Stop splitting on table top - Woodworking Talk

platinum8 · 03-23-2009, 10:46 PM

Hey fellas,

I was reading a post about someone trying to stop some cracking on their solid wood top. I am having the same problem. Someone mentioned about putting dowels in the breadboard with slots going across the end grain of the top itself. I didn't totally understand how to do so. I was wondering if you guys could elaborate more if give me some other ideas? Do i use glue if I use the dowel idea? I have the top on a peice of hardware that acts like a strong back and the screw holes are not slotted which I think they should be. should I just drill the holes larger and use some washers on the screws to allow them to move a little? The hardware is to allow the top to raise up to your chest as you are sitting down to work or eat easier.

Not my top

The top is solid B.E. maple 3/4" thick with with a 8/4 wood edge 2" wide by 1 5/8 thick. I rabbited out a half inch of the wood edge and glued in a solid cherry strip. This is the second time I am remaking it

and would like it to be my last.

Thanks guys

clampman · 03-24-2009, 12:15 AM

Here's a link to one article with a picture.

http://books.google.com/books?id=TE1...esult#PPT62,M1

I would do a google or yahoo search for breadboard ends. There are a wide variety of ways to do them. In general, the thicker your top is the better for the sliding dovetail method.

What you might be referring to is multiple long tennons into a deep dado with only the center one glued. Then you peg through a cross grain slotz in the bottom into the outside tennons inside the mortises to hold the bread board onto the end. This would allow the table to shrink and expand. But I am guessing here since I haven't read what you are talking about.

platinum8 · 03-24-2009, 08:01 PM

thanks clampman, I didn't even think of that. my only concern is how will the miters look with the pieces running the long way with the table grain? Should I glue them or does that defeat the purpose? I just wanna keep those miters tight and I think I am in a lose lose situtation.

Julian the woodnut · 03-24-2009, 09:03 PM

You're not going to be able to miter the corners with a breadboard end. The whole idea is to let the top move while the breadboard keeps it flat.

Webster · 03-24-2009, 10:25 PM

Platinum8,

If I understand correctly, your tabletop is glued up maple with a breadboard edge already fixed on.

A few questions....
Where is the the cracking/splitting happening? between the boards and/or at the breadboard joint?
Does the tenon for the breadboard go straight though the ends? (can you see the tenon) or does it act like a cap.
How's the breadboard edge attached now?
Can you remove it?

If you can post a picture, that would be very helpful.

Rick

platinum8 · 03-25-2009, 07:10 AM

I have actually ripped the top apart. I am ready to put it back together but the split happened right in the middle of the table. Maybe i misunderstood exactly what a breadboard was but I have a 3/4" maple top and I am going to wrap all the edges with 8/4 maple with a cherry inlay rabbitted into the 8/4. the 8/4 will be mitered at the corners. So I can do anything at this point to hopefully prevent the splitting again. I can try and grab some pics but like I said it isn't together anymore. I wish i toke some before. i forgot.

thanks guys sorry if i confused ya

jeffreythree · 03-25-2009, 08:47 AM

If you are glueing that 8/4 maple to the 3/4 maple all of the way around, then there is your problem. No place for the wood to go, and it is probably drying a little more once it is inside. The 8/4 is holding the perimeter in place so the only way the 3/4 piece can shrink is to crack in the center. If the center 3/4 piece was floating in the 8/4 frame with a little room to swell and shrink, you would have no problems. A breadboard could have the same problem if it is glued along the entire side of the top.

platinum8 · 03-25-2009, 07:16 PM

So I think I have a solution. Tell me what you guys think. I am going to route a tounge in the 3/4 maple and a groove in the 8/4 maple. I am going to put "space balls" in the gooves and leave about an 1/8" between the 3/4 and 8/4. I will glue the miters on the 8/4 and make sure the T&G is realitivly tight (with out glue obliviously)

I am not worried bout seeing the gap because i am going to leave an 1/8" lip on the 8/4 and put a 1/4" piece of glass with a bevel over the 3/4 maple.

Webster · 03-25-2009, 10:21 PM

Platinum8

Here's a quick diagram. It's much easier for me to show, than tell.
With the way you mentioned, your mitered corners will be pushed apart from the boards swelling (top figure) as jeffreythree mentioned. The result is the end board loose.

