OT: Carbon fiber reinforced foam...

[bitrex]

Could you build a re-inforced box-girder like structure out of rigid
polystyrene foam by sandwiching it with carbon fiber tape + epoxy?

Carbon-fiber plated foam core is filthy expensive, but raw polystyrene
board and carbon fiber tape are pretty cheap individually.

Maybe any light aircraft/surfing people would know.

 

[Phil Hobbs]

On 2020-10-18 12:06, bitrex wrote:

Could you build a re-inforced box-girder like structure out of rigid
polystyrene foam by sandwiching it with carbon fiber tape + epoxy?

Carbon-fiber plated foam core is filthy expensive, but raw polystyrene
board and carbon fiber tape are pretty cheap individually.

Maybe any light aircraft/surfing people would know.

The buckling mode involves squashing the filler, which is why surfboards
and stuff are (classically) made of fibreglass over balsa with the grain
oriented along the shortest axis of the board--it\'s far stronger in that
direction.

You wouldn\'t have that advantage with foam, but it might work OK if the
foam were strong enough. Of course, \"strong\" and \'styrofoam\' aren\'t
usually used together.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[server]

On Sunday, 18 October 2020 19:13:58 UTC+1, Phil Hobbs wrote:

On 2020-10-18 12:06, bitrex wrote:
Could you build a re-inforced box-girder like structure out of rigid
polystyrene foam by sandwiching it with carbon fiber tape + epoxy?

Carbon-fiber plated foam core is filthy expensive, but raw polystyrene
board and carbon fiber tape are pretty cheap individually.

Maybe any light aircraft/surfing people would know.

The buckling mode involves squashing the filler, which is why surfboards
and stuff are (classically) made of fibreglass over balsa with the grain
oriented along the shortest axis of the board--it\'s far stronger in that
direction.

You wouldn\'t have that advantage with foam, but it might work OK if the
foam were strong enough. Of course, \"strong\" and \'styrofoam\' aren\'t
usually used together.

Polyamide foam (nylon) is used for radomes on the Eurofighter and for
the core of the tailfin of Airbus planes.
I have some samples which I obtained for use as an \"invisible\" substrate
when prototyping microwave antenna designs (a trick I learned from a
Nokia paper).

John

 

[bitrex]

On 10/18/2020 2:13 PM, Phil Hobbs wrote:

On 2020-10-18 12:06, bitrex wrote:
Could you build a re-inforced box-girder like structure out of rigid
polystyrene foam by sandwiching it with carbon fiber tape + epoxy?

Carbon-fiber plated foam core is filthy expensive, but raw polystyrene
board and carbon fiber tape are pretty cheap individually.

Maybe any light aircraft/surfing people would know.

The buckling mode involves squashing the filler, which is why surfboards
and stuff are (classically) made of fibreglass over balsa with the grain
oriented along the shortest axis of the board--it\'s far stronger in that
direction.

You wouldn\'t have that advantage with foam, but it might work OK if the
foam were strong enough.  Of course, \"strong\" and \'styrofoam\' aren\'t
usually used together.

Cheers

Phil Hobbs

Yeah, I guess the \"reinforced\" foam would be much stronger in the
compression-direction. Might need to use carbon-fiber rods or something,
like rebar.

It\'s nothing important I just want a lightweight custom modular table
for my model choo-choos, and don\'t really own any woodworking equipment.

It\'s fun to think about a table incorporating carbon fiber, anything\'s
possible with enough $$$ thrown at the problem even a table made
completely of composite plate. Best guess for the price on that would be
into the thousands for a 4x8.

I\'ll probably contract this job out, it\'s not a large one and the custom
benchwork guys (they exist!) could likely use the money. I much prefer
doing wiring and working on models I can fit on a small worktable than
looking like I\'m re-framing my house.

 

[bitrex]

On 10/18/2020 3:31 PM, bitrex wrote:

On 10/18/2020 2:13 PM, Phil Hobbs wrote:
On 2020-10-18 12:06, bitrex wrote:
Could you build a re-inforced box-girder like structure out of rigid
polystyrene foam by sandwiching it with carbon fiber tape + epoxy?

Carbon-fiber plated foam core is filthy expensive, but raw polystyrene
board and carbon fiber tape are pretty cheap individually.

Maybe any light aircraft/surfing people would know.

The buckling mode involves squashing the filler, which is why
surfboards and stuff are (classically) made of fibreglass over balsa
with the grain oriented along the shortest axis of the board--it\'s far
stronger in that direction.

You wouldn\'t have that advantage with foam, but it might work OK if
the foam were strong enough.  Of course, \"strong\" and \'styrofoam\'
aren\'t usually used together.

Cheers

Phil Hobbs


Yeah, I guess the \"reinforced\" foam would

wouldn\'t be, rather

 

[Lasse Langwadt Christensen]

søndag den 18. oktober 2020 kl. 21.31.28 UTC+2 skrev bitrex:

On 10/18/2020 2:13 PM, Phil Hobbs wrote:
On 2020-10-18 12:06, bitrex wrote:
Could you build a re-inforced box-girder like structure out of rigid
polystyrene foam by sandwiching it with carbon fiber tape + epoxy?

Carbon-fiber plated foam core is filthy expensive, but raw polystyrene
board and carbon fiber tape are pretty cheap individually.

Maybe any light aircraft/surfing people would know.

The buckling mode involves squashing the filler, which is why surfboards
and stuff are (classically) made of fibreglass over balsa with the grain
oriented along the shortest axis of the board--it\'s far stronger in that
direction.

You wouldn\'t have that advantage with foam, but it might work OK if the
foam were strong enough.  Of course, \"strong\" and \'styrofoam\' aren\'t
usually used together.

