Need to build a lift table

[watrout]

This is my first post here so I apologize in advance if this is too off topic for this forum.
I want to build an air lift (or air float) table for our panel laminating process station and the closest thing that I could think of is the reverse air tables found on some CNC woodworking routers. I was hoping someone could give me some insight as to how this type of table works or if someone knows the calculations needed to determine how much air flow is needed to do what I want to do. I need to float 4'x8' sheets (ranging from ¼” thick to 1 ½” thick) from the panel loading station to a pinch roller. I wanted to make this a one man operation but right now it take two people to move a sheet of this size. I thought about roller wheels, or a conveyor belt but I’m afraid the glue would be problematic with that type of system and cost prohibitive.

I’m not sure what diameter and what quantity of holes would be needed nor what CFM and/or PSI is necessary for this type of application. If anyone has some insight to this dilemma it would me much appreciated.

Thanks

[Kipper]

Could you buy an old "air hockey" table or investigate one?

[watrout]

Originally Posted by Kipper Could you buy an old "air hockey" table or investigate one?

That's what I started investigating but I've found very little about DIY hockey tables. I could buy one, but it would be too small for this application.

[skippy]

a couple of comments:
you could spend a day working out theoretical air flow and pressure requirements, frictional losses, blah, blah, blah, OR you could just built it and see what happens.
Me personally, I would make a box using a sheet of mdf on top and a sheet of melamine particle board on the bottom with ribs in between, say about 2 - 4" high (sort of like a simplified version of Gerry's torsion box construction). Melamine doesn't pass air but the mdf does. Drill your holes (say 1mm) in the top sheet and connect it up to the outlet side of a vac cleaner and see what happens. You don't need a compressor for this because you need low pressure but reasonable flow (cfm). It might be better with an aluminium top but deburring would be a pain.

[ger21]

Our saw at work has 4 air tables, each about 24x48 or a little longer. Each has it's own motor and fan. The holes are about 2 to 2-1/2" apart, and each has a type of ball valve to block the airflow where it's not needed. The balls just "float" in a short chamber and the air lifts them to the top when it's on. The boards push them down to release the air. The holes are about 5/16". Don't know the horsepower, but the motors are small, about 4" diameter and maybe 8" long. The fans are about 18" diameter by 3-4" wide. They are quite loud, especially when all 4 are running.

[Kipper]

I quite like this method.

[ger21]

Those N-600 nozzles look like the ones our tables use. But $8 each?

[Geof]

I like skippy's suggestion; build it and see if it works. But I think his hole size might be a bit small, I did some calculations but don't know how valid they are.

The air has to escape through the gap between the table and the sheet. If the sheet is lifted and 1/32" by the air this area of the gap around the perimeter of the sheet is about 9 square inches. This is just the total perimeter of 288 inches multiplied by the 1/32" height.

Nine square inches is equivalent to a round nozzle about 3" in diameter so that seems to put the ides in the range of a big shop vac.

Regarding the holes: I think you would need much more hole area on the table than there is gap area between the table and sheet because you do not want the holes choking the air flow. Just picking a number I used 5 times for a total hole area of 45 square inches and if you use skippy's 1mm hole you will need many thousands of them; I would make the holes something like 3/16" or 1/4". You still need a lot but it is now in the many hundreds.

I have no idea if my 1/32" gap is sensible. Maybe 1/64" would be fine or less. It will depend a bit on how flat both the table and sheet are because it has to lift high enough to clear the high spots.

I am confident a large shop vac would do it but you would need the little ball valve things to stop air being wasted out the exposed holes.

[Kipper]

Capillaries? I noticed this near me. Not sure how many holes are needed :shrug: but it's cheap enough to play with

[Geof]

Originally Posted by Kipper Capillaries? I noticed this near me. Not sure how many holes are needed :shrug: but it's cheap enough to play with

Kipper I think your definition of cheap might differ from some . That looks like the stuff I used to roof my solarium; I know what it costs at least in Canada.

This stuff would probably work really great as a sandwich between two pieces of MDF for a vacuum table adapter. Drill holes in the both sides, build manifolds across the ends, place on machine table, place work on top and apply vacuum.

The vacuum works through the bottom MDF to hold it down to the machine table and through the top to hold the part down

[Kipper]

Geof £35 for 6M is cheap surely? My definition of cheap is almost free..and preferably free :yes: I'm a Yorkshireman after all....

[Geof]

Originally Posted by Kipper Geof £35 for 6M is cheap surely? My definition of cheap is almost free..and preferably free :yes: I'm a Yorkshireman after all....

Your picture mislead me; it looked like the 19mm which I used and that is much more than around $79 CDN. I know what you mean about Yorkshiremen, I are one and got a reputation for being cheap when I worked in Aberdeen for a year.

I think the thicker stuff would be needed for my vacuum sandwich idea.