Tuesday, July 01, 2008

Pedestal Table: The Spider

Traditionally, pedestal tables have a steel brace called a spider attached to their undersides which serves to protect the joint between the legs and column from the stresses of being moved around on the floor.   When made properly, and with modern glues, the long sliding-dovetail joint that attaches the legs is quite robust.  Even so, over the years that joint is bound to suffer a lot of stress from the weight of everything above it including the tabletop itself.  The photo below shows the underside of the pedestal without a spider.  In it you can see the ends of the dovetail-shaped tenons that slide into corresponding mortises on the column.

The first step in making a spider is to come up with a template.  I like to make the central disk separate from the tines that attach to the legs.  That way, the tines can be individually tweaked until they're perfectly centered on their respective legs.  Once I have each tine where I want it, I attach it to the disk with a little spot of glue.

At the shop where I apprenticed, we always made our own spiders from 1/16" thick sheet steel, cutting the pattern with a metal-cutting jigsaw blade.  When I called my old boss Harrison for a couple of reminders about the finer points of spiders, he mentioned that he'd found a local metalworker who would make custom spiders for a very reasonable price.  Below you see the pattern I provided to Larry the Spider Maker and the spider I picked up at his shop this morning.  I was interested to see that the tines were welded on.

A spider should be attached to the pedestal in the four spots between the leg joints and in two spots along the underside of each leg.  I marked the hole locations with a center punch (actually all I had handy was a ground-down nail set) then bored the holes with my drill press set at a very low speed.  I was sure to use plenty of oil as I did so, and I used a scrap of plywood to protect my drill press table from becoming an oily mess.

After countersinking all of the holes, I used a bevel gauge set to the initial angle between the bottom of the column and the legs.  With the spider clamped to my bench I then bent each tine to match that angle.

Once all  of the tines were bent, I was ready to install the spider.

Here's a shot of the spider screwed into place with #10 wood screws.

Tomorrow morning I'll do a little bit more rubbing out and waxing of the finish, and then it will be time to move on to the next project!

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