aluminium sheet+ eps/xps board

What works and what doesn't. Share design ideas, references and contacts for paipo board builders.
asier esnal
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aluminium sheet+ eps/xps board

Unread post by asier esnal » Fri Mar 22, 2019 7:33 am

I have seen surfboards alsurfboards and I thought it was a very interesting job, so I started thinking about that idea. I put a graphic with what I thought.

 aluminum sheet up and down in 0.8 or 1mm thickness the marine reference is 5083, but I can not buy it in such fine thickness, this have 4% magnesium. but if you have offered me the reference 5754, which has 3% I have been assured that with a layer of varnish will not attack too much the saltpeter

of nucleo eps or xps. in any construction store. come out cheap

rails in the corecork , this I can get in thickness up to 50mm in a shop near home at a good price

all glued with d4 polyurethane glue that is 100% resistant to salt water, the 750g bore goes to 18e, I can also buy it near home like the rest of materials, so I'm very happy with the idea, for me it's important have unlimited access to be able to do experiments. the price of the full paipo will be around 50e

everything will be 100 recyclable material. So I'm also happy about that. less work effort, I do not have to laminate, polish ..., just glue the pieces and put some sandbags to make pressure, I do not even need vacuum pump, or volsas to throw in the garbage

I have many doubts with the flex of the table, if it comes out too flexible you can get it by sticking a stringer, but if it comes out very rigid .... complicated to give solution

what do you think? I think it's going to be the work of the next few weeks


es

he visto las tablas de surf alsurfboard y me ha parecido un trabajo de lo mas interesante, asi que me he puesto a dar vueltas a esa idea. os pongo un grafico con lo que he pensado.

chapa de aluminio arriba y abajo en 0.8 o 1mm de espesor la referencia marina es de 5083, pero no la puedo comprar en espesor tan fino, esta tienen 4% de magnesio. pero si me han ofrecido la referencia 5754, que tiene 3% me han asegurado que con una capa de barniz no le atacara demasiado el salitre

de nucleo eps o xps. en cualquier tienda de construccion. sale barato

en los cantos corecork, esto lo puedo conseguir en expesor asta 50mm en una tienda cerca de casa a buen precio

todo pegado con cola de poliuretano d4 que es 100% resistente al agua salada, el bore de 750g sale a 18e, tambien lo puedo comprar cerca de casa como el resto de materiales, asi que estoy muy contento con la idea, para mi es importante tener acceso ilimitado para poder hacer experimentos. el precio del paipo completo saldra en torno a los 50e

todo sera material 100 reciclable. asi que tambien estoy contento por eso. menos esfuerzo de trabajo, no tengo que laminar, pulir..., solo encolar las piezas y poner unos sacos de arena para hacer presion, ni siquiera me hace falta bomba de vacio, ni volsas que tirar a la basura

tengo muchas dudas con el flex de la tabla, si sale demasiado flexible se puede areglar metiendo un stringer, pero si sale muy rigida.... complicado darle solucion

que os parece? creo que va a ser el trabajo de las proximas semanas
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asier esnal
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Re: aluminium sheet+ eps/xps board

Unread post by asier esnal » Fri Mar 22, 2019 7:40 am

I have been comparing the mechanical properties of fiberglass and aluminum. is very curious, have the same density 2700: same weight, elastic limit 90/120 in the references that I have said with temple h111 is very similar, there are other thermal treatments that combine those same references in much harder and more rigid that are not interesting

by the calclulos that I have done, I am not an engineer a sheet of 0.8mm is equivalent to 4 + 4oz and that of 1mm would be 6 + 6 or volan +4

es

he estado comparando las propiedades mecánicas de la fibra de vidrio y el aluminio. es muy curioso, tienen la misma densidad 2700: mismo peso, limite elastico 90/120 en las referencias que he dicho con temple h111 es muy parecido, hay otros tratamientos termicos que combierten a esas mismas referencias en mucho mas duras y rigidas que no interesan

por los calclulos que he hecho, no soy ingeniero una chapa de 0.8mm equivale a 4+4oz y la de 1mm seria 6+6 o volan +4

asier esnal
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Re: aluminium sheet+ eps/xps board

