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#1
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Thermal expansion question
I have a question for any pipe smokers in the group. It is often
claimed that too much carbon build up inside the pipe bowl--the cake--can cause the bowl to crack. It seems to me the only way this could happen is if the thermal expansion of carbon is significantly greater than that of briar wood. Can anyone confirm or deny this? Bradley |
#2
Posted to rec.woodworking
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Thermal expansion question
wrote in message oups.com... I have a question for any pipe smokers in the group. It is often claimed that too much carbon build up inside the pipe bowl--the cake--can cause the bowl to crack. It seems to me the only way this could happen is if the thermal expansion of carbon is significantly greater than that of briar wood. Can anyone confirm or deny this? I've not smoke a pipe for over 30 years now; but I never heard of that being a problem. I never let the cake build up all that much either I guess. Anything is possible, but in reality, wouldn't the cake also expand to the center of the bowl and relives some of the stress if it did expand more than the bowl? |
#3
Posted to rec.woodworking
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Thermal expansion question
"Edwin Pawlowski" writes:
[...] guess. Anything is possible, but in reality, wouldn't the cake also expand to the center of the bowl and relives some of the stress if it did expand more than the bowl? No. If that were the case wood when shrinking would not develop cracks but compression zones... -- Dr. Juergen Hannappel http://lisa2.physik.uni-bonn.de/~hannappe Phone: +49 228 73 2447 FAX ... 7869 Physikalisches Institut der Uni Bonn Nussallee 12, D-53115 Bonn, Germany CERN: Phone: +412276 76461 Fax: ..77930 Bat. 892-R-A13 CH-1211 Geneve 23 |
#4
Posted to rec.woodworking
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Thermal expansion question
wrote in message oups.com... I have a question for any pipe smokers in the group. It is often claimed that too much carbon build up inside the pipe bowl--the cake--can cause the bowl to crack. It seems to me the only way this could happen is if the thermal expansion of carbon is significantly greater than that of briar wood. Can anyone confirm or deny this? The "cake," so far as I recall, was unburned tobacco residue. The briar merely charred on breaking in, thereafter the burning tobacco was contained within the "cake," which was periodically thinned to maintain capacity and avoid the taste of partially burned tars. Also, in spite of assertions otherwise, expansion takes place in the direction of least resistance. If the coefficient of expansion were radically different, the "cake" would flake off on its own. |
#6
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Thermal expansion question
Juergen Hannappel wrote:
"Edwin Pawlowski" writes: [...] guess. Anything is possible, but in reality, wouldn't the cake also expand to the center of the bowl and relives some of the stress if it did expand more than the bowl? No. If that were the case wood when shrinking would not develop cracks but compression zones... Everyone know that a disk expands. A hole in a sheet expands just like the disk does. At the molecular or atomic level the reason for the whole expansion is also clear. |
#7
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Thermal expansion question
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#8
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Thermal expansion question
If heat is the primary culprit, then an uncaked bowl would be much more
likely to crack than a bowl lined with a carbon cake since the cake provides insulation. But in a bowl without cake, burnout will occur before cracking. The specific claim I am questioning is that a thick cake is a cause of cracking a bowl. I'm not sure I understand your claim that given equal coffecients of expansion the higher temperature of carbon along with lack of resilience could cause a crack in the bowl. Are you saying that the heat is what causes the crack and not the thickness of the carbon? Bradley |
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