Creating a level plane without jointer

[Greg Woloshyn]

Since I don't own a jointer at the moment I need to find a way to accurately construct a flat plane for building my torsion box tabletop. Jointing the sides of 2 x 4's seems like the common way to do it. Would it work to make a series of I-beam shaped pieces made out of plywood? I figure the I-beam design will resist any bending in the middle and since I'm only running a length of 6 feet I shouldn't have a problem with sagging.

[Bradley Gray]

If you have a table saw, rip strips of ply and use a simple butt joint where the cross pieces meet the 6 foot lengths. a 6" grid will be very strong and stable.

[Greg Woloshyn]

I have a tablesaw and plan to make the actual torsion box entirely from 1/2" MDF. What I need to do is create a level and flat surface to reference from, so that's why I'm thinking of making straight plywood I beam pieces to start with.

[Jim Matthews]

Get a few aluminum framing levels and some shims.

You'll likely need five levels - four to act as temporary beams while you build,
and one to check that the base for building is level.

Verify that the levels are all the same dimensions.
Add masking tape to get them so close as you are able.

These take the place of the jointed and planed 2x4 lumber in the video below.

Harbor Freight should be able to supply them, keep the receipt
so you can return the ones you don't want to keep.

(FYI - I use two such levels as my winding sticks, also mentioned in the video below.)

Lay those out on an open space, such as a garage bay.
Use the shims to get the levels coplanar.

Lay the lower skin of MDF on top of the levels and build up from there.

******

See the video at 3:00 to illustrate the concept as shown by David Marks.


http://vimeo.com/5082731

[Art Mann]

I am going to attempt to answer your original question, which seems to have been understood. Yes, you can create very straight supports from which to build your torsion box using plywood fashioned into I beams. You need a tablesaw that will cut straight and parallel lines. Actually, I think that is a clever alternative to trying to mill 6 foot 2 X 4s flat on a jointer. Of course, you will still need to use a good level to make sure all the I beams are coplanar.

[Greg Woloshyn]

I am going to attempt to answer your original question, which seems to have been understood. Yes, you can create very straight supports from which to build your torsion box using plywood fashioned into I beams. You need a tablesaw that will cut straight and parallel lines. Actually, I think that is a clever alternative to trying to mill 6 foot 2 X 4s flat on a jointer. Of course, you will still need to use a good level to make sure all the I beams are coplanar.

I should be getting my blades back from sharpening this week and I'll be checking my tablesaw for alignment before I start.

Instead of a full I-beam shape, maybe I will just create a T shape, this should keep my plywood pieces upright and square and save on plywood.

[Shawn Pixley]

If your table saw is tuned and the plywood is flat, I would avoid the i-beam or T construction. I would cut them to make vertical half laps to get the gridded structure. Then you can laminate the plywood to each "face." You could do the glue-up on the TS top.

[Art Mann]

Read the original post. The guy isn't asking how to build a torsion box. He is asking how to come up with straight flat stringers to support the construction of a torsion box rather than using the typical 2X4's. Presumably, they will span between saw horses to form a flat plane on which to construct the torsion box.

[Benjamin Miller]

You could use 2x4s with screws partially driven in. A taut stringline, sighting down them all, or a long flat level will help you get them all in the same plane.

[Jim Matthews]

You could use 2x4s with screws partially driven in. A taut stringline, sighting down them all, or a long flat level will help you get them all in the same plane.

Okay, that's clever.
As is often the case in the Creek,
this was a moment of "Why didn't I think of that?"