# 4X6 diy table top problems



## danielac (Mar 18, 2014)

Hi everybody,

A few months ago I built a heavy table top by gluing together 5 foot lengths of 4x6 Douglas fir. I applied the glue evenly (Titebond 2), and then ratcheted the entire table top together with about 5 ratchet straps as tight as I could get them. I then braced the bottom with 3 2x4's (glued and screwed) spaced evenly. It's an apronless design so the legs are attached using hanger bolts. The tabletop was then stained and sealed on all sides (top, sides, and bottom) as well as the legs.

The design was too optimistic, as I'm now starting to see some sagging and separating. The 2x4's have bowed under the weight of the wood, which I should have expected, and there is a gap forming where the glue is starting to separate between two of the lengths.

I have a few questions:

Any recommendations on how to fix this? I put the table on top of saw horses and ratcheted some braces across the top to straighten it out. Any better ideas? Once it's straight, what kind of bracing would you recommend on the bottom to keep it from sagging in the future? Also, what's the best way to close the gap in the middle so that it won't open again?

Because I really like the table design, I would like to build another one using more or less the same method but obviously structurally more sound. What would you do design-wise to prevent these problems? I'm thinking of using those metal stakes like they use for concrete, drilling some holes in it, and using those for braces with some lag screws. Better ideas? 

If I prevent the sagging, will that also prevent the wood separation? What do I need to do to make sure that the glue joints stay closed? Do I need to run giant lag screws across the length?

Too many questions, and if you made it this far then I appreciate it. Let me know your thoughts.

Here's a picture when it was new to give you an idea of what we're working with (the bolts on the side are just for show, only 2 inches long):










Thanks,
danielac


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## ryan50hrl (Jun 30, 2012)

A number of things have likely occurred. 1st is that the wood probably wasn't dry and stable. 

2nd is the design didn't account for wood movement. The only way to make wood not move, is to slice it up and make plywood. Since no one wants a plywood table, you need to account for wood moving. There isn't anything you can build and expect to look good that will contain woods movement. 

3rd, an apron serves a purpose, it supports the top and helps minimize sagging. Sadly I think your table is doomed to sag and split. 


Sorry for the bad news.


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## tinstar (Mar 5, 2014)

Did the top sag or cup? If you glued and screwed the 2x4's perpendicular to the top, the 4x6's shrunk( probably a high moisture content because they are construction lumber) and the joints pulled apart because the 2x4's didn't allow for movement . You'll have to cut it to reuse the lumber.

Bad news is it might not be worth the effort to repair.

For your next table, I would make sure the wood is dry and the joints are tight. You could use a wood spline or dowels if you like. Get some pipe clamps instead of ratchet straps. I would leave out the 2x4's. I don't think you'll need an apron or supports with a 3 1/2" thick top. You should be able to span 5' without sag.


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## Alchymist (Jan 2, 2011)

If the fit between the 4X6's is not flat, ie, no bow or gaps, that can cause problems. Mating surfaces must be near dead flat. A trip through a jointer is probably the best guarantee, and of course dry wood.


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## woodnthings (Jan 24, 2009)

*It this were my table ...*

I would just use the 4" X 6" without any underbracing, because that's your problem. The 2" X 4's won't allow expansion and contraction of the 4 X 6's. 

A pretty stable table top could be made using the 4" X 6" alone, possibly with splines to align them while gluing.
You might want to make more of the joints/seams by using a small round over bit IF they didn't come already rounded. That way any small gaps won't "read" as much as they would if a glue line joint was used.

It is a handsome design, and I would not have thought to make one this way. I would like to see you succeed with it.

I hope the legs are securely fastened because they will certainly want to get racked from side to side. Maybe a large tenon into the bottom of the 4 X 6's.... Maybe make a recess into the bottom the same size as the legs...?
Some ideas here:
http://forums.finewoodworking.com/f.../attaching-legs-thick-table-top-without-apron


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## Oneal-Woodworking (Apr 14, 2013)

danielac said:


> Any recommendations on how to fix this? I put the table on top of saw horses and ratcheted some braces across the top to straighten it out. Any better ideas? Once it's straight, what kind of bracing would you recommend on the bottom to keep it from sagging in the future? Also, what's the best way to close the gap in the middle so that it won't open again?
> 
> Because I really like the table design, I would like to build another one using more or less the same method but obviously structurally more sound. What would you do design-wise to prevent these problems? I'm thinking of using those metal stakes like they use for concrete, drilling some holes in it, and using those for braces with some lag screws. Better ideas?
> 
> ...


