Saggy table blues

[Walter Holloman]

Hi - I have a long 8' by 4' outfeed table on risers and wheels. When lowered it is the same height as my tablesaw and acts as an outfeed and worktable. When it is raised on wheels it rolls and covers my table saw for storage and to park cars in the garage. Thus, it is U-shaped and does not have any apron on the long side that rolls over and encloses the table table saw. It's made of many 1.5" x 8' KD pine boards I ripped from 2x4's. So each board runs the entire length of the 8' table top.
Here's my question for y'all...I know you're wiser than I and hope you can help with the remedy. My tabletop is starting to sag a bit in the middle AND I just got a new tablesaw so I need to make it almost 2 feet longer. How do I proceed?
I'm thinking about dismantling the top, flipping it over, add 2' in length and attach bed frame angle iron in several places running the length of the newly-elongated-table-top . Seems like it would work, but here's the tricky part. Seems like I should make sure that each angle iron is attached to only one board in several places to allow for wood expansion. Repeat this 4 or 5 times for more angle irons, each iron on only one board. Then I will rely on the stronger-reinforced boards to support their adjacent boards. If I join the angle iron to more than one single board, I'm afraid the top might warp or cup because I've not allowed for expansion.
Does this make sense?

[Marshall Harrison]

A picture would really help us out.

[George Yetka]

Could you add an apron on one side and another on the opposite side with a hinge so it can swing up to clear the TS?

[Jim Becker]

Angle iron can definitely help with the issue, but over a longer span, even angle iron will have some deflection. Laminating the top with a second layer of whatever sheet goods you used might also stiffen things up. Given they way you must keep the underside open so you can cover the saw for space reasons when not working, the combination of the angle iron and never putting anything of any concentrated weight on the open edge is probably the best you can do.

[Bill Dufour]

For cross grain breadboard ends the normal way is a single screw hole in center with slots everywhere else to allow the wood to move. I would have metal running both ways and weld it together.
Bill D.

[glenn bradley]

To Jim's point; if you have minimal clearance when "stored" you could laminate 1/8" hardboard to each side to add some rigidity. You want to roll the glue over the entire surface prior to applying the hardboard to get the tension benefit.

[Carl Beckett]

If you have the space underneath, you might consider a torsion box type design. May mean a redesign though.

Otherwise steel i-beams. Or even laminated structural lumber on edge. But I dont see a way that doesnt add considerable thickness and rob your space underneath.

In general, beam deflection goes with distance from the bending centerline (moment of inertia). So relatively thin designs dont have a chance.

If you are storing a cabinet underneath, could you make it integral so the cabinet provide the support and the top didnt cover such a long span...

[Walter Holloman]

Thanks, Brothers! I should have provided a photo or two and will do so over the weekend. I guess I was waiting to see if there would be a response as this was the first time I’ve ever posed a question. I appreciate the time you took to reply and am digesting your responses.

[Walter Holloman]

oops, learning how to post a photo

[Walter Holloman]

Ok here a a couple photos (dont mind the mess). One shot is the open side, which will roll over the table saw and basically occupy the same footprint. The other side is closed so i use it to hang tools, blades, etc.

I’ve been pondering your thoughts. Didn’t realize how much clutter had accumulated on the table top. that’s the first thing to fix - no clutter weighing down on it.

the underside of the table top is flat and that is where I was thinking to install some angle iron.

[Matt Lau]

I'm not sure if there's enough space, but what about a torsion box?

[Walter Holloman]

I'm not sure if there's enough space, but what about a torsion box?

Thank you, Matt. Do you mean replace the table top with a torsion box? Or adhere a torsion box to the underside? I know of torsion boxes through reading, but have never worked with one.

[Paul F Mills]

When you slide the saw under the table, slip some shims in to support the table when stored. The sag is not likely from when using the table.

[Carl Beckett]

That top looks like the top of my workbench - there is always some clutter on it. Which just means that is reality, and you need to be able to support it. Essentially a workbench top.

It just looks too thin for the span to be satisfying over the long run.

If you can give up the space on even one edge, I would start with two pieces of 3/4" plywood on edge. Maybe 3-4 inches wide. Attach it along the back edge so the table still slides over your tablesaw up until it hits that support rail. (or even better, just box in the back). Or angle iron, but over that span even angle iron is going to need some height to it. Just saying it 'might' not have to be down the center and might make a big gain even if just the back edge.

[Robert Engel]

Torsion box ++

[Josh Belleville]

I have a similar issue, but my 600# 8’ X 4’ Bench/tool wall/wood storage has the front open for a rolling cart for benchtop power tools that lowers and goes underneath. After about 3 yrs, it was opening up, to about a 1/8” drop in the middle. I ran a webbing of 2x4 on edge underneath, but still failed the engineering!

I put a screw jack for travel trailer steps on a spare 4x4 for a center leg. Takes about 2 twists with the adjustable wrench to put it in or out. $12 fix.

407949407950

[Alan Lightstone]

I was thinking of a 4x4 on a caster permanently attached to the middle. That should work fine.

I've also taken the angle iron approach in the past, but it's not foolproof.

Torsion box, IMHO, is the best solution.

[Tom Bender]

If you are going to make it 2' longer will you make a new top? I'm guessing yes.

So make the new top stiffer and with a little arch.

To get an arch;
Just study your boards, are they all flat? Take advantage of any bowed ones and focus on the saggy edge.
Where the ends overhang your frame pull the boards down a bit to flex them up in the center. This depends on a very stiff frame so you might need to work on that first.

To make it stiffer;
On the saggy side use one or two Oak boards.
Connect the boards together by screwing 2 or 3 pieces of 1/8" x 1" steel to the bottom.
Stiffen the saggy edge board by screwing 1/8" x 1" x 10' steel lengthwise on the bottom. This will add tensile strength to the bottom surface.

[Charlie Velasquez]

If you were thinking angle iron you have some metal working capabilities??
If so, consider this (ignore the poor quality of the doodles)

409101

Parameters: open side to roll over table saw, thin top, 2’ longer table top, Continuous 8’ (retro to 10’) is a long span
You need to add 2’ anyway so
1. Cut the table in half (red)
2. Move the two halves outward to add the 2’ in the middle
3. The only place to gain support is the long side where you have the clamp board and paper roll dispenser so we will use that side. Add a piece of 1/8” x 3” flat steel (steel in yellow) to your base above where you have the paper dispenser. *
4. Instead of right angle, weld two 1 and 1/2” high t-angles (blue) perpendicular to the flat steel 2’ apart.
5. Place the 2’ extension between the t-angles,
6. Place the two 4’ sections to the outsides, supported by the end of your base and the t-angle.

I have seen a welded right angle bracket support a car engine, albeit thicker steel, but we are just trying to eliminate sag.

* Alternately run your support vertically, and add a brace for the vertical legs.

[Jack Frederick]

How about a couple hinged triangular supports off the open side. Actually, rectangular would be better. The hinge would allow the leafs to fold and still fit over the table saw. Get a couple rod couplings and some all thread and you could make the top and bottom adjustable. A couple stiff legs will work off the back. The thing about level on a moving table is that "level" ends up depending exactly upon floor placement. The All thread might help with that. If this passes the smell test, do you have a friend who can weld the rod cplgs or can you? If not, I can knock four together for you.