Lightweight material needed

[Bigbandguy]

I hope this is the right place for this one.

I am involved with an activity that uses a lot of platforms or tables. PVC frame with 5/8 (or whatever it is called now) decks. Uniform size of each flat is 3 feet x 5 feet.

There are ten of these and each weighs about 45 pounds including the legs which are also of PVC (2 inch as is the frame). These really work well for the purpose.

The problem is the weight of the decks. They have to be strong with an ability to hold up to 400 pounds (current configuration was tested at nearly 600). These assemble into portable stage like assembly and cannot flex, which is why we do not use thinner plywood.

Is there a material that is much lighter than plywood but as strong? Someone suggested the material that airliner floors are made of but I have no idea what that is. Cost is also a factor, and would be a consideration.

Suggestions would be welcome.

 

[Dumber than lumber]

In the jet customization industry I have heard it called honeycomb board. Specialized connectors. Not cheap from what I have heard.
Another possibility- You might check with the companies that make trade show booths.

 

[BB Sig]

Look up Nidacore. They make some lite weight core materials for boat decks. Make sure you research how to finish the edges.

Barry
North Florida

 

[4xdog]

How long does it have to last? What kind of environment will it be exposed to?

There sre some multiwall, honeycombed paperboard structures that can be quite rigid and strong. Similar to ‘lumber’s suggestion of core+face aerospace panels, but a much simpler industrial product. Sometimes used in packaging, as in paperboard pallets.

Similar to the construction of hollow-core doors.

 

[Marctrees]

Photo would help

Marc

 

[ZRX61]

Is there a material that is much lighter than plywood but as strong? Someone suggested the material that airliner floors are made of but I have no idea what that is. Cost is also a factor, and would be a consideration.

The price will make your head spin. The cheap version is aluminum faced balsa panels

 

[theoldwizard1]

Look up Nidacore. They make some lite weight core materials for boat decks.

Great stuff. VERY EXPENSIVE ! It still requires a couple of layer of fiberglass and epoxy, on each side, to get strength enough to support that much weight.

Epoxy does not like sunlight so it must be painted.

 

[theoldwizard1]

Aluminum decking like used in stadiums.

 

[Bigbandguy]

Thanks gents. This gives me a few places to look. These platforms are used at least once a month . They lock together by means of a ratchet strap connecting the outside flats with about 15 pounds of pressure. This is enough to remove any tendency to sway or wobble even with weight on them. The only issue is moving them around. I will try to round up a picture. No sunlight issue at all, always used indoors and stored out of sunlight.

This is a portable stage made up of these 3 x 5 flats. Some are taller than others depending on leg length. The Nida Core looks interesting. If I can get hold of a sample I will make up a test version to evaluate. This stage system has been in continuous use at a frequency of at least 1X a month (many times more than that) for over 10 years. Durability has been excellent with the only drawback being the weight of the 5/8 plywood decking. I already know that the system works perfectly. If I can find a lighter decking we would be golden.

 

[Marctrees]

https://www.downeastboatforum.com/threads/nidacore-vs-plywood.1595/

Marc

 

[4xdog]

There are various molded wood pallets that can be pretty inexpensive for their load-carrying capacity. Here's one of many vendors, this one showing pricing.
https://www.litco.com/molded-wood-pallets/

These have decent durability, but aren't super strong or long-lived in my experience.

One would still need to deck these somehow for a stage, with OSB or ply or something. A riser system would be another project.

 

[Citation]

You might be able to experiment with making something. I haven't done this so it would be your own science experiment. Consider some 1" foam insulation panel and skin it either with thin aluminum or perhaps a wood board product. With the right materials you could probably hit your weight and strength targets. The foam panel will be cheap but I'm not sure about the cost of the skin. Something like aluminum may be somewhat expensive. You would also need to experiment with how to bond the skin to the foam. That might be a multi-step process. Still, you might get lucky and find that fiberglass wall panels + foam + some type of construction adhesive spread really thin does the job. That would be something like $30/ assembled panel.

Here is my first guess at materials.
https://www.lowes.com/pd/48-in-x-8-...-Reinforced-Plastic-FRP-Wall-Panel/1000174771
Presumably these panels have a smooth side that you would want to attach to the foam.

https://www.homedepot.com/p/Owens-C...oam-Board-Insulation-Sheathing-20WE/207179253
I like the extruded better than the expanded material. It seems to be a bit stronger/stiffer. I suspect you want to find something that is rated for use under floors/slabs.

https://www.homedepot.com/p/Liquid-...urface-Construcion-Adhesive-LN-2000/206736831
This stuff because the table says it's good on plastics.

 

[walta]

High-density polyethylene folding tables have amazing strength given their light weight.

They will support 300 pounds and weight less than 30.

https://www.menards.com/main/grocer...-banquet-table/804/p-1444450879064-c-7726.htm


Walta

 

[Bigbandguy]

High-density polyethylene folding tables have amazing strength given their light weight.

