Will this farmhouse table design have expansion issues?

[Joey Stephenson]

I plan on making a farmhouse dining table for a friend, and wanted to check here first to make sure I'm not overlooking anything. There will be one fat leg on each end with a board on top to secure to the table top. There will be a stringer between the legs towards the feet. Pretty typical design (see image for a very simplified drawing of the type of table). The top will be edge-glued planks.

This design shouldn't have much of an issue with expansion since the stringer and table top, being made from the same species, should expand/contract at the same rate, right? I'd hate to have an issue where the top expands more than the bottom and weakens/cracks joints after a few years.

369331

[Mike Cutler]

The expansion and contraction of the stringer versus the top isn't an issue. The grains will run 90 degrees opposite of each other across the face. Stringer will be in a vertical plane, the table top in a horizontal plane.
What you do need to account for is the ability of the table top to expand and contract with the cross members you will mount it to on top of the vertical posts ( legs).
Table irons, sliding dovetails, etc ,will need to be used.

[Joey Stephenson]

The expansion and contraction of the stringer versus the top isn't an issue. The grains will run 90 degrees opposite of each other across the face. Stringer will be in a vertical plane, the table top in a horizontal plane.
What you do need to account for is the ability of the table top to expand and contract with the cross members you will mount it to on top of the vertical posts ( legs).
Table irons, sliding dovetails, etc ,will need to be used.

Good point! I'm not familiar with table irons, what is that?
What if, instead of a single piece connecting board with grain perpendicular to the top, I edge glued planks to make the board in order to put their grain parallel to the table top? Would that mitigate the need for any special connection there, or is that not recommended for strength issues?

[Marc Jeske]

As others said above... There are a number of ways to handle the issue, the common idea is allowing the top to expand and contract independently of the members it sits on.

A simplified explanation below.. with one solution... Marc

http://followyourheartwoodworking.blogspot.com/2012/03/please-dont-make-table-like-this.html

http://www.leevalley.com/en/hardware/page.aspx?c=&p=40146&cat=3,41306,41309


More possibilities...

https://www.google.com/search?biw=1229&bih=608&tbm=isch&sa=1&q=wood+table+top+mounting&oq=wood+table+top+mounting&gs_l=psy-ab.3...12163.12751.0.13143.3.3.0.0.0.0.152.395.0j3 .3.0....0...1.1.64.psy-ab..0.0.0....0.aVRysAn0-qo

[Joey Stephenson]

As others said above... There are a number of ways to handle the issue, the common idea is allowing the top to expand and contract independently of the members it sits on.

A simplified explanation below.. with one solution... Marc

http://followyourheartwoodworking.blogspot.com/2012/03/please-dont-make-table-like-this.html

http://www.leevalley.com/en/hardware/page.aspx?c=&p=40146&cat=3,41306,41309


More possibilities...

https://www.google.com/search?biw=1229&bih=608&tbm=isch&sa=1&q=wood+table+top+mounting&oq=wood+table+top+mounting&gs_l=psy-ab.3...12163.12751.0.13143.3.3.0.0.0.0.152.395.0j3 .3.0....0...1.1.64.psy-ab..0.0.0....0.aVRysAn0-qo

Great info, thanks. I just realized that I had myself confused about the direction of expansion. I swear I know that it isn't longitudinal. It's definitely a Monday morning... :eek: :D

[Marc Jeske]

Also, you did not say if the top boards were glued up to make a wider one piece top, or left as individual .

The first method, though providing an easier to wipe off top, will be less forgiving if not mounted correctly than the separate NOT glued up board method.

If you mount it as all have said above, you can make your top either way and be safe.

Marc

[Marc Jeske]

If you look up data of different species width vs length ratio of change, it's quite dramatic the difference.

If you are a reader check out R. Bruce Hoadley "Understanding Wood"

Excellent book.

Highly recommended by many here. Marc

[Pat Barry]

I plan on making a farmhouse dining table for a friend, and wanted to check here first to make sure I'm not overlooking anything. There will be one fat leg on each end with a board on top to secure to the table top. There will be a stringer between the legs towards the feet. Pretty typical design (see image for a very simplified drawing of the type of table).

This design shouldn't have much of an issue with expansion since the stringer and table top, being made from the same species, should expand/contract at the same rate, right? I'd hate to have an issue where the top expands more than the bottom and weakens/cracks joints after a few years.

369331
I suggest that you should add a couple lengthwise aprons to the underside of the top to increase the rigidity. Otherwise, IMO, the top would need to be much thicker than the sketch shows to eliminate sag and bounce in the tabletop.

