# Mitre joint for worktops



## JustinB (11 Dec 2020)

I'm making an island unit that has 30mm birch ply formica laminated worktop on top of a 600 and an 800 base unit. The worktop runs up one side and joins on to the top with a mitre along the full width. 







So my biscuit jointer packet up while doing the masons mitre on the L-shape along the wall  I'm trying to hold out and get a decent biscuit jointer this time. So any ideas on how to tackle this without a biscuit jointer would be most welcome 
Thanks


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## Tris (11 Dec 2020)

Do you have a router? If you have then a loose spline could be an option. 
I'm thinking out loud here as I don't have a lot of experience and there are probably better ways to do this


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## Spectric (11 Dec 2020)

Have you cut the mitres yet? They will need to be very accurate and probably routed. To join the loose spline could be an option or dowels but with a decent doweling jig like the Dowelmax and the 45°mitre plate or dominos. Depends what tooling you have at your disposal.


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## Rorton (11 Dec 2020)

those mitre lock router bits look good if you do have a router?


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## Distinterior (11 Dec 2020)

If you cut that 90 degree mitre joint on a laminate worktop,....it will be as sharp as a razor blade! If you try and soften the point of the mitre to avoid the sharp edge, you will start to expose the laminate core and you will see a dark line....Just a heads up!


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## JustinB (11 Dec 2020)

Tris said:


> Do you have a router? If you have then a loose spline could be an option.
> I'm thinking out loud here as I don't have a lot of experience and there are probably better ways to do this



I have a router. I also have a lamelo groove cutter with a guide wheel that could be used for biscuits or your spline idea. I'm just not sure how I would route at that angle along the mitre.


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## Just4Fun (11 Dec 2020)

Perhaps I am misunderstanding this, but if you are covering up the wood with formica, why do you need to mitre the wood? OK, You might want to mitre the formica on the edges of the boards but why mitre the boards themselves?


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## JustinB (11 Dec 2020)

Distinterior said:


> If you cut that 90 degree mitre joint on a laminate worktop,....it will be as sharp as a razor blade! If you try and soften the point of the mitre to avoid the sharp edge, you will start to expose the laminate core and you will see a dark line....Just a heads up!



I am making a feature of the edge. It won't be sharp. I'll either break/round the edges, much the same as I do on the square edges, so that when it goes together you get a neat black edge with a bit a ply showing along the mitre. I've seen this done and it looks really good if done well. I wouldn't attempt to get a perfect corner edge here. It will be both impossible and sharp, like you say.

I also might take it one step further and put a flat on both edges.


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## JustinB (11 Dec 2020)

Rorton said:


> those mitre lock router bits look good if you do have a router?View attachment 98158



Thanks. I like the look of these joints but they would scare the hell out of me on ply boards of this size. This joint is extremely weak and brittle because of the grain fibre direction in these types of boards and you only get one chance. No dry run is possible. They work much better on solid wood and much smaller joints I think.


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## JustinB (11 Dec 2020)

Just4Fun said:


> Perhaps I am misunderstanding this, but if you are covering up the wood with formica, why do you need to mitre the wood? OK, You might want to mitre the formica on the edges of the boards but why mitre the boards themselves?



You tend to use birch ply if you want to feature the board as the edge detail, as it looks attractive. This is what I am doing.
For example -


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## JustinB (11 Dec 2020)

Spectric said:


> Have you cut the mitres yet? They will need to be very accurate and probably routed. To join the loose spline could be an option or dowels but with a decent doweling jig like the Dowelmax and the 45°mitre plate or dominos. Depends what tooling you have at your disposal.



Yes I've cut mitres. I have a 45 degree mitre router cutter for this one.
I don't think there is a way to router the groove for the spline? Or at least I can't see it.
I'll look in to the dowl jigs . thank you!


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## Tris (11 Dec 2020)

Again only random thoughts but I'd imagine clamping a piece of arris rail or similar to support the router on and using a straight cutter, probably no use with a biscuit/slotting cutter


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## JustinB (11 Dec 2020)

Tris said:


> Again only random thoughts but I'd imagine clamping a piece of arris rail or similar to support the router on and using a straight cutter, probably no use with a biscuit/slotting cutter



I hadn't thought about doing it with a straight cutter for some reason :/ . I'll give it some thought... Could be workable with 45degree block/arris on the router base.


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## ArferMo (18 Dec 2020)

It is quite possible to just use a plain mitre, preferably track saw cut. Biscuits, dominos, splines etc. are used for joint location. The problem without a method of location devolves down to a way of clamping that also allows you to position the joint.

I wrote a piece for Practical Woodworking in the 80's on how to do this. I guess there must be other publications by now. I used to demonstrate the technique and prove even a 600mm plain mitre can be assembled and clamped by one person.

I favoured the use a single strand of copper wire from mains flex and connected to a battery charger, positioned in the glue line, to heat and cure the Cascamite glue rapidly; as I needed my jigs for the other corners!


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