pentagonal coffee table

[Jon B]

Hey Everyone, This is my first post here, though I have been following Chris's blog and the forums for some time now. I thought I'd share a recent project that I'm just finishing up, which is a 5 legged coffee table. I have to give inspiration credit to Chris and his pentagonal table, as well as his early blog posts about geometrical design and the golden ratio....topics which I have been interested in for some time. I was asked to build a coffee table and played around with different designs, but I really liked the look of a table with 5 legs. Visually it seems more dynamic somehow. The top being solid wood (glued up boards) I had to devise a way to form a structure to support the top across the grain, so I created a grid structure which follows the lines created by offsetting two pentagons...essentially creating 10 points around the perimeter....hope that makes sense.

Anyways it was a fun project and a good challenge. Looking forward to some more challenging work here on the forum.

-Jon

[Paul Atzenweiler]

I really like that. It looks really good in the upright position and also upside down! You should set it on a mirror

[Brian]

Nice work Jon! Nice tight joinery and excellent design, I love the system of battens especially so.

[Yxoc]

Love it!

Five legs does look good for some reason...

[Chris Hall]

Pentagonal does make a lot of sense as a geometrical form for tables, buildings etc., as the angles of intersection are closest to 4-sided. You get into 10-sides or more, and you start getting closer to a circle, and the meeting angles become broader and trickier to handle, not to mention the shape of the legs.

Nice design by the way. Did you solve the mortise/tenon geometry by way of SketchUp? How are the cross pieces attached to the lower frame and the top?

[Jon B]

Thanks for the positive feedback fellas! The cross pieces are themselves joined by half laps, and then they attach to the legs with tenons. The upper braces are basically setting on top of the lower rails.... I thought about lapping the upper and lower sections together but it seemed like the mortise and tenon joints into the legs would be enough. The top attaches via dovetail keys of hard maple, and this was something that I had never attempted before but it think it worked out ok. I would like the top to be held stationary down the center, allowing for expansion and contraction on either side of center, but I haven't quite resolved how to lock it down yet. As far as the geometry goes, sketchup did really help to visualize things, but I worked out the actual angles by making a full scale drawing and doing a small bit of math. Since the legs are vertical all I really had to do was work with the angles given by a pentagon. A couple of the angles for the upper cross braces were a little more tricky in terms of how they met with the legs, and to lay out those I simply laid the assembled structure onto the full scale drawing to mark out the locations of the mortises, along with a sliding bevel.

The design of the joinery was a challenge and I still have a lot to learn when it comes to designing/proportioning joints, how much relish to leave at the end....lots of things really. I have gleaned a lot of good info off of the forums here though.

[Chris Hall]

Since the legs are vertical all I really had to do was work with the angles given by a pentagon.

ohhh. It looked like the legs were splayed in the drawing, so I thought you had taken a trip into the world of compound joinery. All the same, excellent work!

[AntoineLaMothe]

Very precise and clean work, bravo!

[RLSIII]

great piece I like its stance. thank you for sharing.
Rob S