They will support 300 pounds and weight less than 30.

https://www.menards.com/main/grocer...-banquet-table/804/p-1444450879064-c-7726.htm

Walta we actually did look into those. The leg system would have to be adapted to the height we use and the result would be too thick for the space available for transport. Good idea though.

Excellent suggestions here . If I manage to try something I will report results.

 

[ClappedOutBport]

So from a Mechanical engineering student's POV, what you need is a hollow core material. Stiffness of a material is directly linked to the area moment of inertia which increases as a square for hollow material. I'll spare you the math, but lets take that a piece of 5/8" plywood for example.

Inertia 5/8" plywood =Width*0.0203 in^4

No lets look at two 1/4" pieces spaced out 1 inch. The inside could be filled with vertical strips, honeycomb pattern, etc, for a similar weight.

Inertia 2x 1/4" spaced = Width*0.0628 in^4.

In other words, the single 1.5" tall 1/4" plywood stack is over 3 times stiffer with no increased weight. So getting some airgap in there is your friend.

I'd be more concerned about the pcv legs. How is that not super wobbly?

 

[rockettgpw]

http://www.monopan.ca/about/

This honeycomb panel was used by two blokes I met to build a motor home and a caravan (travel trailer). Pretty tough stuff.

 

[readhead]

This sounds like more of a handling issue than a material weight issue, although the two are obviously related. Rather than rebuilding the existing units what about rethinking how you transport and set them up with some kind of material handling equipment.

 

[matt_i]

I was thinking like Readhead, figure out a cart or integrate travel-wheels is going to be your easiest solution.

However, 5/8" plywood is 2.6 lbs/sqft and 1/8" aluminum is around 1.7 lbs/sqft. So there's some savings there. But one would need an under-structure to support the weight across the span, which might eat that same difference up or come close to it with no gain. I can't tell you exactly what structure would be needed without some experimentation and prototypes.

One could do a cheaper experiment with wood, drop down to say 1/4" ply and screw/glue an understructure of solid wood ribs to it.

This is along the lines of a the way a honeycomb material builds its structure, just maybe not optimized for weight but certainly for cost!

 

[MushCreek]

Foam with fiberglass laminated on both sides is very light and strong, but probably too expensive. They've been building boats and other structures that way for many years. The best examples are vacuum bagged to force the resin into the foam better.

 

[TLGriff]

Rigid foam insulation board with a thin plywood skin on each side would make a very strong and light weight deck. You would need to use a water based contact cement to laminate and for the edging.

Tom

 

[Bigbandguy]

I'd be more concerned about the pcv legs. How is that not super wobbly?

That is the big secret of the system. One flat, particularly the ones with longer legs tends to be wobbly although we tested one with three 200plus pound individuals on it wiggling around and it didn't break.

Each of the flats has six legs, ends and middle. Next to each middle leg is a D ring. That is two D rings per flat. No matter which flat ends up on the outside of a row they all have the same rings. When the stage is assembled, the two outside flats are connected by a good old HF ratchet strap hooked onto the rings. The strap is tightened to about 15 pounds positive pressure. When that happens the entire system become as solid as if it was built there. There is no wobble at all. It has proved to be an elegant solution .

Again the only issue is weight. We are simply trying to make the setup easier.

 

[Copymutt]

Pretty sure i grasp what your after. I just spent considerable time researching lightweight structural panels for a project.
For your application, how about multiples of these scaffolding components. I perceive speed of set up due to the hooks, alum. is strong/lightweight. For the legs? Perhaps prefabbed sawhorses. Can you gang them together, saving total parts?
https://www.scaffoldexpress.com/3-Raised-Hook-Steel-Plank-p/psv-sp-03.htm

 

[Bigbandguy]

Finally rounded up a picture of the under side. The wheel does not need re-inventing. All I want to do is come up with a deck that will hold as much as 5/8 plywood but weigh about half as much or less. That is all I need to do. Everything else works like we want it to.

We can set this puppy up (10 of them) in half an hour but lighter flats would be nice. Note that the legs clip inside the rail for storage. The frame is bolted to the deck under each of the six leg sockets. The legs slip fit and stay in place just fine. Note the D rings mentioned above.

 

[firebirdparts]

Interesting and good design. If you had a leg right in the middle of that, then you could use a thinner plywood. FWIW.

 

[Bigbandguy]

Interesting and good design. If you had a leg right in the middle of that, then you could use a thinner plywood. FWIW.

We considered that but could find no good way to attach a center leg without adding weight and the difficulty of attaching a cross piece to the center fittings. I think there is such a PVC fitting but they were not readily available. We also made one prototype with 1/2 inch decking but it flexed way too much. Overall it works pretty well for cheap staging.

