Demi lune table

[NickM]

I've decided that my next project is going to be a Demi lune table, not least because I want to have a go at making something with a curve in it. Mine will be a half ellipse as I want something a bit wider and shallower than a semi-circle would give me.

I'll try to make this into a proper build thread when I get going, but I have a few initial questions which the wise amongst you might be able to help with.

The basic design will have two rear legs at the junction of the curved front apron and the straight rear apron. There will be two front legs "attached" to the front apron (how they're attached is one of my questions). I've decided to go with bent lamination for the apron because I have the tools to do that. The idea is to re-saw thin strips and glue them together in a male/female mould.

I'm thinking ahead to the leg joinery. My questions are:

1. Do I make a one-piece front apron and "slot" that into open mortises cut in from the tops of the legs (I think this method typically involves a rebate on rear of the apron only), or do I have the apron in three pieces with more conventional mortise and tenon joinery? One advantage of the three-piece route is that my lamination moulds will be a lot smaller as they only take in part of the curve (there would be two moulds - one for the centre piece and one for the outer pieces). However, I can see that the joinery might be a bit harder with the three-piece.

2. I'm struggling a bit to envisage how I would lay out the joinery because of the curved surfaces. Even if I go with a one piece front apron, I will still need to mortise and tenon into the rear legs. Are there any good techniques/tricks I can use here? I can see that a full scale drawing might help so that I can measure angles, but the lack of a flat reference face for some parts will be a challenge I think.

As ever, any thoughts and suggestions would be much appreciated.

(I'm not sure it's all that relevant, but I'll be making this in oak - I'm trying to limit the types of timber I'm using at the moment as it keeps things simple. I was looking for a "special" piece of oak at the timber yard on Saturday to use for the top, but couldn't find anything quite right so I might replace the top at a later stage if I find something. I did find one piece which initially looked ideal - packed with medullary rays - but on further inspection it was also packed with worm holes/tracks! Most of these tables tend to have a lot of inlay and marquetry work, but I'm going for a clean look on mine!)

 

[AndyT]

That sounds an interesting project and some good challenges. I don't know the answers to your questions as I have never built one, but I can offer a couple of pages from Charles Hayward's book 'Period Furniture Designs' showing how an 18th century original was made. It's more complicated as the top folds out and there is a folding leg but I hope it helps the planning stages.

Also two pages from Jones, The Practical Woodworker.

I shall follow your build with interest.

 

[NickM]

Thanks Andy, that's very helpful.

Bridle joint was what I meant when I said open mortise! I've seen other drawings which show it as option B on the first page, but with a rebate only on the rear of the apron. Option A looks tricky to me...

I think I'll give option B a bit more thought. I've also seen designs which have a rail running from the inside of the leg to the rear apron to provide additional strength, so I might be able to add that in too.

I think mortise and tenons are the only sensible way to proceed on the back legs.

As an aside, I did consider the "brick" constructed front apron as shown in the pages above with a veneered front, but I decided to avoid veneering. I'm sure I'll have a crack at that one day though!

As another aside, I need a copy of Charle's Haywards book!

 

[AndyT]

As another aside, I need a copy of Charle's Haywards book!

There are quite a few. All have excellent clear writing and diagrams. It can be confusing when buying them, especially if you have to buy on-line. A lot of titles went through one or more revisions to update them, and online listings often use a stock photo which could be of a different edition.

Also, quite a bit of content crops up in several similar books. I could have taken those drawings from the very similar 'Antique Furniture Designs' and some of the text in that book also appeared in 'English Period Furniture'. But for anyone who looks at old furniture and wants to know how it was made, they provide the sort of details ordinary picture books on antiques just leave out, and I recommend them.

 

[MikeG.]

Sounds a great project, Nick, and I very much look forward to the thread on its build. I have one of these on my long list (two or three years hence), and I had envisaged doing a bent lamination skirt in one piece.

