basically use the widest chisel that fits the space, at least to mark your cuts. It's easier to keep longer lines straight than it is to keep a series of short ones straight.

Don't worry too much about the scribed lines showing a bit when done or if the ends of the mortise aren't perfect. I have an LJ&G Stickley rocking chair (two of Gustav Stickley's brothers) where the scribed lines for the mortises are clearly visible. In this age of perfectly machined joints a little evidence of handwork happening isn't such a bad thing in my opinion.
Rodney

I am building the Hayrake Table that was featured in Fine Woodworking about 1 year ago. I do have a Domino and am planning on using that for the non-thru tenons, but will remain true to the other mortise and tenon connections.

[Adam Cruea]

I used a half-inch pigsticker to do 1" wide mortises on my workbench made of hickory.

You're probably going to have a twisting chisel unless you start small. I would take about 1/2" out on the first pass with a pig sticker just to get everything all squared, then just go to town and start hogging. Who necessarily cares what the inside looks like (unless it doesn't come anywhere close to the tenon)? I also did drawn tenons though, so I wasn't overly concerned about maximum contact area in the mortise.

[Matt Radtke]

I would do this two ways.

I would chop the mortise full-sized, but only 1/8" deep everywhere. Clean edges. Then hog with the router.

or

I'd hog with the router but stop 1/4" from the ends of the mortise. This would give you enough wood to hold the chisel and cut it square.

[Derek Cohen]

If the issue is to square the ends of a 7/8" mortice, I would score the lines deeply, undercut from the inside, and pare away to the line - ala a dovetail. I'd rather use a narrower chisel than one that feels too wide and requires too much down force. In any event, precision here is unnecessary - it wll be hidden by the tenon.

Regards from Mont Tremblant

Derek

[Joe Cowan]

Thanks for all the help. One thing that I thought would be good, but nobody mentioned, would be the use of a mortising machine to square the corners or do most of the work. I guess this is the hand tool forum so that figures. I do not own one, but if I had one, I think I would have drilled the corners first, then put the router to work.....

[Charlie Stanford]

I just finished chopping out some through mortises on a table project. The legs were 2 7/8" thick. After using a router and jig to make the 7/8" X 2" mortise, I squared it up with regular chisels. Being new at this, I found it hard to hold the chisel square to the cut and it wanted to twist as I went down the cut. I do not own any mortise chisels but it had me wondering if that would work better? BTW, I did not have a 7/8" chisel, so had to do this with a 1/2" chisel. Any better way to square these up?

This is where a plain, square edged (not beveled) firmer chisel excels. Search FleaBay for "Marples Firmer Chisel" to see examples.

[george wilson]

It is largely a matter of developing skill. But,try to have a full width chisel and don't take off so much at a time that you cannot keep the chisel square. I've cut plenty of mortises with regular chisels. You have to have skill to not break them!!