Does this hatch profile look manufacturable?

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Re: Does this hatch profile look manufacturable?

Postby gpr5027 » Fri Jan 31, 2020 6:32 pm

New question:

Is there any reason the galley NEEDS the plywood skin in between the wooden frame and the aluminum skin? Seems to me that the spars could be used for mounting things like lights/handles/etc, and you could bond the aluminum (perhaps in 0.063 or 0.080) to the frame with, say, 3M 5200, and use clamps and perhaps a few screws to keep it in place while curing. The rear of the trailer won't see any real aero loads or road debris, and assuming the wooden frame is where all of the stiffness is coming from anyway, the wood skin feels kind of redundant. Unless I'm missing something obvious, which is definitely possible, but I like deleting the challenge of bending the wood to that contour... Thoughts?
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Re: Does this hatch profile look manufacturable?

Postby tony.latham » Fri Jan 31, 2020 7:06 pm

the wood skin feels kind of redundant.


I'm going to say yes, you need the skin. The skin glued to all of those structural elements acts as a giant gusset and locks everything in place. Perhaps you could do the same with aluminum and the 3M. (Perhaps it would work. Glueing wood to wood with PVA glue is tough to beat. It's permanent.)

I would think that aluminum that thick might weigh more than if it were sheathed with .040 over 1/8" Baltic.

I skin both the top and bottom of the hatch with 1/8" Baltic. And thus it is a torsion box.

I also add foam board to support the plywood internally. (And keep the galley cool during the heat of the day.) On my first (factory) teardrop, the hatch got shut without inserting the water jug. It penetrated the plywood. It didn't have foam inside it.

The foam in this new hatch adds 3.5 pounds to it and fully supports both layers of Baltic.

I attached my paper towel holder to a spar. So skinning the inside doesn't preclude this.



When you get yours done, make sure you play that music for the first opening. :shock:

Tony
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Re: Does this hatch profile look manufacturable?

Postby gpr5027 » Sun Feb 02, 2020 12:51 pm

tony.latham wrote:
the wood skin feels kind of redundant.


I'm going to say yes, you need the skin. The skin glued to all of those structural elements acts as a giant gusset and locks everything in place. Perhaps you could do the same with aluminum and the 3M. (Perhaps it would work. Glueing wood to wood with PVA glue is tough to beat. It's permanent.)

I would think that aluminum that thick might weigh more than if it were sheathed with .040 over 1/8" Baltic.

I skin both the top and bottom of the hatch with 1/8" Baltic. And thus it is a torsion box.

I also add foam board to support the plywood internally. (And keep the galley cool during the heat of the day.) On my first (factory) teardrop, the hatch got shut without inserting the water jug. It penetrated the plywood. It didn't have foam inside it.

The foam in this new hatch adds 3.5 pounds to it and fully supports both layers of Baltic.

I attached my paper towel holder to a spar. So skinning the inside doesn't preclude this.

When you get yours done, make sure you play that music for the first opening. :shock:

Tony


All good thoughts. So you built the hatch frame in situ - did you then remove it to glue on the BB skins? How many hands and clamps did this require? I have zero woodworking experience which is why the wooden skin is intimidating me.

For foam board, are you just using the really rigid stuff you can pick up at Home Depot or is it something special? Did you cut it into small strips and glue it in order to follow the hatch curves?

And yeah the thicker aluminum would weigh more than the thinner sheet + the wood skins, it's far more dense (and far more expensive). As for your song choice, I think I can get behind that - especially if it means my hatch will open and close like yours...
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Re: Does this hatch profile look manufacturable?

Postby tony.latham » Sun Feb 02, 2020 1:40 pm

All good thoughts. So you built the hatch frame in situ - did you then remove it to glue on the BB skins? How many hands and clamps did this require? I have zero woodworking experience which is why the wooden skin is intimidating me.

For foam board, are you just using the really rigid stuff you can pick up at Home Depot or is it something special? Did you cut it into small strips and glue it in order to follow the hatch curves?


I build the hatch framework in situ and then removed it for the sheathing installation. 1/8" Baltic birch wants to bend so that's not a problem. Admittedly mine was a little bit of a rodeo to install the interior skin. I used two hands but two others would help. No clamps, just PL Premium glue, and my trusty pneumatic 1/4" staple gun.

Image

Any foam board will work. Pink or blue, your choice.

Image

It's kerf cut to allow it to bend. Just like in the roof.

Image

:thumbsup:

Tony
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Re: Does this hatch profile look manufacturable?

Postby tony.latham » Sun Feb 02, 2020 1:47 pm

And by the way, the title of your post, "Does this hatch profile look manufacturable?", almost sounds like:

Does this hatch make my teardrop look fat?

Kinda like the lady that turns away from her husband and says, "does this dress make me look..."

:frightened: :FNP

Tony
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Re: Does this hatch profile look manufacturable?

Postby gpr5027 » Sun Feb 02, 2020 2:17 pm

tony.latham wrote:Does this hatch make my teardrop look fat?

:NC
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Re: Does this hatch profile look manufacturable?

Postby Tom&Shelly » Sun Feb 02, 2020 4:01 pm

tony.latham wrote:And by the way, the title of your post, "Does this hatch profile look manufacturable?", almost sounds like:

Does this hatch make my teardrop look fat?

Kinda like the lady that turns away from her husband and says, "does this dress make me look..."

:frightened: :FNP

Tony


"No, sweetheart, it's not the dress..."

is, as it turns out, not the right answer. :no:

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