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Half dovetail notches

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Half dovetail notches

Postby Andyp » 14 Jul 2020, 15:24

A quick test before I start butchering my stash of home grown timber.

IMG_20200714_161349441.jpg
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Knowing which is the inside and outside of the board before marking up is critical. Saw cuts were done with a pruning saw!

Quite pleased with the results
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Re: Half dovetail notches

Postby Robert » 14 Jul 2020, 16:40

I like the way that works. Clever.

Looks the sort of think you need to concentrate on to get every cut facing the right way.
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Re: Half dovetail notches

Postby Andyp » 14 Jul 2020, 18:27

That's right Robert,
I have now made notes on the template and on my instructions to make sure the high side of that joint is always on the inside of the board.
The joint is typical on log cabins where the angled faces are designed to shed any water out of, and away from, the joint.
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Re: Half dovetail notches

Postby SamQ aka Ah! Q! » 14 Jul 2020, 18:44

Been watching "Barnwood builders" then Andy? Good prog. if tepetitive.

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Re: Half dovetail notches

Postby Andyp » 14 Jul 2020, 20:14

Indeed I have Sam, it’s easy on the eye and the ear and on at tea time here.
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Re: Half dovetail notches

Postby SamQ aka Ah! Q! » 14 Jul 2020, 20:24

I admired their rafter 'birdsmouth' jig for chainsaws. That, and nylon brushing of planking to retain colour, but refresh the surface. After that, as I said, repetitive (just a little).

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Re: Half dovetail notches

Postby Woodbloke » 14 Jul 2020, 22:37

Robert wrote:I like the way that works. Clever.

Looks the sort of think you need to concentrate on to get every cut facing the right way.


Nice job Andy, I can see now how they work. Agreed...clever :text-bravo: - Rob
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Re: Half dovetail notches

Postby TrimTheKing » 15 Jul 2020, 11:18

Very good mate, what you planning on building with that technique?
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Re: Half dovetail notches

Postby 9fingers » 15 Jul 2020, 11:44

Might need to think about the vertical position of the cuts when considering the top layer so the notch is not weak as it might be with your current design.

Maybe soak the ends in preservative to cope with your hot summers and maritime wet winters too. Is it terebenthine preservatives that I've seen in the French sheds?

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Re: Half dovetail notches

Postby Andyp » 15 Jul 2020, 12:08

TrimTheKing wrote:Very good mate, what you planning on building with that technique?


Nothing fancy Mark, just a raised bed for the garden. One that I hope to be about 2m x 1m x maybe 1m high.
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Re: Half dovetail notches

Postby Andyp » 15 Jul 2020, 12:13

9fingers wrote:Might need to think about the vertical position of the cuts when considering the top layer so the notch is not weak as it might be with your current design.

Maybe soak the ends in preservative to cope with your hot summers and maritime wet winters too. Is it terebenthine preservatives that I've seen in the French sheds?

Bob


It’s taken me a couple of weeks to get around how to use the template and cut those notches. Final design on how to get things level at the top have not been settled on.
I hope to keep the boards live edge just strip the bark off.
I’d like not to use preservatives off any sort. Not at all sure about terebenthine and it’s suitability around food crops.
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Re: Half dovetail notches

Postby Malc2098 » 15 Jul 2020, 14:43

Nice.

When I was making the roof framing over the deck, I used the blue tape to register the outer and upper faces of all boards. Old carpenters used chisel marks to do this.
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Re: Half dovetail notches

Postby kirkpoore1 » 16 Jul 2020, 16:18

Andyp wrote:I’d like not to use preservatives off any sort. Not at all sure about terebenthine and it’s suitability around food crops.


You could look up the wood species and see how resistant to rot that it is. If the answer is "not very", you could paint any portion that's going to be in contact with the soil, such as the inside or the bottom. Or sheathe the inside in a layer of rot-resistant wood.

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Re: Half dovetail notches

Postby Andyp » 16 Jul 2020, 19:49

Most of it is douglas fir Kirk, moderately resistant. The top row will probably have to be black pine, poor resistance.
Those notches will leave a fair gap between the boards which will be uneven live edge. I had thought about lining the bed walls with a waterproof something expecting that any water that gets between the liner and the boards will run down to the gap then evaporate. That will mean of course keeping the bottom row off the ground :eusa-think:
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Re: Half dovetail notches

Postby RogerS » 16 Jul 2020, 21:34

Andyp wrote:.... That will mean of course keeping the bottom row off the ground :eusa-think:


Funny you should say that. You know how much water we get up here...well, my theory is that if you have raised beds then you need to get the water out and away. I wondered about raising the bottom 'bearer' a couple of inches off the surrounding ground level. Running chicken wire netting round the inside and putting a 3" layer of gravel or stone at the bottom. Thus letting the water out.

But then I realised that I was creating a French drain...which would get filled up with fines. Traditional approach is, as you know, a membrane to stop the fines getting through to the gravel. Trouble is that doesn't last long as the fines simply sit on top of the membrane and block that up instead.

So no solution..sorry ! But I DO like those joints.
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Re: Half dovetail notches

Postby Andyp » 17 Jul 2020, 07:14

Thanks Roger, that all makes sense.
Just checked you only get 6” more rain per annum than us.
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Re: Half dovetail notches

Postby RogerS » 17 Jul 2020, 07:46

Andyp wrote:Thanks Roger, that all makes sense.
Just checked you only get 6” more rain per annum than us.


Yebbut on the days that you don't get any rain you get sun ! :D
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