Assembley table dilemma and ideas

[MikeMcCoy]

I am still in the overhead storage mode.

Build a good solid torsion box the size you need. Build a trestle style table support that can be disassembled and stacked. Store overhead when not in use.

And if anyone wants one of those overhead racks and ever gets to Charleston .... I will gladly give you one. Of course, you have to help me take it down from the spot that I mounted it and get absolutely no use out of it.

[poolhound]

Geez, Jon, we keep suggesting solutions, and you keep throwing in more problems.

I am very appreciative and just trying to weigh all the different issues. When dealing with a non dedicated space everythuing is always a tradeoff.

I am going to try moving things around this weekend and see how I can make various different space configurations and see what might work best.

[poolhound]

And if anyone wants one of those overhead racks and ever gets to Charleston .... I will gladly give you one. Of course, you have to help me take it down from the spot that I mounted it and get absolutely no use out of it.

How come you dont use it - is there an issue?

Anyway could you just beam it to Phoenix - Scotty

[MikeMcCoy]

How come you dont use it - is there an issue?

Anyway could you just beam it to Phoenix - Scotty

My thoughts were to store some plywood there since it was the only overhead space that wasn't being used. I measured it out and "thought" I had enough space for 5 or 6 half sheets of ply. I'm not sure where my measuring messed up but once installed, there was only enough room for the rack (empty). My only unused space overhead is over the garage door opening area. Everything else is pretty busy.

[AndyF]

Another folding option

For my worksurface (3'x7' solid core door), I designed a sliding mechanism to raise and lower the work surface and stay inside my 8'6" garage ceiling.

I know you're looking for a larger work surface, but the base may be of interest.

Another person took this idea and had it fold-up in front of some cabinets.


Here's a couple of pictures and I added a zipped PDF file with some more details if you're interested.

Hope this helps,
Andy

[JR]

For my worksurface (3'x7' solid core door), I designed a sliding mechanism to raise and lower the work surface and stay inside my 8'6" garage ceiling.

Oh, that is nice! Well done.

JR

[poolhound]

So after much angst and trying to figure out how to deal with space, storage and function I decided to go for the dual beam aproach al la the FWW article I mentioned earlier.

I pretty much copied it verbatim with the exception of the size (mine are 6'x11") & saw horses. I dont have room to store two big fixed horses so I made some 1'x4' tops for my folding adjustable horses.

For those that didnt see the article the core is a 3/4" ply torsion box faced with laminated particleboard and one face afixed with a homasote top. The homasote face acts as an all purpose non maring benchtop and the opposing laminated face is an easy to clean glue up and assy surface.

Once construced each beam is about as flat as my assembly technique could make it. It really is very flat. The laminated surface (single beam) is within a few thou and the worst gap I could measure anywhere was only .008". The homasote side is less exacting primarily due to the nature of the material but still way within the tolerance of any normal project cutting/machining errors or general ineptitude on my part

I was a little concerned about how well they would line up when used together but I was pleasantly suprised. They line up pretty well and with some carefully placed paper or CC style shims I can get the whole surface flat/level within 0.010". CHeck out the pic of the square rule bridging two surfaces.

As it starts to get used I will report back with any pros/cons I find. SO far I am really pleased and the pros (for me) are.

1. flat reference and assy surface.
2. flexible size
3. easily stored and each beam is nowhere near as heavy as a full size MDF torsion box.

[Tom Miller]

Nicely done!

A couple more benefits:

A single beam will be much more handy for constructing bookcases/shelves/etc, than a big assembly table.

With a gap between the beams you can get more clamps at critical parts of a construction.

Regards,
Tom

[vaking]

What about a folding ping-pong table? You could probably find a used one for a decent price. Not sure how flat it would stay, but you could use some sort of bracing to strengthen it.

Hmm,
My workshop is in the basement. Before I took over the basement for my workshop there was a ping pong table there. My son and us played it when he was a teenager. He is in college now but the ping pong table is still standing folded in the basement taking space. I tried few times to get rid of it but SWMBO objects. So with this idea I will keep peace with my wife and will stop asking her to lose the table. I will just make use of it as assembly table. I am sure after I use it couple times it will have no value to anybody but me.

[poolhound]

Nicely done!

A couple more benefits:

A single beam will be much more handy for constructing bookcases/shelves/etc, than a big assembly table.

With a gap between the beams you can get more clamps at critical parts of a construction.