If it is bowing in the middle you will save time by just recutting it down all the seams and then trueing those surfaces before regluing it all back together correct and flat. You would be surprised at how difficult it is to make a piece of wood flat with metal braces / angle iron when the wood 'wants to be otherwise'. Takes a lot of metal to do much.

It we were just talking about closing a small gap here then the places on the sides where you have the bolts would be a PERFECT place to hide some long sections of allthread and be able to bolt the things together. You would first drill the larger holes on the sides big enough for your nuts / bolts / and tools to get in there and then drill the smaller holes for the allthread that go completely through from side to side connecting the larger holes you already drilled. You could then use larger but very short bolts to 'hide' the holes you made same as you have done already.

Drilling the smaller holes from side to side and having them meet up correctly in the middle is made harder because all of your parts are assembled already... :yes:


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## Steve Neul (Sep 2, 2011)

If I were making a top like that I would have mortised the timbers to accept about 3 pieces of all-thread. It's just too much stress all those heavy timbers pulling against each other.  It's a little late for that. The holes needed to be drilled with a drill press while there were individual timbers. If it is bowing lengthwise I think it's just a fluke. As heavy as those timbers are it shouldn't be sagging. 

If you can remove the top you might take a circular saw and drop cut a slit lengthwise on each side about 2" deep almost the length of it on the underside and insert some 2" angle iron screwing it to the timbers. It will probably initially probably bow the iron however over time I think it will straighten it.


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## Oneal-Woodworking (Apr 14, 2013)

Steve Neul said:


> If I were making a top like that I would have mortised the timbers to accept about 3 pieces of all-thread. It's just too much stress all those heavy timbers pulling against each other. *It's a little late for that.* The holes needed to be drilled with a drill press while there were individual timbers. If it is bowing lengthwise I think it's just a fluke. As heavy as those timbers are it shouldn't be sagging.
> 
> If you can remove the top you might take a circular saw and drop cut a slit lengthwise on each side about 2" deep almost the length of it on the underside and insert some 2" angle iron screwing it to the timbers. It will probably initially probably bow the iron however over time I think it will straighten it.


It can still be done. It just got a lot harder because he has to buy much longer bits and then deal with lining up the holes in the middle.

That part is going to be tricky. :yes:


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## Steve Neul (Sep 2, 2011)

OnealWoodworking said:


> It can still be done. It just got a lot harder because he has to buy much longer bits and then deal with lining up the holes in the middle.
> 
> That part is going to be tricky. :yes:


Even with a ship auger I think that would be awful hard.


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## woodnthings (Jan 24, 2009)

*leave it or fix it*

Fixing it, what ever that means, will not be easy as it is "finished" and glued together. Drilling 30" deep holes, just guessing at that dimension... just won't happen. Sawing the whole thing apart won't be easy either as it is 3 1/2" thick. so...let's just leave it and take the information and suggestions presented and make the next one a bit different. 

It is my experience than timbers that size whether milled Oak or construction lumber will check and split and may even take a curve along the length. So that makes this whole project difficult to accomplish and have "perfect" seams and joints. So I suggested earlier that one solution would be to emphasize them rather than try to hide them or make them glue line perfect.

Another solution would be to make a torsion box and face it with thin stock to give the appearance of a thicker top without the warping and checking of solid wood.


my .02$


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## tinstar (Mar 5, 2014)

The glued and screwed 2x4's are the cause of the problem. I don't think that bolting the top to metal is going to stop movement. Remove the 2x4's. Rip and re-glue. The top is going to check and split but if the glue joints are good it should remain structurally sound.


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## danielac (Mar 18, 2014)

Thanks for all the responses.

First thing I guess I can clear up is that the table top is actually cupping, not sagging. Lengthwise, as you'd expect, there's no problem. It's the width that's giving. I'm going to get rid of the 2x4's on the bottom and then try and straighten out the table top. I might then try and close the gap using clamps or ratcheting and then use an extra long bit (found this idea http://www.instructables.com/id/Wood-harpoon-drill/ I think it'll hold up as long as I only drill a little at a time) to drill across most of the table and drive hhuge lag screws to hold. Seems to be about the best I can do short of taking the table apart (which may be necessary). Bad idea?


