In a small response to years of subtle but predatory marketing on PBS that has newcomers asking about mortising machines for their early projects, I prepared a short primer this morning in the shop to answer a younger man’s question. The entire session, including stock preparation and photography, took 30 minutes. The actual mortise chopping took 4 minutes, and I wrote this up on my lunch break.
First, you need mortise, not paring chisels. These Japanese ones below I bought from Highland Hardware when they first opened more than 2 decades ago to replace the badly worn family ones.
Note the flat bevels in the photo above; not hollow ground and no secondary bevel. These are laminated blades designed for striking, and they come in the exact width of your intended mortise, ¼, 3/8, and ½ inches.
Also note that the backs are hollow ground to facilitate easy flattening as you hone them during their life. You can see the hollow above the edge.
Their bevels should be touched up on the hone every time you use them; your stones ready for use should be a permanent fixture on a corner of your bench. Honing these is easy; just index the flat bevel on the stone. You also need to hone the back dead flat, and I also hone the sides lightly on the fine stone to remove any burrs. I use a set of 4 Arkansas stones all the way to the finest “black” grade, but you can use what you normally sharpen with. I wiped the oil off the stone and chisel for clarity; don’t hone them dry or the stone’s pores will clog.
I do a final stropping on the stitched muslin wheel with Knifemaker’s Green Rouge. Hard felt wheels are the best for this, but they are expensive.
Then I lay out the mortises on the prepared stock. First, the mortise gage double tines are set to the width of this half-inch chisel. Then the mortise gage fence is set for mortise location on the stock, and lines scratched. Want to have the mortises dead center? Simple, just run the fence down the other face of the stock, compare the marks, and adjust the fence until the marks are identical.
It’s a simple matter next to mark your mortise width with try square and marking knife. I’ll cut a simple blind double mortise and have used a pencil to make the lines clear in the photograph. You need to leave your pencils in the drawer for this and other joinery marking, as they are insufficiently precise.
Index your mortise chisel plumb in the end knife cut, and strike with a wood mallet. Do all four ends.
The next chopping sequence is from the center of the mortise, and the waste merely levered out…splitting rather than cutting the wood along its long grain. My training aid today is a 2 X 2 of sopping wet Douglas Fir from the scrap pile out in the weather…. hard, tough and splintery. Your dry cabinet hardwoods will be easier. When working with highly figured wood such as Birdseye Maple you are afraid to split, then simply strike the outline of your mortise lightly with a paring chisel, first.
I repeat chopping from end and center, levering out the waste until I reach the desired depth; then I reverse the chisel and use it bevel-down to clean up the mortise bottom.
The final result is a little furry because of the wet wood, but entirely satisfactory. There is a small chip-out at the top of the right mortise, but this will be completely hidden by the tenon shoulder when assembled.
Frankly, even working in large, commercial, 3-phase shops, I never found many mortising machines that were entirely satisfactory. The bits are difficult to sharpen so you need two sets of them for production work, and the over arm design likes to flex under pressure, especially when the bit is getting dull, which also tends to pull your work piece out of alignment with the fence.
Why bother? These simple, inexpensive tools and a shop-made mallet are all you need to do mortise and tenon joinery on one-off projects for the whole of your lifetime.
“When we build, let us think that we build forever. Let it not be for present delight nor for present use alone. Let it be such work as our descendants will thank us for; and let us think…that a time is to come when those (heirlooms) will be held sacred because our hands have touched them, and that men will say, as they look upon the labor and wrought substance of them, ‘See! This our father did for us.’ “ –John Ruskin.
Replies
Bob,
Nice job, thanks for taking the time.
At the last WW show in Springfield, MA. I specifically sought out the japanese morticing chisels as I was intending to make a purchase. Unfortuneatly, I passed by the Galoots table which, in addition to everything else, had a bunch of used mortice and longish firmer chisels....yum! I never did make it to the Japanese booth.
It may be just me, but I find I need to move the point of the mortice chisel in a 1/16" from the end line....my sense is the force of the hit and the 30 degree bevel push the chisel back a bit....
Bob
thanks for making the time to post this primer.
KUDOS and hats off to you Bob....
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming....
WOW!!! What a Ride!
Nice effort, but the ends of the mortise are a little mangled beyond your gauged lines. No doubt you would plan a four-shouldered tenon... I always leave an 1/8th on the ends to lever against, cleaning up the ends to the lines after the mortise is chopped. That way you get a nice, crisp end right at the gauged line that hasn't born the brunt of the chisel being used as a lever.
