Author Topic: Three legged dining table  (Read 1933 times)

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Offline mrFinpgh

  • Posts: 496
Three legged dining table
« on: August 14, 2021, 11:22 PM »
My brother and sister in law could use a new dining table for their condo in Brooklyn.  They could have used it a couple years ago, too, but I work pretty slowly.  It's not the biggest place, and having something that could accommodate a couple guests would be good.  It would be nice if could also be easily moved, since it's a 4th floor condo and no elevator. I remembered seeing a cool table in Christopher Schwarz's book The Anarchist Design Book, where the legs joined the table through a fat sub-base and connected via 2" round tenons and corresponding mortises. The table was designed to be 'knock down' in the sense that the legs didn't have to be glued in.  I also thought it looked pretty darn good and also appropriate for their use case.  I sent a couple photos of it to my brother and he liked the idea.

link to the inspiration

Earlier this year, I got a decent sized (for me) stack of 5/4 and 8//4 walnut lumber from a local woodworker who had gotten some fallen trees milled and air dried them for the last year or so.  Many of the boards are quite nice in terms of color and grain, though the presence of pith  in a number of them is something I could do without (more on that later).  The price was very good, so i bought more than I probably should have, but I'm glad I did as this let me be more picky about grain.

The top of the table is 1" thick and about 40" in diameter. Wide, and a bit awkward to handle, especially before cutting out the circle.  I milled the boards down over a period of about a six weeks to 1 1/8" thickness (these were all roughsawn to a very fat 5/4, which gave me a lot of room ) - 3 milling sessions in total. 

Here's what it looked like during the initial phase of layout:

And then during a second pass:

And finally:

Obviously, this still needs to be smoothed out a bit, but I've gotten it very close to flat w/ my jack plane traversing and on the diagonal.

One small issue I ran into is that a fair number of the boards I was working with had the pith in them still.

I know that some folks don't find pith in walnut to be a significant issue - it's not like red oak in terms of instability - but I wasn't comfortable with it, particularly on a table top where I'm hoping it stays relatively flat over 40" in every direction. So, I ended up 1) pulling some more boards and finding some other interesting pieces to use 2) finding pith in those as well, and cutting out the pith, sometimes at interesting angles relative to the initial rectangle I was working with 3) jointing and regluing those boards back together. 

Incidentally, this much jointing (and at these lengths) has highlighted to me that my jointer plane is not flat. It's an old bedrock #7 with a new PM-V11 blade in it. It isn't out by a lot, but it's enough that I get a more concave edge with that than my low angle jack plane. I'm sure some of it is my technique, but I'd rather blame the tool.

Speaking of jointing, I also had the occasion to finally try the 'mirror cutting' technique I've read about on here.  While most of the joints on the top are a mild spring joint, springing two 20" wide pieces of 1" thick walnut is difficult at best.  The spring joints from the other boards also meant my jointed center seam was not quite right once I had glued the other sections together.  So, I clamped everything snug and took a couple passes with a 28t blade.  This worked out well! The joint wasn't perfect - just the slightest line compared to a hand planed joint, and I needed to use three clamps instead of one to get it closed all the way across (I'm becoming very conservative about clamping pressure, so I only tighten to where my fingers feel resistance -- no bearing down for me).  When all was said and done, though, the joints look good to me.

I cut out the circle using a quick home-brewed router jig (a scrap of plywood, a trim head screw, and a couple countersunk holes) and my OF1400 with a straight bit as well as a jigsaw to rough cut most of the waste of.  This is an area where I did run into something new to me.. some very rough end grain tear out from the router.

I'm not sure how I'm going to repair this yet.  I don't think it's going to look right if I try to sand down the tearout, and I think epoxy would only highlight the pattern.   In the past, I've done okay with using hide glue and sanding dust/saw dust to repair some pretty rough chip out, so I might go down that road.  Perhaps someone on here will have a better idea.  For what it's worth, I'll probably be finishing the table with a hardwax oil finish.

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Offline mrFinpgh

  • Posts: 496
Re: Three legged dining table
« Reply #1 on: August 14, 2021, 11:36 PM »
The sub-top is where the action is in terms of shaping and joinery.  There will be three holes for the tenons and the sub-top also will have a bevel cut into it to lighten it up.

Since it's 1 3/8" thick, I used 8/4 material.  I wasn't quite as picky about appearance here but did try to emphasize getting quarter and rift sawn stuff in the name of stability.  I also tried to plan my cuts to avoid having to take a ton of material off w/ the planer.