 

[NickM]

Thanks Mike.

I'm leaning towards the one-piece skirt. It would be easier to do it that way if I didn't make a two-part (i.e. male and female) mould for the lamination and instead just bent the laminations around a concave former (probably using some ratchet straps as well as a few clamps to hold it together. I think I've got some hardboard lying around so could use that as a caul. Hopefully that would work well enough. Only one way to find out I suppose...

 

[NickM]

I did a drawing to guide me, although I wouldn't be surprised if I adapt things a bit as I go along. (It's clearer if you click on it.)

I think I'm going to start by making the table top in MDF and then make another MDF shape which would match the inside face of the skirt. Having the MDF top will be useful as a reference and, in due course, I can use it as a pattern for the actual top. I'll need a stack of MDF shapes for the inside of the skirt to use as a former for laminating the skirt.

I still can't quite see how I will lay out the joinery, but hopefully with some of the components made it will become clearer...

 

[MikeG.]

I wondered to myself the other day whether I would perhaps start with the apron, and then adapt the shape of the table top to whatever popped out of the formers, given that springback can be an issue. The alternative of trying to tighten up the curve of an apron that was say 6 or 8mm from how you wanted it struck my as being just a bit tricky.

 

[NickM]

I think that's a good point Mike and it's partly why I'll only make the top in MDF to begin with. I think it will help me visualise if I have the overall dimensions and shape about right. If I can't get the apron fit the top then I can always start the top again having only lost some time and a bit of MDF.

I've made a jig for the router which will enable me to cut ellipses (lot's of examples on the web, but I'll try to take a picture). There will be a bit of trial and error to get the dimensions right but it should help with symmetry etc. It would be a lot easier if I was going with a semi-circle, but that's not the shape I really want.

 

[NickM]

Here's a photo of the jig. It's a bit hard to visualise how it works, but there are two "carriages" which slide in the slots. You set one of the carriages for the longer axis of the ellipse and one for the short axis. As the router moves, the carriages slide and the router describes the arc of the ellipse.

As it happens, I couldn't quite get the shape I drew. If I had it 1200mm wide, 440mm was the shallowest I could make it and that was too deep for me. I think I ended up at 112 wide and 380 deep which looks OK in the couple of places where this table might live.

 

[MikeG.]

That looks a fun floor to sweep up sawdust from!

 

[NickM]

That looks a fun floor to sweep up sawdust from!

Yes, it's better designed for channelling horse wee into the drain!

I usually sweep up the worst of the shavings and then use the dust extractor to suck up the remaining dust so it's not too bad.

The bigger issue is that it's not flat and also that nothing can be wheeled around on it. I'm happy to live with it and couldn't do anything about it even if I wanted to!

 

[NickM]

I had a go at making the curved apron over the weekend. I'm afraid I didn't take many photos - just one at the end of this post.

I started by using my homemade ellipse jig (see previous post) to rout out several layers of MDF to glue up to make a former. The jig worked really well and after glue up and sanding the edge I ended up with a very solid and smooth former.

Preparing the thin layers of oak was hard work. I had intended to use my cheapo p/t but I couldn't get the bow out of the board I was using so ended up doing it by hand. The process was: hand plane a flat face, bandsaw off about 2.5/3mm, hand plane the face, repeat with bandsaw etc. Once that was done, I hand planed off the worst of the saw marks from the back of each thin slice.

The positives of the process were:

1. I was very pleased with the job the bandsaw did. I spent a bit of time tuning it up before I started, but I managed to get a very even and thin slice each time; and

2. I discovered a good way of holding the thin slices for planing. I stuck a 5" length of masking tape at one end of my bench and another piece across the end of the slice. I then superglued it down (glue between the masking tape). That was enough to hold it. I only had it come adrift once when the plane dug in a little.

The downside was that it was very hard work. I wouldn't fancy making an 8' x 4' sheet of oak plywood by hand!

