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UK diy (uk.d-i-y) For the discussion of all topics related to diy (do-it-yourself) in the UK. All levels of experience and proficency are welcome to join in to ask questions or offer solutions. |
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#1
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Hot or cold for expansion ?
I'm making a 50mm long aluminium sleeve for a 12mm steel shaft; it is
just a support sleeve, no rotary motion. I've reamed the Al. out to the 12mm required and tried fitting the steel shaft. It went in fine, but I suspect it's picked up a little flake of the Al as I went to withdraw it and has stuck fast. Do I heat it to assist removal or deep-freeze it ? The second bush is fine with the same reamer setting, but I made sure there was no debris lying around on the trial fit with an identical bit of steel. Thanks Rob |
#2
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Hot or cold for expansion ?
On Sun, 16 May 2010 06:04:18 -0700 (PDT), robgraham wrote:
Do I heat it to assist removal or deep-freeze it ? Google is your friend: "coefficient of expansion metal*" First hit: http://en.wikipedia.org/wiki/Coeffic...rmal_expansion I'll leave the drawing of the answer as a excercise for the OP. -- Cheers Dave. |
#3
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Hot or cold for expansion ?
"robgraham" wrote in message ... I'm making a 50mm long aluminium sleeve for a 12mm steel shaft; it is just a support sleeve, no rotary motion. I've reamed the Al. out to the 12mm required and tried fitting the steel shaft. It went in fine, but I suspect it's picked up a little flake of the Al as I went to withdraw it and has stuck fast. Do I heat it to assist removal or deep-freeze it ? The second bush is fine with the same reamer setting, but I made sure there was no debris lying around on the trial fit with an identical bit of steel. Thanks Rob http://www.engineeringtoolbox.com/li...ents-d_95.html Looks like aluminium expands twice as much as steel, and as the ally is on the outside, you need to heat it. -- Graham. %Profound_observation% |
#4
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Hot or cold for expansion ?
On 16/05/2010 14:04, robgraham wrote:
I'm making a 50mm long aluminium sleeve for a 12mm steel shaft; it is just a support sleeve, no rotary motion. I've reamed the Al. out to the 12mm required and tried fitting the steel shaft. It went in fine, but I suspect it's picked up a little flake of the Al as I went to withdraw it and has stuck fast. Do I heat it to assist removal or deep-freeze it ? The second bush is fine with the same reamer setting, but I made sure there was no debris lying around on the trial fit with an identical bit of steel. Thanks Rob Don't forget that bimetallic corrosion may occur especially in damp/wet conditions, the results may cause the two metals to corrode and seize up. Don |
#5
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Hot or cold for expansion ?
Unless you've got CO2 or N2 freezing gear, you're only going to get a
20 degree difference by cooling. With boiling water, hot air gun, or a blowtorch - you can easily get much larger temp differences. |
#6
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Hot or cold for expansion ?
On 16 May, 18:19, " wrote:
Unless you've got CO2 or N2 freezing gear, you're only going to get a 20 degree difference by cooling. With boiling water, hot air gun, or a blowtorch - you can easily get much larger temp differences. Thanks guys - I'm afraid the quick answer was I just took a biggish punch and drove it out. And yes, there was Al smeared on the steel and had to be file off. I suppose I should have remembered that Al has the larger Cf of Expansion and just plunged it into some boiling water. Rob |
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