[Marc Jeske]

And even more good stuff.... Marc

https://www.google.com/search?q=wood+movement+round+table&source=lnms&sa=X&ved=0ahUKEwiBxtqr4OPWAhWDYyYKHYEoAmsQ_AUICSgA&biw=1229&bih=608&dpr=1.56

[Marc Jeske]

I think in post #3 you were talking about "Breadboard" ends maybe?

If so, study how they are attached if done properly as designed for years ago.. - Allowing for movement.
Marc

[Mike Cutler]

Good point! I'm not familiar with table irons, what is that?
What if, instead of a single piece connecting board with grain perpendicular to the top, I edge glued planks to make the board in order to put their grain parallel to the table top? Would that mitigate the need for any special connection there, or is that not recommended for strength issues?

Joey, It's not a strength issue so much as just having to accommodate the wood for what it naturally going to do. That top is going to expand and contract across it's width, no matter what you do. If you don't factor this in, the top will split. Wood moves and there is nothing that can done to stop it.
Any time you have wood that intersects in any plane, meeting at an angle other than parallel with the grains, you have to accommodate for expansion and contraction, and each species of wood has it's own properties concerning expansion contraction, and then the way the wood was milled will have an effect on expansion contraction. Wood workers have been dealing with this since the first two logs were piled up to make a chair.
If it were me, that table top would only be kiln dried, quarter sawn wood, as the expansion contraction across "Q-sawn" wood, is the most minimal, but still there.
Then I would use table irons on the bottom to allow the table to "float" on the cross members, but still be able to expand and contract.
Table irons come in a few different styles. Some look like a figure eight and some a flat bar that has a machined slot in it. My preference is the latter. They are mortised in place with a router, a screw is wet into the top and it then passes through a lip in the iron and the tops is "slid" into the slot. The slot applies downward pressure to keep the table top flat, but the slot in the iron allows the table to expand and contract within the slot. I know it sound difficult, but believe me, they are very easy to install. The cross members themselves could be router to provide exactly the same function as a table iron.

[Robert Engel]

Your only expansion issue will be attaching top to trestle supports -- only if the grain is running lengthwise (which I hope it is ;-).

Many way to allow for that (slotted screws, clips, etc) with just a little Googling.

Do yourself a favor and do the breadboards ends as mentioned.

I would glue up that top right away and give it time to acclimate.

Hope all goes well!

[Joey Stephenson]

Wow, so many great responses. Thank you all for helping out. I should mention that the legs/stringer will be yellow pine for this first table. The top may also be the same, depending on the customer's budget. I was considering alder due to price, but it is just as soft, if not softer, than yellow pine based on the janka scale. Would that still be a better choice?


Also, you did not say if the top boards were glued up to make a wider one piece top, or left as individual .

The first method, though providing an easier to wipe off top, will be less forgiving if not mounted correctly than the separate NOT glued up board method.

If you mount it as all have said above, you can make your top either way and be safe.

Marc

Yes, the top planks will be glued together.


I think in post #3 you were talking about "Breadboard" ends maybe?

If so, study how they are attached if done properly as designed for years ago.. - Allowing for movement.
Marc

No, I just described it very poorly haha. I was talking about the cross members that are pictured under the top, used to connect the table to the legs/trestles.


Your only expansion issue will be attaching top to trestle supports -- only if the grain is running lengthwise (which I hope it is ;-).

Many way to allow for that (slotted screws, clips, etc) with just a little Googling.

Do yourself a favor and do the breadboards ends as mentioned.

I would glue up that top right away and give it time to acclimate.

Hope all goes well!

No breadboards on this table! I'm not quite ready to tackle that yet. Once the customer (more like friend..) has picked the wood for the top, I'll let it acclimate to my shop, cut, and then glue together.


Joey, It's not a strength issue so much as just having to accommodate the wood for what it naturally going to do. That top is going to expand and contract across it's width, no matter what you do. If you don't factor this in, the top will split. Wood moves and there is nothing that can done to stop it.
Any time you have wood that intersects in any plane, meeting at an angle other than parallel with the grains, you have to accommodate for expansion and contraction, and each species of wood has it's own properties concerning expansion contraction, and then the way the wood was milled will have an effect on expansion contraction. Wood workers have been dealing with this since the first two logs were piled up to make a chair.
If it were me, that table top would only be kiln dried, quarter sawn wood, as the expansion contraction across "Q-sawn" wood, is the most minimal, but still there.
Then I would use table irons on the bottom to allow the table to "float" on the cross members, but still be able to expand and contract.
Table irons come in a few different styles. Some look like a figure eight and some a flat bar that has a machined slot in it. My preference is the latter. They are mortised in place with a router, a screw is wet into the top and it then passes through a lip in the iron and the tops is "slid" into the slot. The slot applies downward pressure to keep the table top flat, but the slot in the iron allows the table to expand and contract within the slot. I know it sound difficult, but believe me, they are very easy to install. The cross members themselves could be router to provide exactly the same function as a table iron.

