[Grund1019]

I recently glued up a walnut, 3/4" thick table top roughly 5' x 32". I used Titebond III and biscuits to join the boards together. I finished it with ArmRSeal on all sides and everything turned out great. I have a metal pedestal base that I will be mounting the table top onto. The metal base has an 11"x11" square plate that has slotted holes to screw the table top to. I wanted to double the wood thickness in the area the 11"x11" plate would attach to on the bottom side of the table. I added a small glued up square of the same thickness of walnut. I glued and screwed this second slab on. So I would have 1.5" total thickness of wood where I was going to screw into. I did this only to give me more material to screw into to connect my metal base. The picture shows exactly what I did (pre ArmRSeal). Also added a picture of the finished product top side.


I'm now really starting to second guess this because the top slab needs to be able to move and adapt to whatever environment it is in. I'm thinking that my second glued up section will restrict the actual table top from being able to move. And my second section is going crossways from the board direction of my actual table top. My question is, do I just wait and see if this thing starts cracking because I didn't allow my top surface to move? Just looking for any opinions on what to expect/what to do. Since I glued everything together, really not sure how to go back from that. Any advice would be greatly appreciated.


Thanks!

 

[Steve Neul]

The plate on the bottom would be alright if the holes for the screws were elongated. If you use pan head screws with washers and not torque the screws down real tight it would allow for wood movement. It would be a whole lot easier to adjust the plate now rather than waiting until the top cracks. With the rounded shape of the top it would be difficult at best to reglue.

 

[woodnthings]

All you had to do is ....

If you had oriented the second plate "with" the long grain of the top all the wood would move in the same direction at the same time and no movement issues would come up. Sorry, but I'm a bit late with my advice..... :sad2:

 

[Tennessee Tim]

I recently glued up a walnut, 3/4" thick table top roughly 5' x 32". I used Titebond III and biscuits to join the boards together. I finished it with ArmRSeal on all sides and everything turned out great. I have a metal pedestal base that I will be mounting the table top onto. The metal base has an 11"x11" square plate that has slotted holes to screw the table top to. I wanted to double the wood thickness in the area the 11"x11" plate would attach to on the bottom side of the table. I added a small glued up square of the same thickness of walnut. I glued and screwed this second slab on. So I would have 1.5" total thickness of wood where I was going to screw into. I did this only to give me more material to screw into to connect my metal base. The picture shows exactly what I did (pre ArmRSeal). Also added a picture of the finished product top side.


I'm now really starting to second guess this because the top slab needs to be able to move and adapt to whatever environment it is in. I'm thinking that my second glued up section will restrict the actual table top from being able to move. And my second section is going crossways from the board direction of my actual table top. My question is, do I just wait and see if this thing starts cracking because I didn't allow my top surface to move? Just looking for any opinions on what to expect/what to do. Since I glued everything together, really not sure how to go back from that. Any advice would be greatly appreciated.


Thanks!

The MAIN "problem" is you glued it cross grain which will give you trouble in time....you could've glued IF with the grain as movement will be same direction. Elongated screws holes only crossgrained would've worked as it would allow MC changes to work together, BUT you'd probably used a screw longer than 3/4" to anchor top THEN you'd be back to the movement issue as the screw goes from one into the other crossgrain.

 

[Toolman50]

The second wooden plate you made will most likely wreck your table.
We have post after post describing tables cracking, splitting, buckling etc. because the wood cannot move. Even seasoned kiln dried wood will move with changes in the humidity.
The pedestal had elongated holes which were made purposely to allow for this wood movement.
If you had screwed this stand directly to your table top and only snugged the screws you will be much better off.

 

[Grund1019]

Thanks for all the quick responses, I appreciate that. This overall was just a stupid mistake. I knew about table movement, but definitely wasn't on my mind enough when I made the decision to do what I did with that second plate. All the responses have definitely confirmed my thoughts/fear. Last question though, do I just wait and see what happens now? I glued that second wooden plate down and screwed it. Last night I went back and loosened all the screws, but the plate is still held down by glue. If I try to take that second wooden plate off after it has been glued, would that be impossible and would it just wreck everything? I know glue is super strong so would I even be able to get that plate off without tearing my table top apart? At the back of my mind I was hoping that maybe it wouldn't be a huge issue since the second smaller plate is so much smaller in comparison to the overall size of the table top.

Thanks again for the help.

 

[woodnthings]

You can either .....

You can let it "self destruct" , which it may not, OR you can attempt to remove the second plate. You can break the "rules" sometimes and get away with it, I know I have. A wait and see approach is what I would do in this case. Others may not agree, but whether you destroy it OR it cracks on it's own, won't make much difference at this point. Best of luck to you! :wink:

 

[Grund1019]

To remove the smaller second wooden plate, my thought is to take my skillsaw and set the depth to 3/4" and take swipes at that second plate every 1/4 inch or so. The depth would be set so I don't contact my top plate. Then when there is also splinters and small strips left, I can go at it with a chisel and eventually my ros?

Thoughts?

 

[Toolman50]

I would remove the second plate. I’d start with a chisel and take my time. If you’re careful, when you get it within about 1/8” from the table bottom, you can practice your hand plane skills until the only evidence remains will be your screw holes.

 

[Steve Neul]

If it were me I would remove the screws and see if I could drive a chisel under the bracked and see if it would pop off. If not then run a long sawzall blade under it and see if I could cut it off. Even if it gouges the top the bracket and the top would have the same shape so you could just elongate the holes on that bracket and put it back on.

 

[woodnthings]

This is the best approach ...

To remove the smaller second wooden plate, my thought is to take my skillsaw and set the depth to 3/4" and take swipes at that second plate every 1/4 inch or so. The depth would be set so I don't contact my top plate. Then when there is also splinters and small strips left, I can go at it with a chisel and eventually my ros?

