Hinge guru needed...

[Gbobo]

Hi all,

I'm working on a fold down shelf for a product but struggling a bit to get the hinges nailed.

A few points on the design:

• Once folded down, the flap should sit at 90 degrees exactly (within 1-2 degrees maybe)
• The product, represented with an anvil in the drawing, itself weights 15kg
• It should be robust enough to allow for people banging the product down so I'd guess rated for say 30kg in total
• The fold-down flap will be actuated no more than 3-5 times per day, but should be designed to last many years
• The product it is designed to hold is premium so the shelf and therefore the hinges should look the part also
• I prefer not to have fold down gas struts or cables holding it in position as it will interfere with putting the product down easily

What would perfect look like?
You fold down the flap say a quarter, it slowly drops to its 90 degree position, similar to soft close drawer if that make sense
I don't think that is easily possible but as stated above, a robust, good looking hinge will be a close second

What I already considered:

• Piano hinge - Know it works, strong given the amount of screws but doesn't look the part and will need additional design to stop it at exactly 90 degrees
• Torque hinges like these. Looks promising but I haven't used them before so not familiar with it
• Gas pistons to hold it in place like this one, combined with a hinge set but as I said, I'm trying to keep the sides open so you don't need to align the product with the shelf as not to catch or snag on the struts
• Not clear from this drawing but a pin drilled into the edge of the flap, stopped at the back at 90 degrees. Could potentially work but I'm trying to see if there is a hinge solution first before going down this route

Any ideas or the name of that "one guy that knows hinges" you might have come across would be much appreciated!

 

[Ollie78]

I am thinking a heavy torque hinge might work, look at Sugatsune, I bought some of theirs for a lid of a toy chest ( other way round to your project of course ) .
You are dealing with quite a bit of leverage here though,

Looking at the drawing the first thing I thought was to have a hinged stay on the back/ bottom of the flap so as it is opened up gravity allows the stay to drop down and contact the wall below at the correct point.
You could either have the stay stop at 45 degrees or so by way of angling it's top part above the hinge, or have a stop or batten of some kind on the wall below. A French cleat maybe.
You could make it full width but only fairly short, like a quarter of the shelf depth. Or a longer central one, one each side etc.
Alternatively go the other way, have a short hinged flap below the shelf with its hinge at the bottom. This would flap down to 45 degrees and the shelf can come down to rest on that.
In this case you could use Soss type hinges to keep them hidden.

You could have pull out stops bellow like a victorian writing desk, or side hinged stops underneath like a mini gate leg table.

I hope that makes some sense, easier to draw these things than explain them.

Another option is large quadrant hinges but you need somewhere for the "quadrant bit" to go when closed and they will be visible ( but shiny looking).

Look at chandlery suppliers maybe, boats/yachts often have things like this as well as caravans and camper vans.

Another idea I thought was something like friction stays ( like in a modern window)
If you fitted one on each end it would work.
The problem with some of these ideas is making them look good.

Ollie

 

[Sachakins]

Angoter 90 Degrees Self-Locking Folding Hinge Dining Table Lift Support Connection Cabinet Hinges Furniture Hardware Accessories Angoter 90 Degrees Self-Locking Folding Hinge Dining Table Lift Support Connection Cabinet Hinges Furniture Hardware Accessories : Amazon.co.uk: DIY & Tools

 

[profchris]

Angoter 90 Degrees Self-Locking Folding Hinge Dining Table Lift Support Connection Cabinet Hinges Furniture Hardware Accessories Angoter 90 Degrees Self-Locking Folding Hinge Dining Table Lift Support Connection Cabinet Hinges Furniture Hardware Accessories : Amazon.co.uk: DIY & Tools

That hinge weighs only 10 grams, so I doubt it would hold 14-30 kg!

Someone who remembers vector maths could calculate the hinge load if the object is dropped as far outboard as possible, but I'd guess it might be 50kg plus. I think that kind of load would need support under the shelf, and couldn't rely on a set of hinges no matter how beefy.

How about a pair of fold-out brackets in the same wood as the shelf, coupled with soft-opening hinges. The user would flip out the brackets, pull down the shelf part way, then pick up the object. Hinging on the brackets might be high-tec, to ensure they open out to 90 degrees to the wall. If you take the backboard lower and attach the hinges to that, it would remain a single unit.

 

[ajs]

Something like this that seem tailor made for the job? Although they do fold down rather than up, don't know if that is a show stopper or not.

https://www.amazon.co.uk/dp/B08PKNF3K6

 

[Ozi]

I was thinking along the same lines as Ollie78 and similar to the product shown by ajs. One or preferably two props fixed pivots at their lower end running in slides on the bottom edge of the shelf. The end of the slide fixes the angle of the shelf and users cannot forget to deploy them and break the thing.

