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Mortise & Tenon vs Half Lap?

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Forum topic by Padriac Riley posted 12-31-2014 06:07 PM 4354 views 1 time favorited 24 replies Add to Favorites Watch
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Padriac Riley

36 posts in 733 days


12-31-2014 06:07 PM

Topic tags/keywords: question mortise tenon half lap

Possibly a stupid and dangerous question but…

Is there any practical benefit to using a mortise and tenon joint over a half lap joint in something like a dresser frame? I mean purely as regards strength with no consideration to personal preference of looks or falling in line with a particular style.

I am building a set of furniture soon (new niece on the way) and I am trying to decide which to use. All of the info I’ve found online seems to fall into one of three categories: 1) A pointless back and forth flame war with religious intensity but little information 2) Directions on how to make one joint or the other. or 3) Discussion of how ugly the end grain a half lap leaves you with is.

I have made mortise and tenon joints before and have no problem making them now but I have trouble seeing how they could be any stronger than a pinned half lap. (I know screws or dowel pins are not necessary with modern glues but doweled joints or doweled over screws have a certain look to them I like.) I also generally like the half lap joint in most applications for a number reasons (strength and stability among them) but I am realizing that I do use it often so I want to sort of do a double take.

The materials I’m going to be using 1 1/4” thick White Oak for the frame and most likely 3/4” thick glued up White Oak panels for the sides, back and top as it leaves more ability for potential damage fixing (going in a kids room remember) of the surface than the thinly veneered plywood available to me where I live. I was briefly tempted to use Baltic Birch or Oak ply for the side and back panels but even on the expensive versions of the plywood available here the “pretty” veneer on it is barely paper thin.


24 replies so far

View Mosquito's profile

Mosquito

8074 posts in 1753 days


#1 posted 12-31-2014 06:16 PM

One advantage to M&T over half-lap is if you’re doing any sort of frame and panel construction, the M&T works better (opinion) as you can chop the mortise in the groove. Another being that the only clamping pressure required for M&T is to pull the joint together (if you draw-bore, then even that isn’t required). Half-lap is likely easier to make, depending on accessible tools, so would be faster.

Otherwise, it kind of sounds like you’ve got your preference. If it fits your aesthetic preference, I’d say go for half-lap.

-- Mos - Twin Cities, MN - http://www.youtube.com/MosquitoMods - http://www.TheModsquito.com

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Padriac Riley

36 posts in 733 days


#2 posted 12-31-2014 06:37 PM

I have a preference for sure but I am realizing that most carpentry preferences are largely a result of whoever taught us and what tools we happen to have to hand. I trying to expand my carpentry into areas I have not had the opportunity to build in before and I would like to look at some things again. Not that everything needs changing for the sake of changing but if the “go to” joint I was taught is not as strong as it could be; that is something I’d like to change.

View Fred Hargis's profile

Fred Hargis

3928 posts in 1954 days


#3 posted 12-31-2014 06:44 PM

A lot of the arguments over which is stronger are fairly silly, IMHO. Most of these joints are strong enough for the furniture we build, whether one is stronger than the other becomes an academic question. So my reply to your question is: use what you want, they are both plenty strong for the purpose.

-- Our village hasn't lost it's idiot, he was elected to congress.

View Richard H's profile

Richard H

489 posts in 1141 days


#4 posted 12-31-2014 06:49 PM

Since a face frame is attached to the carcass of the dresser either joint would seem to me to be plenty strong enough. Pocket screws are another great options for that joint that is ever faster if it’s your thing.

Now for doors I really prefer M&T joints although I recently used bridle joints as something different which turned out really good although I don’t think it was any less work. I did use half laps for a fence gate and shed door I built years ago and both of them have stood up really well so I know that joint will work for even large heavy doors as well, so in the end I think it’s personal preference and tools you have on hand.

View isotope's profile

isotope

146 posts in 1085 days


#5 posted 12-31-2014 06:53 PM

I don’t have any data, but I would guess that an M&T joint is stronger. If you consider both joints, dry fit only, before any glue or screws, the M&T joint can withstand some forces. The half-lap does not. This suggests to me that most of it’s strength comes from the glue/screw/pegs.

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jmartel

6565 posts in 1611 days


#6 posted 12-31-2014 06:59 PM



I don t have any data, but I would guess that an M&T joint is stronger. If you consider both joints, dry fit only, before any glue or screws, the M&T joint can withstand some forces. The half-lap does not. This suggests to me that most of it s strength comes from the glue/screw/pegs.

- isotope

A glued Half lap joint is stronger than a M&T joint, actually. Fine Woodworking did some tests that proved it.

That being said, both should be strong enough for the purpose so it’s just Aesthetic differences. M&T joint has a bit more shoulder to register to and keep it square.

-- The quality of one's woodworking is directly related to the amount of flannel worn.

