Torsion Box question

If you follow Marc’s method, you should be flat when your done. I’ve built a couple of oversize interior doors using Marc’s method and ended up with perfectly flat doors that have not warped.

-- Dave Herron, Boise, ID -- “That which does not crash the browser, makes it stronger”

well, if you rip all the pieces to same width thats one thing, but to assemble them flush – you’ll have to have a dead-flat surface as a reference to doing that – otherwise what guarantees that your assembly is truly flush?

in theory – you are correct – all you really have to do is assemble all pieces flush. in reality – there are too many pieces, and the potential of some of them to be out-of-flush is very high, in order to overcome this – you use a dead-flat surface as a work surface to which you reference all your pieces to, making sure that they are indeeed all flush to that surface, and thus to one-another.

hope this makes sense… lol

-- My Drinking Club has a Woodworking Problem...

The point of a dead flat surface is so that as you add the build out from the edge all of your interior dividers especially the short ones is to keep them square to the outside frame. Since they are only attached (in the beginning) on one side they will follow any curves in the support surface and your errors will magnify as your move across your box. Here is a link to my blog (still in process) on a RAS cabinet and a Torsion box that will be used to support the RAS itself.

One word to wise, be patient and take your time getting the surface dead flat. Make sure you have all of your equipment setup and ready (glue/brad nailer/squares/etc) so that you can get your surface set properly and more right into assembly of the Torsion box. Nothing worse than going though the flattening of the surface then realizing that you forgot to hook up the hose and brad nailer and kicking the saw horse on your way to do that! Argh!

-- //FC - Round Rock, TX - "Experience is what you get just after you need it"

”kicking the saw horse on your way…” hahaha (sorry, but this should have been caught on camera)

;) good one sIKE, how’s the project going along?

-- My Drinking Club has a Woodworking Problem...

I got the torsion box parts cut to size last night, and got my surface dead flat, kicked the saw horse, had to reset the surface up, then I got the 3 Outside edges glued and went to brad them and that crack in my Air Compressor line expanded so big that I had to stop for the evening and I am going to have to swing by the orange box on the way home so I can get that back together so I can get this done. It is only temporary as I am going to replace it here soon.

-- //FC - Round Rock, TX - "Experience is what you get just after you need it"

Thanks everyone for the advice. I’ll confess, I am having trouble getting a dead flat surface using the methods diplayed by Marc in the Wood Whisperer video. I have only a crappy bench top jointer, and my other methods of making perfectly straight and flat 2×4’’s are not working so well. (lack of experience and skill I am afraid). I am new to woodworking, and have been hooked since I started. It seems like projects like these are a good way to gain knowledge and still get valuable equipment before before moving on to more traditional projects. I will continue to shim and do what ever it takes to create a flat platform.

Thanks again, it is very much appreciated.

thats all fair and square TPE – we all run into difficulties, and at times seem like we cant get things straight ourselves – you’re not alone.

that being said – practice practice practice and learn as much as you can to get perfect 90s and 45s, flat edges, and clean surfaces – and with time these things will come as second nature – and your work will be more about what projects to do, and how to do them as opposed to how to get the right cut on the pieces of wood for the project…

but a torsion box is a great way to start – if you can get that going, at least you’ll have 1 truly flat surface that you can use as a reference to ALL your other projects, and work.

hope this helps :)

-- My Drinking Club has a Woodworking Problem...

When I built my Torsion box, I first constructed the cabinets that it was going to sit on. I accurately leveled the cabinets in relation to each other and then built the torsion box on top of them. It was very easy to keep all of my parts flat this way.

-- Tony, Ohio

Or you can move into a house that has unlevel floors, mark your torsion box with a reference to match the slopes in the various rooms and your furniture will sit flat.

-- Tim -- http://tmuli.com

I started the assembly of my small torsion box this evening. I did manage to get a nice and flat surface. I based my design and process off of Season 4, Episode 9 of Wood Works. David Marks makes it look so dang easy! I am have the hardest time with my brads not running true when I have to toe nail in from the back side. This makes keeping the grid nice and square impossible. I am trying to keep it as tight as possible.

Lesson learned make sure that you consider the size of the space of your grid to (if possible) insure the nailer can fit in the space. Also, don’t use 1 1/4” brads instead use the recommended 1 1/4” finishing nails. Hope this helps!

-- //FC - Round Rock, TX - "Experience is what you get just after you need it"

sIKE

You have been warned and the SPCA has been notified!!!!!!!!

.....................kicking saw horses in deed…...............

When I finally found a flat surface on which to build my torsion box, it raised the question “why do I need 2 flat surfaces?”.

This lasted only until the wife kicked my projects off the dining room table.

-- I can so I wood but why are my learning curves always circles

When I built my first torsion box I used the shop floor. Only place I could find a flat enough surface. It’s really important when you glue/nail the skins on to have a really flat surface. I use glue and brads. I apply glue, add the skin, place weights on the surface to make sure it is pressed flat, then nail.

-- Dave Herron, Boise, ID -- “That which does not crash the browser, makes it stronger”

I built a torsion box 4’ x 8’ about 4” thick and designed a hole in the middle for my Sears Craftsman table saw to sit flush with the surface. I then built three more torsion boxes . two that formed the ends and a lower one for the saw to sit on. I put wheels on the bottom of the end boxes and now I have a table saw big enough to cut full sheets of plywood by myself and I can roll it out of the way. I use the surface to build on being very flat and the whole thing is so strong I mounted a hinged router table to the end.

-- Dave Dahlke

Hello all,
I finished the torsion box and have another question for the experts. I worked very hard to create a level platform before I began assembly, but am a little disapointed in my final results. Despite my best efforts, I have a slight warp in my finished table. I have made a 6’x4’ table, and when putting a straight edge along the length, I have about a 1/16” of an inch dip in the middle, (or bow in the opposite side). My question is this, is this an acceptable tolerence variation for a table like this, or should I begin to attempt to resolve this issue.
As of now, the only solution to this problem that I can think of is to create a router sled and use this method to flatten the surface, but this technique is above my current skill grade. (might be a good learning experiece though).
Thanks for the help.

The 1/16” variance will come back to haunt you at some future date during a glue up. What did you use for a top surface?
I built a 4’ x 4’ version of Marc’s TB and using the 3/4” mdf it came out dead level using his methods.
My TB Table build
You’ll have to scroll down and locate the TB picture set.

-- Seldom wrong, but never in doubt

Harley,
Thanks for the response. I used 1/2 mdf for the top and bottom skins. I looked at the photos you provided, and it looks almost exactly like the process I attempted. After I installed the first skin, I checked for flatness, and all was good. I somehow screwed up when I flipped it over to apply the other surface.
I do want to get the surface dead flat if possible. The only options I can think of at this point is to create a sled to route it flat, or pour on a self leveling epoxy, then installing the hardboard top. I would really hate to waste the material by starting over.
Thanks again for the help.

I think if it were me I would go with the self leveling compound and then put another skin of 1/2” MDF on, then add the hardboard.
I thought about using the 1/2” as top/bottom skins but decided to go ahead and spring for the 3/4” thickness just for stability factor.

-- Seldom wrong, but never in doubt