Em 26/7/2011 16:04, Oli Glaser escreveu:
> On 26/07/2011 18:54, Isaac Marino Bavaresco wrote:
>> There's a simpler one:
>>
>> Tie a cotton thread soaked in alcohol around the bottle (or lamp), set
>> fire to it and let it burn for some time. Before it extinguishes, dip
>> the bottle in cold water.
>>
>> The bottle will break instantly along the line defined by the cotton
>> thread. Use a thread of around 1mm diameter.
>>
>>
>> When I used this technique, the break line usually got a little skewed
>> at the knot (I think it burned hotter there because of the extra
>> concentration of alcohol). Otherwise the break line is very straight and
>> clean.
>>
>> Perhaps one can avoid the knot by using a thinner thread and wrapping it
>> twice around the bottle, twisting it around itself all the way.
>>
> Sounds like a good method - another idea is maybe (if doing this=20
> regularly) to avoid the knot/alcohol/flame you could replace the thread=20
> with something like nichrome wire and current source? Also you might=20
> have more control over the heat this way.


Again a problem may happen at the point where the knot would be, you
must leave a gap so the wire doesn't get shorted and it may cause a
defect also.

Isaac

--=20
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