In the end, this worked to be something more like a giant cutting board, laminating many narrowish thick strips together.

Thick strips, stacked and stickered:

Laminated together:

I used the router for this circle as well, although I used a different jig that I had built a few years ago when I was making some speakers. That jig is adjustable and uses a sliding bar to set the radius. Bill Hylton and Pat Warner both have highlighted very similar designs, although theirs look good whereas mine was made from leftovers from another project.

I had used the router here because I had hoped to avoid trying to cut a 30" diameter circle from 1 3/8" thick lumber on my 10" bandsaw. Partially, because I didn't want to go buy plywood to build a circle cutting jig. Also because my bandsaw has 6" of table to the right of the blade and I'm not sure how stable a circle cutting jig is going to be at 15" out.  I wish I could fit a bigger saw in, but until I get out of the basement, this is about as good as it gets for me.

The router make a very clean circle that needs minimal cleanup, especially when you take no more than about 2mm per pass.  However, even w/ the dust extractor running, it's a messy, prolonged, and wasteful operation to route that much material away. A bandsaw could do it in much less time (i think I did 15 passes on the router for this part) and it wouldn't be nearly as loud and probably a bit less mess. 

So, I thought I'd avoid the circle cutting jig and just do the bevel by hand w/ a spokeshave and block plane.  After about an hour or so of that effort, I realized that I should really just make the circle cutting jig and cut that bevel on the bandsaw.   [laughing]

Offline mattbyington

  • Posts: 733
Re: Three legged dining table
« Reply #2 on: August 17, 2021, 10:52 AM »
@mrFinpgh this is looking awesome!! Nice work man. Also like that you were creative with board selection and working around boards that had the pith in it still. Nice work and looking great!


Offline Packard

  • Posts: 854
Re: Three legged dining table
« Reply #3 on: August 17, 2021, 12:33 PM »
Notwithstanding the fact that a 3 legged table will always have all three legs in contact with the floor, I have found that those tables are very tippy unless the base is substantially heavier than the top. 

And even if it is, resting elbows on the table in certain spots will make it tip. 

When I mounted my studio light stands on casters, I made a circular base with five casters around the perimeter.  It was far more stable than either the tripod version or a 4 caster version.  Going to six casters did not make for a noticeable improvement in stability.

The workmanship on your table looks remarkable.
« Last Edit: August 17, 2021, 12:45 PM by Packard »

Offline mrFinpgh

  • Posts: 496
Re: Three legged dining table
« Reply #4 on: August 21, 2021, 12:50 AM »
@mrFinpgh this is looking awesome!! Nice work man. Also like that you were creative with board selection and working around boards that had the pith in it still. Nice work and looking great!

@mattbyington: thank you very much.

@Packard: I hope that it isn't the case here.  The top is pretty heavy - the inner 30" diameter of the circle is going to be around 2.5" thick.  The legs will be relatively light.  Perhaps one thing I have going in my favor is the legs have about 14 degrees of splay - so the bottom of the leg is almost aligned with the outside edge of the table. 

@Scopingwoods : i hope to post more updates soon.  My shop is also my basement/laundry/storage area, so a lot of times I don't want to post photos because it's embarassing how much mess tends to gather when I'm working on these projects.  The legs are intended to be detachable - basically 2" x 2" round tenons going into deep holes.

I have made some progress on the table this past week. 

After my last post, I built a circle cutting jig for my bandsaw.  As I was expecting, the weight of a 30" diameter 1.5" thick piece of wood is a bit much for a 10" bandsaw. It actually moved the entire table when I put it all on there with no support!  I needed to build a support for the outside edge of the jig.  Fortunately, a Sys 2 and some scraps of different thicknesses took care of things.  Unfortunately, when cutting the circle out my blade decided it was time to explode.  Even though I could see it wobbling right before hand, the sound of a bandsaw blade braking is never anything less than anxiety inducing.  Shame, as that blade was still pretty sharp and up until then cutting without any significant drift.   [huh]. I changed to another blade i had lying around.. that one must have been used for resawing some anigre, because it had a very specific smell when I started cutting and it was rather dull. So i switch to another blade - this one brand new.  It did the job just fine and I cleaned up the cut w/ a spokeshave and card scraper.

