First Table Design -- Critiques / Suggestions?

[landslide]

I was inspired by the latest episode of the Dogon Platform Bed guild project to finally, finally, commit myself to trying SketchUp (http://thewoodwhispe...ng-in-sketchup/).

Marc's tutorial / advice was great and, in the course of a few hours, I got good enough to design my first project: a small dining table.

While there's a place on this forum for critiquing *finished* projects, there's no clearly delineated space to post designs and have *those* critiqued. As this is my first design, I wonder if some of the old pros have some criticisms with respect to proportion, joinery, etc... two attempts are in the attached sketchup file.

Thanks!

etienne

First Table.skp

[Guillaume Breton]

Clean,

i see you made 1''x.5''x3/4 deep tenons, not sure it will be strong enough. If you bring your tenons closer to the front, you woull be able to make them longer. Since you already cut on the strenght of the joint by making that particular design, it might be needed.

You will drop the top on these dados ? are you going to glue it in or screw it or something ? might not be able to just glue a solid wood top like that since the sides will prevent the top from expanding/shrinking just like you never glue a solid wood panel into its groves.

If you make the same kind of design and apply them to each corner, the effort you put into making them in the 1st place might show better instead of being hidden by the top.

i'll mod your design a little just to give you an idea of what i meant.

i modded the table 2 front left corner.

another tip, have a windows setup kinda like this and spend some time learning all the keyboard shotcuts it makes it so much easier. Dont be afraid to use the X-ray view, it helps alot also. You make good use of components for the legs, you could also have made the same for the rails. Everything that appears more than once. If you end up needing a unique component for a particular piece, you right click on it and click "make unique"

you can see the most used shortcuts here.

key-english.txt

overall its nice. another option would be to increase the height of these rails. As long as you respect the "normal" dimentions of a dining table.

here is a link you might find interesting.

http://furniture.abo...easurements.htm

First Table modded.skp

[Tom Crawford]

Since your rails are made to give the top a floating effect I would suggest that you put a bevel on the bottom side of the top so the edge appears thinner.

[landslide]

Since you already cut on the strenght of the joint by making that particular design, it might be needed.

Hmm. Can you explain what you mean by this? In addition to being new to design... I'm fairly new to woodworking and certainly new to furniture building. How does my design cut on the strength of the joint?

You will drop the top on these dados ? are you going to glue it in or screw it or something ?

That was the plan. Just drop it on there with glue. I was going to glue up the top from 4 or 5 boards (maybe with some biscuits for alignment) and make the dados.

[You] might not be able to just glue a solid wood top like that since the sides will prevent the top from expanding/shrinking just like you never glue a solid wood panel into its groves.

Never glue a solid wood panel into grooves... I thought I'd seen that very thing done... maybe I don't understand.

you can see the most used shortcuts here.

another option would be to increase the height of these rails.

http://furniture.abo...easurements.htm

I think I will heighten the rails.. I want to accentuate the floating top. And thanks VERY VERY much for both the SketchUp Shortcuts and especially the link to furniture conventions. Can't thank you enough!

etienne

[Guillaume Breton]

hello ! Sorry, sometimes explaining stuff in english is not super easy for me !

what i meant by cutting into the strenght of the joint is that you reduced the height of your rails with that desigh, meaning that the tenon itself is smaller than if you would have had a full height rail.

as for the glueing, let me try to explain with super cool paint graphics.

wood will ALWAYS expand/shrink in width (across the grain) and much less in length (almost negligible) with the grain. So if you glue a piece of wood across the grain of a solid top of a table for example, you prevent it from shrinking/expanding. The top needs to be able to shrink/expand, or else, it will unglue your rail or worse, when it will shrink, it will just split in the middle.

