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Planning a cherry dining table

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Forum topic by crank49 posted 08-30-2011 12:10 AM 5181 views 0 times favorited 9 replies Add to Favorites Watch
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crank49

3981 posts in 2437 days


08-30-2011 12:10 AM

Topic tags/keywords: table design question

I am planning to build a large dining table. More specifically; what’s called a farm table I believe. It’s got to seat 10 people so I was thinking 42” wide and 106” long. I want to make this along a design for a Stickly table I saw recently. 1-1/2” to 2” thick top; 3” or 4” legs, through tennons with pegs, no apron.

Any suggestions as to wheather this long of a table will sag without an apron. I reallly want a simple clean design. the wood I plan to use is cherry. Or a combination of cherry top and sycamore legs and stretchers.

-- Michael: Hillary has a long list of accomplishments, though most DAs would refer to them as felonies.


9 replies so far

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rcs47

182 posts in 2596 days


#1 posted 08-30-2011 04:11 AM

You can look at this like a shelf and use the “sagulator” to calculate how much it will sag under load conditions:

Worst case – 98” between 4” legs
42” deep
1-1/2 thick
Cherry
@ 50#/foot load you will see a .04” sag/foot

@100#/foot, that increases to .08” sag/foot

Assume the legs are inset 6” from the ends making the length 86”
@100#/ft, now you get .05”/foot

If you go to a 2” top:
@ 100#/foot you get .022”/foot

I’m not sure about the load. At 100#/foot, that’s 880#s for your table. That’s a lot of food, drink, dishware, and silverware.

Good luck,

Doug

-- Doug - As my Dad taught me, you're not a cabinet maker until you can hide your mistakes.

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Bernie

416 posts in 2303 days


#2 posted 08-30-2011 04:19 AM

I’m no expert, but 42” is a long span and I bet it will sag, even a 2” thick. When the wood fibers all run in the same direction, the stress overcomes them on that long of a span.

Options I think… sandwich 2 one inch boards and cover the glue-up with a simple straight frame. You could even use a different type of wood like a light wood (ash or white oak) or dark wood (walnut, mahogany). Or you could slice a strip off the top board to match the grain and blend it in. Or you could use the veneer strips that are melted on with an iron.

The other option is to cut a couple of strips and glue them on the underside.

By the way, cherry is a beautiful wood, but may change color when left in the sunlight. Good luck with your project!

-- Bernie: It never gets hot or cold in New Hampshire, just seasonal!

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Bernie

416 posts in 2303 days


#3 posted 08-30-2011 04:26 AM

Wow Doug… quite technical info way beyond my experience. Your post came up while I was typing. I will try out that Sagulator link. Thanks!

The only word of caution is that lots of folks like myself tend to lean on a table especially while getting up from it. I don’t know what kind of pressure or stress this may cause.

-- Bernie: It never gets hot or cold in New Hampshire, just seasonal!

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rcs47

182 posts in 2596 days


#4 posted 08-30-2011 05:56 AM

I’ve been thinking about your table legs. You said through tenons with pegs, but I’m sure you mean wedges. I’m not sure if four 1-1/2” or 2” wedged tenons through the top will hold up to years of racking pressure. The weight of the wood, everything you put on the table, and as Bernie says, people pushing on the table will pry on these joints a part.

I have seen similar large tables made by Borkholder Amish Furniture. When I first saw their furniture (15 years ago), I really liked their tables with 1-1/2” and 2” thick tops. Here is a picture of one of there tables (6/4×40” x 84”). You will notice they are connecting the legs to the table via a stretcher between the end legs. They connect the end legs to reduce any racking. They also set the legs in from the ends (reduces the sag too).

This is the link to Borkholder, but I keep getting a “bandwidth limit exceeded” error message saying to try again later. Maybe you will have better luck.

You are talking about a large table that will weight a lot. You need to factor in how you will keep the legs from folding. You could use two 45 degree wood braces on each leg to increase their strength. Or, use a design similar to the Borkholder, but use bent lamination to bow the brace the runs between legs, up to the top, or any other shape you want.

Have fun!

Doug

-- Doug - As my Dad taught me, you're not a cabinet maker until you can hide your mistakes.

