Exploding glass knobs

houseimprover

Being serious here but can someone explain the physics behind how an innate object can explode without the use of heat or being smashed with a larger object?

thanks

Valli

houseimprover wrote: »

Being serious here but can someone explain the physics behind how an innate object can explode without the use of heat or being smashed with a larger object?

thanks

While I haven't looked at the knobs in question earlier posts suggest that there are two screws, or metal rods, within the glass knobs. If, upon fitting, these became (even slightly) misaligned such that they were no longer COMPLETELY parallel along their entire length then stresses would build up inside the knobs, causing them to crack or shatter eventually.

tumbledowngirl

houseimprover wrote: »

Being serious here but can someone explain the physics behind how an innate object can explode without the use of heat or being smashed with a larger object?

thanks

When we first spoke to someone in the furniture department in store, she said that it was obvious they hadn't been tested adequately and suggested temperature variation as a possible reason.
I am in no way a scientist/physicist, so can't given an answer - all I can say is that we found the fixings still in the wardrobe drawer and the glass all over the carpet the morning after they were fitted.

tumbledowngirl

Valli wrote: »

While I haven't looked at the knobs in question earlier posts suggest that there are two screws, or metal rods, within the glass knobs. If, upon fitting, these became (even slightly) misaligned such that they were no longer COMPLETELY parallel along their entire length then stresses would build up inside the knobs, causing them to crack or shatter eventually.

Not quite - the knobs have one long screw fitting from front to back, that goes through a hole at the front of the knob and out through the back and into the furniture. On the remaining knobs, the holes appear to be pretty much aligned. However, looking at other knobs instore, there is a wide variation and some of the holes are way off.

mikb

houseimprover wrote: »

Being serious here but can someone explain the physics behind how an innate object can explode without the use of heat or being smashed with a larger object?

thanks

In the most fun way, as seen livening up physics demos ;-

http://en.wikipedia.org/wiki/Bologna_bottle

http://www.youtube.com/watch?v=6V2eCFsDkK0

http://www.youtube.com/watch?v=xe-f4gokRBs

Or more boring explanations

http://en.wikipedia.org/wiki/Spontaneous_glass_breakage

I'm not saying the OP did overtighten anything, but it's very easy for some people to "hand tighten" things to the point where tools are needed to reverse it

frugal_mike

mikb wrote: »

In the most fun way, as seen livening up physics demos ;-

http://en.wikipedia.org/wiki/Bologna_bottle

http://www.youtube.com/watch?v=6V2eCFsDkK0

http://www.youtube.com/watch?v=xe-f4gokRBs

Or more boring explanations

http://en.wikipedia.org/wiki/Spontaneous_glass_breakage

I'm not saying the OP did overtighten anything, but it's very easy for some people to "hand tighten" things to the point where tools are needed to reverse it

Thanks. I was trying to find a video on the Prince Rupert Drop to post here but I couldn't remember what it was called. I couldn't find the right search terms relating to glass breaking due to internal forces to find it!

tumbledowngirl

Thanks for your replies, guys.

Regarding the issue of hand tightening, all the knobs were fitted in the same way (a total of 16), which suggests that maybe the knobs that exploded had an inherent fault. There was no fitting instructions with the knobs, if that makes any difference.

Since this happened the day after delivery, ie within 6 months of purchase, is it not the case that M&S have to prove the knobs were perfect, rather than me having to prove they had a fault?

Also, if this is the case, is M&S then liable to repair/replace the damaged furniture, as consequential damage?