Specialist hinges?

[JohnW2]

Add a couple of gas struts and you would not need to go flat to the roof.

I've certainly considered that, but I don't think it would be straightforward if one wanted to avoid people potentially hitting there heads on the lid when going through the hatch, since that would require it to open more than 90° - which, which simple struts, would put them into 'pneumatic tension', rather than compression, and I'm not sure whether that works satisfactory.

In any event, the issue of wanting the lid to go flat on the roof (i.e. to open slightly more than 180°) is a very trivial one, since that 'need' could, in itself, be removed by putting a brick./block/whatever on an appropriate place on the roof for the lid to rest on (at, or alightly above, 'the horizontal'.

Kind Regards, John

 

[blup]

Garage type gate hinges, there is space in the gap to screwfix them

Blup

 

[robinbanks]

I had in mind the stainless fire door hinges that hold all my house doors on -they're just a regular butt hinge but fairly chunky

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But you've just reminded me I did drill extra holes in a parliament hinge to make for a more secure mounting, plus your hinges are a good whack larger than these which moves the screw holes away from the lid edge.. A timber fillet approach would allow you to add extra holes to one or both leaves of the hinge if you like; I think the bolting though approach is good

 

[JohnW2]

I had in mind the stainless fire door hinges that hold all my house doors on -they're just a regular butt hinge but fairly chunky

I've got plenty of them, but, being just but hinges, they suffer from the issue which robinbanks has highlighted of the screw holes being close to the hinge pin (and would, of course, require the ;timber fillet approach').

But you've just reminded me I did drill extra holes in a parliament hinge to make for a more secure mounting, plus your hinges are a good whack larger than these which moves the screw holes away from the lid edge..

Yes, I would definitely make some more holes in the part of the hinge attached to the lid. However, on the 'fixed side, there is not really any option to do that (other than in-line with the existing ones), since there is little scope (with the hinges I have) to move the bed any further from the holes.

A timber fillet approach would allow you to add extra holes to one or both leaves of the hinge if you like;

Indeed - but, as above, if it were a butt hinge, or anything like it, there would be no option to add holes which were significantly further from the hinge's pin than are the existing ones.

I think the bolting though approach is good

I've always been intending to do that, whatever arrangement of hinges I decide upon - and I can't really see that nuts+bolts, with metal on both sides (hinge one side, plate the other side) would ever pull out. As I recently wrote, if anything 'happened', it would presumably be damage to, or destruction of, the hinge, not the fasteners 'coming out'.

Kind Regards, John

 

[JohnW2]

OK, I've been thinking and playing over the weekend. I suspect that I'm probably 'over-thinking' a lot of this, in that many of the approaches we've been discussing would probably be OK, at least in the medium-term (and, at my age, I'm not too concerned about achieving something which will last for ('further') 'decades'!).

As a bit more background, I've been thinking about the weight of the lid, which I don't think is all that high. It's about 1,200 x 800 mm. From recollection (I'm currently ~100 miles from it), the frame of the lid is made of something like 45 x 75mm timber, with a skirt of about 100mm x 20mm down each side and a covering about about 9mm (maybe thinner) something (I think plywood). On that basis, some very rough calculations suggest that it probably weighs no more than about 15kg at most - maybe about half the weight of a solid wood exterior door. I'm probably going to make a new lid, anyway, so could theoretically probably make it a bit lighter - but I presume it would not be a good idea to make it 'too light' (quite apart from the fact that 'lighter' would probably mean 'more flimsy')?

The more I've thought about it, the more I've come to the conclusion that the 'width' of the leaves of the hinges are one of the most important considerations, with any of the approaches, including the 'wooden triangle' one. With anything like standard butt hinges (at least as bad with the cranked 'storm proof' ones, the fixing holes are far to close to the hinge pin, because that would result in the fixings (be they screws or bolts) being perilously close to the edge of the lid (or even the 'wooden triangle', albeit the fixings could go beyond that.

I therefore think that I need to be using hinges which have much wider leaves than butt hinges - maybe parliament ones, like the one I experimented with, or maybe even modified 'tee' hinges (although they usually only have one {very} wide leaf). In fact, that may almost answer my implicit question, since (whether I use my approach, bending the hinge, or robin's approach with the 'triangle of wood'), parliament hinges, like the one I've used, are about the only readily-available hinges of which I am aware which are relatively sturdy and have two 'wide leaves'.

Many thanks to all of you who have contributed thoughts. Any further thoughts/suggestions?

Kind Regards, John

 

[robinbanks]

Just a couple of things; If redesigning the lid I dare say you could do something to keep the hinges out of the elements

And b) I don't know what the insulation arrangements re below the lid (maybe it's in a cold roof) but it could be a good opportunity to add any necessary draft excluder and insulation

 

[JohnW2]

Just a couple of things; If redesigning the lid I dare say you could do something to keep the hinges out of the elements

That has been one of my primary thoughts/concerns throughout, and really one of the main reasons why I asked here about any clever ideas regarding the hinging.

