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By Just4Fun
#1332430
I want to join panels together at 90 degrees. I plan on cutting them like this:
Apart.png


So they can be pushed together like this:
Together.png


I am using solid wood panels I have created by edge jointing and glueing several strips, but I guess the same technique could be used for manufactured panels such as plywood or MDF.

What is this joint called?
Any tips on how to cut it accurately and cleanly, by hand? For my application it is important that all angles are exactly 90 degrees and ideally I would like the joint to be "invisible". Any tips?
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By thetyreman
#1332450
it's a cross lap or halving joint,

I would always measure the size of the joint from the other mating piece of wood, then use knifewall with waste on the inside of the joint, similar to a dado, the knifewall will prevent any tear out and should make it look clean all the way around including underneath. Be careful that they're not too tight though or it may crack, you can carefullly go over the edges with a flat buarstuard file until it's a perfect fit down to the knifewall line.
By Just4Fun
#1332460
MikeG. wrote:It's a halving joint. Bear in mind that if the horizontal element is a shelf that half of it won't be supported.

Agree about the "unsupported" issue, at least as far as my drawing goes. In my actual project this is part of a cabinet and the otherwise unsupported edge of the horizontal piece will be dadoed into a vertical panel so it should gain strength there. It will never carry heavy loads anyway, so I am not concerned about that but it is a fair point in general.
By Just4Fun
#1332466
thetyreman wrote:I would always measure the size of the joint from the other mating piece of wood, then use knifewall with waste on the inside of the joint, similar to a dado

I usually cut dadoes with a chisel, especially stopped dadoes. Would you do that in this case? Or, since the cut will go all the way through the thickness of the panel, would you use a saw?
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By thetyreman
#1332468
Just4Fun wrote:
thetyreman wrote:I would always measure the size of the joint from the other mating piece of wood, then use knifewall with waste on the inside of the joint, similar to a dado

I usually cut dadoes with a chisel, especially stopped dadoes. Would you do that in this case? Or, since the cut will go all the way through the thickness of the panel, would you use a saw?


I also use chisels but I do the knifewall first and with the first chisel cuts am careful not to over do it or you'll move the knifewall back when the wood compresses, especially in softwoods.

yes I'd use my ryobi saw using the cross cut side, which gives a far cleaner cut, then any slight waste clear out carefully with a very sharp chisel and fine file, being careful not to go over the knifewall reference line.
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By woodbloke66
#1332470
Personally, I would never use a halving joint in material that wide. I'd either join the vertical member(s) to the horizontal using either dominos, biscuits (anyone use them anymore? :lol: ) or if I want to be very Alan Peters, a plywood spline - Rob
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By MikeG.
#1332474
woodbloke66 wrote:Personally, I would never use a halving joint in material that wide. I'd either join the vertical member(s) to the horizontal using either dominos, biscuits (anyone use them anymore? :lol: ) or if I want to be very Alan Peters, a plywood spline - Rob


I'd just house out.
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By AndyT
#1332487
woodbloke66 wrote:Personally, I would never use a halving joint in material that wide.


That's the nub of it - it might be ok for some tiny shelves up to about 80mm deep - but what size does the OP have in mind? Is this a bookcase or some tiny pigeon hole arrangement?
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By Jacob
#1332488
Shelves through in one piece horizontally. Verticals cut to fit between either nailed/screwed, or in shallow housings in the shelf. Or one edge housed the other nailed through the housing, if you see what I mean.
By Just4Fun
#1332515
Interesting opinions. My main rationale for this approach is just to do something a bit different. I am not wedded to this idea so I could certainly change the design if there is good reason to do so. I would prefer the option of shallow housings in the top & bottom of the horizontal pieces to locate the verticals rather than nails or screws, but that is just me preferring joinery to fixings.

The horizontal shelves will be about 250mm front to back and (in total) 570mm left to right, end to end. The ends and back will be supported in dadoes in the sides and back of the cabinet and there will be one vertical divider mid way between the sides of the cabinet. Something like this:
Dado.png

I am working with birch (solid birch, not plywood).

Personally I would not anticipate any problem with the strength of the half lap approach in this configuration. Am I wrong?
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By thetyreman
#1332516
It should be strong enough, why is there no top or bottom? and how will the back be attached? what's this going to be used for?
Last edited by thetyreman on 26 Jan 2020, 15:59, edited 1 time in total.
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By AndyT
#1332523
Well, if nobody fills up the shelves with encyclopedias it could be a nice challenge!

There are some variants that I have seen in books but never made which attempt to get round the problem that in the simplest form of the joint, half the width of each shelf is unsupported. I know you say you plan to support your shelves in housings but I'll add a couple of pictures in case you fancy trying either of them. This is probably easier to cut:

edge_halflap_square.png


while this is said to be suitable for hand tool work

edge_halflap_bevel.png


Both are illustrated in narrower, thicker wood - you don't say how thick your birch is. I'd be interested in some photos if you go ahead.
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By Just4Fun
#1332526
thetyreman wrote:why is there no top or bottom? and how will the back be attached? what's this going to be used for?

There will be a top & bottom but this was a quick sketch to illustrate my post rather than to provide a working diagram. The "back" isn't really a back, it is just the back of this part of the project and again I didn't show the rest because it wasn't important for my question. In reality the unit will be accessed from both front and back so what I have shown as the back will really be the middle. It will be housed in dadoes top, bottom & both sides.

As for what it will be used for I find it difficult to give the piece a meaningful name. A small sort of cabinet, or table with storage below it. The main reason for building it is to try out a few ideas I have and for the enjoyment of building it. Beyond that its only purpose will be to clutter up the house of whoever i give it to. I rarely keep the things I make.
By Just4Fun
#1332527
AndyT wrote:I know you say you plan to support your shelves in housings but I'll add a couple of pictures in case you fancy trying either of them.

Thanks Andy. I will give those some thought before finalising my approach. They look interesting but I suspect that my panels might be a bit too thin by the time I have flattened them. Right now I have just glued them up and they haven't come out as well as I hoped so I may lose thickness correcting that.