Unread post by asier esnal » Fri Mar 22, 2019 7:46 am

I have made tests sticking 2 aluminum plates with this glue, it has been terribly difficult to separate them with a special knife to open oysters. very happy with the result, I have not done the test eps / xps aluminum, it will be the next test.

es

he hecho pruebas pegando 2 chapas de aluminio con esta cola , me ha sido terriblemente dificil separarlas con un chuchillo especial para abrir ostras. muy contento con el resultado, no he hecho la prueva eps/xps aluminio, sera el siguiente ensayo.
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Nels
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Re: aluminium sheet+ eps/xps board

Unread post by Nels » Fri Mar 22, 2019 6:42 pm

Aluminum could make a deadly material if dinged into a jagged edge. It also conducts heat so that could be an issue on sunny days, at least for wax retention, if that is an issue.

That said, double layers increase weight, although I think it would be very strong. AL comes in various tempers, which affect hardness. Softer are easier to work with, harder is stronger. From fading memory of my time in aerospace, a material like 6061 at "0" condition was "soft", heat treated to "T-4" was somewhat harder, and "T-6" was hard enough for finished exterior aircraft use.

Sounds like an interesting experiment.

asier esnal
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Re: aluminium sheet+ eps/xps board

Unread post by asier esnal » Sat Mar 23, 2019 7:17 am

I live in the Basque Country is a zone of very temperate climate, winter is rare on days that we have 5 degrees and in summer on very few occasions we have more than 35 degrees obligatory to put a cap of gore tex on everything to keep the table inside the car

aluminum: in this attached message a table with different hardnesses of the same aluminum according to the thermal treatment that they have will be harder or more flexible. in the case of this paipo I am looking for a bit of flexibility it will be more pleasant to take it in the wave and in the highs for more it will not hurt me so much in the ribs

I know I can reduce the thickness of the sheets by putting a sheet with a harder treatment example a sheet of a millimeter thick could be replaced by a 0.8 with an X6 treatment but at the moment I'm not looking to refine the project so much apart for the paipo I prefer it to be a little heavier in waves of wind Jump less. in case it works well and try to make a high performance surfboard if it will be parameters that you have to take into account

Safety: this is a section that has me quite concerned an aluminum sheet can make a strong cut, but we have all seen what happens when a surfboard breaks out pieces of fiberglass hanging that really if they are dangerous, the boards of aluminum surfing as I have seen in a photo of Alsurfboards, they bend. therefore in case of torture I see aluminum somewhat safer.

I have two very important concerns. behavior of the aluminum in the water touch sensitivity flexibility. and the second in case of giving a strong blow as the arrangement I still do not have at all thought. It could be bodybuilder paste. subject to study in the future

Es

vivo en el País Vasco es una zona de clima muy templada, el invierno es raro los días que tenemos 5 grados y en verano en muy pocas ocasiones tenemos más de 35 grados. obligatorio ponerle un tapón de goretex sobre todo para guardar la tabla dentro del coche

aluminio: en este mensaje adjunto una tabla con diferentes durezas del mismo aluminio según el tratamiento térmico que tengan será más duro o más flexible. en el caso de este paipo busco un poco de flexibilidad será más agradable llevarlo en la ola y en los altos por más picada no me hará tanto daño en las costillas

sé que puedo reducir el espesor de las chapas poniendo una chapa con un tratamiento más duro ejemplo una chapa de un milímetro de espesor podría ser sustituida por una de 0,8 con un tratamiento X6 pero en este momento no estoy buscando afinar tanto el proyecto aparte para el paipo prefiero que sea un poquito más pesado en olas de viento Salta menos. en caso de funcionar bien e intentar hacer una tabla de surf de alto rendimiento si será parámetros que tenga que tener en cuenta

seguridad: este es un apartado que me tiene bastante preocupada una chapa de aluminio de puede hacer un corte fuerte, pero todos hemos visto qué pasa cuando una tabla de surf se rompe salen trozos de fibra de vidrio colgando que realmente si son peligrosos, las tablas de surf de aluminio como he visto en una foto de Alsurfboards, se doblan . por lo tanto en caso de tortura veo algo más seguro el aluminio.