As far as I can see, if one uses fairly 'conventional' hinges of any sort (as is the case with both 'your' and 'my' suggested approaches) the geometrical considerations dictate that at least the knuckle of the hinge (if not also one leaf) has to be 'on the outside' of the lid, and hence potentially very exposed. About the only thing I can think of in such a situation is to 'drape' a piece of roofing rubber over the hinges (which would therefore 'fold' when the hatch was opened) to at least reduce the 'direct exposure' to the elements. Do you have any other ideas?

The ideal would, I suppose, be the big brother of the (geometrically) 'clever' hinges one sees used on kitchen cabinet doors (probably involving levers/struts etc.), which enable the geometrical considerations to be satisfied with a hinge which is entirely inside the lid (hence not exposed at all), but I'm not aware of any such animal that would be man enough for this job?

And b) I don't know what the insulation arrangements re below the lid (maybe it's in a cold roof) but it could be a good opportunity to add any necessary draft excluder and insulation

I think that insulation of the lid/hatch is probably the least of my concerns, given the nature of the rest of the roof! The house was built in the 1870s, and the roof may well be the original. I've known the house since the 1960s, and am sure that nothing major has been done to the roof since then (other than repeated attention to minor 'leaks'!) - and very probably never.

As far as I can make out, there is no insulation at all, the roof just consisting of boards sitting on substantial ('ceiling') joists - without, I think (I need to check), even any insulation between boards and ceiling. However, I'll certainly be trying to do something about 'draft exclusion' and probably some token insulation of the lid, even if a bit moot in terms of the 'big picture'!

Do you agree with what I said in my last post that, if I am going to stick with 'fairly conventional' hinges (as per either of our suggested approaches) that parliament hinges (such as I have been playing with) are probably the only readily-available ones which would provide a reasonable distance from knuckle to fixings (on both leaves)?

One thing we haven't really discussed is that neither your approach nor mine is particularly 'irrevocable'- so that If I try one and the result seems 'iffy', I would have the option to change to the other.

Many thanks for your continuing valuable input!

Kind Regards, John

 

[robinbanks]

Do you have any other ideas?

Broadly similar to those doscussed; the bent hinge can be mounted on the dry side, as can a square batten and regular butt hinge amounting to more or less the same thing. A drip mould of eg rubber as you suggest will largely prevent water running down the angled section (which allows the lid to open beyond horizontal to rest on the flat roof) ..

I'm not aware of any such animal that would be man enough for this job?

Me neither, but I'm also struck that there are plenty of hinges in the world that are installed such that they're directly exposed to the elements; probably every outward opening patio or bifold door set you've ever seen has some/all hinges thus arranged, and in real harsh environments too

Agree on the parliament hinges for fixing opportunities in this configuration, and especially that if, post install, you come to think "that could do with a bit of reinforcement" with a parliament hinge you likely have the luxury of being able to drill another hole in the section towards the hinge pin and put another fixing in; can't really that with a butt hinge!

Indeed, each/all can be worked into the other, or hybridised; if you had a bent hinge and thought it needed more support, a triangle of wood below, or square of wood (or metal in either case) above and another fixing could increase the support. Even riveting on another L bracket the other side of the bend to make a T; all possible

Dare say you'll end up with something engineered to outlast the rest of the roof

 

[JohnW2]

Broadly similar to those doscussed; the bent hinge can be mounted on the dry side, as can a square batten and regular butt hinge amounting to more or less the same thing. A drip mould of eg rubber as you suggest will largely prevent water running down the angled section (which allows the lid to open beyond horizontal to rest on the flat roof) ..

Of course! I had completely overlooked the ('obvious'') fact that the need for 'slightly over 180°) could be addressed by just bevelling the bottom edge of the lid (with just a 'rectangular'; block between hinge and frame) - as they say, 'Simples' Many thanks!

Mind you, although there is no problem on the 'frame side', the situation on the lid side of the hinge underlines the need for a hinge (like a parliament one) with a pretty wide leaf. With a standard butt hinge (say a 4" one, with a leaf of about 25mm), not only would the fixings then be 'perilously close' to the edge of the lid, but the bevel would make that even worse, and the bevel would also frustrate attempts to improve the situation by using nut/bolt (rather than screw) fixings - since the situation would be something like this ....

.

However, my parliament hinge (which ha a leaf width of about 50mm - and larger are available) would allow much less iffy fixing, something like ...

Me neither, but I'm also struck that there are plenty of hinges in the world that are installed such that they're directly exposed to the elements; probably every outward opening patio or bifold door set you've ever seen has some/all hinges thus arranged, and in real harsh environments too

Indeed so. In fact, a lot of the parliament hinges I've been looking at are (non-stainless) steel, plated with chrome or brass (sometimes not plated at all) and most mention that a common use is for outward-opening patio/'French' doors, in which case a substantial amount of the hinge, including the knuckle+pin, would be very exposed to the elements. Mind you, I suppose they are likely to be opened much more often/ frequently than my roof hatch, hence less likely to 'seize up'.