If you glue your rails, only glue the rails that go in the same direction as the fibers, do not glue the rails that go across the top, or IF you do, just put a little glue in the MIDDLE of the rail so the rest can expand, in the grove, freely.

what i meant by solid wood framing is this:

these kind of montages are done in a specific way to avoid splitting just like you would do a raised panel door. The center panel is not glued with the outside frame. Instead, there is a grove that goes all around the 4 frame pieces, and the center is free in these groves. a couple milimietes all around is enough. If you glue the frame directly to the solid wood center, your miters will just split open, or your center will split when it will try to skrink (the part of the frame going across the grain will try to prevent movement, and bad things will happen)

So, gluing these short rails across the table top is just like framing that top. You "cannot" do that if you want to avoid problems. The fibers of the short rails will go across the fibers of the top. The rails will not expand in length while the top WILL expand/shrink in width. Dont fool yourself into thinking that enough glue will just prevent wood movement. The glue will hold, but something else will have to give up, believe me.

i also agree with Tom that your efforts into trying to make that top float about the table legs need to be more apparent. cutting the corners would be an option, or not having the top wider than the base, or something else i can'T think of cause its 2 am !

i hope its a but more clear! ask any other questions if its not !

also, i dont know if you downloaded my modded sketchup model of your table. You'll see that i moved the tenons on the outside of the legs, off centered, so they can be longer.

you could also reduced the tenon'S width to like 3/8 or even 1/4, that'S plenty of wood, and you avoid weakening the legs themselves by removing so much wood in them for the mortises. Also, im sure there are 1/2 mortise chisels, but 1/4 or 3/8 is more common. always remember to build your projects according to what tool is available and to try to always stay close to the commercially available wood thickness.

Guillaume

edit: check that other modded design i made from your original table

the tenons are smaller, centered again, and i gave them more height. You only need like 1/16 - 1/8 at the top/bottom of your tenons just so that if you look from the side, you cannot see the mortise at all. Makes the joinery cleaner overall and lets you have larger tenons.

First Table modded again.skp

[Guillaume Breton]

this quick design tutorial might also help you getting started up.

the fibonacci sequence/golden ratio is somethign to keep in mind in any design

edit: quick tenon/mortise guidelines:

1) Tenon thickness should be 1/3 the thickness of the stock being mortised to ensure the stock being mortised doesn't weaken. (or width of the mortise is the width of the chisel that you own that is closest to 1/3 the thickness of the stock)

2) Tenon width should be no more than 5 times its thickness, 4" being the max before more than one tenon should be used.

3) For a blind mortise, the mortise depth should be 2/3 the width of the board being mortised.

more info on the golden ratio à la Steve! Always interesting to watch

Golden Caliper Parts.skp

[thewoodwhisperer]

I love raised top tables like this. Looks like you are on the right track man. I don't have much to add to the previous recommendations other than to give you a great resource to check out. George Walker's blog is pretty awesome, as are his DVDs: http://georgewalkerdesign.wordpress.com/

What I like about Walker's teaching is the fact that he tends to focus on whole number ratios instead of focusing too much on the golden section and complex calculations. This simplified system really appeals to me personally and is something I try to incorporate into everything I build. Worth looking into.

[Tom Crawford]

I just noticed that one of the two in your original Sketchup has tapered legs. You seem to have the tapers on the 'outside' of the leg. Generally, when only two sides are tapered, the legs are tapered on the inside - so the tapered sides are facing each other.

[landslide]

I just noticed that one of the two in your original Sketchup has tapered legs. You seem to have the tapers on the 'outside' of the leg. Generally, when only two sides are tapered, the legs are tapered on the inside - so the tapered sides are facing each other.

Yep... again, I'm new to design. I figured the tapers should be on the "outside" so that the "square" parts of the leg would be on the "inside"... meaning that the tenon / mortise connection would be flush. I guess I'm wrong about this. I suppose that with the tapers on the inside there's still very little gap between the leg and rail near the top of the leg...

[landslide]

edit: check that other modded design i made from your original table

First Table modded again.skp

See the updated design. It has two tables that are only different in length. They take into account a few things (given you various information);

1) standard table conventions for rectangular table length and height

2) I think I standardized the mortise sizes (I used 3/8" wide)

3) The legs, rails, and other bits were all resized with actual construction (from 8/4 or 4/4 stock) in mind

4) I changed the mortises... and they ended up smaller.. but I think I followed your instructions about the right mortise size... I might have misunderstood though.

thanks!

etienne

Maple Table Version 3.skp

[Tom Crawford]

The leg tapers should start just below the bottom of the rail - about 1/2" or so.