Yes I plan on orienting the wood this way. I'm still having trouble finding information about the table irons (they sound basically like T-slots???) Do you have a link where I could purchase them? I'm having a bit of trouble visualizing this completely, but I get the general idea.


I suggest that you should add a couple lengthwise aprons to the underside of the top to increase the rigidity. Otherwise, IMO, the top would need to be much thicker than the sketch shows to eliminate sag and bounce in the tabletop.
I definitely will do this, I just left them out of the drawing so that the crossmembers/connectors were visible on the legs. :)

[Marc Jeske]

"Yes I plan on orienting the wood this way. I'm still having trouble finding information about the table irons (they sound basically like T-slots???) Do you have a link where I could purchase them? I'm having a bit of trouble visualizing this completely, but I get the general idea."

Don't my links work ??

Post #4 ? Marc

[Joey Stephenson]

Don't my links work ??

Post #4 ? Marc

Yes I viewed them, but I guess I was expecting something a bit different (and they dont use the "table irons" terminology anywhere that I saw), so I didn't realize that's what was being described. I'm pretty new to this type of work, so I'm a bit slow on the uptake right now! Thanks again.

[Marc Jeske]

Joey - Another also..If you use SYP for the top, keep in mind it is typically dried to only 19% when it leaves the kiln, BUT... I have found stuff sitting in the yard seems to acclimate quickly, cause I seem to find it often around 11% where I live.

Now, keep in mind in my case I am talking a higher grade of 3/4, not 1 1/2 like you would be using, so it may not sell/turnover as fast.

And, if you ARE using 2x construction lumber, it is more probably called "SPF" - a mix of Spruce, Somekinda Pine, and Somekinda Fir, so the hardness varies.

That stuff I would assume will be closer to 19%, so you definitely need to account for the shrinkage.

Please put your location so it shows under your name - As extremes.. Dry AZ will make your top shrink more than wet New Orleans.

Bottom line, even though the entire thread has valid pertinent info, don't get deflated by it.

But I would seriously consider not gluing up the top. Marc

[Marc Jeske]

I'm pretty sure the below link is the talked about "Table Irons"

Otherwise, I got no clue what they are. Marc

http://www.leevalley.com/en/hardware/page.aspx?c=&p=40146&cat=3,41306,41309

[Bill Adamsen]

The leg stretcher (stringer in your verbiage?) is so low that I don't think you'll have any issue. As Robert said ... used breadboard ends to keep the top flat. How much lateral resistance is that "board" attached to the top of the legs providing and what is the contribution of the stretcher? Is it a box stretcher (four pieces)?

[Joey Stephenson]

Joey - Another also..If you use SYP for the top, keep in mind it is typically dried to only 19% when it leaves the kiln, BUT... I have found stuff sitting in the yard seems to acclimate quickly, cause I seem to find it often around 11% where I live.

Now, keep in mind in my case I am talking a higher grade of 3/4, not 1 1/2 like you would be using, so it may not sell/turnover as fast.

And, if you ARE using 2x construction lumber, it is more probably called "SPF" - a mix of Spruce, Somekinda Pine, and Somekinda Fir, so the hardness varies.

That stuff I would assume will be closer to 19%, so you definitely need to account for the shrinkage.

Please put your location so it shows under your name - As extremes.. Dry AZ will make your top shrink more than wet New Orleans.

Bottom line, even though the entire thread has valid pertinent info, don't get deflated by it.

But I would seriously consider not gluing up the top. Marc

I think its SYP. I'm in the north GA area, btw. Can you explain why you wouldn't glue the top? How would that affect expansion if they are edge joined and expanding together?

[Joey Stephenson]

The leg stretcher (stringer in your verbiage?) is so low that I don't think you'll have any issue. As Robert said ... used breadboard ends to keep the top flat. How much lateral resistance is that "board" attached to the top of the legs providing and what is the contribution of the stretcher? Is it a box stretcher (four pieces)?

Well, the board on the legs is basically a crossmember, but mostly the method of connecting the table to the legs (table top will most likely be glued together). I'm all for suggestions for a better way, though!
The purpose of the stretch is for looks and also general stability for the table. That's usually their purpose, right?