Cheers

Phil Hobbs


Yeah, I guess the \"reinforced\" foam would be much stronger in the
compression-direction. Might need to use carbon-fiber rods or something,
like rebar.

It\'s nothing important I just want a lightweight custom modular table
for my model choo-choos, and don\'t really own any woodworking equipment.

It\'s fun to think about a table incorporating carbon fiber, anything\'s
possible with enough $$$ thrown at the problem even a table made
completely of composite plate. Best guess for the price on that would be
into the thousands for a 4x8.

I\'ll probably contract this job out, it\'s not a large one and the custom
benchwork guys (they exist!) could likely use the money. I much prefer
doing wiring and working on models I can fit on a small worktable than
looking like I\'m re-framing my house.

https://youtu.be/3Pc-Sd_J26E

 

[Ricketty C]

On Sunday, October 18, 2020 at 3:31:28 PM UTC-4, bitrex wrote:

On 10/18/2020 2:13 PM, Phil Hobbs wrote:
On 2020-10-18 12:06, bitrex wrote:
Could you build a re-inforced box-girder like structure out of rigid
polystyrene foam by sandwiching it with carbon fiber tape + epoxy?

Carbon-fiber plated foam core is filthy expensive, but raw polystyrene
board and carbon fiber tape are pretty cheap individually.

Maybe any light aircraft/surfing people would know.

The buckling mode involves squashing the filler, which is why surfboards
and stuff are (classically) made of fibreglass over balsa with the grain
oriented along the shortest axis of the board--it\'s far stronger in that
direction.

You wouldn\'t have that advantage with foam, but it might work OK if the
foam were strong enough.  Of course, \"strong\" and \'styrofoam\' aren\'t
usually used together.

Cheers

Phil Hobbs


Yeah, I guess the \"reinforced\" foam would be much stronger in the
compression-direction. Might need to use carbon-fiber rods or something,
like rebar.

It\'s nothing important I just want a lightweight custom modular table
for my model choo-choos, and don\'t really own any woodworking equipment.

It\'s fun to think about a table incorporating carbon fiber, anything\'s
possible with enough $$$ thrown at the problem even a table made
completely of composite plate. Best guess for the price on that would be
into the thousands for a 4x8.

I\'ll probably contract this job out, it\'s not a large one and the custom
benchwork guys (they exist!) could likely use the money. I much prefer
doing wiring and working on models I can fit on a small worktable than
looking like I\'m re-framing my house.

I\'m not sure carbon fiber would bring a lot to the party other than cool looks. They make kayaks out of layered plastics with a weaker and lighter plastic as a core and a sturdier, but heavier plastic on the outside for strength. I thought that fiberglass over foam was a common technique for things like surf and body boards.

I\'ve seen hollow plastic tables which won\'t hold much weight. They flex terribly. Giving them a core and stronger covering would certainly be stronger, but less flexible. When the limit is reached it would just fold. Look at the construction of a sumac tree. The core is all pith with the only real strength in the outer section.

The concept is doable, but I don\'t think tape would work. The point is for the outer layer to have compression strength and the inner layer provides spacing to provide gain, i.e. leverage.

A layer of plywood, even just 1/4 inch with a lattice of 1x4 underneath, on edge will provide lots of strength. Secure 1x4 to the edges as a frame and you\'ve got a nice train board. My dad made something like that when we were kids.

--

Rick C.

+ Get 1,000 miles of free Supercharging
+ Tesla referral code - https://ts.la/richard11209

 

[Lasse Langwadt Christensen]

søndag den 18. oktober 2020 kl. 23.10.16 UTC+2 skrev Ricketty C:

On Sunday, October 18, 2020 at 3:31:28 PM UTC-4, bitrex wrote:
On 10/18/2020 2:13 PM, Phil Hobbs wrote:
On 2020-10-18 12:06, bitrex wrote:
Could you build a re-inforced box-girder like structure out of rigid
polystyrene foam by sandwiching it with carbon fiber tape + epoxy?

Carbon-fiber plated foam core is filthy expensive, but raw polystyrene
board and carbon fiber tape are pretty cheap individually.

Maybe any light aircraft/surfing people would know.

The buckling mode involves squashing the filler, which is why surfboards
and stuff are (classically) made of fibreglass over balsa with the grain
oriented along the shortest axis of the board--it\'s far stronger in that
direction.

You wouldn\'t have that advantage with foam, but it might work OK if the
foam were strong enough.  Of course, \"strong\" and \'styrofoam\' aren\'t
usually used together.

Cheers

Phil Hobbs


Yeah, I guess the \"reinforced\" foam would be much stronger in the
compression-direction. Might need to use carbon-fiber rods or something,
like rebar.

It\'s nothing important I just want a lightweight custom modular table
for my model choo-choos, and don\'t really own any woodworking equipment..

It\'s fun to think about a table incorporating carbon fiber, anything\'s
possible with enough $$$ thrown at the problem even a table made
completely of composite plate. Best guess for the price on that would be
into the thousands for a 4x8.

I\'ll probably contract this job out, it\'s not a large one and the custom
benchwork guys (they exist!) could likely use the money. I much prefer
doing wiring and working on models I can fit on a small worktable than
looking like I\'m re-framing my house.

I\'m not sure carbon fiber would bring a lot to the party other than cool looks. They make kayaks out of layered plastics with a weaker and lighter plastic as a core and a sturdier, but heavier plastic on the outside for strength. I thought that fiberglass over foam was a common technique for things like surf and body boards.

I\'ve seen hollow plastic tables which won\'t hold much weight. They flex terribly. Giving them a core and stronger covering would certainly be stronger, but less flexible. When the limit is reached it would just fold. Look at the construction of a sumac tree. The core is all pith with the only real strength in the outer section.