tengo dos inquietudes muy importantes. comportamiento del aluminio en el agua tacto sensibilidad flexibilidad. y la segunda en caso de darle un fuerte golpe como la arreglo todavía no tengo del todo pensado. podría ser pasta de carrocero tema a estudiar a futuro
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asier esnal
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Re: aluminium sheet+ eps/xps board

Unread post by asier esnal » Mon Mar 25, 2019 1:49 pm

Today I made the test, I cut with the saw a sheet of 0.8mm thick, during the process I made a small cut in my hand, nothing serious, quiet, but it was a sign, a premonition, a warning What would happen to me if I entered with the aluminum paipo in the water. Directly I have discarded the idea I am not going to fafricar the aluminum paipo, it is dangerous

so I learn, trial and error. better for the capping process than regretting after an accident :oops: :|

es


hoy he hecho la prueba, he cortado con la sierra una chapa de 0.8mm de espesor, durante el proceso me he hecho un pequeño corte en la mano, nada grave, tranquilos, pero ha sido una señal, una premonicion, un aviso de lo que me pasaria si entrase con el paipo de aluminio en el agua. directametne he deshechado la idea no voy a fafricar el paipo de aluminio, es peligroso

asi aprendo, ensayo y error. mejor para el proceso de cabricacion que lamentar despues un accidente

asier esnal
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Re: aluminium sheet+ eps/xps board

Unread post by asier esnal » Mon Mar 25, 2019 4:01 pm

like a knife
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zensuni
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Re: aluminium sheet+ eps/xps board

Unread post by zensuni » Wed Mar 27, 2019 11:37 am

I think that is a wise decision not to use aluminium in the board making process.
It sounds dangerous, more than wood. Also, what would be the advantage ?

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Re: aluminium sheet+ eps/xps board

Unread post by asier esnal » Thu Mar 28, 2019 4:43 am

there are aluminum that do not rot with salt water like boats, wood if it is not paulownia yes, it is very thin, 0.8 so it does not alter the shape of eps, it has properties similar to glass fiber, it is not necessary to do hotcoat ... faster manufacturing, it is economical and I have unlimited access in a store very close to my house. all this led me to the conclusion that it could be used.

  but the reality has been different, it did not count on the cutting process, and because it is so fine it doubles, it has been a failure.

I'm still looking for ways to build paipos quickly with good flex properties. I made a sandwich with okume marina wood, rails in corecork inside xps. a failure, it has been light but it does not have flex, it is ultra rigid, if I have even taken it to the beach, to the garbage

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Re: aluminium sheet+ eps/xps board

Unread post by Uncle Grumpy » Thu Mar 28, 2019 10:38 am

I've been on a similar quest for the perfect flex for a few years now and most of my experiments ended up either too heavy or too stiff for my taste as well.
Always end up back at solid wood (Paulownia) boards shaped just thin enough but no more....coincidentally I just placed an order for more Paulownia. :)
Paipo surfer in repose,
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See how fast he goes!
What is it he knows?

asier esnal
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Re: aluminium sheet+ eps/xps board

Unread post by asier esnal » Thu Mar 28, 2019 1:58 pm

the problem of making paipos of only wood is the lack of buoyancy, I do not want a bodyboard but something that floats a bit more than my current paulownia

asier esnal
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Re: aluminium sheet+ eps/xps board