[Marc Jeske]

Well, just for the fact that there will be slight gaps form between the boards, rather than cracks in a wider glued up area.

Like if a gap opens or closes a bit, it won't be near as obvious as a crack(s).

Again - If you mount the top so it can be unrestricted.... + and -... you can make the top either way.

But even then, you may have another problem in that depending on the grain on your boards, and if you alternate or not when gluing...some in your control..some not.. it still is safer cause the gaps between planks kinda buffer everything.

The main thing by far that will affect how it looks after being in the Kitchen for a year, is what the MC was when you made it, and what it acclimates to in the house.

The farther apart those two numbers are, the more it will have moved.

So with wet lumber, WAY safer to use like 2x6.. not wider.. and NOT glue up.

AND... study the grain compared to the link below..to decide WHICH side of the board to put "Up"

And, consider the above sentence even when picking the boards for the top at the yard.

Lay them out the correct side up and make sure the tops look good, and you have enough.

Also, you will also see why Quartersawn is the most desirable in the image.

You just have to assume that using this type of wettish wood you will have a "Rustic" look, and it will change in time, possibly even more Rustic !!

But still beautiful in it's own way.

Know what I mean? Marc

369343 YARRRRR can't see that.. heres the link..
http://www.deckmagazine.com/design-construction/finishes-maintenance/wood-decks-that-last_o

[Marc Jeske]

See, even though that article above is about Decking boards, EVERYTHING in it totally applies to your tabletop.

For the relatively minimal $ and time you will have in this table, it will be beautiful.

Hey, it's a Farmhouse Table. Look at the real originals, basic and often made from flawed semi reject wood for economy... usually not by choice.

Marc

[Joey Stephenson]

Well, just for the fact that there will be slight gaps form between the boards, rather than cracks in a wider glued up area.

Like if a gap opens or closes a bit, it won't be near as obvious as a crack(s).

Again - If you mount the top so it can be unrestricted.... + and -... you can make the top either way.

But even then, you may have another problem in that depending on the grain on your boards, and if you alternate or not when gluing...some in your control..some not.. it still is safer cause the gaps between planks kinda buffer everything.

The main thing by far that will affect how it looks after being in the Kitchen for a year, is what the MC was when you made it, and what it acclimates to in the house.

The farther apart those two numbers are, the more it will have moved.

So with wet lumber, WAY safer to use like 2x6.. not wider.. and NOT glue up.

AND... study the grain compared to the link below..to decide WHICH side of the board to put "Up"

And, consider the above sentence even when picking the boards for the top at the yard.

Lay them out the correct side up and make sure the tops look good, and you have enough.

Also, you will also see why Quartersawn is the most desirable in the image.

You just have to assume that using this type of wettish wood you will have a "Rustic" look, and it will change in time, possibly even more Rustic !!

But still beautiful in it's own way.

Know what I mean? Marc

369343 YARRRRR can't see that.. heres the link..
http://www.deckmagazine.com/design-construction/finishes-maintenance/wood-decks-that-last_o

Marc, I really appreciate your input. I will definitely take all of this into consideration. So, when I see table tops at something like restaurants that have many planks edge glued, how do they mitigate these problems that you mentioned? Are most of them usually 5" planks or narrower? I wouldn't try to edge glue 2x12's or anything, but its just good to know what the limit should be in this case.

This is the wood I'm using for the legs/stringer, and may possibly cut into 3" - 5" planks for the top. Any suggestion for inexpensive hardwoods as an alternative?

EDIT: forgot to add link to wood :rolleyes: --- http://www.homedepot.com/p/2-in-x-12-in-x-10-ft-2-Prime-Kiln-Dried-Southern-Yellow-Pine-Lumber-937282/202085957

[Marc Jeske]

One can make a 5 foot wide table from ONE super wide board (measured across grain, NOT length) ... and IF it was allowed to achieve the MC that it will eventually achieve (equilibrium) where it will be used BEFORE it was final thicknessed, AND the humidity in the place used was pretty constant, it could, depending on stuff, but could stay pretty flat.

Google info on making tabletops and you'll get a wealth of info.

Texting is too difficult, too slow for me.

You will do fine no matter what you do, just make sure whoever owns this table realizez "Rustic".

Joey - Sending you PM in a moment. Marc

[Joey Stephenson]

Good page about wood movement, definitely a good reference.

http://workshopcompanion.com/KnowHow/Design/Nature_of_Wood/2_Wood_Movement/2_Wood_Movement.htm

[Bill Adamsen]

Well, the board on the legs is basically a crossmember, but mostly the method of connecting the table to the legs (table top will most likely be glued together). I'm all for suggestions for a better way, though! The purpose of the stretch is for looks and also general stability for the table. That's usually their purpose, right?

