Deconstructing a fold down bench

[radhak]

As many others here, I am fan of Mathias Wandel (http://woodgears.ca/index.html), but have not gotten around to making any of his designs yet.

Now this looks something I could try, for my back/patio : http://woodgears.ca/dads_furniture/fold_down_bench.html.

What do you think the seat is hinged by : should be strong enough to hold the weight of the seat and then also to support people sitting on it? Large Steel hinges?

And then, how do you think the lower supports hinge/swing in and out? Doesn't look like steel hinges were used.

And am thinking there should some sort of stops to disallow those supports from being knocked out of position while somebody was sitting on it - whadya say?

I have an email in to Mathias to ask him about it, and shall update if he responds, but he might be busy.

[pelligrini]

Looks like the brackets pivot at the bottom. Probably wouldn't need stops, as I bet the brackets would be difficult to move if someone was seated on it.

A rule-joint would give a lot more support for the bench, like on a drop leaf table. Example

It also appears that there are just a few metal hinges in the middle, the ends are supported with the brackets. Judging by the thickness of the seat board the hinges aren't used to support the load. They probably just to keep the geometry right. Most all of the loading would be on the brackets.

[Mr__Bill]

I would be interesting if he made them out of wood, although I can't see how and they do look like strap hinges in the picture.


Bill
over here in the rain

[phi1l]

ya . it looks like the hinge is just a pin in block at the top & bottom it looks like there is a substantial support attachment at the back of the fold down seat that ties the whole thing to the wall. It looks like the pivots are 1" dowels or round tenons, I expect those should be strong enough to support the seat. I guess you could put some shallow wedge stops if you some really vial pranksters around, but I think gravity & friction would normally hold the supports in place when someone is sitting on the seat.

It looks like an interesting project... I'm sure we are all patiently awaiting the pictures

Edit:

ya .. it looks like the there are just a few strap hinges attaching the seat to the support, this should be OK it looks like the major forces (both horizontal & vertical) are transferred to the wall though the supports & those massive pin pivots.

[LarryG]

It looks to me like there might be round tenons formed on the ends of the pivoting brackets that fit into socket-like mortises top and bottom.

In the last photo, I can see what looks like cabinet door hinges holding the folding seat to the wall-mounted rail. With the three wooden brackets supporting the weight of the occupants, these hinges wouldn't have to be particularly robust.

I agree with Erik about the brackets not really needing stops. Their triangular shape would make them unlikely to get knocked out of kilter as someone was sliding in to sit down, and once the person was seated the bracket shouldn't move at all.

[cabinetman]

It looks like the vertical member on the rear of the supports pivots in the lower block. The top may be similar (could be done with dowels). The folding part should be set out further so when in the down position it would be straight. For the stop, a stopped dadoe in the underside of the seat would let the support drop in. As for a seat hinge, IMO, any leaf or strap type would work.
.

[radhak]

Wow - all of you are right!

I received Mathias email, and he confirms it (pretty prompt of him, btw):

The bench itself hinges off the fixed pard on the back of it with store bought hinges. Its screwed into the wall, directly into the 2x4's.
The supports pivot on pegs. The ogee shaped support is mortised into the vertical piece, which is a about 5 x 5 cm solid oak. A thick peg (something like 1") sticks out of this top and bottom. The top part protrudes into a blind hole in the fixed back rail, and on the bottom side, it protrudes into a sort of cup.

Hope that helps.

Matthias

The additional info is that the vertical support is a 2"x2", so by comparison all the rest seems to be nominal 1" (3/4") thick, right?

So does this look strong enough for adults to sit on? My area has similar length or a bit more, say 4', so maybe I could add a 3rd support in the middle.

And while he has used Oak, I have to contend with rain splatter and oversprays, so maybe Cedar or Mahogany would be better? I guess I can't use any ply, right? (not sure I want to use treated).

[LarryG]

The additional info is that the vertical support is a 2"x2", so by comparison all the rest seems to be nominal 1" (3/4") thick, right?

The shaped brackets and the cleats that are attached to the wall do appear to be 3/4" material. The seat and hinge rail look more like 5/4" ... finished thickness of 1-1/16" or 1-1/8", somewhere in there.

Look again at his pictures. Unless my eyes are deceiving me, he HAS three brackets on his bench.

My only real concern strength-wise would be the little blocks that the lower end of the brackets pivot on. Their grain runs vertically, and they're not very tall, so it looks to me like they could split apart along the grain pretty easily if someone sat down hard, or weighed a lot. There's also not a lot of meat there to attach the pivot blocks to the vertical cleat. I'd make them about twice as tall, if only for peace of mind.

[pelligrini]

Another easy way to do the brackets is with piano hinges. They're pretty strong, and you wouldn't have to mess with the bottom pivot cleats.

[radhak]

The shaped brackets and the cleats that are attached to the wall do appear to be 3/4" material. The seat and hinge rail look more like 5/4" ... finished thickness of 1-1/16" or 1-1/8", somewhere in there.

Look again at his pictures. Unless my eyes are deceiving me, he HAS three brackets on his bench.

My only real concern strength-wise would be the little blocks that the lower end of the brackets pivot on. Their grain runs vertically, and they're not very tall, so it looks to me like they could split apart along the grain pretty easily if someone sat down hard, or weighed a lot. There's also not a lot of meat there to attach the pivot blocks to the vertical cleat. I'd make them about twice as tall, if only for peace of mind.

Ok - thicker for those, at least. And you are right - he has three brackets. Maybe I'd make it four (because I get a feeling mine will be slightly longer).

Now that you mentioned it, I was thinking of using thicker and longer blocks for the lower end : I'd allow them to reach the floor and be fully supported from below.

I think the wall I am choosing is mortar/cement. I will need to secure the back stretcher and bracket support with tapcon or something.