Sagging?

[CWatters]

It can be quite hard gluing rods into blind holes. The epoxy can form a seal. You push the rod in compressing the air which then pushes the rod out again. Dril some tiny holes into the blind end to let the air out. Some epoxy will also come out of those holes so take care not to get it everywhere

Another method is to make the rods a tighter fit, assemble without glue then drip low viscosity super glue into the air holes. The danger with this is that super glue can sometimes wick a long way through the grain causing marks.

 

[wizer]

Cheers Chris, it's taken most of the day, but I think I see how to make a jig. The leg should be easy on the drill press, the tops pose a bit more of a problem, but I guess if I make a blank/practise leg, I can use that as a guide/jig to drill the holes in the top. :-k This diagonal idea might be a good one. I think trial and error is the best way to work all this out. I'll make up some test pieces and see what I can come up with. So much for this being a simple quick project

Colin I see what you mean about the air holes. I will bare that in mind.

As ever, I'll keep you informed.

 

[Jake]

I think they look better in your original drawing.

 

[wizer]

Decisions Decisions

Angled or Straight... ipp dipp... :-k

 

[MikeG.]

Square Tom....not angled!! Easy decision.

As for the problem of the rods at 90 degrees to each other......only one set is needed for the strength, so the others can be a dummy set.....penetrating the table top by say 2mm (did someone already say that?).

But.........

......I don't think this will be a strong enough top design. 22mm timber with an 8mm rod leaves 7mm of timber each side of the support. Apply a load, and that stainless steel bar will soon crack 7mm of whatever wood you use.

Personally, I wouldn't span 1100 with 22mm timber anyway. I reckon that even if it were strong enough, which I doubt, it certainly won't look strong enough. And that is before you try and fix it with a hole in the end-grain.

Sorry to sound so negative.......

A positive suggestion then......I reckon this design would look so much better if the tops of the legs finished say 20 to 40 mm above the level of the table top. It wouldn't take a second to make it that way and cut them off if you didn't like it...........or even to do a quick SU model.

Sorry to sound like a party-pooper!!

Mike

 

[wizer]

Mike, It's a point I had missed about the amount of timber above the rod actually being the bearer of the 'weight'. Before I saw your post last night I'd gone off in a tangent in SU and designed this:

Taking the advice given here, I have done away with the transverse rods. The idea was to route out a slot in the legs for the rod and then fill it with inlay. The inlay would then be carried on through the table. I like this idea but not realise that I can't do this because of the issues raised by Mike i.e. the weight of the top would be all on the glued-in inlay.

So now I am working on this:

Stuck with the idea of routed slots, inlayed. Done away with the top inlay.

I'm not experienced enough to predict what will happen with sagging. As a kind of middle ground, I have reduced the overall length by 100mm and increased the size of the legs to 110mm squared at the top.

Mike I have played with the legs being higher than the top and TBH I'm not keen, thanks for the suggestion tho.

I'm not starting this until at least Saturday, by wich time I will have a proper respirator. No risks with this. Might even look into barrier cream.

 

[thomvic]

Have you thought about full length rods sitting in channels routed on the underside of the top and shelf? Just one rod set in each side like this will resolve any sag issues. You could cover the rods with inlay or just leave the channels open.

Richard

 

[wizer]

No I hadn't thought about it that way... hmmm :-k

 

[Jake]

Then you do have to start thinking about wood movement.

 

[wizer]

Surely not if the rods are glued into the legs but not the tops? The top just sits on the bars via a routed slot down the length? Allowing the top to move freely?

 

[Jake]

Depends if you just run the rods just one direction, or both. Not saying it is insurmountable, just that it becomes a genuine consideration.

 

[MikeG.]

Have you thought about full length rods sitting in channels routed on the underside of the top and shelf? Just one rod set in each side like this will resolve any sag issues.
Richard

No it won't! For it to prevent sagging the rods would have to be in tension.

It would certainly, however, help with the problem of the thin cover over the rods from the previous design........you could end up with 14mm above the steel. How would you hold the top down, though? You could have the amusing situation of someone going to shift the table to vacuum underneath it, and coming away with just the top in their hands!

Mike

(edit......**** should have been ***f* = shift)

 

[Jake]

You could have the amusing situation of someone going to **** the table to vacuum underneath it, and coming away with just the top in their hands!

Funny habits in your house.

 

[Jake]

U-clips under the rods would hold it down, but might be difficult to source, or make neatly enough.

Or you could have a double-thickness edge (dealing with the too-thin for the size issue), and sandwich the rod in the middle.

 

[wizer]

I dunno, maybe I should forget this idea. I'm also a bit worried that the legs would be laminated from 21-22mm sections. That means 5 boards with engdrain showing, not sure if that's going to look very nice?

Back to trawling google photos for inspiration!

 

[MikeG.]

You could have the amusing situation of someone going to **** the table to vacuum underneath it, and coming away with just the top in their hands!

Funny habits in your house.

see my edit.....

 

[wizer]

Whilst looking around for alternatives I found this:

Spooky. No such thing as original.

 

[MikeG.]

Tom,

I reckon the reason that looks so good is the chunkiness of the woodwork.....I would guess that top is at least 30mm and could even be 40. It makes a great deal of difference to the final look.

You really do have too much time in front of the computer, don't you!!!

Mike

 

[wizer]

You really do have too much time in front of the computer, don't you!!!

Without a doubt, to my regret. It's better than the TV tho isn't it? leest aam lernin (slowly).

You are right about that tables chunkiness, but then surely that increases the chance of sagging? I could laminate two boards of Iroko together, or maybe run an edging around it. Lots of mitres tho :-k

I'm going to have a play with the legs this weekend. I want to see what 5 laminates of Iroko looks like when glued up (a dogs dinner, I don't doubt). I may go for beech legs, but I think you have to be careful when playing with contrasting timbers, it can look busy.

If that experiment fails then it really is back to the drawing board. I should start a project thread because I have to finish this before December the 27th, Or else. :shock:

 

[MikeG.]

You are right about that tables chunkiness, but then surely that increases the chance of sagging?

Oooooooh Tom..........you and I are going to have to have a little chat about some structural principals........