Thread: Warped NYW Table Top

Dear Bruce,

Not much sage advice here I'm afraid but I was wondering what's the point of the two table top pieces glued and screwed? Is it to get:
1) Stronger top
2) Thicker top

or something else?

Regards,

David

I would back the boards with whatever you put on the top.eg laminex on top,laminex on the bottom,you've struck the old problem of out if balance wood ,one side absorbs moisture quicker than the other,Scuff the bottom layer so you get a good key for the adhesive to stick to.

This was a problem for the manufacturers of drafting tables made of ply or other manufactured boards. They solved it by running shallow cuts of about 1/3 depth on the rear of the board and bracing it hevily.

i do the same for slab benchtops and the like and many flooring manufacturers also do so.

Taking the cuts allows the underside to swell without making the board as a whole swell and hence move.

I have a router table top from PWS - close inspection reveals that it's two sheets laminated together (a single layer of laminate in the middle, as well as one each top and bottom). I coated the exposed non-laminated surfaces with polyurethane to seal them, and I saw no departure from dead flat. But, to be on the safe side, I screwed 4 lengths of heavy aluminium channel to the bottom surface, as a kind of subframe. (Obviously the channel is clear of all fittings to the stand as well as the plate recess.) Any warpage could then only be along a diagonal of the subframe. I expect the whole thing to still be flat when one of my grandchildren inherits it.

- Michael

Can you run some saw kerfs on the underside about 1/3 of the depth of the MDF laminated top and then run some jointed peices (braces) at a right angle to the kerfs? slightly enlarge the holes in the braces and screw the braces to the underside of the top. You can use shims under the bracing to level the top where it's low. When you get the top perfectly flat screw the screws down tight, If the top moves again add or remove the shims to make it perfectly flat again.

When I need to get a wood top perfectly flat, I'll go to the dollar strore and get some cheap made in oversea lands feeler gauges to use as shim stock. Because they are cheap and I don't care about cutting them up.

A common misconception is that MDF is stable... well it's really not. It's made of wood and subject to environmental factors like temperature and humidity that can cause it to move. Granted MDF is more stable than a solid piece of wood but it's still wood and will still move a little, just not as much as solid wood would subject to the same environmental factors.

By the way that's gonna be a nice router table, don't give up on it - sometimes you just have to show wood who's the boss

Thanks

Thanks for all the feedback it's much appriciated!. I've decided to use a combiantion of your suggestions and try using some angle aluminium (I just remembered my sister in law can get it at cost as she works in the industry) I'll seal the underside and screw the aluminium in place to hold it flat (I'll screw it in such a way that it locates the top in relation to the dust collection compartment then some additional lengths parallel to the out side faces) then apply the HPL to the top and all going well everything will stay flat !

I'll post some photos once it's done if anyones interested and let you know whether it was successfull

Many thanks

Bruce