Dovetail Layout - Advice Required Please!

[OPJ]

Hi guys,

I've started machining up some English Cherry for a wall-mounted bookshelf with dovetailed corners, 1000m tall x 600mm wide. The joints at the top will be half-lap/half-blind dovetails with throughs at the bottom. Timber has a finished size of 230mm wide 22mm thick

Trouble is, I've had to join two boards edge-to-edge in order to get the width. As I don't like centrelines though, I decide to offset the "centre"-line by 10mm... I think it works quite well (I've already done this part in the workshop!) although it isn't that obvious.

Anyway. I'm assuming it's best to have a tail rather than pin over the join but, I can't decide how to arrange the rest of them.

Should I keep them all uniform across the 230mm width? If so, how would you do this marking out the tails first?

Or, should I try something different - in which case, I'm open to ideas and suggestions! :wink:

Here are the throughs:

And the half-laps:

Any thoughts or suggestions would be much appreciated,

Olly.

 

[SketchUp Guru]

My personal preference is a pin/socket on the centerline of the board. If you did that here, would the pin miss the glue line?

I like that the tails are wider than the pins but I'd prefer to see even wide ones.

 

[OPJ]

Hi Dave,

Yes, with a pin centred on 115mm that should work. They're only 3mm wide at their narrowest point. Good point on the width of the tails too. To me, it does look over-crowded at the moment.

I'll see what I can come up with, thanks. :wink:

 

[MikeG.]

Hi Olly......

I agree with the bigger tails idea. My preference is always for bigger tails in the middle and smaller ones towards the edges. If I am going to the effort of handcutting dovetails I wouldn't want anyone thinking they were machined (not that I can machine them...........but they don't know that).

If you've done a decent job of your board joint, which I know you will have, I wouldn't be worried about it being in the middle, nor would I worry too much where it occurred in my joint (although I would aviod it being on a cut line).

I've not yet worked with cherry.......what's it like?

Mike

 

[OPJ]

If you've done a decent job of your board joint, which I know you will have, I wouldn't be worried about it being in the middle, nor would I worry too much where it occurred in my joint (although I would aviod it being on a cut line).

Hi Mike,

Well... The joint itself is very clean and tidy. When I bought this cherry though, I basically bought all they had left (just enough for me!), which meant that not all boards appear to have come from the same tree so, I've been stuck with a couple of matches that are a little odd... One side will be hidden by a wall so, I've put them on that side. The 'face' side is not as bad. :wink:

I joined the boards with cascamite (urea formaldehyde) so, there's little chance that the boards will suddenly spring apart!

This is English Cherry and its my first time using it. It only likes sharp planer knives - and even then, I had one problem with the grain where my thicknesser took a big chunk out!! :? There are quite a few dead knots in these boards that I'll have to replace. It's not as knotty as some of the elm I've seen but it's certainly more so than American cherry, which tends to be darker and, perhaps, a bit easier to work?

I've also had to look at these boards carefully to ensure I won't run in to any short-grain problems when laying out the dovetails.

For now though, I think I'd better get back to SketchUp!

 

[Steve Maskery]

With that sort of width, you have room to play, don't you?
I'd certainly have a wide one in the middle and narrower ones to the edges, but how do you decide on the spacings?

Here are some ideas:

Use Fibonacci for the centre lines of the pins

Use an arithmetic or geometric progression.

Draw up a set of Hambridge rectangles and use the spacings from those for the centre lines.

Oooh, lots of options!
S

 

[SketchUp Guru]

Hambridge? Isn't that how you get your pigs to market when you live on the other side of the river? :lol:

 

[maltrout512]

Sorry to but in, am I missing something here. From the 2 diagrams that OPJ has put up what's wrong with leaving it as is shown. I think the pins are set out ok and the sockets will be the same set up and the join in the upright comes almost well near in between the socket so the joint in the upright will not come apart. I still think I'm missing the point. :sign3:

 

[SketchUp Guru]

Malcolm, the second image shows the mating board in place although OPJ didn't complete it to fill in a face.

There's really nothing wrong with the layout but he asked for suggestions. We're suggesting wider tails and even tails of varying widths. I think that would add an aesthetically pleasing aspect the joint. As shown, it looks more like a mass produced sort of joint.

 

[MikeG.]

Use Fibonacci for the centre lines of the pins
S

I like this idea Steve!!! I use the Golden Section when I can....and to apply the maths from the golden section to the setting out of dovetails.....well, whilst only the sharp-eyed and mathematical would spot it, it would give me a big smile!!!!

Mike

 

[OPJ]

Thanks, Steve. I do understand how most of those work but... I'm not entirely sure how to apply when it comes to setting out dovetail pins. Anyway, I've come up with a couple more ideas:

I'm leaning towards the second one at the moment, purely because there's a great distinction between the widths of the pins. I've been playing with various ideas and have decided I can't get away with any less pins or tails than this. Any more would over crowd it so, I reckon this is a good number - just need to decide on the spacings.

 

[OPJ]

I'm still looking at this and I don't think the 'pin in the centre' idea is going to work so close to the glue line. So, I'm looking to put a tail in the centre instead...

My first thoughts were that this one has too few pins:

I like the idea of the tails getting narrower towards the outside. Perhaps I made this one too narrow though?:

I don't think this one works too well:

Perhaps something like this?:

Right now, I'm leaning towards the second one in this post... :wink:

 

[Steve Maskery]

Yes, 2 or 4.

All the above would work, but, as you say, the first does not have enough pins. In the third one, I don't don't think there is enough difference between the large and small tails. 2 and 4 are good.
S

 

[OPJ]

Thanks, Steve.

 

[tnimble]

I'm with Steve, prefer no 4 a bit more than 2.