The concept is doable, but I don\'t think tape would work. The point is for the outer layer to have compression strength and the inner layer provides spacing to provide gain, i.e. leverage.

A layer of plywood, even just 1/4 inch with a lattice of 1x4 underneath, on edge will provide lots of strength. Secure 1x4 to the edges as a frame and you\'ve got a nice train board. My dad made something like that when we were kids.

and that is basically what you get in a ikea table top or if you want to feel like a hacker a hollow core interior door

 

[whit3rd]

On Sunday, October 18, 2020 at 11:13:58 AM UTC-7, Phil Hobbs wrote:

On 2020-10-18 12:06, bitrex wrote:
Could you build a re-inforced box-girder like structure out of rigid
polystyrene foam by sandwiching it with carbon fiber tape + epoxy?

The buckling mode involves squashing the filler, which is why surfboards
and stuff are (classically) made of fibreglass over balsa with the grain
oriented along the shortest axis of the board--it\'s far stronger in that
direction.

You wouldn\'t have that advantage with foam, but it might work OK if the
foam were strong enough. Of course, \"strong\" and \'styrofoam\' aren\'t
usually used together.

Some of the construction foam insulation boards are stiff enough
that you can pour concrete against \'em without crushing, but
there\'s no long-stick internal structure in a foam (more-or-less,
it\'s bubbles packed together) so the compressive strength is compromised:
all the bubble walls form pre-kinked columns, with poor performance
regardless of materials used.

 

[Ricketty C]

On Sunday, October 18, 2020 at 5:39:31 PM UTC-4, Lasse Langwadt Christensen wrote:

søndag den 18. oktober 2020 kl. 23.10.16 UTC+2 skrev Ricketty C:
On Sunday, October 18, 2020 at 3:31:28 PM UTC-4, bitrex wrote:
On 10/18/2020 2:13 PM, Phil Hobbs wrote:
On 2020-10-18 12:06, bitrex wrote:
Could you build a re-inforced box-girder like structure out of rigid
polystyrene foam by sandwiching it with carbon fiber tape + epoxy?

Carbon-fiber plated foam core is filthy expensive, but raw polystyrene
board and carbon fiber tape are pretty cheap individually.

Maybe any light aircraft/surfing people would know.

The buckling mode involves squashing the filler, which is why surfboards
and stuff are (classically) made of fibreglass over balsa with the grain
oriented along the shortest axis of the board--it\'s far stronger in that
direction.

You wouldn\'t have that advantage with foam, but it might work OK if the
foam were strong enough.  Of course, \"strong\" and \'styrofoam\' aren\'t
usually used together.

Cheers

Phil Hobbs


Yeah, I guess the \"reinforced\" foam would be much stronger in the
compression-direction. Might need to use carbon-fiber rods or something,
like rebar.

It\'s nothing important I just want a lightweight custom modular table
for my model choo-choos, and don\'t really own any woodworking equipment.

It\'s fun to think about a table incorporating carbon fiber, anything\'s
possible with enough $$$ thrown at the problem even a table made
completely of composite plate. Best guess for the price on that would be
into the thousands for a 4x8.

I\'ll probably contract this job out, it\'s not a large one and the custom
benchwork guys (they exist!) could likely use the money. I much prefer
doing wiring and working on models I can fit on a small worktable than
looking like I\'m re-framing my house.

I\'m not sure carbon fiber would bring a lot to the party other than cool looks. They make kayaks out of layered plastics with a weaker and lighter plastic as a core and a sturdier, but heavier plastic on the outside for strength. I thought that fiberglass over foam was a common technique for things like surf and body boards.

I\'ve seen hollow plastic tables which won\'t hold much weight. They flex terribly. Giving them a core and stronger covering would certainly be stronger, but less flexible. When the limit is reached it would just fold. Look at the construction of a sumac tree. The core is all pith with the only real strength in the outer section.

The concept is doable, but I don\'t think tape would work. The point is for the outer layer to have compression strength and the inner layer provides spacing to provide gain, i.e. leverage.

A layer of plywood, even just 1/4 inch with a lattice of 1x4 underneath, on edge will provide lots of strength. Secure 1x4 to the edges as a frame and you\'ve got a nice train board. My dad made something like that when we were kids.


and that is basically what you get in a ikea table top or if you want to feel like a hacker a hollow core interior door

For a train table, a couple of hollow core doors would do pretty well. They are usually truly hollow however and so have only the strength of the thin door material. Put anything remotely heavy on it and the surface will bow easily. It\'s also very easily dented. Ideal would be a foam core, thin laminate for looks and fiberglass surface for toughness.

I have a shallow desk made up from two saw horses, two 1x4 and a hollow core door. It was at the lake house so a girl friend could work from there instead of home. People like being right next to the water. I may use it for a work space soon.

--

Rick C.

- Get 1,000 miles of free Supercharging
- Tesla referral code - https://ts.la/richard11209

 

[bitrex]

On 10/18/2020 6:35 PM, Ricketty C wrote:

On Sunday, October 18, 2020 at 5:39:31 PM UTC-4, Lasse Langwadt Christensen wrote:
søndag den 18. oktober 2020 kl. 23.10.16 UTC+2 skrev Ricketty C:
On Sunday, October 18, 2020 at 3:31:28 PM UTC-4, bitrex wrote:
On 10/18/2020 2:13 PM, Phil Hobbs wrote:
On 2020-10-18 12:06, bitrex wrote:
Could you build a re-inforced box-girder like structure out of rigid
polystyrene foam by sandwiching it with carbon fiber tape + epoxy?