The next 2 figures is a type of breadboard edge, It has a tenon, which goes deeper in the board. No glue in the joint except to hold the dowels in. Idealy, the holes in the table top are slightly elongated to allow the top to swell/contract - free moving, but snug & offset the holes in the top to pull the end piece tight against the top.
It's similar, but not the same, to a kitchen cabinet door with a raised panel. That's usually a rail and style type, but still the same idea. The panel isn't glued in, but free floating, in a groove.

Or you could just use a sheet of plywood for the top. Even double up the plywood. Frame around it, and problem solved. But I don't think that is what you're looking for.

I would use biscuts to join any glued up boards.
The top probably goes though a lot of torture being raised up and down alot, without having anything much under it, for support.

Rick

platinum8 · 03-26-2009, 08:03 PM

webster,

Thats exactly what i was going to do is make it like a cab door. I just don't totally understand the point of the dowels if i went that route? i wasn't going to put any glue on the 3/4 maple, just the 8/4 at the miters and like i mentioned i am going to leave an 1/8" space all around the 3/4 while the tounge is still in the 8/4. Do you think i need the dowels?

I would use plywood but i just didn't want to put anymore $ into this. plus i had some hardwood left over.

Thanks for your input.

Webster · 03-26-2009, 11:34 PM

Well, I wouldn't think your miters alone would be strong enough. After a while of raising and lowering the top, they would loosen up. Like using a picture frame for a top.
I understand what you're saying and what you want to end up with..........maybe if you used a half lap in the corners and miter them.....that would give you some more stability. More real estate of wood to be glued together & still the look you want.
But, no, you wouldn't use dowels for that. The dowels in the breadboard allow the glued up vertical boards to move freely (in theory, but not loose) in a board in the end.

I would do you a picture , but I'm beat right now. I can show you tomorrow, if you need it.

Maybe someone else has an idea about this........

Rick

platinum8 · 03-27-2009, 06:46 AM

hey webster,

No I think I am good with a pic. Thank you very much for the help. I will think about the half lap. I did think bout that and i was thinking a couple dowels through the miters but the half lap might work pretty good too. Maybe I will do both, but i appreciate your help and pics.

Deano

clampman · 04-11-2009, 11:09 AM

The half lap miter is a good idea in that situation, with either screws or dowels up from the bottom. They do not have to show on top unless you like the look.

I had thought the 8/4 wrap would be flush with the top of the table. Since it will be proud of the "field" by 1/4 you will be fine. You can either dowel or screw and glue through the 8/4 and the field in the center of the end boards ONLY to hold the end onto the field.

That will also force the field to expand and contract the same amount into the dados running lengthwise on both sides of the top. I would make the dados and the tongues as deep and as long as you can.

Unless you have a moisture meter and can check the moisture content of both your table material and other wood that has been in the house for a long time, you will not know which way your top will be moving from its present state (ie. shrinking or expanding).

So it's best to leave room for plenty of movement. Chances are, it will shrink from where it is now if you use heat in the winter.

Chances are, if you live somewhere hot (like south florida) and have the AC on now where the boards are, and rarely have heat on in the winter, it will expand in the winter when you turn off the AC.

I once saw a kitchen island made from 16/4 resawed beams split down the center, leaving a crack about a half inch wide full length. This happened about 2 months after being installed in the winter in Connecticut. It was banded just as you did the first time.

I would allow 5/16ths for movement either direction into or out of the sides and forget the space balls.

Tony B · 04-11-2009, 11:47 PM

Your top is made of several planks/boards. Glue the center board to the end pieces to keep your edge centered. The rest of the planks have elongated holes to allow for top board movement.

mdeiley · 04-14-2009, 05:16 PM

Platinum8,
I am not trying to hijack your thread but I was wondering about the lift mechanism you have used on your table. Where did you get it and was it expensive? I can purchase one similar from Rockler but I think it is a little to pricey. (185.00)

platinum8 · 04-15-2009, 08:28 PM

no worries,

I think I did get it at rockler. If not there it was one of those magazines. I only paid $135 but that was 4 years ago now. If you google it you might find some that are cheaper. Any other ?'s feel free.

Deano