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crank49

3981 posts in 2437 days


#5 posted 08-30-2011 02:30 PM

Thanks for the comments and the Sagulator link.

The table I had in mind does have a stretcher tying the legs together, its just that my version will be 2 feet longer.

-- Michael: Hillary has a long list of accomplishments, though most DAs would refer to them as felonies.

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BobTheFish

361 posts in 2018 days


#6 posted 08-31-2011 02:57 AM

Add legs at the center point on both of the long sides. An apron may not be necessary, but it would help. The stretchers are necessary if the apron is gone, because it keeps the legs from splaying outward (or inward) with any tangential forces to them, (even downward pressure can be tangential if there’s too much movement in the joint or the legs start to splay due to compression/tension pressing downward on the top away from the legs can cause a slight splay and thusly and tangential pressure).

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rcs47

182 posts in 2596 days


#7 posted 08-31-2011 03:04 AM

The picture helps. I was looking at the Stickley site last night and didn’t see this table. If you work with the loading and leg placement, you shouldn’t have any problems.

Any suggestions for loading out there? 100#/foot of table? 150#? 200#?

Lets look at people pushing down on the table. If all ten people push down at the same time..

- One on each end
- One over each leg (assuming you inset them enough)
- That leaves four people pushing down between the legs

The people over the legs should not add to the sag.
The people pushing on the ends will counter some of the people in the middle.
So, how much do you push down on the table when you get up? Got a bathroom scale? Is it 30#? Maybe 50#? Give them 100#/person.

Four people over four feet = 400# for pushing without taking away anything for the end people because they might not push at the same time all the time.

Sorry, I’m an engineer. It just comes out, I try to stop it, but it still does.

Doug

-- Doug - As my Dad taught me, you're not a cabinet maker until you can hide your mistakes.

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BobTheFish

361 posts in 2018 days


#8 posted 08-31-2011 04:47 AM

Doug, I have little idea as to the pound pressure that you’re describing. I tend to go at it instinctively, and I feel that the best thing is, as you expand a table, to add extra legs.

The only rule I can come up with for tables that I remember is that they should be around 30” high, and you should try for about 30” wide, giving space for people on both sides and space to place things in the center. Additionally, plan 24” per place setting.

Here’s where I learned about it about a year ago:

http://www.tablelegs.com/WoodworkingPlansAndArticles/DiningTableDesignBasics.aspx

Here’s another article that might give some help:

http://www.tablelegs.com/WoodworkingPlansAndArticles/ColonialAmericanTavernTable.aspx

Otherwise, on the web, THE ONLY thing I found about tables and legs (which is what I was talking about) is that tables over 96” (8ft) tend to have additional legs for every 4 or so feet of length to add additional stability.

So go with 6 legs, and built a double H style stretcher, with stub tenons on the legs, and through tenons on each end, with a pin mechanism to hold them in place (it’ll hold better than a wedge or stub tenon).

Don’t build this table with only 4 legs.

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rcs47

182 posts in 2596 days


#9 posted 09-01-2011 04:07 AM

Bob, thanks for the links. They give good rules of thumb for design.

First, I have not done the calculations myself, just used a prewritten program to answer the question, “wheather this long of a table will sag without an apron?” IMO, with a solid 2” thick top, you should not notice sag (assuming the legs are inset 14” giving 70” between the legs, with a load of 175#/foot).

I have not looked at the column strength of the 4” square legs, or if the leg design in the picture will provide adequate horizontal/racking support for the above load. If you were really going to see this load on an ongoing basis, the table will need some type of truss base.

To ensure you do not have any sag, you can add an extra leg as Bob suggests, or add tie in support to the cross stretcher similar to this table.

You can use a 1-1/2” top with a center support/leg assuming heavy loads too. If you add the center support, cutting the span length to 35”, and shelf thickness to 1-1/2”, you can raise the load to 550#/foot before you notice the sag.

Crank49, you have a lot of options to consider. I understand your desire to keep the design simple. I like the table you picked and will save it for my future use.

Doug

-- Doug - As my Dad taught me, you're not a cabinet maker until you can hide your mistakes.

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