[dcustoms]

Great design! That will make a beautiful table. You can not however attach the table top to the skirting with the dado joints you are showing. A hardwood top will expand and contact across it's width and break apart the base if not allowed to move. You can purchase clips that attach to the top and float in a saw kerf along the skirting.

Also to make your tenons longer you can miter the end of them to they can meet inside the leg.

As for the leg taper you can do what ever you want. The norm is to taper the two inside faces until just below the apron like Tom said above. The only risk you run tapering the two outside faces is that the legs might look out of plumb from the top.

Good luck!

[landslide]

The leg tapers should start just below the bottom of the rail - about 1/2" or so.

Mmmk. Thanks for the heads up. Any particular reason why the tapers should be "out" rather than "in." Is it just a design convention?

[thewoodwhisperer]

OK I had time to look at the design a bit more so I can offer a few cents worth. One thing I might recommend is that you increase your reveal. Moving the tenons forward gave you deeper tenons, but it took away much of your apron/leg reveal. I like a reveal to be at least 1/8" and it looks like yours is about 1/8" at the top and 1/16" at the bottom of the apron. Not sure if this is intentional or of it is a flub in the model. Either way, a 1/16" reveal just isn't enough to do the intended job, especially after you ease the edge of the leg or round it over. So one way to accomplish this is to off-set your tenons on the aprons. Instead of being centered along the thickness of the apron, the tenon would be pushed toward the front. So the mortises would still be in the same positions but the apron would be pushed back a bit. It would only be about a 1/8" off-set but when you're talking about a reveal, that extra 1/8" can have a big visual impact.

[thewoodwhisperer]

Another thing I would be inclined to do is increase the impact of the floating top. On a dining room table, this effect can be very tricky to achieve given the vantage point the table will usually be viewed at. Most people just won't see it until they pick something up off the ground. So one way to make it a little more visually impactful is to widen the apron and lower it. I think the design has room for it since the curve results in only about 2" in width at the center. So in the absolutely horrible rough sketch I made, I lowered the rail by 1/2" and tried to approximate the continuation of the curve. While my Sketch is lacking in refinement, lol, it should give you an idea of what I'm talking about. I think by lowering the apron 1/2", you get a pretty substantial increase in the visual effect of the floating top. Just something to consider.

[landslide]

One thing I might recommend is that you increase your reveal. Moving the tenons forward gave you deeper tenons, but it took away much of your apron/leg reveal.

Another thing I would be inclined to do is increase the impact of the floating top.

Hi Marc --

thanks for your suggestions. I totally agree about the reveal not being strong enough. I had to look at some furniture around my house to get a sense of what you meant... in Sketchup I get really misled by the fact that I can zoom and what looks like a clear articulation in design is, in fact, something like 1/16" ... I upped the reveal to 1/4". As for lowering the apron, I agree, and I lowered it by 1/2". If any more visual impact is necessary, I might shrink the size of the top by a quarter inch.

Thanks! Only real question I have is whether or not those tenons are going to be strong enough to hold the whole thing together.

I also wonder if a hardware solution is better to join the frame... it'd be nice to disassemble the table for moving...

etienne

Maple Table Version 4.skp

[thewoodwhisperer]

Admittedly, I have trouble guesstimating when a tenon is long enough or wide enough for the job. I think most of us tend to over-engineer for that reason. Better safe than sorry. So if you can beef the tenons up a bit without doing anything major to the design, go for it. A couple things to consider. You can make the tenons a little longer by cutting a 45 degree miter on the ends. So essentially you're creating a miter joint inside the two mortises. Second thing you can do is make your tenons wider. While the bottom of the tenon is flush with the bottom of the apron, it looks like the top is 1/4" down from the top of the apron. So you can bring that up a bit. You can maximize your tenon width by reducing from a 1/4" shoulder to an 1/8" or 1/16" shoulder.

I honestly don't know how much strength either of those options actually buys you, but I would it buys you at least something.

