I decided to re-engineer the whole thing.
The previous owner had put on an aluminum extrusion table, but had left the underlying MDF table in place. MDF has no strength over a span, so I replaced it with 3/4" phenolic-faced baltic birch plywood.
http://www.flickr.com/photos/gleepdc/64 ... otostream/
http://www.flickr.com/photos/gleepdc/64 ... otostream/
The angle iron along the sides of the table was attached to the HDPE end plates and the MDF tabletop with drywall screws! The holes were of course all ovaled out from flexing.
http://www.flickr.com/photos/gleepdc/64 ... otostream/
I took out the drywall screws, drilled out the angle iron, and put in 1/4" all-thread with jam nuts and washers to act as a leveling mechanism. The all-thread goes down into the HDPE end plates about 1 1/2". The bottom washer spreads the load, the bottom nut is the height adjustment, the middle nut is the lock to keep the bottom nut from moving. Above that, another nut and lock washer tighten down the T-nut in the extrusion above.
http://www.flickr.com/photos/gleepdc/64 ... otostream/
http://www.flickr.com/photos/gleepdc/64 ... otostream/
The all-thread goes through the angle iron and plywood into T-nuts in the extrusion.
Then I drilled holes along the path of the extrusions for T-nuts. This makes the plywood, extrusions, and angle iron all one unit. One major design flaw of the previous design was the extrusion was only fastened at the ends of the MDF, allowing the extrusion and MDF to sag and separate in the middle.
http://www.flickr.com/photos/gleepdc/64 ... otostream/
http://www.flickr.com/photos/gleepdc/64 ... otostream/
End result is a easily leveled table that is flat to 0.001"
.http://www.flickr.com/photos/gleepdc/64 ... otostream/
Now to deal with the unsupported rail droop
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