Dead flat router table top

[martink]

Have been searching around for a method of creating a dead flat router table top. There are many suggestions here on what to make it out of but none suggesting how to make it dead flat.

One suggestion I remember reading somewhere was to glue a peice of hardboard to a 19mm peice of Ply. Then turn it upside-down whilse the glue was still wet (so the hardboard was on the bottom, then place it on a cast saw table and put some sand bags on top of it until it dries. This sounds like it would work a treat, the only problem is I don't have access to a large cast iron saw table :(

Anyone got any ideas of what I could try?

[journeyman Mick]

Martink,
Go to a cabinetmaker and buy a piece of "aquaban" off him to your required size as well as an offcut of laminate, or possibly an already laminated offcut. This is 33mm thick particle board with a melamine coating on one side. If you laminate it all round and fix it to a true and stable base you'll have a top that will be as flat and stable as you can get without resorting to a piece of cast iron that's been surface ground. Ply won't be anywhere near as stable.

Mick

[Harry72]

Make it from steel, buy decent quality(not import stuff... BHP is the go)its flat enough for woodwork, support it properly and it will stay flat for longer than you live...
For support dont weld as it will warp the plate, using countersunk head bolts drill holes and countersink with some angle underneath.