Carbon-fiber plated foam core is filthy expensive, but raw polystyrene
board and carbon fiber tape are pretty cheap individually.

Maybe any light aircraft/surfing people would know.

The buckling mode involves squashing the filler, which is why surfboards
and stuff are (classically) made of fibreglass over balsa with the grain
oriented along the shortest axis of the board--it\'s far stronger in that
direction.

You wouldn\'t have that advantage with foam, but it might work OK if the
foam were strong enough.  Of course, \"strong\" and \'styrofoam\' aren\'t
usually used together.

Cheers

Phil Hobbs


Yeah, I guess the \"reinforced\" foam would be much stronger in the
compression-direction. Might need to use carbon-fiber rods or something,
like rebar.

It\'s nothing important I just want a lightweight custom modular table
for my model choo-choos, and don\'t really own any woodworking equipment.

It\'s fun to think about a table incorporating carbon fiber, anything\'s
possible with enough $$$ thrown at the problem even a table made
completely of composite plate. Best guess for the price on that would be
into the thousands for a 4x8.

I\'ll probably contract this job out, it\'s not a large one and the custom
benchwork guys (they exist!) could likely use the money. I much prefer
doing wiring and working on models I can fit on a small worktable than
looking like I\'m re-framing my house.

I\'m not sure carbon fiber would bring a lot to the party other than cool looks. They make kayaks out of layered plastics with a weaker and lighter plastic as a core and a sturdier, but heavier plastic on the outside for strength. I thought that fiberglass over foam was a common technique for things like surf and body boards.

I\'ve seen hollow plastic tables which won\'t hold much weight. They flex terribly. Giving them a core and stronger covering would certainly be stronger, but less flexible. When the limit is reached it would just fold. Look at the construction of a sumac tree. The core is all pith with the only real strength in the outer section.

The concept is doable, but I don\'t think tape would work. The point is for the outer layer to have compression strength and the inner layer provides spacing to provide gain, i.e. leverage.

A layer of plywood, even just 1/4 inch with a lattice of 1x4 underneath, on edge will provide lots of strength. Secure 1x4 to the edges as a frame and you\'ve got a nice train board. My dad made something like that when we were kids.


and that is basically what you get in a ikea table top or if you want to feel like a hacker a hollow core interior door

For a train table, a couple of hollow core doors would do pretty well. They are usually truly hollow however and so have only the strength of the thin door material. Put anything remotely heavy on it and the surface will bow easily. It\'s also very easily dented. Ideal would be a foam core, thin laminate for looks and fiberglass surface for toughness.

I have a shallow desk made up from two saw horses, two 1x4 and a hollow core door. It was at the lake house so a girl friend could work from there instead of home. People like being right next to the water. I may use it for a work space soon.

I don\'t suppose they make doors 14\" deep and 10\' long...

 

[Clifford Heath]

On 19/10/20 8:10 am, Ricketty C wrote:
> I\'m not sure carbon fiber would bring a lot to the party other than cool looks. They make kayaks out of layered plastics with a weaker and lighter plastic as a core and a sturdier, but heavier plastic on the outside for strength. I thought that fiberglass over foam was a common technique for things like surf and body boards.

Yes. I had a racing catamaran made that way, fibreglass sandwich. Fully
rigged 14\' cat which weighed only 50kg...

My neighbour at the time was a retired composite plastics engineer who
had invented many fabrication techniques, and he pointed out that the
glass foam sandwich of the same weight as a thinner carbon-reinforced
glass sheet had about the same strength but much greater toughness. You
could almost poke your finger through the CRP but it was difficult to
penetrate the glass sandwich without a large hammer.

So the layered construction does have advantages.

I\'ve seen Nomex honeycomb being used as sandwich filler too.

CH

 

[Jasen Betts]

On 2020-10-18, bitrex <user@example.net> wrote:

Yeah, I guess the \"reinforced\" foam would be much stronger in the
compression-direction. Might need to use carbon-fiber rods or something,
like rebar.

It\'s nothing important I just want a lightweight custom modular table
for my model choo-choos, and don\'t really own any woodworking equipment.

Hollow doors, or that Ikea hollow tabletop \"Linnmon\" which is
basically the same thing, but with less wood at the edges because no
hinges or latches are needed.

--
Jasen.

 

[whit3rd]

On Sunday, October 18, 2020 at 12:31:28 PM UTC-7, bitrex wrote:

On 10/18/2020 2:13 PM, Phil Hobbs wrote:
On 2020-10-18 12:06, bitrex wrote:
Could you build a re-inforced box-girder like structure out of rigid
polystyrene foam by sandwiching it with carbon fiber tape + epoxy? ...

It\'s nothing important I just want a lightweight custom modular table
for my model choo-choos, and don\'t really own any woodworking equipment.

If you have a flat spot, you can lay out a sheet of plywood, apply Liquid Nails to it,
and put a sheet of foam and another layer of adhesive, then another sheet of plywood.
4 x 8 foot foam and thin plywood are widely available construction materials.

Just be sure to test the glue against a sample of the foam, it might dissolve.

 

[Lasse Langwadt Christensen]

mandag den 19. oktober 2020 kl. 00.47.40 UTC+2 skrev bitrex:

On 10/18/2020 6:35 PM, Ricketty C wrote:
On Sunday, October 18, 2020 at 5:39:31 PM UTC-4, Lasse Langwadt Christensen wrote:
søndag den 18. oktober 2020 kl. 23.10.16 UTC+2 skrev Ricketty C:
On Sunday, October 18, 2020 at 3:31:28 PM UTC-4, bitrex wrote:
On 10/18/2020 2:13 PM, Phil Hobbs wrote:
On 2020-10-18 12:06, bitrex wrote:
Could you build a re-inforced box-girder like structure out of rigid
polystyrene foam by sandwiching it with carbon fiber tape + epoxy?