Agree on the parliament hinges for fixing opportunities in this configuration, and especially that if, post install, you come to think "that could do with a bit of reinforcement" with a parliament hinge you likely have the luxury of being able to drill another hole in the section towards the hinge pin and put another fixing in; can't really that with a butt hinge!

Not just 'post-install'. If the installation method was such that the whole of the 'leaf' was in contact with timber, it was always my intention to drill at least a couple of extra holes, since there is a whole pile of metal just 'crying out' for extra holes ...

Indeed, each/all can be worked into the other, or hybridised; if you had a bent hinge and thought it needed more support, a triangle of wood below, or square of wood (or metal in either case) above and another fixing could increase the support. Even riveting on another L bracket the other side of the bend to make a T; all possible

Indeed, there are many additional bites of the cherry I could consider if it proved to be desirable.

Dare say you'll end up with something engineered to outlast the rest of the roof

I think that's probably inevitable (and, unfortunately, probably also 'outlast' me!), given that the entire roof is probably many decades past its 'sell-by' date!

Thanks again. You've given me lots of things, including some new ones, to think about.

Kind Regards, John

 

[JohnW2]

@robinbanks , I've been doing some more 'over-thinking', primarily on the basis of my (perhaps flawed!) 'intuition', albeit it is somewhat reminiscent of the many decades ago when I was doing A-Level and S-Level Applied Maths

It seems that there is a probably a trade-off to be had between the security of hinge fixings and the extent to which the hingers are exposed to the elements. In all of the below (for both our approaches) I am assuming the use of parliament hinges or suchlike, since the knuckle-fixing distance is frighteningly small for standard butt hinges.

It seems to me that the most potentially 'worrying' situation is when the lid is vertical (i.,e. opened 90°), since its entire weight is then being experienced, in one way or another, by the hinges and their fixings. The first pair of diagrams below show the situation, as I see it, with each iof our methods if one minimises the amount of the hinges which is exposed (i.e. by attaching the hinges to the inside of the lid). In that situation, their seems to be a degree of iffiness with both of our approaches, at least if one uses screw fixing, since the entire weight of the lid is trying to pull out the screws into the lid - particularly given that those screws will be short, since they are going into a bit of the lid which is only about 20mm tick, if that. That situation would be considerably improved if one used nuts/bolts, even more so if that was combined with a metal plate on the outside of the lid. There is really no problem with the fixing of the 'fixed' leaf of the hinges, even with screws, since there is at least 50mm of pretty solid wood for them to screw into.

Th second pair of diagrams below showed the situations when one attaches the leaves of the hinges to the outside of the lid (thereby making them more 'exposed') - mine using a 'bent hinge', and the nearest equivalent I can think of using your approach. Only my approach invokes the 'crowbar effect' which concerned you (which attempts to tear out the fixings of the 'fixed' leaf of the hinge). However, I don't think that, in itself, would be a problem, probably not even with screws (and particularly not with nut/bolt/plate). If anything happened as a result of that 'crowbar effect'. it would be an attempt to 'unbend' my hinge - but given how difficult it was to bend it when cold (even with energetic use of a large club hammer!), I doubt that would be an issue with a lid weighing under 20 kg.

However, even with screws, with neither of our methods is the weight of the lid trying to pull the screws out of the screws into the lid - which, to my mind, makes it the more 'attractive' of the two options, even though it leaves a lot more of the hinges potentially exposed (although, as discussed, that could be addressed to some extent by the use of 'flaps of rubber/whatever).

Any thoughts? Is my thinking reasonable (or 'all wrong'? )

Kind Regards, John

with

 

[robinbanks]

All reasonable, in my eyes. I favour the top two and improving the fix to the lid with a bolt-through approach. Also a drip mould (which could be the stainless plate the bolts go through) should be more enduring than rubber

 

[JohnW2]

All reasonable, in my eyes. I favour the top two and improving the fix to the lid with a bolt-through approach. Also a drip mould (which could be the stainless plate the bolts go through) should be more enduring than rubber

Yes, that all makes sense.

As I see it, the only real downside of the 'bottom two' (hinges on outside of lid) is that of reduced 'exposure to the elements', the 'upside' being that they probably are structurally advantageous. In view of that, my first reaction was to suggest (and start drawing) that one could address that by installing a 'cover' over the outer hinge leaf - which, if made of metal or plastic, could be very thin, "... and then covering all that with the rubber (or whatever) covering of the lid" - but, when I had drawn it, I realised that the (rigid) 'cover' was probably redundant, and that just the rubber/whatever would probably do. At the least, the rubber could dangle down below the hinge, but it's also possible that I could actually 'attach' it at the bottom, effectively totally enclosing the hinge within the rubber.

The diagrams below indicate what I'm talking about, with the (probably redundant) 'cover' (in blue below) still shown, both with and without the bottom of the rubber (in purple below) 'attached'.

Kind Regards, John