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## Steve Neul (Sep 2, 2011)

If the table has a skirt where you can hide it, you might replace the 2x4's with angle iron. Just elongate the mounting holes and install it with lag screws leaving the screws a tiny bit loose. If that doesn't initially pull the bow out I think it would straighten over time.


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## GeorgeC (Jul 30, 2008)

tinstar said:


> Did the top sag or cup? If you glued and screwed the 2x4's perpendicular to the top, the 4x6's shrunk( probably a high moisture content because they are construction lumber) and the joints pulled apart because the 2x4's didn't allow for movement . You'll have to cut it to reuse the lumber.
> 
> Bad news is it might not be worth the effort to repair.
> 
> For your next table, I would make sure the wood is dry and the joints are tight. You could use a wood spline or dowels if you like. Get some pipe clamps instead of ratchet straps. I would leave out the 2x4's. I don't think you'll need an apron or supports with a 3 1/2" thick top. You should be able to span 5' without sag.


Cupping is most likely. I cannot imagine a 4x6 sagging, unless you have been resting your engine block on it.

George


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## Oneal-Woodworking (Apr 14, 2013)

Steve Neul said:


> Even with a ship auger I think that would be awful hard.


 
Last time I did something similar - I bought and used regular (meaning NOT Spade or Auger bits) drill bits that were @ 24" long. I started with the smallest dia. bit in the set and drilled slightly more than halfway through each side of my material. Once I had the small holes 'connecting' I slowly went up in sizes with my bits until I got to the finished size hole that I needed for the allthread to fit inside of. 

I am guessing the width of the top I worked on was @ 40 or so inches 

FWIW - The one I worked on was cupped as well and the angle Iron did not do jack but bend to fit the curve in the top and break lag bolts. Total waste of time and had to eventually recut along every seam to get it back 'right'. Wasted an entire day screwing with the angle iron because I 'thought' it would be faster and easier than recutting and reassembling / refinishing. This guys tops is a good bit thicker that the one I dealt with and going to be harder to bend with steel in my opinion.


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## ryan50hrl (Jun 30, 2012)

The thickness and size of steel that would be needed to force that back to flat would be visible from all sides and weigh enough to give you a hernia wrestling it in place. Woods surprisingly strong.


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## Oneal-Woodworking (Apr 14, 2013)

danielac said:


> Thanks for all the responses.
> 
> First thing I guess I can clear up is that the table top is actually cupping, not sagging. Lengthwise, as you'd expect, there's no problem. It's the width that's giving. I'm going to get rid of the 2x4's on the bottom and then try and straighten out the table top. I might then try and close the gap using clamps or ratcheting and then use an extra long bit (found this idea http://www.instructables.com/id/Wood-harpoon-drill/ I think it'll hold up as long as I only drill a little at a time) to drill across most of the table and drive hhuge lag screws to hold. Seems to be about the best I can do short of taking the table apart (which may be necessary). Bad idea?


That is not the bit you want to use... You will have hell getting that to go in even a semi straight line at any sort of distance or depth... :yes:

This is what I used: http://www.harborfreight.com/516-in-38-in-716-in-25-in-long-wood-bit-set-3-pc-68823.html


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## Oneal-Woodworking (Apr 14, 2013)

woodnthings said:


> Fixing it, what ever that means, will not be easy as it is "finished" and glued together. *Drilling 30" deep holes, just guessing at that dimension... just won't happen.* *Sawing the whole thing apart won't be easy either as it is 3 1/2" thick.* so...let's just leave it and take the information and suggestions presented and make the next one a bit different.
> 
> my .02$


Would take less than 30 minutes for me to drill those holes if they were 'only' 30 inches long. That is really only 15 (+ a little extra) inches deep if coming at it from both sides and meeting in the middle. 

Sawing it apart can be done easily with a skillsaw and a straight edge / guide if one is willing to flip it over and cut from both sides. Pieces are going to have to be 'joined' anyway (or should be) before reassembly no matter what saw is used to cut it apart.


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## Steve Neul (Sep 2, 2011)

The problem with drilling a hole like that with a paddle bit is it will tend to follow the soft part of the grain and could turn and come out the face or the bottom instead. A ship auger if you manage to get it going parallel with the face will be more likely to continue going in a straight line. I think with 6 4x6's the size of the top is closer to 33" wide.


