Thread: Table Top Police Needed

Cruzi - I'm no policeman, but here's my 2c worth.

First, that contrasting end strip is going to give you trouble, the way you've drawn it. It will be perfectly ok on the 'long' sides, as the grain directions match. But, I presume the breadboard end is going to be conventional long grain across the table (your drawing renders it as if the grain matches the table boards). That means, at the ends, you are going to be fixing long grain to cross grain on one side or the other (or both) of that contrast strip.

I think you have several options. The simplest would be to do what you've shown it in the second drawing, but glue the contrast strip to the breadboard end (no problems, grain is matching), not the table end, which is begging for trouble. Put your 3 or 4 dominoes in over about 125-160mm in the centre, then put the outer ones with slightly elongated slots, as you've shown - nice, snug fit, but DON'T glue these - only the centre ones (which is probably what you are thinking). The main risk as I see it is that you are expecting a few dominoes to do the work usually done by a thick tongue or sliding dovetail that goes right across the table end in the conventional breadboard style. You could add a few more unglued dominoes in lengthened slots, which would be more like the conventional tongue.

A slightly more difficult option is to glue your contrast strip to the b/board as before & make a full tongue on the end of the long boards to fit snugly in a rebate on the b/board. A couple of dowel pegs from below holds it on.

The Rolls-Royce method, IMO, is to proceed as above, but make a sliding dovetail instead of a tongue. Not half as difficult as it might seem if you have a router & the appropriate bit. It does involve making up a simple jig, which takes all of 30 minutes or less. A single small dowel peg in the centre is all that's needed to hold it in place.

Should look good when it's done........
Cheers,

Thanks for answer, was thinking of doing mortice and tenon with 3/4 dowel (dowel only goes through 3/4 of the way so it doesn't show on top), but reading about offset dowel pins and elongated holes got confusing.

Is it possible to use 8mm dowel to pin the 10x50 dominos?

Point about the lighter timber being attached to breadboard is well taken, the method you suggest had occured after drawings were done.

A sliding dovetail was also thought of but the contrasting strip presents a few problems (to me), the timber of choice,(african ash) is only available in 7/8" or there-abouts and wish to use it that wide all the way around, I have it in 25mm undressed only.

To overcome this, the "H" pattern with stopped sliding dovetails for the breadboard, (will do another drawing, cannot yet do sliding dovetail drawings in sketch-up) with the SD's along the ends of the breadboard seems an alternative?

Umm, dunno how you could do "stopped" sliding dovetails, Cruzi?! Or am I misunderstanding you?
Doing a dovetail shouldn't affect your strip - cut the female part in the strip on the breadboard (doesn't show from top or bottom) and the tail is cut on the table end - like the pic attached, only imagine it as a a D/T instead of a tongue.

I have absolutely no experience of dominoes, so only have the vaguest idea of their size. I wouldn't think it necessary to pin them, anyway - glue the centre few, & just leave the outer ones free (unless you wanted to make it so you could dismantle more easily at some future date). If you choose a nice stable piece for the breadboard, it should remain straight & reasonably snug to the table end. The table pictured only has a couple of 3/8 dowels pinning it in the centre, (it's also about 1200mm wide) and it has been through two big moisture cycles this year with no dramas.
(Touch wood! )

The ends certainly projected a bit during damp weather, though....

Cheers,

OK, this is what I mean about "H" pattern, showing where stopped dovetails would be.


A couple of dominos in middle of breadboard to hold it centre, no glue on sliding dovetails, what worries me about this is the breadboard expanding would push the other boards out, or am I wrong again. The humidty here is nearly always 45-60% (often reaches 90%) whereas inland near Toowoomba for example around 20% is norm, meaning it will be pulling in tighter???????

I like sliding dovetails and can do them but the contrasting timber is providing a few obstacles, maybe I should just concentrate on finding a way to make it happen.

A thought.....

If the middle of the table top was made full length, the ends sliced off, insert added, ends re-attached, sides attached would this work or am I being confusing again?

Cruzi - if I read it right, that's a possible solution, and interesting, but still doesn't get away from wood movement. You don't have to worry about the breadboard end moving, 'cos there is negligible moisture-related movent along the grain. However, the wood in the main section, between the two long outer pieces is gong to expand & contact, which may put a bit of stress on your dovetails!

The message is, enclosing a big chunk of wood like this is going to cause structural inconsistencies, and whatever approach you take, it's going to involve compromises. The reason I did a simple through tongue & housing for the table above is partly because the boss wanted it to look simple & countryish like the one she'd seen in a shop, but I was happy with that aapproach because I knew I was dealing with a pretty lively species (Jacaranda). However, I was still surprised at how much obvious movement there is - it can go from sticking out 4mm to pulling in 4mm in a few days. And before you ask, yes, it is thoroughly coated with polyurethane top & bottom. As a proportion of the table's width, it isn't so much, really (<1%) so I shouldn't be.....

