Help for 7ft round table

CGIII · January 10, 2019, 11:04:32 AM

I'm looking for resources to help me build a 7 foot diameter, round, dining room table. I've googled and youtube'd but cant find anything close to 7 feet in size. I'm using Ambrosia Maple 13/16" for the top. (I would prefer thicker but that's what the store near me has available.) I'm using dowels for alignment.
My main areas of ignorance are:
How do I ensure the ends dont go in different directions when the weather changes? Since it's round I've ruled out a breadboard end.
Attaching to the base? Are z clips enough for something this size?

GAB · January 10, 2019, 11:31:48 AM

Just be careful not to build something that you can't get into the house.
GAB

btulloh · January 10, 2019, 11:51:33 AM

If it's edge glued the ends will stay together. You might get a little wave depending on the grain. Choose your lumber carefully with regard to where it came from in the tree. Not close to bark, not too close to the pith. Quarter sawn would be more stable, but that may not be the look you want. The apron can help keep the edges of the top from doing something you don't want. The apron can act like battens and one of it's jobs is to keep the top flat. You might even think about using making a round apron, although that adds a lot of complexity.

I'm not a fan of the z-clips or some of the other metal fasteners especially on larger pieces. I prefer slotting the apron to allow for wood movement across the grain. Use pan head screws to fasten the apron if you do the slots.

Just my .02.

Brad_bb · January 10, 2019, 03:16:09 PM

You probably want the edge to be thicker so I imagine you'll be gluing curved pieces about the same thickness to the underside around the perimeter. How are you planning to make it. Straight glue up square and then cutting it out in a circle? or making pie wedge sections? There are many ways to do it.

CGIII · January 10, 2019, 03:49:47 PM

I'm gluing it square then cutting out the circle with a router.

bwstout · January 10, 2019, 04:08:38 PM

Make sure the moisture content is at or below 10% and you lumber has set inside your house for 3 to 4 weeks to accumulated to the climate inside. this will be a big factor in it moving after you have it built the z clamps should be enough the top will need to be able to move some as the climate changes inside your house. You might have more issue with the thinner lumber cupping at the ends. I built one square with 3/4 made 2 mistake of not letting it accumulate and not finishing it on the underside it cupped and I had it screwed down with pocket screws. but have done 3 more with 1" and 2" have had no issue with them. Dry lumber is the key and finishing on both sides.

low_48 · January 10, 2019, 10:53:51 PM

Dowels will drive you crazy to get good alignment over a 7' board. They won't add any more strength than the glue itself. What kind of clamps do you have that are 8' long? Are you going to use some kind of floor sander to flatten it? Since we have no idea what the base design is, it's hard to say if z clips will work. At 7', it could change as much as 3/4" in width from season to season. No clips have that long of leg. It's going to be incredible difficult to get to the center to apply a finish. The center of that thing is going to be a wasteland when everyone is sitting around it.

Ianab · January 11, 2019, 01:54:58 AM

Quote from: CGIII on January 10, 2019, 03:49:47 PM
I'm gluing it square then cutting out the circle with a router.

You will save some wood if you do your blank in a roundish shape. The middle boards will of course have to be 7 ft, but they can taper off towards each side. The outside ones may only need to be 4ft long? Some graph paper and compass will let you work this out, depending on the width of your original boards.
I agree dowels will be pain in the behind. They aren't needed for strength, but if you want something to help with alignment as you are gluing up, biscuits or some small splines don't have to be as precise, they only have to line up exactly on depth, and that's easier. Make sure they are far enough in so you don't cut into them as you trim up the final circle.
As for attaching the top? I use wooden "buttons". That's a "fat L" shaped piece of wood. It screws into the bottom of the tabletop, and the "Tab" then slots into a groove along the apron under the table. Tab, in a groove, so it can move as much as it needs. The centre of the top can be attached as firmly as you want, as long as it's able to slide further out. If you go that way, only attach it to the end aprons, the top could be sliding up to 1/2 an inch at the edges, and bad things might happen if it's fixed there. When you attach the top, you are really just making sure it can't be knocked off the base, you can't affix it so it can't move, or things will try and pull apart. So 2 solid attachment points, and some buttons (or Z clips ) further out will be plenty.
Finishing? Yeah that's a challenge. Make sure you do both sides, although the bottom doesn't need as much attention to detail, just a similar film coat. Otherwise seasonal movement is going to uneven, and the top will try and cup. I'd think about propping it up vertically with some sort of temporary rack? It's going to be a pain to move about, but if you can simply lean it slightly left and right in a rack you should be able to apply multiple coats of finish to bother sides without too much hassle?

CGIII · January 11, 2019, 01:59:53 PM

Thank you for all the advice. I wanted to answer some of the questions you have asked.
The wood is quartersawn, I didn't know to ask for it when I ordered it but think I've lucked out in that department.

I considered a round apron but...seems like it ups the difficulty and I feel like I'm already teetering on the brink of my current ability.
I didn't know to finish the underside, I'll make sure to do that. That being said, one of my biggest concerns are the ends moving if I dont have a round apron.

I'm planning on using some X shaped legs I had from a previous project. I built a frame that mounts to the legs that the top will sit on. I thought that would give me a lot of mounting points for z clips or buttons and be easier to build than a round apron. I'll include a pic. I'm curious if that's a good way to go about it or not?

I'm using pipe clamps. My plan was to glue it in 2 foot increments (so about 4 smaller sections). Then add two sections together to get half the table, then put the two halves together. I thought that would give me more control and would be simpler and easier than trying to glue the whole thing at once. It'll take longer but I think I'll get a much better result.

The room this thing is going in is square, that makes a rectangular table look odd. The couple that had the house before us had a round table in the room and it looked really good. We would have bought it from them but they had it custom made and wanted to put it in their new house.

Ianab · January 11, 2019, 04:44:37 PM

Only thing I'd be concerned about with that base is the small footprint of the feet. How stable will the top be if someone leans on the outer edge? My dining table is a trestle style base, but the feet and top supports are almost the width of the top. You can sit on one side, and it doesn't move.

The glue up plan sounds good. Yes it will take maybe 3 days, but it will be a HEAP easier than trying to align 7ft of glue-up in one go. Joining 2 x 3'6" boards together on day 3 sounds much easier.

CGIII · September 26, 2019, 02:58:24 PM

I finally finished the table. I had to change wood because I couldn't get enough Ambrosia Maple that would match. I went with Alder and used Early American stain. I finished the top and bottom to keep cupping/movement to a minimum. I really appreciate all of the advice/wisdom shared on the thread. Here's what it ended up looking like.