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Torsion Box Question

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Forum topic by twobyfour16 posted 240 days ago 798 views 0 times favorited 10 replies Add to Favorites Watch
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twobyfour16

52 posts in 2119 days


240 days ago

Topic tags/keywords: assembly table torsion box leveling advice outfeed tablesaw question

Hey LJ’s – Quick question regarding torsion box assembly table construction. I am preparing to build a Wood Whisperer / David Marks style assembly table that will also serve as an outfeed table for my table saw. The videos I’ve watched typically create a dead-flat surface by painstakingly leveling and squaring a few 2×4’s on top of a couple sawhorses. My question is, would it make more sense to build the assembly table cabinet FIRST, and use it as a surface on which I could build the torsion box? My assembly table cabinet will have 6 levelling feet on it, so it seems logical that I could build the cabinet, level it, and then proceed with the torsion box construction. Am I missing something?

-- Allan, Portland, OR


10 replies so far

View Fred Hargis's profile

Fred Hargis

1737 posts in 1127 days


#1 posted 240 days ago

Nope, unless you are confusing flat with level. The key is to have a perfectly FLAT surface to build the torsion box on. If your cabinet top is perfectly flat and level, you’re good to go. If I recall correctly, Marks didn’t put his on a cabinet, just some plywood supports, that may be why he worked do hard to get it flat, which is what the winding sticks did for him. I’ve never seen any of that other guy’s stuff.

-- Our village hasn't lost it's idiot, we sent 'em to Washington.

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RockyTopScott

1135 posts in 2113 days


#2 posted 239 days ago

I have plans to build one but it won’t be like the WW or Marks, but will incorporate a structure similar to a bench that will have rails which will be flat and level.

In essence building it where it will permanently reside.

Fred is correct, don’t confuse level with flat.

-- “When you want to help people, you tell them the truth. When you want to help yourself, you tell them what they want to hear.” ― Thomas Sowell

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Pezking7p

1118 posts in 286 days


#3 posted 239 days ago

WW guy says somewhere in his comments that it’s perfectly acceptable to do what you’ve just suggested.

Also in his comments, someone suggests making the frame out of half-jointed boards instead of cutting and nailing all those tiny little pieces. Having built the table the way he does it in the video…save yourself some time and do the half-joint method. You’ll be done in 1/4 the time.

I’m not sure what the exact name of the joint is, but it looks like this:

-- -Dan

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RockyTopScott

1135 posts in 2113 days


#4 posted 239 days ago

Look here too.

-- “When you want to help people, you tell them the truth. When you want to help yourself, you tell them what they want to hear.” ― Thomas Sowell

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SPalm

4791 posts in 2516 days


#5 posted 239 days ago

Yes to the discussion of flat vs level. Simple but you need to keep that in mind.

I built a lot of Tboxes and was in a lot of discussions when I was building CNC stuff years ago. Anyway, the consensus was to make sure to glue everything. The internal web does not really matter as to how it is made, little short blocks are the easiest, just glue and an air gun makes it quick. They can be staggered to make it easier. Think of a hollow core door and how flat it is, with just paper webbing inside. These things get heavy quick, so thin webbing helps if you want to keep it light. MDF is great for all of this, comes flat, but heavy and the outside needs protection from moisture.

By the way, most floors are really flat. And the kitchen floor included. Check it all out with some straight edges or winding sticks. Just to use it until the glue dries, then move it. It will be flat for life.

Steve

-- -- I'm no rocket surgeon

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brtech

664 posts in 1557 days


#6 posted 239 days ago

I really appreciated the link that RockyTopScott provided. I’ve watched the WW episode on his assembly bench a couple of times, but I’ve always wondered why he didn’t use interlocking slots. Why, SPalm, do you think the little short block method is easier than the interlocking method shown in the AmericanWoodworker article? Seems like you would have much less work doing it that way, and it ought to be easier in general to assemble because you have fewer pieces and they interlock.

Doing the slots using a key block, like a box joint jig, is a great idea to speed up cutting.

One thing I didn’t get about the AW method is why they built the web as a standalone part (built on top of the top skin with plastic film to protect from glue drips. Why not build the web directly on, and glued to, the bottom skin?

I want to build a combined assembly table, outfeed table. One design detail I’m puzzling over is how to build the miter slots into the Tbox. I can clearly arrange the web so that I have a web slat directly under the slot, but its not clear to me what else I need to do to make the Tbox strong enough in that area. The top skin would essentially be cut through in that part of the Tbox.

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a1Jim

112018 posts in 2211 days


#7 posted 239 days ago

I’m a big fan of Daivid Marks ,but I guess I’ve always missed the point of a TB ,I’ve been working off of a work table for 15 years that has double layers of melamine and it has been flat an level all that time. If you need some thing portable then a TB might make sense .

-- http://artisticwoodstudio.com Custom furniture

View twobyfour16's profile

twobyfour16

52 posts in 2119 days


#8 posted 239 days ago

Thanks for the responses everyone! For the record, I will be working on getting a FLAT surface to build upon. I will leave the drawers & doors off of my cabinet, lay down my MDF, and shim underneath where necessary to achieve a very flat surface. Also, Rocky & Pez, I will definitely be using a half-lap instead of cutting a bunch of smaller pieces – seems to make more sense to me.
Steve – good advice on gluing everything – no problem there! Also, I think I will use 1/2” MDF for the webbing & bottom skin – and 3/4” on the top skin – along with 1/8” hardboard on top. That way, brtech, I think I will have enough thickness in the top to make miter slots without blowing through the top skin.
Thanks again for the input.

-- Allan, Portland, OR

View SPalm's profile

SPalm

4791 posts in 2516 days


#9 posted 239 days ago

Just a note on the small pieces that I mentioned. It does not matter. It was faster for us to cut and glue and pin nail a whole bunch of little blocks than cut the notches for interlocking. Notching MDF is not a lot of fun – messy stuff. They both work when glued. Dealers choice.

You can cut holes and slots into the structure. A sheet rocked wall is a torsion box. You can cut holes in it with no ill effects – of course within limits. This is a engineered structure.

Do what you are doing and don’t worry about it. It will be great.
Steve

-- -- I'm no rocket surgeon

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twobyfour16

52 posts in 2119 days


#10 posted 238 days ago

Thanks Steve – Good point about the messy MDF – I had not considered that until you mentioned it. Obviously, I am not looking forward to cutting the MDF in the first place, so doing the half-lap joints will add much more mess to the process. Time to reconsider just doing the small pieces & lots of brads…
I have moved & have taken the opportunity to improve my shop (still in a 2-car garage), including a Penn State cyclone dust collector & soon a new Saw Stop saw. So, I will wait until I have both of those up & running before I start whittling away at MDF for the torsion box.
Once again, thanks for the input.
-Allan

-- Allan, Portland, OR

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