Bonding wood to steel

In reply to VolvoHeretic :

How did I never think of this?  You're like, smart and stuff.

Curtis73 (Forum Supporter) said:   
The only real downside (other than weight) is that you can no longer bolt two flats together and have a flush surface.  

That seems pretty easy with oblong holes. 
 

The 2 sided flats are trickier to bolt together. But that problem could be solved too. 

Note:  these bracket alignment connectors would also act as hinges for flats that met at something other than 180*

If you're gonna take the time to make them out of steel, then go big. 
 

Connecting bolt at the top could double as an attachment point for an adjustable brace to hold up the flat. 

...add hole in bottom connecting bracket here:

To screw bottom of flat to the floor

In reply to SV reX :

I had been thinking about hinging.  They will all have jigged holes about 3" in from the edge on all sides so any flat can bolt to any other one.  I'm resisting the urge to put something permanent on the sides or top in case I need to make a large solid wall.  They would need to meet flush.

I will likely make or adapt some hinges much like they use for glass doors - a channel that slips over the outside with a pin.  The other option was to tack some hinges on the back and pull the pins to disassemble.  That would only allow hinging back, and it would be a royal pain to get 50 hinges lined up perfectly so that they were mix-n-match.  Drilling a bunch of 3/8" holes in a jig with 5/16" bolts will allow for easy alignment before tightening.

wae said:

They're going for a slightly more permanent solution than you are, I think, but what do RV manufacturers use to attach the luan to the frames?

Discovery channel had a "How Its Made" show about manufactured homes which is now blocked on YouTube. For the ceilings they laid the drywall on the ground, placed the roof trusses onto the drywall and sprayed an expanding foam adhesive onto the corner of the truss and drywall contact area. That's it, no screws. They then lifted the entire roof with a crane and set it onto the walls. I would normally use PL400 construction adhesive on the edge of the metal/plywood edge after wiping down the steel with acetone and use heat to soften it up to remove it. I think that you are going to have to make a bunch of test samples to test everybody's recommendations. I like this method:

In reply to Curtis73 (Forum Supporter) :

If you made brackets like my sketch, they could be bolted on. Just put a standardized threads hole in the edge of each flat. 
 

You will gain some advantages going to steel. One of them will be consistent straight edges.  Another could be simple connectivity and double sided.

The thing with bolting the flats together is that you loose the ability for them to be double sided, because it will prevent you from getting to the holes for the nuts and bolts.

My sketch would enable them to be double sided AND attach to each other. 

Help me understand what a theater flat is.  

I'm assuming it is a wall/partition?  

One issue with adhering wood to steel is expansion/contraction. 

Wood and metal have different thermal expansion rates, also metal could care less about humidity.  Your adhesive needs to have some amount of flexibility to deal with this.   Anchoring with screws will make it worse as they will fix the metal to the wood in points.  If you keep it at a relatively constant temp and humidity it will probably be fine.   But over time I suspect separation will occur. 

Coupling this with your metal question assuming people won't be walking on these or they aren't used to support load, why not make them sandwich panels.  

Assuming you are making 4*8 with 3 verticals as shown your around $40 in metal, plus $20ish for luan on one side.  

Make a wood perimeter (Rip 2*4 to make the frame for ~$6 out of 1.5 2*4) around a piece of 1.5" polystyrene foam board ($18).   Use wood glue to glue luan on the entire piece and frame. 

Or to be real cheap, use builders board ($35 for 38.5"*50') floor protection paper for the surfaces.   Yes you would have to make them only 3' wide but I had some mock-up sandwich panels that I was thinking about for Aero parts made this way in my uninsulated garage for 2 years with no degradation.   

Just some thoughts.  

SV reX said:

The thing with bolting the flats together is that you loose the ability for them to be double sided, because it will prevent you from getting to the holes for the nuts and bolts.

My sketch would enable them to be double sided AND attach to each other. 

I wouldn't leave them double-sided permanently, but per your previous suggestion, when the lauan gets wasted on one side, I could rip it off, leave it ugly, and skin the opposite side.  That means I'd only be cleaning adhesive every 4 years.  I would always have one side open.

I suppose I could keep a few double sided on hand for certain things, but the applications where I would need to screw them down, they likely will only be seen from one side.  I also had the crazy idea (for screw-down applications) of lining the edge of some lauan with magnetic tape.  Do my connections inside, then snap the lauan on the face.

nocones said:

Help me understand what a theater flat is.  

I'm assuming it is a wall/partition?  

One issue with adhering wood to steel is expansion/contraction. 

Wood and metal have different thermal expansion rates, also metal could care less about humidity.  Your adhesive needs to have some amount of flexibility to deal with this.   Anchoring with screws will make it worse as they will fix the metal to the wood in points.  If you keep it at a relatively constant temp and humidity it will probably be fine.   But over time I suspect separation will occur. 

 

Coupling this with your metal question assuming people won't be walking on these or they aren't used to support load, why not make them sandwich panels.  

Assuming you are making 4*8 with 3 verticals as shown your around $40 in metal, plus $20ish for luan on one side.  

Make a wood perimeter (Rip 2*4 to make the frame for ~$6 out of 1.5 2*4) around a piece of 1.5" polystyrene foam board ($18).   Use wood glue to glue luan on the entire piece and frame. 

Or to be real cheap, use builders board ($35 for 38.5"*50') floor protection paper for the surfaces.   Yes you would have to make them only 3' wide but I had some mock-up sandwich panels that I was thinking about for Aero parts made this way in my uninsulated garage for 2 years with no degradation.   

 

Just some thoughts.  

An example.  This wall pictured below was constructed from 4' x 8' individual wall flats screwed together.