Edited 4/1/2004 8:02 am ET by BossCrunk
This was done to answer a beginner's question and I wanted to keep it real simple. He can figure that out on his own later.
In hardwoods...even Doug Fir....the amount of edge rounded by levering is hidden by the tenon and has no consequence on the strength of the glue bond.“When we build, let us think that we build forever. Let it not be for present delight nor for present use alone. Let it be such work as our descendants will thank us for; and let us think...that a time is to come when those (heirlooms) will be held sacred because our hands have touched them, and that men will say, as they look upon the labor and wrought substance of them, ‘See! This our father did for us.’ “ --John Ruskin.
True, but only if you cut a four-shouldered tenon. The end of a mortise has to be perfect on a two-shouldered tenon because it will show if it's mangled. This is important information for a beginner, especially if they are following a set of off the shelf plans.
I always leave the extra 1/8th at the ends and then pare it with one blow after the mortise has been excavated. The result is a clean end right on the gauged line.
Thanks Bob, As a beginner in learning hand tool techniques I have a question. Do you prefer to chop your mortises first then size your tenons accordingly or do you cut your tenons first then chop your mortises to match? Thanks again for taking the time to help us.
Mortise first when using mortising chisels....the mortise width is set by the size of the chisel.
Then saw the tenon to match. Tenons can be sawed by hand or vertically using a tenon jig in the TS or also horizontally on the TS using the miter gage and a dado blade ( a fast way to do it when making multiples). You'll hear the argument that using the dado blade makes a rough surface not ideal for glue, but I haven't found that to be the case.
You can chop a 16th out off the ends for a neater mortise than mine in the pics, or you can drill out the mortise with Forstener bits and pare the sides, but generally, all that is slower and really unnecessary.
I'm trying to stress how simple and fast the technique is using the correct chisel.
Ebay is full of old Buck Bros chisels in the 10-20 dollar range....gander at my other article on rehabbing chisels and you can put together a nice set for a pittance. Problem is, most antique tool dealers don't know a mortising chisel from a paring chisel...they are listed wrong and you have to look at every single chisel to find what you want.
“When we build, let us think that we build forever. Let it not be for present delight nor for present use alone. Let it be such work as our descendants will thank us for; and let us think...that a time is to come when those (heirlooms) will be held sacred because our hands have touched them, and that men will say, as they look upon the labor and wrought substance of them, ‘See! This our father did for us.’ “ --John Ruskin.
Edited 4/1/2004 8:40 am ET by Bob Smalser
Thanks again Bob, I am going to take a look a your chisel article and also peek at ebay today for some older hand tools, mostly chisels and planes. For those of us who are learning, you have been a great help. By the way, what hand planes would you purchase with if you starting over today?
I have a couple articles on rehabbing Bailey-pattern planes I'll post later.
To start, you need a smoother, a jack and a jointer. Either a 4, 5 and 7 or 4 1/2, 5, and 8. The jack can be used as a scrub plane. Also eventually a shoulder plane that can double as a rabbet plane for a while.
I'd learn what the different Stanley types are and look for Type 11-16 planes as the best values.
http://www.hyperkitten.com/tools/stanley_bench_plane/
Edited 4/1/2004 9:06 am ET by Bob Smalser
If you use a true mortise chisel the walls of the mortise will be smooth if you take reasonable care when levering out the waste - i.e. not using side-to-side motion. The end result will be a mortise of exactly the same width as the chisel. You can then gauge your tenon off the mortise chisel and saw in as detailed in many books.
Boss,
Not that you need to know this, but I agree with you and the bit of distance from the end. I also like to cut in the entire mortice area (remove about a 1/16") with a japanese chisel (kinda like cutting a mortice for a hinge)....it helps keep the point of the mortice chisel away from the top sides and helps square up the chisel...
Yep, I pare back from my gauged lines, much the same way I do on a the gauged line for a dovetail. It's quick and assures that during chopping the material does not tear or chip across the gauged line into a part of the workpiece that will show after the parts are assembled. This is essential with stringy stock. Ash can be particularly bad in my experience.
Thanks for the great tutorial! Your technique is a little different from chopping with bench chisels that I learned at Homestead Heritage. (That technique chops from one end to the other).
I found a few antique mortise chisels in a flea market for $5 apiece, so I'll have a chance to compare methods with different chisel types.
