Stubborn Desk
December 2nd, 2008*#^%*#%%*#!!
I took a piece of scrap aluminum and screwed it to the bottom of my heavy MDF desk, in hopes that it might take a dip out of the center of the desk’s top. No dice. The aluminum is fairly sturdy, and I checked to see if it was straight before I attached it, but I guess the desk is too strong for it. Maybe I should have forced the desk into a true plane before I put in the screws. The aluminum exerted a lot of force on the table as I put in the screws to attach it, however, so I am sure it’s pushing against the bow.
I don’t know what to do now. I’m wondering if I could put a turnbuckle under the front of the table and connect it to the ends with cable. Then maybe if I tightened it, it would pull the table out of the bowed shape.
The steps I have taken so far cost about two dollars, so I don’t feel too bad.
I wonder if I could get a long threaded bolt and run it between the front feet of the table and use it to pull them together.
December 2nd, 2008 at 5:19 PM
You need something that’s already flat. Your garage floor may be flat enough, or perhaps the concrete of your patio. You also need something heavy. If the garage floor is flat, one of the front wheels of the T-Bird has enough weight to do the job.
Take the legs and structure off. Lay the top, face down, on a flat surface. Wet it thoroughly. Place heavy weights on it, then go away and leave it alone. A couple of days isn’t too long. A week wouldn’t hurt.
While you’re waiting, go to a truck marshalling yard and ask for a couple of pieces of “dunnage”. This is oak 2x4s, fully 2″ by 4″ and unplaned, used to cushion pipes and similar heavy objects in transit. They normally have broken pieces no longer usable but entirely long enough for this project. Rip them as perfectly straight as you can on the table saw. Use those to make a subframe to go under the desk, leaving enough space for the router where you want it. The subframe should have four pieces around the perimeter, 2-3″ in from the edge, and either cross-braces every 4-6″ or an “X” across the middle. Also make legs to suit your compression ratio, and cross-braces for the legs; those can be softwood if you don’t get enough oak dunnage.
When the top is dry on the surface it still won’t be completely flat. Make the “pocket” where the router and lift will attach before going on. Attach the subframe to the underside of the top using construction adhesive and deck screws, drilling clearance holes for the screws first. That will pull it as flat as you are going to get it.
MDF makes a lovely tabletop, but it creeps under load. The structure underneath has to resist the weight, with the MDF just providing a nice surface.
Regards,
Ric