Engineering Help

[SONICJK]

Alright guys, as some of you know I have a woodworking business
Lately I have been building a lot of tables and the tops require glue up and its getting tedious to clamp everything up.

So i put some fab skills to work and came up with this

Basically its a steel table (read flat) surrounded by 1/4 inch angle iron. The back and sides are welded to the table and the front piece (on the right in the picture) is free floating.
The principle is, I toss a table top in there and then there are 3 acme screws that i toss the impact on

Tighten the shit out of it and instant clamp

the problem im having is this: To get the middle screw in there it had to be placed above the centerline so that the table top can fit underneath it, this when tightened causes the whole angle iron to tilt effectively negating any clamping force.

so finally (long winded) my question is:
How can i transfer the force of this screw tightening to the BOTTOM of this piece of metal as opposed to the top to get rid of this twisting effect?

 

[DesmoBro]

Clamp the angle irons down to the table so they don't twist in

 

[SONICJK]

As you can see in the picture, I just did that but i cant clamp in the center where the twist is.

 

[DesmoBro]

Do you need a bigger clamp to reach from the edge of the table? like some long welding Vice grips or something....Or maybe you could weld the part thats twisting to the table and tighten from the other end....Maybe i'm not understanding whats happening

 

[SONICJK]

Youre on the right track, i dont have a clamp thats deep enough, but I need to figure out another solution, as the widths of the tables are all different so it has to be able to clamp to any size, so just clamping it to the table isnt really the solution im looking for.

Hell i dont know if there is a solution, im just hoping there is haha

 

[SONICJK]

Just realized I mistyped "center" on my picture, wow.

 

[DesmoBro]

Slide the entire contraption closer to the edge if possible and use 2 more clamps one on either side of the bolt to keep the cenmter haha from lifting up....would that work?

 

[DesmoBro]

put some holes in the angle iron & table and bolt it down?....go back to flintstone era and use 9 pipe clamps

 

[sasquach]

Bolt it to the table also

 

[SONICJK]

If i have 4 sides bolted to the table that makes......a table with sides.
I need a clamp haha

 

[DesmoBro]

Get 2 or 3 of those long welding Vice grips that will work for now maybe not with a smaller size tho since the edge will be really far away like the ones in the bottom right hand corner of this pic

 

[Turnturtle]

What about something that mimics a carpenters wood screw clamp. You would need 2 threaded rods and a stiffener to keep the rod in compression from bending or collapsing.

 

[SONICJK]

What about something that mimics a carpenters wood screw clamp. You would need 2 threaded rods and a stiffener to keep the rod in compression from bending or collapsing.

Elaborate?

 

[DesmoBro]

Make a Big ass wood screw clamp? i think thats what he means

 

[Ringo]

Have you tried just clamping it without the center rod? With that size angle iron, I can't see there being much flexing at all. If that doesn't work, maybe pick up a couple pieces of really heavy angle iron, or box section?

If it's beefy enough, you shouldn't need the center rod.

 

[Turnturtle]

Think of it as a rocker arm. One end pushes at the bottom of your angle iron frame. The middle (pivot) is your threaded rod under tension. The other end, in order to be adjustable, is also threaded rod, but under compression (lots of it!). It would need to be stiffened to avoid failure.

 

[chillinfellow]

How about notching out one or maybe two strips on the steel top so you have room to slide clamps up to the angle.

 

[SONICJK]

Have you tried just clamping it without the center rod? With that size angle iron, I can't see there being much flexing at all. If that doesn't work, maybe pick up a couple pieces of really heavy angle iron, or box section?

If it's beefy enough, you shouldn't need the center rod.

The original design was just the 2 rods but believe it or not I got over 1/2 inch of flex in the angle iron in the center hence the 3rd rod

 

[Tim]

Would this help? I'm no engineer, but it would seem this should transfer the load to the bottom plane of the angle iron.

 

[Tim]

Oh, and clearly I'm no artiste either