The glue up was quite fraught and I had the whole family on the job so we could get glue on each layer as quickly as possible.

Unfortunately, I'm not very happy with the end result. I clamped it with ratchet straps around the former but I just couldn't get the gaps out between the layers. Anyway, I'll leave it in the clamps for 24 hours and see what happens. The edge won't be seen, so if the face looks OK and the shape is alright, I might get away with it (I might even be able to hide the bottom edge by adding a beaded lip along the bottom). If not, I think I'll revert to trying a male/female mould rather than the former. However, if I do that I think I'll make the apron in 3 sections.

Here it is clamped up.

I can't imagine that the whole thing won't simply spring back to a flat board when I take the straps off!

 

[NickM]

I took the straps off and this is what I've got:

I got negligible springbuck which is good.

I'm really kicking myself that I didn't spend a bit more time making sure my stack of layers was even, because unfortunately they've slipped around a bit. I think I can deal with that though as I have some spare width to play with. I think the answer will be to plan one edge flat and square, and then scribe the width off that and plane down to the line. Of course, holding it to plane it is tricky!

It is also quite gappy. Hopefully some of that will disappear as I plane the edges. I'll post some more photos once I've tidied it up a bit.

 

[AndyT]

That looks really promising. Are you sure you haven't made one of these before?

 

[NickM]

Not unless you believe in reincarnation!

Thank you for the kind words.

 

[Inspector]

To even it up you can use the table saw. If one of the veneers sits proud enough to bear on the fence you cut just enough to clean off the other edge. Then use that face to saw the first off. It is something that requires a thorough understanding of the potential dangers so don't try it if you aren't comfortable doing it. Probably the easier to clamp a straight edge or similar and use a bearing/bushing guided router to cut it straight. Or hand work it like you are thinking.

Pete

Come to think of it you could also joint one edge on a surfacer and then through the thicknesser for the second edge.

 

[NickM]

To even it up you can use the table saw. If one of the veneers sits proud enough to bear on the fence you cut just enough to clean off the other edge. Then use that face to saw the first off. It is something that requires a thorough understanding of the potential dangers so don't try it if you aren't comfortable doing it. Probably the easier to clamp a straight edge or similar and use a bearing/bushing guided router to cut it straight. Or hand work it like you are thinking.

Pete

Come to think of it you could also joint one edge on a surfacer and then through the thicknesser for the second edge.

I wouldn't fancy doing it on the table saw. I think I could run it through the bandsaw to take the worst of it off. Bearing guided router bit is an excellent idea. I think I could do something with the former to make that work.

I'll have a crack it with hand tools first though.

 

[NickM]

I've had a go at the apron and I think it will be fine.

Here it is (just look at the grain pattern in that MDF top - it will French polish beautifully...):

As mentioned in an earlier post, there are some gaps in the layers. The good, the bad and the ugly...

I don't think any of that will be a problem really.

I can't decide whether I've done the easy bit or the hard bit. The next job is to make the tapered legs, but I still have't got the faintest idea how to mark out for the joinery!

 

[Hornbeam]

Hi Nick. I am sure you will get away with that level of gap in your joints.. If doing any laminating in the future, my approach is
Only make the former about 2mm wider than your laminates and then screw small arms on top and bottom of teh former to prevent the laminate sliding more than 2mm. Everything seems to go well when you do a dry run but as soon as you apply glue everthing slides all over the place. Use a slow setting glue and polythene sheet to stop it sticking to the mould
A ratchet strap just doesnt apply enough pressure but is good to get things into the general shape
I put an additional layer of 4 or 6 mm plywood to act as a spreader
To apply pressure to the laminates I use studding and blocks. I think this method is in Tag Frids book http://www.stumpynubs.com/book--tage-frid.html or certainly David Charlesworth (I will make that dining table one day). Lighter and easier than G clamps and very quick with a drill driver
Ian