View bondogaposis's profile

bondogaposis

4024 posts in 1812 days


#7 posted 12-31-2014 07:06 PM

My take is that M&T’s are easier to make as most of the joint is not visible. Whereas half laps are highly visible and therefore take more time and care so that they don’t look horrendous w/ gaps, etc. I also would make the case that M&T is stronger. Assemble a M&T frame w/o glue and you can pick it up by one member, try that w/ a half lap frame and you get a pile of sticks.

-- Bondo Gaposis

View Moron's profile

Moron

5032 posts in 3354 days


#8 posted 12-31-2014 07:45 PM

Im not sure if there is a right answer, I think that giving a right answer would require knowing how the joint is used in building something. Certainly one could mortise a bed rail, into a head boards post, and use nuts and bolts to draw the parts together and keep it permanently rigid in perpetuity. A seamless, somewhat hidden joint but would it be stronger then if it was half lapped glued and screwed….. I rather doubt one is stronger then the other.

In some old warehouses, say for example a massive web frame was built to store huge oak barrels to age whisky, spirits, where the barrels were stacked 14 high, and 500 barrels long, they wouldn’t mortise and tenon the structure, they would half lap it, When bolted, together, the structure is way stronger in half laps.

Seeing the end grain of a half lapped barn door, seems fitting and its also stronger. Just like plywood, LVL beams, strength is built by laminating layers of wood, where grain direction changes to increase strength, much the same as a half lap. But aesthetically speaking, a face framed cabinet/furniture, with embedded bead mold, haunched and mortised cant be matched through a half lap, even though one is stronger then the other, ....it just doesnt work. Sometimes end grain just doesn’t suit the intended look of the piece.

Think of a crucifix. If the pieces were mortised and tenoned, vs half lapped, which would last longer. A half lap of course, but looking at it, from only one side, you couldn’t really tell which joint was used, unless you looked at the other side, so in some circumstances, a half lap works much better : )

-- "Good artists borrow, great artists steal”…..Picasso

View bandit571's profile

bandit571

14547 posts in 2144 days


#9 posted 12-31-2014 07:47 PM

There is a fancy option to the half-lap joint….a mitered half-lap. From the front, it looks like a miter joint, from the inside, it looks like a half-lap. A bit more involved to make, but looks better on the outside.

I usually use just M&T joints for mine. Just the way the shop is set up.

-- A Planer? I'M the planer, this is what I use

View JayT's profile

JayT

4772 posts in 1672 days


#10 posted 12-31-2014 07:59 PM

M&T joint has a bit more shoulder to register to and keep it square.

This would be my main reason to use M&T or a bridle joint over a half lap (plus I like the look better). Much easier to keep square when assembling. With modern glues, any of those is more than strong enough.

-- "Good judgement is the result of experience. A lot of experience is the result of poor judgement."

View Moron's profile

Moron

5032 posts in 3354 days


#11 posted 12-31-2014 08:11 PM

as in any joint, it wouldn’t matter what joint you do, the ability to keep corners at desired angles, is almost always determined, by the precision in the execution of the joint. Nothing will scream louder and point out the obvious faster, then a poorly done butt joint, much less the more difficult joints.

unwatch ; ))

-- "Good artists borrow, great artists steal”…..Picasso

View bobro's profile

bobro

308 posts in 771 days


#12 posted 12-31-2014 08:19 PM

I like to use a different joint than either M+T or half-lap:


The one pictured is glued and doweled, but usually I prefer glueless and a square peg, with the square peg sanded flush like on my workbench on my blog here, or with the peg sticking out and beveled like on the recent “glueless” post I did here.

There is a name for this joint, found it in a 1929 book, but I can’t remember it. It makes the end grain prettier because it’s a dovetail.

edit: obviously this joint isn’t suitable for every occasion, because you need a certain thickness and a certain minimum of meat around the points of the pin. So the corner of a cabinet frame would either require a pin not centered on the rail, but centered lower, or the stock might not be enough to use the joint on a corner.

A through- pegged bridle joint is also strong and fairly decorative.

-- Lao Ma: You are so full of anger and hatred. Xena: Everybody's gotta be full of something.

View bandit571's profile

bandit571

14547 posts in 2144 days


#13 posted 12-31-2014 08:32 PM

Fancy mortise and tenon joints

With a 45 in the corner. Or, when it is in the middle

Doubled up. Might have a close up

Raised panel goes into the groove, mortises will be chopped into the lowered areas

and fitted out.

-- A Planer? I'M the planer, this is what I use

View Moron's profile

Moron

5032 posts in 3354 days


#14 posted 12-31-2014 08:34 PM

BoBro and others, make a visual example of my point, exactly.

-- "Good artists borrow, great artists steal”…..Picasso

View pintodeluxe's profile

pintodeluxe

4853 posts in 2274 days


#15 posted 12-31-2014 09:27 PM

Well I use both, but mortise and tenon a lot more frequently. I like how the shoulder of a M & T joint tends to keep things nice and square with little effort.
Plus, how am I going to use my new mortiser on a half lap?

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

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