Thread: Mega Extension Dinner Table Rails Advice Needed

Aluminium is going to be your go to rail material on this project IMHO, and specifically extruded hollow section.

What timber are you planing on using? & what thickness for the leaves?

Originally Posted by Feckit

Aluminium is going to be your go to rail material on this project IMHO, and specifically extruded hollow section.

What timber are you planing on using? & what thickness for the leaves?

I'll be using 3/4" (19mm) red oak. I've been drying this oak for 2 years now. Each one currently 1" by 10" by 16'. After planing, they will be 3/4".

All of the aluminum rails I find are for shorter tables. Who has the longer aluminum rails?

Who has the longer aluminum rails?

Not too sure about your part of the world Bill.

Sounds very ambitious Bill, what will the centre span be ?
Have a look at osme 18th /19 th century table designs, they had ingenious ways af making very large extending tables, sometimes incorporating concertina actions.
A common design was to have 2 "D" shaped ends than could be connected to a central double drop-leaf table.
Maybe you could make wooden "I" beams.
3/4" thick seems a bit skinny for dining table top.

If you are wanting to use aluminium maybe shorter lengths could be joined with a connector of some kind.

Hi Bill. I make timber ones for my tables.
Its not so much which material gives the most strength and least flex as it is what Table design does that for you . Metal flexes same as steel does.

With wood.
There are two basic styles that I refer to in 18th and 19th century tables. The way The English did it and the way the French did it .

One form the English did.
The English made a box that slid in another box and went on and on depending on how long it was going to be . They also planed curves into rails and plough planed off that to give arched grooves that made the table open up forming an arch . This formed a high point in the center which was there to compensate for the weight of the leaves. When the leaves were fitted the arch flexed down and the table sat flat. This is a form of over complicated madness IMHO Although pretty impressive as well .

The English also did versions with center legs . Great idea . This supports and keeps the rails straight. not so much complicated arching .
Both these designs were normally so tight that big metal threaded winding systems and a crank handle were needed to get them open and closed.

The French did a dovetailed rail system , no boxes. And had one or two sets of center legs . The rails could be
left a loose enough fit to allow it to be pushed and pulled open by hand . The center legs kept everything up straight.

Here are some I did a while back with French style rails.

Dovetailed rails sawn and routed out . Metal stops made up with a little welding . 45 degree braces made to stop the center legs twisting . you cant do without them .
I don't think its possible to build any of these well without drawing it up first . Work it out on paper to get an understanding of the important parts. How long the rails slide and where they stop.

The other thing is making the top . These tables are the only thing I know of where you build the top from the under side up . Meaning you have to get the under side of both ends flat and fitted . Then the leaves. Leaving all tops too high and rough , Then gauge from the bottom up to get the leaf locating dowel holes . Once that is all done plane down the two ends and get them perfect . Then one leaf at a time to match the ends. Thats the basics of how how you end up with a set of leaves that are interchangeable and all fit flush like how the old tables worked .

img163.jpgimg167.jpgimg169.jpgimg170.jpgimg174.jpgimg176.jpgimg177.jpgimg348.jpg

There used to be a supplier of this style of wooden rail that could be bought in the US for making your own tables . I did a search but couldnt locate it . Ill have another go later .

I did find this which looks like a good read .
https://www.amishfurniturefactory.co...e-slide-types/



Rob

What a great example. Thanks for the photos and explanation.
How often would you get an order like that?

Originally Posted by Lappa

What a great example. Thanks for the photos and explanation.
How often would you get an order like that?

I get decent sized tables orders on average once every two months I suppose, as well as all the other stuff I make. Its not very often I get Extensions tables of that sort . Haven't had one for about seven years . I don't push them along , sort of . like if I wanted to I could make one to put on the showroom floor. Then Id get orders for them . There is a lot more things I like making and Id rather make those things for showing off and selling when I can fit them in . I do a type of two leaf extension table which only can take two leaves. They are a type I was constantly doing until I sold the last one off the floor and didn't replace it .They slowed. Last one of those was a year ago.

Auscab,

You have some great ideas and the pictures are a help (1 picture is worth a 1000 words). I did not know of the English box rails. Only of the French rails. I was thinking of using the French idea.

I live in Southeast Texas, USA and will be using Texas red oak cut locally and dried in my green house that was converted to a kiln. The boards are cut mostly 1 1/4 inch thick. I think they lost some in the drying. I'll be doing the paining so I can make them as thick as I possibly can. The oak will be used mostly for the top and leaves.

I have a great deal of Texas ash that may be better for the rails. This is a guess on my part.

Like in your pictures, I was envisioning using support legs that pull out when the table is lengthened (I don't know the appropriate name).

Is there a ratio I should be concerned with about the length of the rail to the rail height or thickness?