Finally, you might consider even drawboring the tenons. You have 5/8" of leg space to work with on the inside of the legs and you can drawbore the joints without anyone ever seeing, as these would be applied from the inside of the table. Of course if you're looking for a knock-down solution, drawboring is a bad idea.

I have no experience with table hardware for disassembly so I won't be much help in that arena.

[landslide]

Thanks Marc. I'll beef up the tenons.

I read somewhere that you don't want to create mortises that are too large for fear they might weaken the leg (in this case).

That said, I think there's room to safely make those tenons larger.

[Bombarde16]

I love raised top tables like this.

Perhaps this is worthy of another thread. May I ask why?

I find them curious, but not the sort of thing that I can't wait to put into my own work. The negative space between the top and the top of the legs just feels weird. Are you supposed to slide your fingers in their to appreciate the top of the leg? Maybe it'd feel better with a glass top where you can survey things while standing normally. But such a conspicuous twist partially obscured at pocket height doesn't really float my boat...

(groans)

Of course, I'll accept that this is just me. I've seen such floating table tops in plenty of top flight work; so there must be something I'm missing.

[Bombarde16]

Admittedly, I have trouble guesstimating when a tenon is long enough or wide enough for the job. I think most of us tend to over-engineer for that reason. Better safe than sorry.

I honestly don't have the skills to do the math, but this design doesn't pass the eyeball test. The potential for racking the skinny aprons out of their mortises just jumps out at you; so this is a case where overkill is more than justified.

You can make the tenons a little longer by cutting a 45 degree miter on the ends. So essentially you're creating a miter joint inside the two mortises.

I'd go further still and make it a finger joint, lengthening the tenons to the point of making them through tenons.

Not an easy joint to cut by any stretch, but that's how I'd play it.

[Eric.]

Perhaps this is worthy of another thread. May I ask why?

I find them curious, but not the sort of thing that I can't wait to put into my own work. The negative space between the top and the top of the legs just feels weird. Are you supposed to slide your fingers in their to appreciate the top of the leg? Maybe it'd feel better with a glass top where you can survey things while standing normally. But such a conspicuous twist partially obscured at pocket height doesn't really float my boat...

(groans)

Of course, I'll accept that this is just me. I've seen such floating table tops in plenty of top flight work; so there must be something I'm missing.

I was a little ambivalent about them, too, until I saw the latest issue of FWW. It's a pretty sweet design. Check it out...

[thewoodwhisperer]

Explaining why I like floating tops is a little like explaining why I like Dr. Pepper. Cause it tastes good to me.

Seriously though, I think floating tops are much more at home on smaller tables. On something as big as a dining room table, the effect is easily lost. But that's not to say it can't be done. I'm interested to see where this ends up.

[landslide]

Seriously though, I think floating tops are much more at home on smaller tables. On something as big as a dining room table, the effect is easily lost. But that's not to say it can't be done. I'm interested to see where this ends up.

The inspiration came from a floating top dining table at my sister's (saw it over thanksgiving). I took a bunch of pictures thinking that, way down the road, I might be able to build it. Then the SketchUp episode arrived and things took off from there.

Marc's kind of right, though. I didn't notice it was a floating top, really, until I dropped something and looked under the table. On the latest design I have here, the floating top is ... floated ... higher than on the original I saw, so maybe it will increase the visual impact. We'll see!

Rob -- that finger joint looks... intimidating! I'll have to make a test piece to see if I can even pull it off.

etienne

[Guillaume Breton]

you got any pictures of the original table you are trying to reproduce ?

[Bombarde16]

Dr. Pepper needs no explanation. That stuff's the best.

Seriously though, I think floating tops are much more at home on smaller tables.

I think we're on the same track here. What occured to me is this: In a smaller table, the distance between leg and the underside of the top seems to run about the same size as or bigger than the cross section of the leg itself. Going back to the design at hand, that vertical dimension is only about a third the thickness of the leg. Even though it's a negative space, it's introducing something smaller in an overall massive piece.

This suggests a possible fix: Shorten the legs, leaving more breathing room between leg and top. Then your stretchers would need to be redesigned with a more pronounced curve. Potentially, you could give yourself more breathing room for the joinery there as well.