squaring off the top of a table base?

[neeboy74]

Hello to all:

I am trying and failing to make a level 4-legged base for a tabletop.  This table is for a laser cutter build and must be as DEAD FLAT as possible...so i prolly shouldn't have used dimensional lumber, althoug it's wood that's over 10 years old and has been stored inside in a climate-controlled storage locker.

So I've made this base and it's nice and solid, doesn't rack...but the sheet of 3/4" melamine I've put on top is not laying flat.  It wobbles ever so slightly and I've been trying for several hours over several days to shimm-up the top so it's level across, but no dice, I shimm-up one edge and then it throws off another edge.

The last thing I can think to do is build an impromptu frame around it on its own legs, and use a surfacing sled with a router to go over all the top edges ever so slightly.  ANyone else agree...or disagree and have a better idea?  Thanks in advance for any replies!

[jteneyck]

Hello to all:

I am trying and failing to make a level 4-legged base for a tabletop.  This table is for a laser cutter build and must be as DEAD FLAT as possible...so i prolly shouldn't have used dimensional lumber, althoug it's wood that's over 10 years old and has been stored inside in a climate-controlled storage locker.

So I've made this base and it's nice and solid, doesn't rack...but the sheet of 3/4" melamine I've put on top is not laying flat.  It wobbles ever so slightly and I've been trying for several hours over several days to shimm-up the top so it's level across, but no dice, I shimm-up one edge and then it throws off another edge.

The last thing I can think to do is build an impromptu frame around it on its own legs, and use a surfacing sled with a router to go over all the top edges ever so slightly.  ANyone else agree...or disagree and have a better idea?  Thanks in advance for any replies!

Are you sure the base is on a flat surface?  If all four legs are the same length then the top of the legs all should be in the same plane if the feet sit on a flat surface AND the base isn't racked.  If you are confident the base is OK then the Melamine might not be flat.  

John

[neeboy74]

Are you sure the base is on a flat surface?  If all four legs are the same length then the top of the legs all should be in the same plane if the feet sit on a flat surface AND the base isn't racked.  If you are confident the base is OK then the Melamine might not be flat.  

John

ok good follow-up point worth mentioning....I didnt make the legs go all the way up to the top surface.  I made the 4-sided frame its own box and then attached the legs underneath that.  BOOOO on my part

[jdonhowe]

One thing I've done to make smaller (router plate, table saw insert) surfaces wobble-free is to put dabs of hot melt glue in each corner, and quickly press down firmly. The glue acts as kind of a liquid shim, which fills any gaps just the right amount when it solidifies.

[Willyou]

Check your frame/base for flatness by running some string (something slick without any fuzzyness, like fishing line, works best) across the diagonals (corner to corner). Make them taunt. If the lines touch in the middle, your base is flat. If you find the the base is flat, lay your melamine top on it and see if there are any gaps between the top and the base. If so, clamp the top down removing the gaps. Check it for flatness the same way. Elevate your strings using some same thickness blocks at the corners. You say your base is rigid, but make sure clamping the top down to it doesn't lift any legs.