Carbon-fiber plated foam core is filthy expensive, but raw polystyrene
board and carbon fiber tape are pretty cheap individually.

Maybe any light aircraft/surfing people would know.

The buckling mode involves squashing the filler, which is why surfboards
and stuff are (classically) made of fibreglass over balsa with the grain
oriented along the shortest axis of the board--it\'s far stronger in that
direction.

You wouldn\'t have that advantage with foam, but it might work OK if the
foam were strong enough.  Of course, \"strong\" and \'styrofoam\' aren\'t
usually used together.

Cheers

Phil Hobbs


Yeah, I guess the \"reinforced\" foam would be much stronger in the
compression-direction. Might need to use carbon-fiber rods or something,
like rebar.

It\'s nothing important I just want a lightweight custom modular table
for my model choo-choos, and don\'t really own any woodworking equipment.

It\'s fun to think about a table incorporating carbon fiber, anything\'s
possible with enough $$$ thrown at the problem even a table made
completely of composite plate. Best guess for the price on that would be
into the thousands for a 4x8.

I\'ll probably contract this job out, it\'s not a large one and the custom
benchwork guys (they exist!) could likely use the money. I much prefer
doing wiring and working on models I can fit on a small worktable than
looking like I\'m re-framing my house.

I\'m not sure carbon fiber would bring a lot to the party other than cool looks. They make kayaks out of layered plastics with a weaker and lighter plastic as a core and a sturdier, but heavier plastic on the outside for strength. I thought that fiberglass over foam was a common technique for things like surf and body boards.

I\'ve seen hollow plastic tables which won\'t hold much weight. They flex terribly. Giving them a core and stronger covering would certainly be stronger, but less flexible. When the limit is reached it would just fold. Look at the construction of a sumac tree. The core is all pith with the only real strength in the outer section.

The concept is doable, but I don\'t think tape would work. The point is for the outer layer to have compression strength and the inner layer provides spacing to provide gain, i.e. leverage.

A layer of plywood, even just 1/4 inch with a lattice of 1x4 underneath, on edge will provide lots of strength. Secure 1x4 to the edges as a frame and you\'ve got a nice train board. My dad made something like that when we were kids.


and that is basically what you get in a ikea table top or if you want to feel like a hacker a hollow core interior door

For a train table, a couple of hollow core doors would do pretty well. They are usually truly hollow however and so have only the strength of the thin door material. Put anything remotely heavy on it and the surface will bow easily. It\'s also very easily dented. Ideal would be a foam core, thin laminate for looks and fiberglass surface for toughness.

I have a shallow desk made up from two saw horses, two 1x4 and a hollow core door. It was at the lake house so a girl friend could work from there instead of home. People like being right next to the water. I may use it for a work space soon.


I don\'t suppose they make doors 14\" deep and 10\' long...

split one of half and glue in a piece of trim will be close

https://www.makeitmissoula.com/2013/07/repurposing-hollow-core-doors-into-shelves/

 

[Joe Chisolm]

On Sun, 18 Oct 2020 12:06:59 -0400, bitrex wrote:

Could you build a re-inforced box-girder like structure out of rigid
polystyrene foam by sandwiching it with carbon fiber tape + epoxy?

Carbon-fiber plated foam core is filthy expensive, but raw polystyrene
board and carbon fiber tape are pretty cheap individually.

Maybe any light aircraft/surfing people would know.

What kind of strength are you looking for? Weight?
Carbon Fibre gives you some advantage in strength/weight but
if weight is not a big issue normal fiber glass would work and
is a lot cheaper.

Most composite books have a diagram that shows a 2t core
thickness gives you +6 stiffness, +2.5 strength at +.03 weight.
4t is +36, +8.2 at +.06 weight. That\'s for a solid foam core.
Unless you really need the weight savings I would not recommend
honeycomb core unless you have done it before or want to learn.
The foam core wont have much compressive strength. You have
to pay special attention to bolts going through the core.
Connector loading has to be carefully considered.

The fiber is gonna have most strength in tension. Lots
of info on the web.

--
Chisolm
Texas-American
Building composite experimental aircraft.

 

[Ricketty C]

On Monday, October 19, 2020 at 2:38:02 PM UTC-4, Lasse Langwadt Christensen wrote:

mandag den 19. oktober 2020 kl. 00.47.40 UTC+2 skrev bitrex:
On 10/18/2020 6:35 PM, Ricketty C wrote:
On Sunday, October 18, 2020 at 5:39:31 PM UTC-4, Lasse Langwadt Christensen wrote:
søndag den 18. oktober 2020 kl. 23.10.16 UTC+2 skrev Ricketty C:
On Sunday, October 18, 2020 at 3:31:28 PM UTC-4, bitrex wrote:
On 10/18/2020 2:13 PM, Phil Hobbs wrote:
On 2020-10-18 12:06, bitrex wrote:
Could you build a re-inforced box-girder like structure out of rigid
polystyrene foam by sandwiching it with carbon fiber tape + epoxy?

Carbon-fiber plated foam core is filthy expensive, but raw polystyrene
board and carbon fiber tape are pretty cheap individually.

Maybe any light aircraft/surfing people would know.

The buckling mode involves squashing the filler, which is why surfboards
and stuff are (classically) made of fibreglass over balsa with the grain
oriented along the shortest axis of the board--it\'s far stronger in that
direction.

You wouldn\'t have that advantage with foam, but it might work OK if the
foam were strong enough.  Of course, \"strong\" and \'styrofoam\' aren\'t
usually used together.

