I am going with what Ryan has said, “tables are less important and perfectly flat tables are unnecessary” at least for my through cutting 2D projects (it’s all I do).
So with that, my questions are pertaining to building just a table top that will be flat enough and yet big enough for full size machine and here is the kicker, be light enough to move and store on its long end (no cnc attached) against my shop wall.
My design is based mostly on Ryan’s table with a lot of Doug’s influences. Rather than gluing and screwing each grid block, I will use ribs and groves to make the grid (like building giant model airplane wing. LOL ).
I was thinking of using 1/2 ACX plywood (good quality, limited voids, etc) for my ribs based on Doug’s parametric table rib designs at 3” wide, with 1-1/2” slots to form the torsion grid.
My question is will 3” torsion grid all glued up with 1/2” MDF top, open bottom hold up or will it be too wobbly? This will be like 110” long and 62” wide. I’m sure it will be just fine when in use laying on another table, but my concern is the forces of nature on the table top when its is moved off the table and stored.
Why 3”? Because I can fit all the ribs and struts on one sheet of 1/2” plywood. And it would be lighter than 4” or 6” wide.
Thanks in advance for the replies and pulling me out of the table rabbit hole .
I made Ryan’s design (MDF for accuracy, doesn’t have big “slots” so I just made it on the table saw and it’s engineered to be a little more rigid) with hardboard top and bottom. I then have a removeable mdf spooilboard which makes the whole thing “light enough” to move around without killing myself.
I agree with using a thin (1/8") hardboard top and bottom with a removable spoilboard to keep it light. Having both top and bottom adds a lot of rigidity, and reportedly it is the skin of the top/bottom that adds strength, not necessarily the thickness.
3" vs. 4" MAY be ok. I’m not an engineer, there are others here who should be able to answer definitively. As long as you handle it carefully, forces shouldn’t be too crazy.
How do you plan to cut out the slots? A good tight fit is important, and having the corners at 90 degrees is also necessary. A full cut through with a table saw should give you the square corners, but may lack the accuracy to give a tight fit. Also it may give you a less than smooth line on the bottom edge of the slot (multiple passes through the saw to cut the full width).
Dado Blade each notch. will use shims in dado on scrap until I get the tight square fit needed. Unless y’all got a better idea. I could make a template and use router but that is probably much more work and not any more accurate.
I am just now getting table saw out and fixin’ to start ripping
Just be aware that Ryan’s design Parametric Table - #156 by Jonathjon is different than this one, and doesn’t have slots, but I think the end result of either will be “more than good enough!”
So, you want to keep it light, but you’re adding to the thickness?
I will use the example of ikea tabletops. The Linnmon desktop and Lack tables are about 2" thick, made from 3mm hardboard, with literally paper reinforcement inside them. (Stiff paper, sure, but thinner than a cereal box.) These are stiff and strong enough to stand up to a lot of weight, even over quite respectable spans.
It appears to me that you’re making your ribs and spars from fairly thick material. (18mm?) This is probably mostly unnecessary weight, and the 4" thickness is most definitely more than needed. Nice that it fits on a sheet, but I don’t think that you need to use the whole sheet for a table.
Me? Yeah, I go for overkill torsion box tables, realizing full well that they’re way heavier than they need to be.
I know, crazy right!!! After rethinking (yet again) I am going back to my original 3" wide ribs and 1/8" sheet on top (and adding one on bottom). it will be what it will be, which I’m sure will be just fine. thank you for the rope, I see the light at the top of the hole now.
in my opinion way to much of over kill in struts and cross members
my table cutting size is 1300 x 3100mm or 50 x 122 inch
and uses way less
if your going to use the collapsible saw horses like in (Portable Lowrider in Annapolis - #38 by wcs39204)
you don’t need the 4 long struts
if you use 2 x 140x 30 on edge in the outer edges of horses , cut out top notches for struts , bottom notches for horses they don’t need to be tight fits , mine have 3mm play
dont worry about glue just screw on angle from top make sure 2 sides touch each other . only 1 screw per strut , next strut screw opposite so it pulls back to last strut
throw on you spoil board ,
i used kwila decking as my runners, due to hardness and rigid i know it wont warp, in shed
itf you have laser with squaring lasers this makes life easy here set it up where 0.0 will be with machine kick u r saw horses till bed is square , move spoil board to be square also screw spoilboard than screw decking done ridgid as shit
That should work if you use blocks to control the cut. You may want to consider clamping several pieces together in order to reduce the number of cuts required (although messing up a cut could result in multiple pieces being ruined)