Thoughts?

This method is the least likely to damage to underside of the top. Just be certain to remove all the glue using a scraper, a hand plane and maybe some hot water and rags IF you are going to glue another piece back on with the grain running parallel to the top.

 

[Grund1019]

Thanks for all the feed back guys. I tried the skill saw method and then I took things down with a hand plane. Had to go back to work so I couldn't finish but I will tonight. I'm glad I decided to do the extra work now instead of taking a chance later down the road.

For mounting the table top to the metal base (metal base attachment point is a 11"x11"x1/8" piece of metal with 4 slots) will putting 4 pan head screws probably 1/2" deep into the wood be enough? Wish I had more beef to screw into, but the table top is only 3/4" thick. And overall size again is roughly 5'x32".

 

[woodnthings]

That doesn't seem like enough to me.....

Thanks for all the feed back guys. I tried the skill saw method and then I took things down with a hand plane. Had to go back to work so I couldn't finish but I will tonight. I'm glad I decided to do the extra work now instead of taking a chance later down the road.

For mounting the table top to the metal base (metal base attachment point is a 11"x11"x1/8" piece of metal with 4 slots) will putting 4 pan head screws probably 1/2" deep into the wood be enough? Wish I had more beef to screw into, but the table top is only 3/4" thick. And overall size again is roughly 5'x32".

Not only are there too few screws but they don't go deep enough. If you make a second plate and orient it as suggested, with the grain, that would offer way more support and screw penetration for longer and larger diameter screws. An "unscheduled" pressure applied by a child or elderly person for support would be what I'm most concerned with.

 

[woodnthings]

So, I'm typing away on a round top table on a steel base

The 48" diameter table I'm typing on has a round top made of particle board. Underneath is a 24" square of 3/4" plywood screwed to the particle board. Obviously, the particle board won't move like a glued up section of hardwood, so that's not an issue. What you could do is use a 3/4" square under your hardwood and use slotted holes to secure it to allow for movement. It's a simple solution maybe worth a try..... :surprise2:

 

[Toolman50]

Instead of continuing with a 2nd square for addition support, consider two boards each about 3” wide, 30” long and at least 3/4” thick. These two boards would center on the mount holes running lengthways. This will give you more support lengthways. Each board could be attached to the table bottom with 4 screws. This adds more screws and adds more support to the length.

 

[Grund1019]

If I went with the route Toolman50 suggested, if that 30" board ran across a main table top seam longitudinally (this is how things work out with regard to where the metal base mounting holes are) so the 30" board is overlapping two boards. I would attach that 30" board with screws to two different boards that make up the table top, do you think that will restrict movement of the table top? Then I was planning on screwing through the metal base into the double thickness. Base has slots though so table movement wouldn't be restricted.

 

[Toolman50]

If I went with the route Toolman50 suggested, if that 30" board ran across a main table top seam longitudinally (this is how things work out with regard to where the metal base mounting holes are) so the 30" board is overlapping two boards. I would attach that 30" board with screws to two different boards that make up the table top, do you think that will restrict movement of the table top? Then I was planning on screwing through the metal base into the double thickness. Base has slots though so table movement wouldn't be restricted.

I was thinking of running two support boards lengthways, with the grain of the wood. Not at a 90 degree across the table. I thought this could be done without spanning multiple boards with the 3” support.
If the 3” support spans the seam on two boards, I would only install screws in one of the two boards.

 

[Alchymist]

Thanks for all the feed back guys. I tried the skill saw method and then I took things down with a hand plane. Had to go back to work so I couldn't finish but I will tonight. I'm glad I decided to do the extra work now instead of taking a chance later down the road.

For mounting the table top to the metal base (metal base attachment point is a 11"x11"x1/8" piece of metal with 4 slots) will putting 4 pan head screws probably 1/2" deep into the wood be enough? Wish I had more beef to screw into, but the table top is only 3/4" thick. And overall size again is roughly 5'x32".

Another approach: 2 pieces of light angle iron perhaps 1X1 inch about 18-20 inches long. Angle cut the ends and smooth. Bolt these to the top of the pedestal base. Use 3/4" screws in several places in each angle iron, in slotted holes. Paint angle iron to match pedestal. Will give a much longer support base, and be hardly noticeable. with a 20" length, 5 screws per side wouldn't be unreasonable.

 

[35015]

Hello,

If you are interested in a more traditional and long term solution to your challenge with this table, or others like it in the future...I use and recommend some version of a sliding dovetail joint assembly often...or...(in some cases) a method by which the top is "sewn" to the apron which is probably beyond the scope of this discussion or project.

Both work remarkably well, and there is not glue involved either...only joinery systems.

Below is the best example I can think of in my files. Miya San's work is well know in the furniture world and based on millenia old traditions. It is much easier that it appears to facilitate this type of joint...

Good Luck,

j

https://youtu.be/rMtSc2MJLcw?t=1158

 

[woodnthings]

How would that work?

Hello,

If you are interested in a more traditional and long term solution to your challenge with this table, or others like it in the future...I use and recommend some version of a sliding dovetail joint assembly often...or...(in some cases) a method by which the top is "sewn" to the apron which is probably beyond the scope of this discussion or project.

Both work remarkably well, and there is not glue involved either...only joinery systems.

Below is the best example I can think of in my files. Maya San's work is well know in the furniture world and based on millenia old traditions. It is much easier that it appears to facilitate this type of joint...

Good Luck,

j

https://youtu.be/rMtSc2MJLcw?t=1158

I can't envision how a sliding dovetail would work on this top which has no apron and a steel base. I'm confused. :sad2:
I did enjoy the video and the coffee table was beautiful.