After drilling the mortise holes, I face glued the subtop to the top.  I don't think I fully appreciated the quantity of glue involved in that. I used some Titebond liquid hide glue.  All my old brown glue is out of date by a year or more at this point. I still use it sometimes, but didn't want to take the chance on a structural joint like this. I could have used PVA, but there was a ton of squeeze out so I'm kind of glad I didn't. :-)

I've spent the last two nights shaping the tenons for the legs. This is the definition of tedium - shinto rasp and medium files ad nauseum until the tenon fits the hole a little bit, then pull it out and figure out where the high spot is, file more, repeat.  It's times like this I really with I had a lathe.

Offline mrFinpgh

  • Posts: 496
Re: Three legged dining table
« Reply #5 on: August 22, 2021, 01:27 AM »
More progress the past couple days:

First, I was able to finish fitting the tenons. these are Large 2" x 2" tenons fitting into 2" holes.  As i don't have a lathe, my process was one of layout out the diameter on the end grain and then filing, filing, and more filing until I could start to fit it into a piece where I drilled a hole using the same bit as the table base.

This took a while!  Once I could start to fit the legs into the table, I sanded away burnished areas and retried.

You can see here that I marked the tenon to correspond to a specific hole. I notched small grooves in the tenon and then used a sharpie to darken them.  This way, at least some of it won't rub off over time.  I did this because each tenon is essentially scribed to the individual hole that I drilled. My drill press has some runout and I think the jig i used to angle the workpiece flexed during drilling, as the holes seem to be elongated along one axis.  So the tenons are snug - you can almost pick up the table by the legs when they are fit in there - but you can move the leg forward and backward a little when there isn't a table top pressing down on it and the floor pressing up on it.

The next step was to cut the tapers.  Fortunately I already had laid out the small dimensions, so I just needed to extend the layout to the faces of the leg and connect to the outside corners of the shoulder of the tenon.  Once that was done, a little bit of time with the bandsaw and some cleanup with plane got me to here:

I decided today was probably a good time to also fill a couple knots and other issues with some epoxy. Fortunately, the knots were all relatively small and I didn't need to do much of this.  Tomorrow I will trim down the excess and hopefully start the process of prepping for finishing.

Having tapered the legs, time to move on to the octagons.  I was excited about this part, as I have never done an octagonal leg before.

First step is the layout. I set my dividers from the centerpoint of the tapered end to a corner:

Then I used this distance to mark one corner of the octagon:

And repeated the process, referencing each corner of the square to get two of the points of the octagon.  This is a little more accurate than just laying out 3rds - the diagonals _should_ be equal in length to the other edges. 

I repeated this process along the top, using the larger centerpoint to corner distance (I had pre-gauged this before cutting out and shaping the tenons).

To the right, you can see my low angle jack plane - by far my favorite plane, as well as my very sophisticated planing cradle - a scrap of cherry w/ a notch cut out of it.   

Fast forward through a lot of planing and sweating:

It's an octagon! 

Not quite perfect relative to the circle, but from a foot away it's quite captivating to look at.

I repeated this process again to do another leg:

I still need to clean up some pretty intense tear-out. Some seems to be coming from the grain on the board just changing direction, while other tear-out probably results from the legs being made from two pieces laminated together.. so the grain is running one way on part of the facet, and the other way on the other side of the facet. 

This poses an interesting challenge, as every swipe of a plane or sandpaper has the potential to widen one facet while narrowing the adjacent facets on either side. This can make the tapered octagon start to look lopsided pretty quickly. Yet the tearout must get addressed.  Best I can come up with right now is to simple pay attention to what's happening as I clean up one face and adjust as I go along.  The legs are about 18" apart at their closest point, so if they are all slightly different it won't be a problem. I think as long as they all look like octagons that taper from the top to the bottom, that will be pretty good.

Offline mrFinpgh

  • Posts: 496
Re: Three legged dining table
« Reply #6 on: September 28, 2021, 11:17 PM »
A few interruptions and a planned vacation have kept me away from working on the table with any consistency.  I'm coming up on the home stretch now.

First, I finished tapering my octagons. This was really satisfying and I like the facets. I took pains to avoid any more than the minimal amount of sanding on the legs, and only with a block of wood behind some 320 paper.  i really didn't want to lose that crispness.

Then I brought the whole thing upstairs to the flattest floor in the house (I should know.. i used a lot of feather finish to level it before putting down the vinyl). To get the whole thing to level.  Surprisingly this only required a small amount of shimming.

To mark where to trim the feet, I used a block of wood with a half a carpenters pencil on it and scribed around each foot.  This is something Chris Schwarz talks about in his books.  It's a lot like the razorscribe tool, but with pencil instead of a blade. And much bigger. 

