Making a Variable-height Flip-Top Table *PICS*

Making a Variable-height Flip-Top Table *PICS*

Garrett in Victoria BC

>SWMBO - or in boating parlance, the Admiral - decreed that our boat needed a hybrid table that could spend most of its time small and low in front of the settee, but that could be raised for dinner for two, or for dinner and bridge for four. We looked hard but found nothing available commercially.

The solution, she 'suggested', was to make one, and although not quite finished as I�m waiting on the hinges by mail from Lee Valley, it meets all of her specifications:

Coffee Table, 24� high, 30� by 15� top

Pivoting to full-top position

Before flipping

Flipped open for dinner and/or bridge for 4, 31� high, 30� x 30� top

The top consists of two identical pieces, in this case � ply laminated on both sides with Formica trimmed with mahogany to match the rest of the boat. The 'aprons' are an open box, 2� x 3/4" solid mahogany � narrow because seat heights on the boat are 20� - with a �� plywood bottom assembled with pocket screws.

The only difficult part in making the top and aprons is determining the pivot point, as considerable precision is required to have the top overhangs line up perfectly on all 4 sides in both open and closed modes. The theory says:

1) lay the apron assembly on the top as it would be seen from underneath in the open position, and draw diagonals from the corners of the top across the aprons. It helps to have a solid base for this step;

2) lay the apron assembly on the top in the closed position; and

3) picking one of the diagonals, find the centre-point of the distance from the cross-over point of the diagonals to the overhanging edge of the top - NOT the edge of the apron � and that, theoretically, is the magical pivot point.

Unfortunately even a small error produces a top that is visibly mis-aligned. You will thank me if you take my advice and make a full-size blank out of �� material, because after several tries it was clear that the theory delivers a pivot point that in practice is close, but not dead-on. (I had to make another half top as a consequence of assuming the geometry and I would be perfect. We weren�t, and I ended up with a pocked marked under-side.) By drilling a 1/8� hole through the mock up and the bottom of the apron assembly - which I also replaced - for the pivot point and using the drill bit as the pivot, I finally found the right spot, and carefully circled that hole so as not to confuse it with several others in the neighbourhood.

I made the full-size pivot as follows. I bought 2 3/8� tee nuts, one that hammers in and one that has 3 small holes in a smooth flange. I drilled the threads out of the first one and used it as a bearing, counter sinking it into the bottom of the apron assembly with a 1� Forstner bit.

Overkill, perhaps, but I also took a scrap of aluminum, drilled a 3/8� hole, and screwed it to the other side of the plywood. There will be no slop in this assembly! I countersunk the other T nut into a piece of 1� maple and screwed that into the underside of the pivoting half top.

Assembly is just a matter of inserting a 3/8� hex bolt through the apron assembly into the second T nut. NOTE: This is the only fixed connection between aprons and tops, so the table cannot be lifted by the top(s). I installed a 1 �� brass barrel bolt to one of the long aprons and drilled 2 matching holes in the underside of the fixed half-top so that it cannot move in either the open or closed position. (Visible in the next photo.) The little dot in the middle of the right side of the top is the other hole. When the table is moved to the closed position, that hole rotates directly over the barrel bolt.

This style of table can be made square, rectangular, or with a gentle boat shape, and usually has 4 legs and fixed height, but because our requirement necessitated variable height, I purchased and modified a heavy restaurant pedestal from a used furniture store. Normally, a long bolt runs through the tube to the spider at the top and ties the three pieces together. I cut the tube down, and welded a nut inside it at the bottom so I could attach the tube to the base. I glued up a wooden blank and turned a 2 �� dowel to an easy fit inside the tube. I then made three shallow grooves along the length, and glued in rub strips that I hand-planed to emulate a smooth-sliding �piston� fit. (Don�t want any wobble.) That done, I drilled a 1� hole most of the way through the length of the dowel � I needed to keep the lower 2/3 clear for the next step � and then drilled the remainder all the way through at 3/8� so I could bolt the dowel to the spider.

Underneath

With all the pieces assembled, I drilled a single through hole at the top of the tube and a series of matching holes through the lower part of the dowel. Inserting a brass pin � an old piece of a drain stopper � provides the desired height.

Cheers, Garrett