Cheers

Phil Hobbs


Yeah, I guess the \"reinforced\" foam would be much stronger in the
compression-direction. Might need to use carbon-fiber rods or something,
like rebar.

It\'s nothing important I just want a lightweight custom modular table
for my model choo-choos, and don\'t really own any woodworking equipment.

It\'s fun to think about a table incorporating carbon fiber, anything\'s
possible with enough $$$ thrown at the problem even a table made
completely of composite plate. Best guess for the price on that would be
into the thousands for a 4x8.

I\'ll probably contract this job out, it\'s not a large one and the custom
benchwork guys (they exist!) could likely use the money. I much prefer
doing wiring and working on models I can fit on a small worktable than
looking like I\'m re-framing my house.

I\'m not sure carbon fiber would bring a lot to the party other than cool looks. They make kayaks out of layered plastics with a weaker and lighter plastic as a core and a sturdier, but heavier plastic on the outside for strength. I thought that fiberglass over foam was a common technique for things like surf and body boards.

I\'ve seen hollow plastic tables which won\'t hold much weight. They flex terribly. Giving them a core and stronger covering would certainly be stronger, but less flexible. When the limit is reached it would just fold. Look at the construction of a sumac tree. The core is all pith with the only real strength in the outer section.

The concept is doable, but I don\'t think tape would work. The point is for the outer layer to have compression strength and the inner layer provides spacing to provide gain, i.e. leverage.

A layer of plywood, even just 1/4 inch with a lattice of 1x4 underneath, on edge will provide lots of strength. Secure 1x4 to the edges as a frame and you\'ve got a nice train board. My dad made something like that when we were kids.


and that is basically what you get in a ikea table top or if you want to feel like a hacker a hollow core interior door

For a train table, a couple of hollow core doors would do pretty well.. They are usually truly hollow however and so have only the strength of the thin door material. Put anything remotely heavy on it and the surface will bow easily. It\'s also very easily dented. Ideal would be a foam core, thin laminate for looks and fiberglass surface for toughness.

I have a shallow desk made up from two saw horses, two 1x4 and a hollow core door. It was at the lake house so a girl friend could work from there instead of home. People like being right next to the water. I may use it for a work space soon.


I don\'t suppose they make doors 14\" deep and 10\' long...

split one of half and glue in a piece of trim will be close

https://www.makeitmissoula.com/2013/07/repurposing-hollow-core-doors-into-shelves/

When I was a kid, my dad made a desk for me from hollow core doors, I think it took two, one for the top and one for the four verticals. A few pieces of wood across the bottoms and some rails across the front, add some home made drawers and presto! A complete desk with drawers. It even had supports under the center drawer to store a drafting board (commonly used in those days). I\'ve kept it all these years. The only issue was the drawers were made a bit too snug and as the wood swells from humidity they stick pretty badly. Lots and lots of lubricating soap help but doen\'t fix that.

--

Rick C.

-- Get 1,000 miles of free Supercharging
-- Tesla referral code - https://ts.la/richard11209

 

[Lasse Langwadt Christensen]

tirsdag den 20. oktober 2020 kl. 00.12.25 UTC+2 skrev Ricketty C:

On Monday, October 19, 2020 at 2:38:02 PM UTC-4, Lasse Langwadt Christensen wrote:
mandag den 19. oktober 2020 kl. 00.47.40 UTC+2 skrev bitrex:
On 10/18/2020 6:35 PM, Ricketty C wrote:
On Sunday, October 18, 2020 at 5:39:31 PM UTC-4, Lasse Langwadt Christensen wrote:
søndag den 18. oktober 2020 kl. 23.10.16 UTC+2 skrev Ricketty C:
On Sunday, October 18, 2020 at 3:31:28 PM UTC-4, bitrex wrote:
On 10/18/2020 2:13 PM, Phil Hobbs wrote:
On 2020-10-18 12:06, bitrex wrote:
Could you build a re-inforced box-girder like structure out of rigid
polystyrene foam by sandwiching it with carbon fiber tape + epoxy?

Carbon-fiber plated foam core is filthy expensive, but raw polystyrene
board and carbon fiber tape are pretty cheap individually.

Maybe any light aircraft/surfing people would know.

The buckling mode involves squashing the filler, which is why surfboards
and stuff are (classically) made of fibreglass over balsa with the grain
oriented along the shortest axis of the board--it\'s far stronger in that
direction.

You wouldn\'t have that advantage with foam, but it might work OK if the
foam were strong enough.  Of course, \"strong\" and \'styrofoam\' aren\'t
usually used together.

Cheers

Phil Hobbs


Yeah, I guess the \"reinforced\" foam would be much stronger in the
compression-direction. Might need to use carbon-fiber rods or something,
like rebar.

It\'s nothing important I just want a lightweight custom modular table
for my model choo-choos, and don\'t really own any woodworking equipment.

It\'s fun to think about a table incorporating carbon fiber, anything\'s
possible with enough $$$ thrown at the problem even a table made
completely of composite plate. Best guess for the price on that would be
into the thousands for a 4x8.

I\'ll probably contract this job out, it\'s not a large one and the custom
benchwork guys (they exist!) could likely use the money. I much prefer
doing wiring and working on models I can fit on a small worktable than
looking like I\'m re-framing my house.

I\'m not sure carbon fiber would bring a lot to the party other than cool looks. They make kayaks out of layered plastics with a weaker and lighter plastic as a core and a sturdier, but heavier plastic on the outside for strength. I thought that fiberglass over foam was a common technique for things like surf and body boards.

I\'ve seen hollow plastic tables which won\'t hold much weight. They flex terribly. Giving them a core and stronger covering would certainly be stronger, but less flexible. When the limit is reached it would just fold. Look at the construction of a sumac tree. The core is all pith with the only real strength in the outer section.

