Torsion Box

Torsion Box · 02-01-2008, 03:48 PM

When you are constructing a torsion box, and creating the lattice work that will be the interior, what is the best method of contstruction? I have searched around the web and found two different methods. The top method of my pic would appear the easiest to construct, but most of what I have seen on the WWW seems to be the bottom method.

1. Anyone have any ideas, thoughts, suggestions on why?
2. What are the pros and cons of each method?

Ray.

Ray Martin · 02-01-2008, 03:52 PM

Ray,

I haven't built one... I'll have to defer to David Marks. He built one on his show using the bottom method (from your graphic).

Ray

sediener · 02-01-2008, 04:33 PM

I think Alan in little Washington built one and documented it here using the first method...

http://www.ncwoodworker.net/forums/s...assembly+table

there you go...

- Steve

sediener · 02-01-2008, 04:34 PM

http://www.ncwoodworker.net/forums/s...assembly+table

there's the WIP thread.

- Steve

Travis Porter · 02-01-2008, 08:06 PM

A lot more cutting and measuring on the upper one. On the bottom one you can just cut all your pieces to length and then just use spacers to lay them out and tack them. Just my .02

sediener · 02-01-2008, 08:24 PM

Originally Posted by Travis Porter

A lot more cutting and measuring on the upper one. On the bottom one you can just cut all your pieces to length and then just use spacers to lay them out and tack them. Just my .02

With the top one you can gang them all together and make a few passes over the dado blade and you are done. I think it would be about the same amount of work to cut but much easier to assemble.

- Steve

Travis Porter · 02-01-2008, 08:32 PM

That is true. Once you get everything lined up and set up, it wouldn't be bad.

toolferone · 02-01-2008, 08:36 PM

If you are gluing the pieces together too, then I would think the bottom would be easier. It would be a pain to get glue in to each notched cut. The bottom one would be just putting glue on the edges and putting in place. My .02 cents worth.

bitbight · 02-01-2008, 08:58 PM

I think Alan in little Washington built one and documented it here using the first method...

http://www.ncwoodworker.net/forums/s...assembly+table

I followed this thread and my thoughts were along the same idea as Alan's. It would appear to me the interlace is a simpler method. Create a jig to cut the slots in the lattice, glue and assemble. To me it it looks like a stronger joint. No need for nails or staples and the 90 degree right angle is already made by the interlace. The materials could be of a lighter weight composition and still have strength integrity. This seems like a good solution and definitely uses the KISS method.

Alan in Little Washington · 02-02-2008, 12:07 AM

I vote for Alan's method! Of course I do

With the temp jig I made, it is easy and quick to cut the parts. The big advantage of my method over David Marks's method is when you get to the last row- with David Mark's method, due to the impossible nature of gluing all the little pieces together so each row is exactly the same length, in order to make the grid/table sides flat, Marks had to cut and fit each individual piece!!! A real time consuming and inefficient way to do it.

With my method, none of the strips are cut in two, so the overall dimensions of each grid strip are the same.

Also, you don't need to be precise about the spacing setup of the temp jig. If the spacing is a little off, all the notches/cells except those in the last row will still be identical. The last row of cells may be a different width than the other cells, but all the cells in the last row will be the same width, so who cares.

The only caution- if you are using MDF for the grid parts, you must ensure you cut your half lap notches wide enough so they do not fit too tight, because the MDF can break easily at the half lap.

Trust me, my method is much easier.

Gotcha6 · 02-02-2008, 05:54 AM

I'd think it would be a little tricky, but how about making the notch in method 1 a little narrower then running a dado through the rest of the piece? It would give it strength & you could then apply glue to the dado.

Gofor · 02-02-2008, 10:51 PM

It kinda appears to me that people are putting a lot of weight into David Marks idea because of his obvious talents. I tend to think that in this particular subject (i.e. torsion box and spacers) he may have seen the need to make a segment on it, because of the need for flat surfaces for assembly, etc, but may have run into copyright or patent restrictions. The idea of the half slot cross pieces for stiffening has been around a while (many cardboard drink and shipping boxes are made this way). For a DIY'r to post it on the net is one thing, but David Marks is a big target and makes money off of his publications and productions. He may have used the individual spacer technique to enable him to show how to make a stable flat surface without creating a liability nightmare for himself.
Summary, There may be reasons Marks did not use the technique Alan did that have nothing to do with better quality of the end product.

Just a thought

Go

DavidF · 02-07-2008, 04:23 PM

In my case I don't have a dado blade so the DM method is what I used and it worked out well.

NZAPP1 · 02-07-2008, 07:47 PM

Woodworkers Journal June 07 had a how to build T-box that looked like a good method