When it's all said & done, you may well get away with any of the methods suggested so far; much depends on the wood you choose and how severe the moisture cycles are where you live (sounds like not too severe, from what you report). I see enclosed table tops all the time, which seem to be done in an 'against the rules' way - some seem to be holding up quite ok after some time, but I have been asked to repair a couple, too. One of them had disassembled itself quite spectacularly, trashing epoxied joints & the 5/8" dowels inserted in a futile effort to prevent the joints opening. A good demonstration of the power good, solid 38mm thick hardwood can generate.

I'm surprised more punters haven't weighed in on the discussion - c'mon, don't leave me holding the can..........

Cheers,

the ONLY reliable way to get a table top with that visual appearance is to use veneer over a good substrate and forget solid boards

IanW, mate, I cannot thank you enough for your help so far, it's been great.

The plan is to use NG rosewood for table, timber has been well seasoned and has been aclimatising to here for 6 months now.

Going back to drawing board, how does sliding dovetail for breadboard across end and going back to original inlay plan for highlight sound?

Yep, I've never seen a breadboard enclosed before - you might be headed for trouble using this design. Having said that I like the ideas and the Sketchups

Originally Posted by Cruzi

Going back to drawing board, how does sliding dovetail for breadboard across end and going back to original inlay plan for highlight sound?

Cruzi - that's probably the safest - either a tongue or a sliding dovetail right across that allows any amount of movement without setting up any stresses. But you can do this & still use a solid piece for your contrast strip. Look on the changing edge-match as a useful feature - you can tell what the weather was like a few days ago just by glancing at the end of the table.

I don't altogether agree with Echidna that veneering is the ONLY way to get the look you're after - safer, perhaps, which would be important if you were making it for sale. And veneering brings its own problems, not the least being how to lay up big flat areas of veneer with minimal gear. I confess I have a personal dislike of veneer in this sort of situation - not only does it LOOK like veneer, it just ain't as resistant to hard knocks as solid wood.

NG Rosewood is a medium-hard hardwood, and moderately stable in my experience. I did a very big kitchen benchtop/breakfast bar with some several years ago - it moves a bit with the seasons, but hasn't done anything nasty. I allowed for movement in the join with the adjacent bench top with a loose spline & by screwing it down tightly only at the front - so far it has stood up well (~8 yrs). If you get the right bits it's quite nice to work, too, but some pieces have very rowed grain & are hard to plane & scrape. I reckon it will look quite impressive when you get it done.

Avagooday,

Ian,

Can you tell us more about the jig for doing a sliding dovetail?

Been thinking solid inlay again.....
Well, actually been thinking out loud whole thread




This an idea for full sliding dovetail with solid highlight.
Not entirely happy, concerned about highlight robbing strength, although it would be glued and domino'd in situ, the dovetail still uses it for much of the length.

Originally Posted by Cruzi

This an idea for full sliding dovetail with solid highlight.
Not entirely happy, concerned about highlight robbing strength, although it would be glued and domino'd in situ, the dovetail still uses it for much of the length.

That's pretty much what I had in mind if I were tackling this job, Cruzi. Can't see any problem with strength - it's all side-grain to side-grain glueing, and lots of area. The only reservation is that it would be VERY difficult to cut out a section from the plank for the contrast strip & get a really clean join - best to saw a strip off the end piece & reglue along with the contrast strip. Done carefully, the joint should be near-invisible, and in any cae, the eye will be drawn to the contrast stip.

Use a high-stress glue like Melamine or formaldehyde resin.

Come on - start building. The only way to learn is to make a few mistakes! Most mistakes are repairable..............

Howdya - haven't got any suitable pics of my dovetailing jig - will try to do something in the next couple of days & post it for you. I got it from a very old FWW - so far back I cannot remember the year, but it was at least 20 yrs ago.

Cheers,

Basically you just need the router fence to cut the rebate as above, although I will use a straight bit for initial cut to remove a lot of the material before using a dovetail bit. A board attached to your routers fence to hold it horizontal for the tail. First cut very, very shallow and climb cut to get a clean edge. The tail can be made with a series of creeping cuts to match the rebate.

Thanks again for your help IanW, running out of excuses to put off build now

Cruzi

I don't like it
What you propose just doesn't sound or look right

A breadboard end is usually attached to a long full width tenon (fixed or loose) or, less often, with a sliding dovetail glued in the middle only.
The purpose of the breadboard end is to keep the table top flat.

I can't get my head around using dominos (pinned or not) to attach the breadboard end — the end is supposed to stay still while the table expands and contracts — so one end of each domino would have no glue or pin


as to your inlay strips
as the top expanded and contracted the cross inlay strip would match/not match with the long strips of inlay

The inlay only needs to be 1-2mm thick (once finished) so you don't need Dominos and if you glue the inlay into a matching recess (not a trivial task) before you cut the DT slot you shouldn't have any additional decrease in member strength when you cut the DT slot
as you say, straight bit first then the DT bit when cutting the slot
use a double fence on the router to keep it centred



ian