The concept is doable, but I don\'t think tape would work. The point is for the outer layer to have compression strength and the inner layer provides spacing to provide gain, i.e. leverage.

A layer of plywood, even just 1/4 inch with a lattice of 1x4 underneath, on edge will provide lots of strength. Secure 1x4 to the edges as a frame and you\'ve got a nice train board. My dad made something like that when we were kids.


and that is basically what you get in a ikea table top or if you want to feel like a hacker a hollow core interior door

For a train table, a couple of hollow core doors would do pretty well. They are usually truly hollow however and so have only the strength of the thin door material. Put anything remotely heavy on it and the surface will bow easily. It\'s also very easily dented. Ideal would be a foam core, thin laminate for looks and fiberglass surface for toughness.

I have a shallow desk made up from two saw horses, two 1x4 and a hollow core door. It was at the lake house so a girl friend could work from there instead of home. People like being right next to the water. I may use it for a work space soon.


I don\'t suppose they make doors 14\" deep and 10\' long...

split one of half and glue in a piece of trim will be close

https://www.makeitmissoula.com/2013/07/repurposing-hollow-core-doors-into-shelves/

When I was a kid, my dad made a desk for me from hollow core doors, I think it took two, one for the top and one for the four verticals. A few pieces of wood across the bottoms and some rails across the front, add some home made drawers and presto! A complete desk with drawers. It even had supports under the center drawer to store a drafting board (commonly used in those days). I\'ve kept it all these years. The only issue was the drawers were made a bit too snug and as the wood swells from humidity they stick pretty badly. Lots and lots of lubricating soap help but doen\'t fix that.

there\'s a reason why Ikea makes tables etc. like it, saves on materials and transport and is plenty strong for most things

 

[Lasse Langwadt Christensen]

tirsdag den 20. oktober 2020 kl. 00.50.21 UTC+2 skrev Lasse Langwadt Christensen:

tirsdag den 20. oktober 2020 kl. 00.12.25 UTC+2 skrev Ricketty C:
On Monday, October 19, 2020 at 2:38:02 PM UTC-4, Lasse Langwadt Christensen wrote:
mandag den 19. oktober 2020 kl. 00.47.40 UTC+2 skrev bitrex:
On 10/18/2020 6:35 PM, Ricketty C wrote:
On Sunday, October 18, 2020 at 5:39:31 PM UTC-4, Lasse Langwadt Christensen wrote:
søndag den 18. oktober 2020 kl. 23.10.16 UTC+2 skrev Ricketty C:
On Sunday, October 18, 2020 at 3:31:28 PM UTC-4, bitrex wrote:
On 10/18/2020 2:13 PM, Phil Hobbs wrote:
On 2020-10-18 12:06, bitrex wrote:
Could you build a re-inforced box-girder like structure out of rigid
polystyrene foam by sandwiching it with carbon fiber tape + epoxy?

Carbon-fiber plated foam core is filthy expensive, but raw polystyrene
board and carbon fiber tape are pretty cheap individually.

Maybe any light aircraft/surfing people would know.

The buckling mode involves squashing the filler, which is why surfboards
and stuff are (classically) made of fibreglass over balsa with the grain
oriented along the shortest axis of the board--it\'s far stronger in that
direction.

You wouldn\'t have that advantage with foam, but it might work OK if the
foam were strong enough.  Of course, \"strong\" and \'styrofoam\' aren\'t
usually used together.

Cheers

Phil Hobbs


Yeah, I guess the \"reinforced\" foam would be much stronger in the
compression-direction. Might need to use carbon-fiber rods or something,
like rebar.

It\'s nothing important I just want a lightweight custom modular table
for my model choo-choos, and don\'t really own any woodworking equipment.

It\'s fun to think about a table incorporating carbon fiber, anything\'s
possible with enough $$$ thrown at the problem even a table made
completely of composite plate. Best guess for the price on that would be
into the thousands for a 4x8.

I\'ll probably contract this job out, it\'s not a large one and the custom
benchwork guys (they exist!) could likely use the money. I much prefer
doing wiring and working on models I can fit on a small worktable than
looking like I\'m re-framing my house.

I\'m not sure carbon fiber would bring a lot to the party other than cool looks. They make kayaks out of layered plastics with a weaker and lighter plastic as a core and a sturdier, but heavier plastic on the outside for strength. I thought that fiberglass over foam was a common technique for things like surf and body boards.

I\'ve seen hollow plastic tables which won\'t hold much weight. They flex terribly. Giving them a core and stronger covering would certainly be stronger, but less flexible. When the limit is reached it would just fold. Look at the construction of a sumac tree. The core is all pith with the only real strength in the outer section.

The concept is doable, but I don\'t think tape would work. The point is for the outer layer to have compression strength and the inner layer provides spacing to provide gain, i.e. leverage.

A layer of plywood, even just 1/4 inch with a lattice of 1x4 underneath, on edge will provide lots of strength. Secure 1x4 to the edges as a frame and you\'ve got a nice train board. My dad made something like that when we were kids.


and that is basically what you get in a ikea table top or if you want to feel like a hacker a hollow core interior door

For a train table, a couple of hollow core doors would do pretty well. They are usually truly hollow however and so have only the strength of the thin door material. Put anything remotely heavy on it and the surface will bow easily. It\'s also very easily dented. Ideal would be a foam core, thin laminate for looks and fiberglass surface for toughness.

I have a shallow desk made up from two saw horses, two 1x4 and a hollow core door. It was at the lake house so a girl friend could work from there instead of home. People like being right next to the water. I may use it for a work space soon.


