HURRICANE HINGE & GAS STRUT PROBLEM

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HURRICANE HINGE & GAS STRUT PROBLEM

Postby DWT77 » Mon May 20, 2019 4:46 pm

I didn't have a problem with my galley hatch until I put on some gas springs.

I used the gas spring calculator to help get the correct ones.

Since my teardrop is 5' tall my hatch came out to be 65" and 100 lbs for the dead weight. Spreadsheet said I needed 39" springs at 162 lbs of force each (Total 324 lbs). I was able to find 36" springs at 160 lbs so I gave them a shot. (I may have used the mounting locations from the 39" the spreadsheet recommended I don't remember if I converted the numbers or not)

As far as the force goes they open and close the hatch nicely. It holds the hatch up no problem and is easy to open/close the hatch.

The problem is that the springs have completely detached my hurricane hinge from my roof

I actually have a few different things going on I believe.

The first is the mounting of the gas springs on the gusset. Since the gusset is only 1/2" plywood it has ripped out. I tried to fix it by putting epoxy behind the bracket then screwing it back down ( I did shift it just a bit so I didn't use the same screw holes) but last night I heard it break loose while the hatch was closed
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My first question is, do you think I should move the bracket attachment point from the gusset to the spar in the hatch so it will be stronger?
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My second problem is that the force of the springs ripped the hurricane hinge off of the roof. I used #8 3/4" stainless steel screws to secure the hurricane hinge. I think I have a geometry/physics problem though.
My other question is do you think the hinge attachment points are located to close to the hinge pivot point?
Causing to much vertical force on the hinge?

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Lastly do you think I need to move the location of the bracket mount on the sidewall? Lower closer to the counter top
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You can see here how high the hinge was opening from the locations the brackets are at now.
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Any idea, thoughts or suggestions would be greatly appreciated. Thanks
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Re: HURRICANE HINGE & GAS STRUT PROBLEM

Postby tony.latham » Mon May 20, 2019 5:04 pm

Shit-oh-dear.

Spreadsheet said I needed 39" springs at 162 lbs or force...


:frightened:

What wood did you use for your hatch spar?

As far as the bracket pulling off ––I think what you need to do is connect it with machine bolts and T-nuts --dump the wood screws. Maybe add another piece of 1/2" ply to the gusset first.

:thinking:

T
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Re: HURRICANE HINGE & GAS STRUT PROBLEM

Postby DWT77 » Mon May 20, 2019 9:19 pm

tony.latham wrote:Shit-oh-dear.

Spreadsheet said I needed 39" springs at 162 lbs or force...


:frightened:

What wood did you use for your hatch spar?

As far as the bracket pulling off ––I think what you need to do is connect it with machine bolts and T-nuts --dump the wood screws. Maybe add another piece of 1/2" ply to the gusset first.

:thinking:

T


I used 2 pieces of Oak mated together for the hatch spar.

T-nuts might work. Another piece of wood on the gusset would help displace the force applied to the bracket
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Re: HURRICANE HINGE & GAS STRUT PROBLEM

Postby tony.latham » Mon May 20, 2019 10:40 pm

Is there a way to run #10 screws through the spar and put a nut underneath?


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Re: HURRICANE HINGE & GAS STRUT PROBLEM

Postby DWT77 » Tue May 21, 2019 7:37 pm

tony.latham wrote:Is there a way to run #10 screws through the spar and put a nut underneath?


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Nope no way to get underneath the spar.
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Re: HURRICANE HINGE & GAS STRUT PROBLEM

Postby tony.latham » Tue May 21, 2019 7:53 pm

Nope no way to get underneath the spar.


Then the other option that I can think up is to use bigger diameter screws that are nearly as long as the spar.

T
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Re: HURRICANE HINGE & GAS STRUT PROBLEM

Postby KTM_Guy » Tue May 21, 2019 11:05 pm

I had a similar problem. I had to make some very heavy duty brackets for the struts. My firs bracket was 1/8 angle and it bent, I made new ones out of 3/16" flat bar. Tony seen them and even asked about them. I'll see if I can find some pictures. and post them.

I used 1 3/4" screws for my hinge, they are the same screws you would use to hang kitchen cabinets.

Todd
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Re: HURRICANE HINGE & GAS STRUT PROBLEM

Postby DWT77 » Wed May 22, 2019 6:08 am

tony.latham wrote:
Nope no way to get underneath the spar.