 

[Sachakins]

These take 105kg

90° Self-Locking Hinged Leg Accessories Folding Table Legs for Multifunctional Hinged Beds Folding Consoles Support Table Folding Feet Invisible Feet Furniture Accessories Connectors (2pcs)(2 Hinges) https://amzn.eu/d/37ifyaY

 

[XTiffy]

The hinges sugested by Sachakins might be strong enough but with that much leverage on the flap the fixings would be the problem. There are kitchen fittings (for fold-a-way mixers etc.) but they would need depth in the cabinet. Stays of some sort along with bureau hinges or folding brackets would probably be the best bet. Hafele is great for this kind of research as they show engineering drawings and specifications for a multitude of hinges.
My own computer bureau flap is supported on pull out slides and supports a person leaning on the flap while using the keyboard

 

[Gbobo]

I am thinking a heavy torque hinge might work, look at Sugatsune, I bought some of theirs for a lid of a toy chest ( other way round to your project of course ) .
You are dealing with quite a bit of leverage here though,

Looking at the drawing the first thing I thought was to have a hinged stay on the back/ bottom of the flap so as it is opened up gravity allows the stay to drop down and contact the wall below at the correct point.
You could either have the stay stop at 45 degrees or so by way of angling it's top part above the hinge, or have a stop or batten of some kind on the wall below. A French cleat maybe.
You could make it full width but only fairly short, like a quarter of the shelf depth. Or a longer central one, one each side etc.
Alternatively go the other way, have a short hinged flap below the shelf with its hinge at the bottom. This would flap down to 45 degrees and the shelf can come down to rest on that.
In this case you could use Soss type hinges to keep them hidden.

You could have pull out stops bellow like a victorian writing desk, or side hinged stops underneath like a mini gate leg table.

I hope that makes some sense, easier to draw these things than explain them.

Another option is large quadrant hinges but you need somewhere for the "quadrant bit" to go when closed and they will be visible ( but shiny looking).

Look at chandlery suppliers maybe, boats/yachts often have things like this as well as caravans and camper vans.

Another idea I thought was something like friction stays ( like in a modern window)
If you fitted one on each end it would work.
The problem with some of these ideas is making them look good.

Ollie

Thanks Ollie,

I'll check out the brands you mentioned.
Good call on the yachts tip; bound to look good.

I think I get what you mean with the hinged stay at the back which is probably where I'll start with the prototype.

G

 

[thetyreman]

would grade 13 firedoor hinges not do the job? they are extremely heavy duty.

 

[Gbobo]

That hinge weighs only 10 grams, so I doubt it would hold 14-30 kg!

Someone who remembers vector maths could calculate the hinge load if the object is dropped as far outboard as possible, but I'd guess it might be 50kg plus. I think that kind of load would need support under the shelf, and couldn't rely on a set of hinges no matter how beefy.

How about a pair of fold-out brackets in the same wood as the shelf, coupled with soft-opening hinges. The user would flip out the brackets, pull down the shelf part way, then pick up the object. Hinging on the brackets might be high-tec, to ensure they open out to 90 degrees to the wall. If you take the backboard lower and attach the hinges to that, it would remain a single unit.

Thanks Chris, Not sure I follow exactly without a drawing...

 

[Gbobo]

would grade 13 firedoor hinges not do the job? they are extremely heavy duty.

Thanks, but I think it is the fixings that might become the issue as XTiffy said. I might try and bolt straight through in the prototype

 

[Gbobo]

The hinges sugested by Sachakins might be strong enough but with that much leverage on the flap the fixings would be the problem. There are kitchen fittings (for fold-a-way mixers etc.) but they would need depth in the cabinet. Stays of some sort along with bureau hinges or folding brackets would probably be the best bet. Hafele is great for this kind of research as they show engineering drawings and specifications for a multitude of hinges.
My own computer bureau flap is supported on pull out slides and supports a person leaning on the flap while using the keyboard

Good shout. Thanks XTiffy. I'll check out Hafele.

 

[Gbobo]

These take 105kg

90° Self-Locking Hinged Leg Accessories Folding Table Legs for Multifunctional Hinged Beds Folding Consoles Support Table Folding Feet Invisible Feet Furniture Accessories Connectors (2pcs)(2 Hinges) https://amzn.eu/d/37ifyaY

Thanks! As others have said, it is the leverage that is the issue...

 

[Gbobo]

Something like this that seem tailor made for the job? Although they do fold down rather than up, don't know if that is a show stopper or not.

https://www.amazon.co.uk/dp/B08PKNF3K6

Has to be up unfortunately...

 

[XTiffy]

Gbobo, The neatest way of achieving the result you need is to make two swing out wooden brackets below the flap. If you look up "Pembroke table" you will see that the table flap (at each side of the table) used this method. The brackets are usually finger or "knuckle" jointed such that they stop at right angles. These brackets in the best class of work would be shaped ie slimmer at the extremities to make them less visible. The gap between the two brackets having a reverse shaped piece between the two brackets, so that when stowed almost looked like a single piece of wood. A variation of this is a single swing-out leg that supports the flap but that doesn't seem to be in keeping with your desired design.

 

[Gbobo]

Thanks XTiffy, I might have to go down that route if I dont find a hinge solution that works.