Cutting the feet down was a matter of cutting to the line on each side and connecting the lines until all the way through. I needed to clean up the bottoms a bit, but only a few minutes of work.

Worth mentioning: I put a heavy chamfer on the bottom of each foot.. about 1/8" with a rasp. Then I used some liquid hide glue to apply very thick leather pads to the feet.  That dried overnight and then I trimmed the leather with a utility knife.  I burnished the edges a bit with a piece of scrap just to tidy things up.

Finally, I spent a couple hours sanding the top to clean up some tearout that I couldn't plane away.  As a last step, I added a small chamfer on the top and bottom of the edge - maybe 1/16th or so across.

Then it was time to start applying finish. I didn't have enough time to do the whole table before vacation, so I got the legs done first.
 This let me use the table as a drying rack, as the legs could just sit in the mortises once the finish was applied. The entire thing is done using Osmo Polyx Satin

You can see that my workspace is very crowded. You can also see the stoploss bag I have been using for almost 2 years with the same can of Osmo. Much better than when I tried storing Top Oil in a Jar and lost about 40% of it in a couple months. You can also see the leather pads on the feet in this photo:

After this, we went away for a week and the finish had the opportunity to cure.

When we got back, I did something that was new to me. Usually I finish sanding using a mirka block attached to a vacuum.  This works well and keeps the dust in check. I've often read of creating a slurry with the first coat to help fill the pores with Walnut. Some folks think this is more important with Walnut because the wax can show up as whitish in the pores if the finish gets too wet.  Anyway, I gave it a shot by sanding with a cork block and no dust collection. I tried to keep the movements slow and deliberate to keep the dust on the table top and out of the air.

First coat of Osmo - applied a bit generously in tight circles with a red pad, sit for about 15 minutes, then wiped with the grain using a white pad. Finally buffed off aggressively with shop towels:

Second coat - just a white pad, let it sit for a little bit (10 minutes maybe), then wiped with the grain and buffed off aggressively with shop towels.

Just a more dramatic shot of the same - I turned off the shop light directly over the table. :-)

All in all, I am feeling happy with the look of the table and really enjoy those octagons. There are two outstanding and related issues:

1. The leg mortises have a bit of play, although it is only along one axis. I think this is due to the jig I built bending while drilling the mortises. The tenons aren't loose enough that the legs fall out when the table is flipped upright, and when the table is put together the whole thing is pretty stable, but it does allow for a little bit of movement.  I don't know if over time, that movement is going to create extra stress against the mortises or do something else that would be a problem. It's not ideal though, and seems like a potential point of failure even if I'm not sure how.   

2. I have not finished the mortises or the tenons yet. I am not sure what exactly would happen if I did. In theory, maybe it adds a tiny bit of friction from adding some material. On the other hand, if I'm adding wax maybe it reduces the friction. I'm not really sure whether I should or should not try to put some finish on one or both of these parts.  The other reason I'm holding off on that is I have one idea for how to make those mortises a little tighter and it only works if I don't have a coating of wax on the inside of the mortise.

My idea is this - I could thoroughly wax the tenons and then place some thickened epoxy inside the mortises. Place the tenons in the mortises, flip the whole thing over and put the legs in their 'ideal' position, and let the epoxy cure. In theory, the epoxy ought to fill in the loose areas of the mortises and conform to the tenons.  I think I would need to be very careful about any epoxy dripping out, and make sure the leg positions are dead-on, since the same play that is bugging me right now is also giving me a modicum of adjustability.

Offline Michael Kellough

  • Posts: 5305
Re: Three legged dining table
« Reply #7 on: September 29, 2021, 12:09 AM »
Various ways to tighten tenons here.

Fox lock is what I’d use.

Offline neilc

  • Posts: 3058
Re: Three legged dining table
« Reply #8 on: September 29, 2021, 09:41 PM »
Very nice table!

Offline mrFinpgh

  • Posts: 496
Re: Three legged dining table
« Reply #9 on: October 01, 2021, 11:00 PM »
@Michael Kellough,

Thanks for that link.  I've used some of those techniques before.  They would work, except that the table is designed for the legs to be removeable.  So a fox wedge would effectively provide a wonderfully solid joint if I was looking for permanence. 

@neilc - thank you very much.  I'm looking forward to seeing it all put together now that I have the finish on it.   Then I just need to figure out where to store it until I can deliver it to them!