Sash weights

[chris lewis joinery]

Hi guys

I've just made some sliding sash windows and wondered which weights to use lead or steel ,obviously lead is heavier but steel is cheaper. Which ones do you guys prefer?
Cheers Chris

 

[adzeman]

I would use steel from an arcitectural salvager

 

[G S Haydon]

Hello Chris,

Old steel and then add lead makeweight as needed. If there's not much space in the box and a heavy sash then lead sounds good.

 

[Jacob]

I used to recycle old cast iron ones but if caught short I'd cast my own from scrap lead. Quite easy to do with a sand mould in box - builders soft sand will do.

 

[RogerS]

Depends on how much weight you need. Double glazed units require a LOT more weight. And what the maximum length of sash weight you can accommodate also affects the choice.

And also the dimension...TBH if you've made your sash already then you've possibly boxed yourself into a corner if you've not made the pocket pieced wide enough!

 

[Bradshaw Joinery]

if you have a 50mm box for the weights, generally, (Unless the sashes are abnormally wider than high) steel weights will work.
Try the mighton calculator.

The disadavntage is you need a long pocket to get the weight into the box compared to lead.

 

[Eric The Viking]

As RogerS says: width to height ratio is important: if it's wider than tall, you may have to use lead otherwise you won't have the space (the weight may end up too tall for the weight box). Let's see:

Density of lead: 11.342 grams per cm^3 (approx 88cc/kg)
Density of iron: 7.874 grams per cm^3 (approx 127cc/kg) (source)
Steel will be slightly lighter because of the carbon content.

Weigh the sash (the glass is significant, more so if DG) and divide by two to get an idea of how big the weights need to be.

HTH,

E.

PS: If you're going for balancing perfection, you can use penny washers to fine tune the weight (and small lead/iron weights are available for builders' merchants), BUT, once balanced, tie them together with some copper wire looped through the middle (steel garden wire rusts through!). Otherwise if the cord breaks they'll go everywhere.

If I'm on my own, I use small wooden wedges (rounded over, not squared-off) to jam the cord and pulley each side with the weight at the top of the box (wedge into the pulley over the top of the cord), so I can fit the cord to the side of the sash.

For each sash, I mark the tensioned cord with the position on the exit of the pulley with the weight just touching the bottom of the box and subtract about 1". This gives the max. length of cord (at the point the pulley stops on the side of the sash when at the top). The cords stretch, and it usually stops the weights bottoming (most annoying with the outer sash). I haven't done one for a while now (present house is all casement), but last time I used it the artificial cord (Nylon?) stretched quite a bit more than the traditional stuff.

PPS: In the past I've used laminated glass in ground floor windows (inner sash only), with some success. It's heavier than standard, but nothing like as bad as DG, and is a slightly better insulator (read "slightly worse conductor of heat!"). We had burglar problems in the area at the time, and thin DG units weren't available to me. I know the rules are tricky now, but it might be a last resort (although if you've already made the sash...).

 

[Jacob]

....
Weigh the sash (the glass is significant, more so if DG) and divide by two to get an idea of how big the weights need to be.
....

Ideally the top sash weights should be slightly heavier than the sash (to keep it up) and the bottom lighter so that it stays down. 10% ish. They'll stay in an open position but vibration etc might make them move so it's best for them to move to close.

 

[Eric The Viking]

....
Weigh the sash (the glass is significant, more so if DG) and divide by two to get an idea of how big the weights need to be.
....

Ideally the top sash weights should be slightly heavier than the sash (to keep it up) and the bottom lighter so that it stays down. 10% ish. They'll stay in an open position but vibration etc might make them move so it's best for them to move to close.

I agree, up to a point. That being having to re-glaze panes in big Georgian sashes* because they came down too fast (DAMHIK). Very slight bias on the upper sash, possibly, but I think heavy inner ones are a health hazard, especially for anyone thinning on top!

E.

*Glass is technically liquid, and does flow under gravity over a long time. Old sashes have significantly thinner glass at the top of each pane, and if the putty has gone rock hard it can also be under a bit of tension too, like stretched toffee.

 

[Racers]

Hi Eric

I believe that the liquid glass theory has been disproved http://dwb.unl.edu/Teacher/NSF/C01/C01L ... lorin.html

Pete

 

[RogerS]

Hi Eric

I believe that the liquid glass theory has been disproved http://dwb.unl.edu/Teacher/NSF/C01/C01L ... lorin.html

Pete

That's a shame as Iain Banks RIP used this as an analogy for the longevity of one his characters !

 

[bugbear]

I used to recycle old cast iron ones...

Pedantically that's "reuse" not "recycle". To be clear, reuse is better - less energy used. Your lead was recycled.

(hence the slogan "reduce, reuse, recycle")

BugBear (not criticising)

 

[Eric The Viking]

Hi Eric

I believe that the liquid glass theory has been disproved http://dwb.unl.edu/Teacher/NSF/C01/C01L ... lorin.html

Pete

Fascinating. I *think* I remember being taught it at school (in the context of real supercooled liquids), however it might just have accreted in the brain some time ago. And of course, once one accepts that it isn't (a supercooled liquid), one has an explanation for why things like ancient Roman and Greek glass artefacts haven't sagged in the two thousand years or so that they've been in existence!

Still, I have encountered old glass that's definitely not consistent thickness. It may just be that the original glazier thought putting thinner at the top was the best approach for some reason or other. AND it's still bloomin' annoying to be tapping the stop bead back round a fairly hefty sash when you hear a 'crack'.

But thanks - I've learned something really interesting this morning (should be doing CSS, far more boring!).

E.

 

[Jacob]

....

*Glass is technically liquid, and does flow under gravity over a long time. Old sashes have significantly thinner glass at the top of each pane,

That's because they put them in that way, and stained glass too, usually. I've looked at tons of the stuff over the years. I've got some beautiful scraps of georgian crown glass on the window cill in front of me - perfect as they day they were spun, 200 years ago perhaps.

 

[Jacob]

I used to recycle old cast iron ones...

Pedantically that's "reuse" not "recycle". To be clear, reuse is better - less energy used. Your lead was recycled.

(hence the slogan "reduce, reuse, recycle")

BugBear (not criticising)

Can you please stop trolling after me. If you haven't anything interesting to say better to say nothing.

 

[Eric The Viking]

....

*Glass is technically liquid, and does flow under gravity over a long time. Old sashes have significantly thinner glass at the top of each pane,

That's because they put them in that way, and stained glass too, usually. I've looked at tons of the stuff over the years. I've got some beautiful scraps of Georgian crown glass on the window cill in front of me - perfect as they day they were spun, 200 years ago perhaps.

I've met Americans who didn't realise the panes with nodules on them (and bubbles in them) were the cheap stuff.
They thought it was done to look pretty!

E.

 

[Jacob]

.......
If I'm on my own, I use small wooden wedges (rounded over, not squared-off) to jam the cord and pulley each side with the weight at the top of the box (wedge into the pulley over the top of the cord), so I can fit the cord to the side of the sash. .....

The way to do it is the "cats cradle" - with a mouse you pull the cord through all 4 pulleys and pockets in one piece so it crisscrosses over. Then tie on a weight - pull it up with its cord to where you want to cut and cut it. Then next weight on this cut end and ditto, You end up with 4 weights sitting on the bottom of the box with exactly the right length of cord coming from each pulley if you have done it right, with no wasted offcuts.

 

[Eric The Viking]

I can see how that works, but attaching the cords to the sashes is still "entertaining" with no slack.