I don\'t suppose they make doors 14\" deep and 10\' long...

split one of half and glue in a piece of trim will be close

https://www.makeitmissoula.com/2013/07/repurposing-hollow-core-doors-into-shelves/

When I was a kid, my dad made a desk for me from hollow core doors, I think it took two, one for the top and one for the four verticals. A few pieces of wood across the bottoms and some rails across the front, add some home made drawers and presto! A complete desk with drawers. It even had supports under the center drawer to store a drafting board (commonly used in those days). I\'ve kept it all these years. The only issue was the drawers were made a bit too snug and as the wood swells from humidity they stick pretty badly. Lots and lots of lubricating soap help but doen\'t fix that.


there\'s a reason why Ikea makes tables etc. like it, saves on materials and transport and is plenty strong for most things

a famous one is the LACK side table that cost about ~$10 and is a perfect fit for 19\" gear

 

[Ricketty C]

On Monday, October 19, 2020 at 6:50:21 PM UTC-4, Lasse Langwadt Christensen wrote:

tirsdag den 20. oktober 2020 kl. 00.12.25 UTC+2 skrev Ricketty C:
On Monday, October 19, 2020 at 2:38:02 PM UTC-4, Lasse Langwadt Christensen wrote:
mandag den 19. oktober 2020 kl. 00.47.40 UTC+2 skrev bitrex:
On 10/18/2020 6:35 PM, Ricketty C wrote:
On Sunday, October 18, 2020 at 5:39:31 PM UTC-4, Lasse Langwadt Christensen wrote:
søndag den 18. oktober 2020 kl. 23.10.16 UTC+2 skrev Ricketty C:
On Sunday, October 18, 2020 at 3:31:28 PM UTC-4, bitrex wrote:
On 10/18/2020 2:13 PM, Phil Hobbs wrote:
On 2020-10-18 12:06, bitrex wrote:
Could you build a re-inforced box-girder like structure out of rigid
polystyrene foam by sandwiching it with carbon fiber tape + epoxy?

Carbon-fiber plated foam core is filthy expensive, but raw polystyrene
board and carbon fiber tape are pretty cheap individually.

Maybe any light aircraft/surfing people would know.

The buckling mode involves squashing the filler, which is why surfboards
and stuff are (classically) made of fibreglass over balsa with the grain
oriented along the shortest axis of the board--it\'s far stronger in that
direction.

You wouldn\'t have that advantage with foam, but it might work OK if the
foam were strong enough.  Of course, \"strong\" and \'styrofoam\' aren\'t
usually used together.

Cheers

Phil Hobbs


Yeah, I guess the \"reinforced\" foam would be much stronger in the
compression-direction. Might need to use carbon-fiber rods or something,
like rebar.

It\'s nothing important I just want a lightweight custom modular table
for my model choo-choos, and don\'t really own any woodworking equipment.

It\'s fun to think about a table incorporating carbon fiber, anything\'s
possible with enough $$$ thrown at the problem even a table made
completely of composite plate. Best guess for the price on that would be
into the thousands for a 4x8.

I\'ll probably contract this job out, it\'s not a large one and the custom
benchwork guys (they exist!) could likely use the money. I much prefer
doing wiring and working on models I can fit on a small worktable than
looking like I\'m re-framing my house.

I\'m not sure carbon fiber would bring a lot to the party other than cool looks. They make kayaks out of layered plastics with a weaker and lighter plastic as a core and a sturdier, but heavier plastic on the outside for strength. I thought that fiberglass over foam was a common technique for things like surf and body boards.

I\'ve seen hollow plastic tables which won\'t hold much weight. They flex terribly. Giving them a core and stronger covering would certainly be stronger, but less flexible. When the limit is reached it would just fold. Look at the construction of a sumac tree. The core is all pith with the only real strength in the outer section.

The concept is doable, but I don\'t think tape would work. The point is for the outer layer to have compression strength and the inner layer provides spacing to provide gain, i.e. leverage.

A layer of plywood, even just 1/4 inch with a lattice of 1x4 underneath, on edge will provide lots of strength. Secure 1x4 to the edges as a frame and you\'ve got a nice train board. My dad made something like that when we were kids.


and that is basically what you get in a ikea table top or if you want to feel like a hacker a hollow core interior door

For a train table, a couple of hollow core doors would do pretty well. They are usually truly hollow however and so have only the strength of the thin door material. Put anything remotely heavy on it and the surface will bow easily. It\'s also very easily dented. Ideal would be a foam core, thin laminate for looks and fiberglass surface for toughness.

I have a shallow desk made up from two saw horses, two 1x4 and a hollow core door. It was at the lake house so a girl friend could work from there instead of home. People like being right next to the water. I may use it for a work space soon.


I don\'t suppose they make doors 14\" deep and 10\' long...

split one of half and glue in a piece of trim will be close

https://www.makeitmissoula.com/2013/07/repurposing-hollow-core-doors-into-shelves/

When I was a kid, my dad made a desk for me from hollow core doors, I think it took two, one for the top and one for the four verticals. A few pieces of wood across the bottoms and some rails across the front, add some home made drawers and presto! A complete desk with drawers. It even had supports under the center drawer to store a drafting board (commonly used in those days). I\'ve kept it all these years. The only issue was the drawers were made a bit too snug and as the wood swells from humidity they stick pretty badly. Lots and lots of lubricating soap help but doen\'t fix that.


there\'s a reason why Ikea makes tables etc. like it, saves on materials and transport and is plenty strong for most things

For certain values of \"most things\". Assume cows are spherical...

--

Rick C.

-+ Get 1,000 miles of free Supercharging
-+ Tesla referral code - https://ts.la/richard11209