 

[Dustball]

If you can do one more tee on each long side and a extra cross brace near the center area, you can open up to more decking materials.

I'm thinking cardboard honeycomb panels decked on top with 1/8" masonite for durability.

 

[Marctrees]

Here's a great place...used them few times very good service... and they have "Furniture" fittings.

Marc

https://www.pvcfittingsonline.com/fittings/schedule-40-pvc/4-ways.html

 

[Bigbandguy]

Here's a great place...used them few times very good service... and they have "Furniture" fittings.

Marc

https://www.pvcfittingsonline.com/fittings/schedule-40-pvc/4-ways.html

That is another reason we are concentrating on the deck. The only furniture fittings we could find were 1 1/2 inch and we needed to get them done in a hurry for a show. In order to get any stability out of the legs, 2 inch was needed and was the best compromise for width. Any more and it was too thick to transport and smaller legs were not stable enough.

I think I will concentrate on a lighter weight deck. I really appreciate all the good ideas.

 

[Marctrees]

Let me guess -

Different height political debaters ?

MLM Rah Rah Rah Hotel meets ?

First, Second, and Third place Winner pedestals ?

Itching to find out !!

Marc

 

[Bigbandguy]

Let me guess -

Different height political debaters ?

MLM Rah Rah Rah Hotel meets ?

First, Second, and Third place Winner pedestals ?

Itching to find out !!

Marc

My username might give you a clue!

 

[Daveco]

Honeycomb panel of some variety is the only option that will deliver the characteristics required.

The current plywood and pvc design is probably the best compromise between cost and weight.


Sent from my iPad using Tapatalk

 

[kbs2244]

A entry door is 36 x 80 inches
If you can live with the extra 20 inches a fiberglass slab door blank may work

 

[Copymutt]

Expanded polystyrene grating. You can top w/ any light weight board if that’s what you need.

 

[Bigbandguy]

Expanded polystyrene grating. You can top w/ any light weight board if that’s what you need.

I really like this . 1/2 inch grating topped with 1/4 ply would likely be half the weight of current setup.

Next is to figure out how to lay hands on a sample for prototype and of course cost.

 

[Jaja]

View attachment 981346

Finally rounded up a picture of the under side. The wheel does not need re-inventing. All I want to do is come up with a deck that will hold as much as 5/8 plywood but weigh about half as much or less. That is all I need to do. Everything else works like we want it to.

We can set this puppy up (10 of them) in half an hour but lighter flats would be nice. Note that the legs clip inside the rail for storage. The frame is bolted to the deck under each of the six leg sockets. The legs slip fit and stay in place just fine. Note the D rings mentioned above.

I would update the PVC design so less $$/trouble spent on decking. Click on pic for explanation.

 

[BB Sig]

Can we get pictures of this contraption being used so we get a better idea of the forces at play?

Barry
North Florida

 

[walta]

Walta we actually did look into those. The leg system would have to be adapted to the height we use and the result would be too thick for the space available for transport. Good idea though.

Excellent suggestions here . If I manage to try something I will report results.

I did not expect you would want to use the legs as you currently have a working support system.

The more I think about it should someone fall while on the home made stage the lawyers will eat you alive. The safe bet is to buy something.

http://www.stagedrop.com/portable-s...iIFRiFKA03J9lIZIaWPBZ5Wg03Gp9YLhoC8J0QAvD_BwE

Walta

 

[Marctrees]

Good link Walta !

"Aluminum profile on all sides
Multiple layer sandwich construction (9 mm high-density plywood/7.5 mm honeycomb grid/4 mm high-density plywood)"

Marc

 

[Bigbandguy]

I did not expect you would want to use the legs as you currently have a working support system.

The more I think about it should someone fall while on the home made stage the lawyers will eat you alive. The safe bet is to buy something.

http://www.stagedrop.com/portable-s...iIFRiFKA03J9lIZIaWPBZ5Wg03Gp9YLhoC8J0QAvD_BwE

Walta

As we all know a lawyer can gin up a lawsuit for any purpose and indict a ham sandwich (one famous example). The system described has been in continuous use for over 10 years with a perfect safety record.

There are safety items included but not described because they are not germane to the discussion. The system is in use by people familiar with it and no one else. Liability would be one reason I would never sell something like this as I am not in the business. The system described in your link would be entirely unworkable for our purpose, take too long to set up and tear down, could not be transported easily and likely heavier that what we use now, so no.

All I am looking for is suggestions on how to make the decks lighter and I appreciate all that have done so. I employ an attorney for legal advice.

 

[firebirdparts]

We considered that but could find no good way to attach a center leg without adding weight and the difficulty of attaching a cross piece to the center fittings. I think there is such a PVC fitting but they were not readily available. We also made one prototype with 1/2 inch decking but it flexed way too much. Overall it works pretty well for cheap staging.

If you are looking something easier and cheaper than the center leg, you're not very interested.