Red Oak should be nice Bill . All original tables and any I made all had tops that were 3/4" thick . You can see the Mahogany one I did there has an extra 3/4 edge glued on the under side of the edge of the top to give it a thicker look . The grain going the same direction as the top .
You have to have the wood good and dry doing these . And you have to watch the weather closely when glueing up the top and leaves .
I did a few in US Cherry and one top I glued up , the weather was mild the day I jointed and glued them all up . I took them out of clamps and stacked them around the walls of the workshop. The next morning was a real hot change . A day where the hot dry winds came down from the north . Because I hadn't stacked the tops right the night before . The right way is all on top of each other and covered with a sheet of ply or chipboard , the hot air got to some sides and not others and warped the whole lot so bad that I had to cut them all apart and start again . Lesson never to be forgotten for me.
The rail size can be what ever you like . No rules there . The first one I made which is the long D end one(top left) was copied off an original French table the client owned . They wanted the same but Big and long . Those rails were quite squat . like 75 or 80 mm high , just over 3" . Some of the later ones were closer to 4" high . Pretty sure I did them from 1 1/2 " timber but some like the Mahogany one may have come from 2" thickness . Its the sort of job where you cut everything and let it sit a few days before machining .
One rule with the rails I live by after reading this in a good English book on extension tables is, you make sure you have at least 8" of wood left over lapping when the rails extend out to their stopped ends. More is better .It may mean adding an extra set just to make sure .

Here is some drawings . One is the Mahogany table pictured . The steel braces haven't been drawn in but you can see them on the table . The other drawing is a cherry one I did . If you didn't draw it up you could work out the rails needed by laying out some cut wood the length you have . Determined by the closed size of you table with no leaves . In my pictures The long Cherry D end had heaps of short rails because the closed size was tiny .Remarkably small. The two ends of the D over hanging the base dropped down as well . There was two rule joints in the ends of the top . The Mahogany one was the opposite . The closed size was twice the size of a normal table . The client wanted it that way . So the rails could be quite long because of that.

IMG_1358.JPGIMG_1359.JPG

Rob,

How did you cut the French rails? Did you use a router or table saw? I can only imagine you have a jig to do this. If there is any twist in the wood, i imagine the rails would bind. The longer the rail, the more chance of an inaccuracy and more chance in binding. However, that is why planes and chisels were made.

I can use suggestions in making the rails before I mess up some timber.

Some of the first ones were done on table saw . Then I got a router bit and did the rest on my inverted router . In its own little table . No Jigs for any of it , just a fence. Hogging out the bulk and coming in for nice final finishing passes works in both methods . The table saw leaves a bit in the inside corners that has to be chiseled out though. The important bit is having everything marked out and working off the correct faces.
You don't want any twisting and planing to fix it later on these . Cut the dry wood over size and let it sit a week or two, breathing, before a final re machining . I just let them sit a few days and it was ok with KD US White Oak.
Doing one side first like the female and then running the male side to fit that . Then going around and shaving off the sharp corners with a plane . Its a pretty easy part of the job and rewarding to see what you end up with .

I finished some of mine off with a fine bead on one side you could see when looking down on the open table . Its in one of those drawings . Done with a beech side bead moulding plane . Looks great .
With a bit of wax on the finished rails they glide open and closed . That means nothing binding which would result in a big sag with no center leg support . The beauty is you can just about throw the table open . They make a clackity clack sound as the stops meet each other as opposed to the squeak and creak sound of an English style table being wound open slowly.

Rob,

Thank you again for your input. I find it very valuable.

What router bit should I have to make the rails? I have several 2+ HP routers that have both 1/2" and 1/4" cutlets that I can mount in my router table.

Please recommend what router bit I should use. My research indicates a dovetail bit, but do they come in different angles? Maybe different depths? I don't want my first attempt to fail because I used the wrong router bit.

Again, I am a novice and have not done this before. I have made over 2 dozen raised panel cabinet doors and used rather large router bits.

Looking forward to hearing back.

you can get most of the idea of scale from the detailed photo above. Scale that to the dimensions of the timber and you'll get an idea - but mocking up and testing on sample timber is critical

Originally Posted by bill z

What router bit should I have to make the rails? I have several 2+ HP routers that have both 1/2" and 1/4" cutlets that I can mount in my router table.

I think the router bit was the T1018 1/2 on page 13 from here .

CARB-I-TOOL - Router Bit and Accessories Catalogue - NOVEMBER 2015

They only have 5 Degree and 15 Degree and I think it was the 15 .

For such a job 1/2 " shank is the go not 1/4 .

For the female sides
I normally would pass the rails over the table saw doing three or four cuts spread out , then break out the standing left overs with a lever . Come in after that with a straight bit , then the dovetail bit for doing the final skim cuts.

The male side I think I cut out on table saw and skimmed with router.

Like Poundy said mock up and test where it suits .
Or draw. Its just a pencil and paper. Do you know how to do that with a scale ruler a square and T square?

You have to understand all the parts before you start . Its actually pretty simple. How long your rails are . Where they stop at both ends . Slots and holes also have to be machined in to fit the stops you need to make . All This gets figured out on the drawings or mock ups . I normally draw first then mock up if I have to.

I may have a stop or two left over Ill take a picture of if I can find one . No promises I will but Ill look.

I know I kept left over off cut sets of the rails . Grouped together as they work on a table. I'd show them if I could. I save anything worth looking at later . Problem is I moved house and workshop and my mind only knows where I used to keep them . They are now inside a big pile of covered wood . Ive been out there at the pile three times in the last week looking for one big stick of Sycamore I know I own that I need fof a job . No luck with that .

Rob