There are so many ways to build a table. Have you a multi dimensional drawing or photo of similar? In use, typically one likes to be able to pull a chair up close to a table. To accomplish that, the designer uses an H stretcher (center lengthwise) and extends the ends well beyond the legs (if there is a stretcher) so that a chair can be pulled up to the end. Typically stretchers would attach to the legs and each other with mortise and tenon. My simple understanding of your design was that each leg was perhaps 8" to 10" square with a larger square board on top screwed down into the leg and screwed up into the top. I've never seen a table done like that but it seems like a creative and reasonable solution. If the top is made of an engineered wood (plywood) the approach should work fine. Even with glued boards it should work fine. The distance between the screws on the boards is not that great, and the legs will simply move apart with the expansion/contraction of the top. Now if you expect to stretch a board across two legs on one end of the table – and also screw it into the top – forget it. That's a cross grain construction approach since the top will move seasonally yet the board (grain in opposite direction) screwed in underneath will not move. Over a wider stance (say 28"-30") that is a recipe for eventual failure. Also note that if you are building with boards many (myself included) would recommend some sort of breadboard end to keep the tabletop flat and yet allow seasonal movement. Now there are ways to make that cross grain board "slide" with various techniques such as dovetails or other mechanical connectors specifically designed to slide. Some, like the dovetail can also keep the top flat.

As I said when starting this response ... there are so many ways to build a table.

[Joey Stephenson]

There are so many ways to build a table. Have you a multi dimensional drawing or photo of similar? In use, typically one likes to be able to pull a chair up close to a table. To accomplish that, the designer uses an H stretcher (center lengthwise) and extends the ends well beyond the legs (if there is a stretcher) so that a chair can be pulled up to the end. Typically stretchers would attach to the legs and each other with mortise and tenon. My simple understanding of your design was that each leg was perhaps 8" to 10" square with a larger square board on top screwed down into the leg and screwed up into the top. I've never seen a table done like that but it seems like a creative and reasonable solution. If the top is made of an engineered wood (plywood) the approach should work fine. Even with glued boards it should work fine. The distance between the screws on the boards is not that great, and the legs will simply move apart with the expansion/contraction of the top. Now if you expect to stretch a board across two legs on one end of the table – and also screw it into the top – forget it. That's a cross grain construction approach since the top will move seasonally yet the board (grain in opposite direction) screwed in underneath will not move. Over a wider stance (say 28"-30") that is a recipe for eventual failure. Also note that if you are building with boards many (myself included) would recommend some sort of breadboard end to keep the tabletop flat and yet allow seasonal movement. Now there are ways to make that cross grain board "slide" with various techniques such as dovetails or other mechanical connectors specifically designed to slide. Some, like the dovetail can also keep the top flat. As I said when starting this response ... there are so many ways to build a table.
Bill, yes I plan on attaching the stretcher to the legs with mortise and tenon, or possibly a wedged through-tenon. As for the top, yes it would be essentially a big fat cross brace board which screw into the top of the legs, and then the table would get screwed into that, one on each end. I would use slotted screw holes to allow for movement of the top. Something like that, anyway.
Side note... your post showed up in the middle of page 2 here, even though it is the newest post. I swear, this forum has issues haha.

[Joey Stephenson]

I looked at my dining room table, very similar to what I want to build. Big solid expensive table. It has many narrow ( 3" - 5" ) boards running the length of the 2 halves (breaks in the middle for the leaves). The aprons on it are screwed into the top, no buttons or table fasteners. The apron corners are mitered together, with an interior block screwed to each corner of the apron to help hold it together. I've never noticed any issues with it over the years, yet it seems to break the rules being discussed here (apron hard fastened in across the grain...). What am I missing?

[Marc Jeske]

Bill, yes I plan on attaching the stretcher to the legs with mortise and tenon, or possibly a wedged through-tenon. As for the top, yes it would be essentially a big fat cross brace board which screw into the top of the legs, and then the table would get screwed into that, one on each end. I would use slotted screw holes to allow for movement of the top. Something like that, anyway.
Side note... your post showed up in the middle of page 2 here, even though it is the newest post. I swear, this forum has issues haha.

Yup, the slotted screw holes w the screws not over tight sounds great for this Table.

Re: Your existing DR Table - I'm sure you would know, but if it was veneer over a stable core, how you explained would work.

Otherwise, if solid wood..You are totally correct in understanding that it goes against conventional methods. Marc