Regards,
Tom

The clamping point is a good one. In many cases it wont be necessary to raise the workpiece off the surface as it is using a normal larger flat surface.

[billwheaton]

Questions: I assume that the webbing inside is 3/4 MDF. Has anyone done any engineering analysis about how less strong the torsion box would be with say 1/2" mdf? How about lightening holes in the webbing? How about making the webbing out of built up pieces or chris-cross struts like they use between floor joists sometimes? Speaking of floor joists, what about those new ones you see going down the road made out of OSB and 2 x 2 lumber? Imagine making the webbing out of 3/16 ply in that case. Also, does the bottom have to be the same thickness as the top? I mean, its an assembly table, not an anvil, and you don't work on the bottom. For that matter, you should be able to use 1/4" stock on the bottom with all kinds of lightening holes in it. All of these ideas could cut the weight of the thing by over 50% I would guess.

I'll do up a sketchup drawing and post it over the weekend to see what you guys think. Maybe someone can calculate the moments of inertia on it to see how stiff the whole thing is. That's what really matters, the stiffness.

It could be flatter than flat, but if it bends when you put something on it, then it doesn't count. And massive doesn't count either. you could make a nice flat sandbox that is massive, but it wouldn't be a good assembly table.

I think it's time to pull out those old engineering books...

-Bill
Decatur, GA
(about me: I make telescopes, and found out I needed a few better tools before I screw up some good wood. I've had a BT3k since 1998, and I just now found out about this site. It's kind of like a Volkswagen Beetle club or something.)

[billwheaton]

Here is the tortion box I came up with. Its about 3.5" thick by 1m x 2m in area. Its about 110 pounds. here is a link to the sketchup models http://sketchup.google.com/3dwarehou...6636&scoring=m

[poolhound]

Questions: I assume that the webbing inside is 3/4 MDF.

Bill,

Not sure if you are talking about the typical large MDF torsion box or the beams I built. My beams are built with 3/4" ply cross supports every 12".

The internal structure of the larger MDF variety really depends on what it is skinned with. The thicker the skin the lighter and further apart the "webbing" tends to be and vice versa.

[LarryG]

Bill,

My torsion box assembly table, which copies the design by David Marks on DIY Network's WoodWorks, measures 42" x 60" x 3-3/4" thick and uses 1/2" MDF ribs and 1/2" top and bottom skins. The only 3/4" MDF is the outer perimeter. Marks built his that way so I did too; I'm sure 1/2" would have been fine for this as well.

I built the table a bit less than four years ago and it's holding up fine. Also, Marks has a second, larger table in his shop that measures 4' x 8' which I presume is built the same way.

[poolhound]

Well its been a couple of months since I built my dual beam bench and I said I would report back with how its working out.

Its had some pretty heavy use since I completed it (practically every weekend) and it has lived up to all my expectations. While it would be nice one day to be able to have a more classic solid wood bench the flexibility this approach offers is really awesome.

The minimal storage footprint works perfectly with the way my shop must be organized. Setup takes only a couple of minutes although if I need both surfaces to be perfectly aligned shimming them true can take another 5 or 10 mins. this is primarily an issue with my floor which isnt level in either direction. Given that I am setting it up in the same location 99% of the time I have a set of paper and CC shims handy which always tend to go in the same place so its not too bad.

The flexibility of working with the dual surfaces is the best bit and is not something you can ever get from a conventional bench or assembly surface. Typically I have them set with a 4"-8" gap giving me a 6' x ~30" work area. I can pull the beams out to 4' providing a 6'x4' surface.

The gap in the middle proves useful over and over. If I need to drill a hole or use a jigsaw, the workpiece is supported on all sides while the centeral gap provides the necessary clearance. No more hanging the workpiece off the edge of a bench, which is OK when you need a cut in the edge of a workpiece but is a real PITA when the cut is in the middle - no more. I had a neighbor stop by this past weekend who needed a large whole cut in a door for a dogflap. It was a cinch, pulled the beams apart supporting the door evenly, drilled 4 holes, out with the jigsaw and 15 mins later a doggy door!

Clamping is the other real advantage of having the two beams. Now there is no need to raise the workpiece to get clamps all around plus you can easily clamp it to the bench in multiple locations.

The weight makes it pretty stable. Its probably not the best solution for serious hand tool work. With the beams clamped to the base it is pretty solid but nothing like a heavy HW bench. For now I can live with that and would reccomend anybody who has similar constraints to me to consider building a similar setup.