Then the other option that I can think up is to use bigger diameter screws that are nearly as long as the spar.

T


Tony that is what I was thinking. A bigger longer screw especially since I already have holes in the spar now
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Re: HURRICANE HINGE & GAS STRUT PROBLEM

Postby DWT77 » Wed May 22, 2019 6:08 am

KTM_Guy wrote:I had a similar problem. I had to make some very heavy duty brackets for the struts. My firs bracket was 1/8 angle and it bent, I made new ones out of 3/16" flat bar. Tony seen them and even asked about them. I'll see if I can find some pictures. and post them.

I used 1 3/4" screws for my hinge, they are the same screws you would use to hang kitchen cabinets.

Todd


That would be great Thanks Todd!
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Re: HURRICANE HINGE & GAS STRUT PROBLEM

Postby Tomterrific » Wed May 22, 2019 7:22 am

I'll bring up the possibility of the gas strut being too long closed and something has to give. Measure the mounting distance, hatch to base, and see that the strut has enough room.

I agree that a bolt through is a much stronger attachment than a screw. Stainless steel bolts, nylock nuts and fender washers are easy to find. Put the fender washers on the wood side to distribute force. Put a bedding compound, like non hardening caulk, under the washer and around the bolt. It will squeese out and in to seal absolutely. This may be overkill but I just mounted a TV on an arm this way to be sure it will stand up to a road trip. Screws would never hold up.


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Re: HURRICANE HINGE & GAS STRUT PROBLEM

Postby Ge99ne » Wed May 22, 2019 9:23 am

"My other question is do you think the hinge attachment points are located to close to the hinge pivot point?
Causing to much vertical force on the hinge"
I think you are on the right track with this. The supports are pretty close to the hinge. moving the supports away from hinge will greatly reduce the force imparted on the hinge. Current config is putting a significant lifting force on hinge. Looks like 80 percent of the hatch weight is prying at your hinge. Every bit you can move the strut support away from the hinge will go a long way towards reducing the load on the hinge. Not an easy exercise, with the elliptical hatch.
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Re: HURRICANE HINGE & GAS STRUT PROBLEM

Postby tony.latham » Wed May 22, 2019 10:06 am

Are you sure the strut isn't bottoming out during the stroke?

:frightened: :frightened:

T
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Re: HURRICANE HINGE & GAS STRUT PROBLEM

Postby halfdome, Danny » Wed May 22, 2019 10:13 am

Years ago I solved the problem of the screws wanting to rip out of the gas strut mounts by welding half of a residential door hinge at 90 degrees on the bracket.
It then gives me a nice attachment into the face of my spars, end grain of plywood can weaken over time.
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Without looking at a pile of receipts I believe my gas struts are about 90# each and I'm guessing the lid weighs about 100#.
Their suppose to assist lifting the hatch, not throw it up so hard to rip out screws.
Sound like maybe there's too much force when your hatch is closed.
I always get inside and close the lid to figure out the best spot to mount my gas struts even though I have the measurements noted in my build manual.
Note: My galley cabinets are removeable so I put them after the lid is installed.
My hurricane hinge is attached to a solid Red Oak spar that is attached to the rear bulkhead, very strong.
:D Danny
Last edited by halfdome, Danny on Wed May 22, 2019 11:38 am, edited 1 time in total.
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Re: HURRICANE HINGE & GAS STRUT PROBLEM

Postby Tom&Shelly » Wed May 22, 2019 10:36 am

Wayne, sorry to see the problems you are having. I know this is no consolation, but I'm just beginning to look at the hatch and struts for our build, and this thread is helping immensely. Think I'd've done exactly as you did, so would have exactly the same problems. Thank you for sharing!


KTM_Guy wrote:I had a similar problem. I had to make some very heavy duty brackets for the struts. My firs bracket was 1/8 angle and it bent, I made new ones out of 3/16" flat bar. Tony seen them and even asked about them. I'll see if I can find some pictures. and post them.

I used 1 3/4" screws for my hinge, they are the same screws you would use to hang kitchen cabinets.

Todd


Are your brackets aluminum Todd? I'm looking at what we could use/fabricate. Will be glad to see pictures if you have them.

Tom
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Re: HURRICANE HINGE & GAS STRUT PROBLEM

Postby tony.latham » Wed May 22, 2019 11:29 am

Are your brackets aluminum Todd?


As he mentioned, I've seen them. They're hell-for-stout steel. And his welds don't look like my turkey-dropping globs. :oops:

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