Unread post by asier esnal » Fri Mar 29, 2019 2:42 am

The problem with the null flex in the sandwich construction with okume board has been the thickness of the core. as I put 30mm xps has created an ultra strong structure. the next experiment I'm going to do with a thickness of 10mm xps for the core. I am trying to win flex but without putting 3 okume 5mm badges as would be normal


https://www.boatdesign.net/articles/foam-core/

The sandwich concept is based on two main ideas: increasing the stiffness in bending of a beam or panel and doing so without adding excessive weight. The general term for bending stiffness is flexural rigidity (D), which is the product of the material(s) elastic modulus, and the cross section moment of inertia (I). For a symmetric sandwich beam (both skins have the same thickness and material properties), the formula for flexural rigidity is:




With:
Ef = Elastic Modulus of the Facings (Skins)
Ec = Elastic Modulus of the Core
b = Width of the Beam
d = Distance Between Facing Centroids
t = Thickness of a Facing
c = Core Thickness

If the skins are relatively thin compared to the core (d/t > 6) and the core material is considerably weaker than the skins (Ef/Ec . td2/c3 > 17), the equation can be reduced to:



From this equation, it is apparent that the core material does not directly contribute to the stiffness of the panel or beam, (at least in lower density cores) but it's the distance between the skins that is the overwhelming factor. Increasing the "d" variable will have a much greater effect on the flexural rigidity than any other component in the equation, since every other variable has a linear contribution. When dealing with higher density cores (usually > 5 lb/ft 3 ) and thicker skin laminates, the full equation must be used in order to properly predict the stiffness properties. This is due to the high-density core contributing stiffness in the first case, and the thick skins absorbing more shear stress.

While the core keeps the skins an equal distance apart from each other thereby increasing the stiffness, it also bears most of the shear loading. In bending, the lower skin is in tension, while the upper (or inner) skin is in compression thereby putting the core in shear (See Figure 1). In order for the sandwich to function correctly the adhesive layers between the skins and the core must be able to transfer the loads, and thereby be as least as strong as the core material. Without a proper bond, the three entities work as separate beams/plates and the stiffness is lost. This is why proper core/skin bonding is so critical.



Sandwich vs. Single Skin Fiberglass

Exactly how much stiffer is a sandwich structure versus a single skin laminate, and what are the weight savings? As noted above, the flexural rigidity of a structure is dependent on two factors: the material(s) stiffness or modulus, and the cross sectional geometry or moment of inertia. The material properties are often difficult to change (and sometimes expensive), so a change in the geometry can be done to increase stiffness while not compromising on strength or other properties of a single skin laminate. Figure 2 shows.the difference in stiffness, strength, and weight when a core material is placed between the plies of a single skin laminate (all attributes are approximately normalized).



From just increasing the cross sectional geometry, the stiffness increased 48 times, while the flexural strength increased 6 times, and all with a marginal increase in weight. The increase in strength and stiffness allows builders to use less skin materials, resulting in considerably lower weight structures. Decreased weight helps to increase top speed and acceleration, increases cargo capacity, and reduces fuel consumption. A sandwich construction is compared to a single skin laminate with relatively the same flexural rigidity in Figure 3:




Other advantages of the sandwich construction include: greater insulation, better impact/damage resistance, sound attenuation, and reduced labor. The core material, which is usually cellular in construction, provides a much lower thermal conductivity and higher R-value than a comparable single skin laminate. Labor is reduced since less plies of material are being used and the greater stiffness of the sandwich reduces the number of needed stiffeners. With less stiffeners, and consequently larger panel sizes, impact energy is dissipated more readily. The cellular core materials also reduce the "drum head" effect, thereby reducing noise, resulting in a quieter ride.

Some downsides to sandwich construction include the core material cost and the employee learning curve. Core materials are generally more expensive than the resin and glass that it is replacing, and in some cases the labor savings will not offset the cored laminate price. More care and attention needs to be taken when processing cored laminates. Employees need to be aware of all the possible problems that could occur if the core materials are not handled or bonded to the skins correctly.

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zensuni
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Re: aluminium sheet+ eps/xps board

Unread post by zensuni » Fri Mar 29, 2019 5:42 am

Plywood (1 cm tick) has a lot of downsides, but it does flex quite well if the board is not too wide.

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