Regards,
Dan
Wow,
Nothing like pictures to show how to do something. Thanks for the very clear and enlightening post. I have some plans for a simple Green and Green side table that I have wanted to do, but the through mortises scared me.
Again, much appreciate the time for this.
Michael
Another great little tutorial, Bob! This is almost exactly how I chop mortises by hand. (Only broke down and got a BT mortiser when I started doing production work; the bed with 34 through-mortises was the triggering project.) I learned this from reading Tage Frid's book and then chopping a bunch o'mortises! It really is fast and easy, everybody ought to do this a few times before thinking they need a mortiser.
Boss Crunk and you are both right - it will make a neater mortise to leave 1/8" at each end until the last, but if the tenon will be shouldered it won't matter so it's not worth the bother. In fact an extra 1/8 or so of room in the mortise can be helpful in assembly, and won't affect strength when the joint is glued or pinned.
What's your technique for doing a through-mortise? I transfer the end marks around with the square and chop from both sides. Leaving the 1/8 or so at each end until the last. Is there a more accurate way to ensure that the ends line up? This is one place where accuracy at the ends is crucial, unless you're wedging the tenon.
"Everything should be made as simple as possible, but no simpler." A. Einstein
http://www.albionworks.net
I should say that the four-shouldered tenon does cover up minor bruising of the mortise ends, however, I wouldn't take that as license for wholesale destruction and sloppiness of the ends. Mechanically, the four shoulders could prevent racking in the event of a glue failure, assuming the fit is nice and snug all around.
It's just not that difficult to keep the ends tidy. Just leave a little to lever against and make the last strokes of the chisel the clean up of the ends and you've got it.
"What's your technique for doing a through-mortise?"
Frankly, my preferred technique is a Forstner bit followed by the new commercial Bosch saber saw. But I've both chopped from both sides of the lines scribed by the mortise gage and also drilled and pared.....with double chopping, it's a tossup.“When we build, let us think that we build forever. Let it not be for present delight nor for present use alone. Let it be such work as our descendants will thank us for; and let us think...that a time is to come when those (heirlooms) will be held sacred because our hands have touched them, and that men will say, as they look upon the labor and wrought substance of them, ‘See! This our father did for us.’ “ --John Ruskin.
Drilling and paring... yecch. I don't think I've ever been happy with a joint I've done that way. Chopping always gives me a better fit.
Never tried a saber saw... doesn't sound very traditional! ;-)"Everything should be made as simple as possible, but no simpler." A. Einstein
http://www.albionworks.net
Great tutorial, wish I had the cash on hand to pickup some mortise chisels and proper sharpening equipment to really utilize it. I've got the same marking gauge as you, have you tuned the points on it any to improve performance? Mine seems to just drag on the wood and not give the clean cut I'd like.
-Ray
I sharpen that old Bridgestone just like any other knife, Ray.“When we build, let us think that we build forever. Let it not be for present delight nor for present use alone. Let it be such work as our descendants will thank us for; and let us think...that a time is to come when those (heirlooms) will be held sacred because our hands have touched them, and that men will say, as they look upon the labor and wrought substance of them, ‘See! This our father did for us.’ “ --John Ruskin.
For us folks who have never cut a mortice and tenon or a dovetail joint ect. how tight should the fit be before glue is added[how much is too tight or too loose]?
I make shelves and buy pegs for them and most of the pegs have to be hammered in with a mallot
Do M &T joints have to fit this tight?
BT
When I cut my joints they end up going together with modest hand pressure. After the glue is one then I may have to tap it in with a hammer.Scott C. Frankland
Scott's WOODWORKING Website"He who has the most tools may not win the race of life but he will sure make his wife look like a good catch when she goes to move on."
Depends on the glue, in some cases....some glues require higher clamping pressures and closer tolerances than other. Recorcinol=High and Tight...Epoxy=Loose and Light at the extreme ends of the spectrum.
For general work with PVA, resin, hide or poly, the fit should be sufficiently snug that the joint goes together by a firm hand or with light tapping and not fall apart when turned upside down.“When we build, let us think that we build forever. Let it not be for present delight nor for present use alone. Let it be such work as our descendants will thank us for; and let us think...that a time is to come when those (heirlooms) will be held sacred because our hands have touched them, and that men will say, as they look upon the labor and wrought substance of them, ‘See! This our father did for us.’ “ --John Ruskin.
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