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## woodnthings (Jan 24, 2009)

*If you saw the thing apart...*

If you saw the top apart down the glue joints, none of this "deep hole" drilling discussion is necessary AND in order fix it "correctly" you have to saw the thing apart....:yes:


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## Oneal-Woodworking (Apr 14, 2013)

Steve Neul said:


> The problem with drilling a hole like that with a paddle bit is it will tend to follow the soft part of the grain and could turn and come out the face or the bottom instead. A ship auger if you manage to get it going parallel with the face will be more likely to continue going in a straight line. I think with 6 4x6's the size of the top is closer to 33" wide.


Agree paddle bit is no good but respectfully suggest auger bit may not be so good either as they tend to 'pull' themselves into the workpiece and one may lose a bit of control that way. 

A 'regular' type bit will allow one to go nice and easy (slow) as they get from A to B.


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## Oneal-Woodworking (Apr 14, 2013)

woodnthings said:


> If you saw the top apart down the glue joints, none of this "deep hole" drilling discussion is necessary *AND in order fix it "correctly" you have to saw the thing apart....:yes:*


Yes. :yes:

Steve mentioned proper way to do the allthread near the beginning of this thread. :thumbsup:

Always much harder to 'fix' things after the fact. :yes:


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## woodnthings (Jan 24, 2009)

*leave it alone*

It has "character" now. It ain't perfect.:no:


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## danielac (Mar 18, 2014)

*Drilling tips*

Thanks a lot for all the helpful responses. Once I took the 2x4's off and let the top rest on some saw horses gravity did the trick and straightened the top out.Now it's just a matter of securing it. I really like the allthread idea, and it could be my best bet. The only trick is drilling across the tabletop. If I use an extra long bit, does anybody have any tips on drilling perfectly straight through such a long distance? If I made a homemade bushing drill guide and clamped it to the side of the table, could that be reliable enough to ensure I come out the other side in a decent spot?
If meeting in the middle is recommended, any tips on how to drill precisely enough to pull that off?

Thanks again for the advice. I think the table may be salvageable without tearing it apart, but I may just be being stubborn.


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## Steve Neul (Sep 2, 2011)

danielac said:


> Thanks a lot for all the helpful responses. Once I took the 2x4's off and let the top rest on some saw horses gravity did the trick and straightened the top out.Now it's just a matter of securing it. I really like the allthread idea, and it could be my best bet. The only trick is drilling across the tabletop. If I use an extra long bit, does anybody have any tips on drilling perfectly straight through such a long distance? If I made a homemade bushing drill guide and clamped it to the side of the table, could that be reliable enough to ensure I come out the other side in a decent spot?
> If meeting in the middle is recommended, any tips on how to drill precisely enough to pull that off?
> 
> Thanks again for the advice. I think the table may be salvageable without tearing it apart, but I may just be being stubborn.


At this point I would avoid the allthread like the plague. Even trying to drill half way through from each side it would be as close to impossible to have it meet in the middle as you could get. The drill bit would be more likely to follow the grain and come through the face. The only way to really have done that is to drill each 4x6 on a drill press before it was jointed and glued together. Just keep that in mind for a future project.


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## Oneal-Woodworking (Apr 14, 2013)

danielac said:


> Thanks a lot for all the helpful responses. Once I took the 2x4's off and let the top rest on some saw horses gravity did the trick and straightened the top out.Now it's just a matter of securing it. I really like the allthread idea, and it could be my best bet. The only trick is drilling across the tabletop. If I use an extra long bit, does anybody have any tips on drilling perfectly straight through such a long distance? If I made a homemade bushing drill guide and clamped it to the side of the table, could that be reliable enough to ensure I come out the other side in a decent spot?
> If meeting in the middle is recommended, any tips on how to drill precisely enough to pull that off?
> 
> Thanks again for the advice. I think the table may be salvageable without tearing it apart, but I may just be being stubborn.


I will try to remember to take some pictures for you tomorrow about how to do this...

I ain't in the mood now to type a lot and a few pictures would help you better understand. :yes:


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## Tony B (Jul 30, 2008)

danielac said:


> Hi everybody,
> 
> A few months ago I built a heavy table top by gluing together 5 foot lengths of 4x6 Douglas fir.
> *You probably used lumber grade wood and not furniture grade. The wood would then not have been dried good enough for furniture. Indoors it would start to shrink and warp. *
> ...


 I have not read the other posts here and I'm sure others have suggested ways to re-design.

Best of luck.
Tony B


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