Here is what they look like from the back.  1x3 framing with lauan facing.  I keep a stock of 4x8s, 2x8s, 3x8s, and a few other various flavors so I can pull them out and put them together instead of building every wall every time.

In reply to nocones :

For the size he is taking about, expansion/ contraction is a non-issue. These aren't structural, and no one walks on them. They are "fake walls". 
 

But they need to be straight, be able to be joined neatly, and have the odd additional requirement that they be "flown" (suspended on cables above actors, and raised and lowered multiple times)

I see a few 45 deg corners in there. Do you have any 45 deg. adapters you can screw onto the ends of the large flats? Inside and outside?

I have been thinking about how to join the flats to each other. How about tabs welded onto the framing at intervals of 24" o.c. on the horizontal tubes and 32" o.c. on the vertical tubes to bolt them together. I would also build dedicated inside and outside corner pieces and I am also trying to figure out inside and outside 45 degree corner pieces. You would need jigs to build all of them accurately.

Plan View below

When you were thinking hot glue earlier, I feel like you were on the right path. You were concerned that as soon as you put it on the steel frames it would start to cool and so you'd have a really short working time because the steel acts like a heat sink.

Put the hot glue on the luan instead with it lying flat on the deck, then drop the frame on top. The hot glue will still have a 60-90 second working time (plenty to run a perimeter bead / down the center) and you can cook up a couple blocks on the deck to help with aligning the frame and skin when you drop the frame on. You can also get an industrial hot glue gun that puts out a greater volume / heats faster.

Alcohol helps remove the residue when you decide to reskin.

VolvoHeretic said:

I see a few 45 deg corners in there. Do you have any 45 deg. adapters you can screw onto the ends of the large flats? Inside and outside?

As long as you're at an angle toward the audience, I just set them at the angle I want and drive a 2-1/2" screw through the gap.  Holds them fine.  For something like the steel flats I would need some form of attaching them at an angle like SV reX talked about.  For 90s, it's pretty easy to use existing holes and an angle bracket.

The tabs you drew would be perfect for a floor-installed application where they're also screwed to the floor.  I would be afraid if they're flown like that there would be a tendency to spread.

I'm also thinking about a bracket on the back of the center stud that could accept a support jack for floor installations.

The way I was going to attach them in a flat wall was just make a drill jig with holes that are 4", 44", 52", and 92" along the long side, and 4" and 44" on the short side.  That way no matter how I join them (side to side, or top to side) there are uniform bolt holes ready for attaching.

Then I could have a stock of, let's say, 3" chunks of angle with holes for doing 90 degree walls.  For that matter, I could stuff a 2x2 in the corner and drive a 2.5" screw through the hole in the framing into the lumber to make a variety of angles.

There also may be a world where I could have small-pin hinges for variable angles.  The pin side of the wall would be facing the audience, but I could maybe at least keep them flush with the lauan to minimize the visual impact and/or cover it. 

But I'm thinking way ahead.  I just need to get them built.

My first use of them will be for the next show, so I gotta get cracking.  The proscenium will have a big round portal covered in red stretch velvet.  We're calling it the velvet butthole.  I'll bolt some of these flats together and use PVC or PEX to make the "hoop."

In reply to Curtis73 (Forum Supporter) :

Those are some fancy looking sets there.

In reply to VolvoHeretic :

Thanks.  Trying to make it easier to do pretty things without building new stuff all the time.

Here is my latest version of bolt together panels. I did not put brackets on like you suggested so that you could lay them flat but would be easy to add. My calculations indicate that the 1x1x.065" tubing weighs 27lbs and a sheet of 4x8x1/4" of soft wood plywood weighs 22lbs, so 49 lbs per panel excluding all connection hardware, or about 50lbs each.

Trying to use bolts, screws, pins, or hinges in the vertical edge uprights will prevent you from dropping wire down the tubes to hold them up from the bottom of the panels. The dedicated 45 and 90 inside and outside corners are 1x2x.065" tubes. Dedicated corners also gives you a finished corner with no gap to figure out how to finish off.

The only thing I can think of to improve it would be to make all of the bolt tabs with two holes in each so that you could use a spud bar in one hole in order to line up the other hole to drop a bolt into.

That represents a lot of CAD work.  Super appreciated.  Thank you.

For the wire, I would pass the wire through the whole thing first, then sneak the bolts beside the wire.  Wire first, then bolt together.  I am also toying with the idea of welding a tube in each bolt hole... not so much because I would need it, I'm just envisioning volunteers thinking that tighter is better and crushing the steel.   I'll have to do some maths to figure out if I'll have room for the cable if I do that.  Most stuff would be easily suspended by 1/8", but if it gets big enough I sometimes do 3/16"

I do like the tabs.  Might end up doing both - bolt through for suspended, bolt in the tabs for floor-mount.

In reply to Curtis73 (Forum Supporter) :

Thanks and you are welcome. I need something to do other than just lay on the couch watching true crime network although I am laying on the couch doing this and listening to True Crime Network. The hardest part is figuring how to orientate the XYZ in order to draw in the correct plain. It helps not drawing the true shape of the tubes so that I can snap objects to the theoretical corners. Figure out exactly what you want to build and I can draw it 100.00000 % accurate. 

And another version:

In reply to VolvoHeretic :

Note on 45* angles...

Theatrical walls are rarely 45* angles. They are placed according to the sight lines and the limitations of the theatre to maximize the audience's view (or minimize it for stuff that should be hidden). Might be 39*, or 54*, or just about anything. 
 

That's why I would like to see a design that is hinged. 

In reply to Curtis73 (Forum Supporter) :

Have you ever used casket locks?

It would be interesting to consider if there was a clean way to integrate them. Then no bolts. They self-align as you tighten with an Allen wrench, and lock things together really well. 
 

You'd just have to drill a hole in the luan to allow access with the Allen wrench