Kitchen table design

[pviser]

I agree with Dave Richards' initial post, every word.

 

[tarheelz]

Thinking back to Bryan's original post, there are some client management aspects to this. Perhaps a review of traditional furniture design texts. The client's idea isn't entirely nutty but the design proportions are off.

Random thoughts... -- I have 40 year old, 54 inch round, extruded aluminum table at my in-laws house. Center of gravity appears very high. Fortunately the manufacturer created a lead-weighted base concealed within the 24 ring base. It's plenty stable.

 

[SteveHall]

Fortunately the manufacturer created a lead-weighted base concealed within the 24 ring base. It's plenty stable.

Yes, for the particular table design being discussed in the thread, my diagram shows the weight of the base must be about twice whatever the "maximum tipping load" is for stability. But you can see how just a few adjustments in the geometry can shrink these eccentricities significantly. These could double or triple the load required to tip, meaning the base could be two or three times lighter and still be stable. Or, you can create a water-, steel-, or lead-filled base.

 

[Jeff]

Eliminate the pedestal and start over for stability of the table. Three legs at 120 degrees mortised into the table top.

​

Just a thought that your client may like. Plenty of leg room too.

 

[Shamrock]

You could also try and see if the customer is willing to alter the design of the legs and increase their length at the bottom. I've built a few of these three legged tables and they are "tippy" by nature. If you can keep the contact patch of the bottom legs roughly equivalent to the circumference of the top that helps. Adding a 4th leg in this scenario helps too!

 

[BSevier]

Thanks to all for the input.

I will make recommendations to my client for redesign.

If I am reading this right, it looks like adding a leg (or two), increasing the length of the legs, and increasing the diameter of the column should help with strength and stability of the table.

Would the angle that the legs attach to the column affect the strength or stability at all?

 

[Rick M]

Putting aside the COG issue for a moment, the proportions are off. A 36" base should be fine on a 50" table, plenty of examples have less but the pedestal is too spindly, the legs too delicate (3 is fine if they are strong), the top is too thin, and the overall design of that table is unattractive.

 

[JimD]

I see the issues somewhat the same and somewhat differently than the previous comments. The original design has legs that do not extend far enough from the column and too weak a connection of the top to the column. Especially with three legs, the legs should extend to about the same diameter as the top. I think 2 inches of cherry is strong enough for the column but it will be difficult to connect it to the top and legs securely. The top connection is particularly a concern. Think of a 200 lb or larger person leaning on the table as they stand up. They might put half their body weight on the edge of the table with a 30 inch lever arm (if 60 inch diameter top) to the center connection. I don't see how that can hold. Increasing the diameter of the column would help (decreases the leverage and more points of attachment possible) as would adding rails under the top fastened to the column.

This sort of table is pretty but usually used to hold up a vase of flowers or something like that. A heavily used kitchen table doesn't seem consistent with this design.

Our breakfast table is something north of four feet in diameter made of oak and round with a center column. The column is about a foot in diameter. It has four legs fastened by hanger bolts to the center column. There is a large piece of oak, maybe two feet by two feet, bolted to the edge of the column that fastens to rails that are fastened to the top. This table has survived multiple moves and >20 years use. It doesn't look much like your sketch, however. More delicate legs should be OK, it's the attachment of the legs to the column and column to the top I would improve.

 

[Rick M]

Remember, function always precedes form. Extending the legs will make the table more stable but can get in the way of chairs and feet. Making the legs the width of the top is unnecessary. It's helpful to use dining tables as an example rather than shaker side tables. Since this is a mid-century design, we'll go with mid-century examples. Both examples have better proportions and beefier central columns while still maintaining an elegant, light appearance.

 

[chris_goris]

Ths CG has no impact on the design really. Of course it will free stand since it is a symmetric design. However, The footprint versus lever arm of someone leaning on it (merely with their elbows) negates the design. Sure, you could build it and it would free stand, and as David had mentioned, the attachment in the center is too small. One of the rules I personally live by as a design engineer for over 30 years now is, "If it doesnt look right, it probably isnt" And for me, this exactly what we have here. Unless you just want to "look" at it…..

 

[JimD]

The only way I can think of to make something that looks like the original sketch that would not fail structurally would be to hide a metal structure within a wood wrapping. If you had a metal pipe in the column welded to a metal plate fastened to the top it would be a secure top connection. At the bottom you would weld rods to the column and slide wooden covers over them. I think the legs should still extend closer to the edge of the top, however. But with good welds, metal in dimensions like the sketch or even less will take the loads a kitchen table sees.

 

[Dutchman]

A fewadditional thoughts:
Four legs on this table will allow for four chairs to fit better without interference,…customer should grasp this
You will need a fairly good size bridgeplate under the top. This will allow you to use a “tight” tenon and some lag bolts or screws to attach to the column and attach to the top further out for support (use screws with washers if solid top). I put a cove on the bottom of the bridge plate to reduce the profile of say a 7/8 thick bridge plate. You might even consider increasing the column at the top a little to give you more surface area, will not be seen unless you are laying on the floor.
I think you could get by with a 3” column, adding 1” is not going to affect the visual with the chairs placed around the base. The customer is going after a contemporary look, and 3" is fine for that size top.
With correct joinery, the legs can besecurely attached to a 3” column.

It’s doable, Justmy two cents.

 

[Dutchman]

Quick sketch

 

[SubGuy]

I like this idea and the drawing below the post I am quoting. I would even add that an additional bridgeplate, smaller diameter that the original and lower down the pedestal will allow for more stability. So it would be a stepped design working down and will offer a greater degree of protection from failure at the pedestal joint. The more surface you have preventing compression within the joint, the more a potential load would be spread over the larger mating surface of the wood grain itself. It being smaller in diameter would provide less of a profile to the standing or sitting onlooker than just simply increasing the thickness of the upper bridgeplate.

A fewadditional thoughts:
Four legs on this table will allow for four chairs to fit better without interference,…customer should grasp this
You will need a fairly good size bridgeplate under the top. This will allow you to use a “tight” tenon and some lag bolts or screws to attach to the column and attach to the top further out for support (use screws with washers if solid top). I put a cove on the bottom of the bridge plate to reduce the profile of say a 7/8 thick bridge plate. You might even consider increasing the column at the top a little to give you more surface area, will not be seen unless you are laying on the floor.
I think you could get by with a 3” column, adding 1” is not going to affect the visual with the chairs placed around the base. The customer is going after a contemporary look, and 3" is fine for that size top.
With correct joinery, the legs can besecurely attached to a 3” column.

It’s doable, Justmy two cents.

 

[Jeff]

Here's a thought for consideration. Osborne Products offers a selection of dining room table pedestals and feet. Perhaps your client can find one that's appealing and at the same time solve the table top stability problem.

https://www.osbornewood.com/table-pedestals.aspx