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Getting stuck aluminium collar off a steel shaft
I have a small fan motor that I need to replace, the fan is mounted on
an aluminium (I think) collar which is siezed on the shaft. So, what's a good approach to getting it unstuck? I've drilled out most of the grub screw that should be holding it, I doubt that's the issue now. It's just that the collar is very firmly stuck on the shaft. There's lots of "how to get steel studs out of aluminium cylinder blocks" advice I can find on the web but my problem is the other way around. Is there anything in particular that might help apart from all the usual things like soaking in penetrating oil, bashing it, etc.? It's quite small, the shaft is about 7mm (possibly 1/4") diameter. The end protrudes only 1cm or so beyond the fan, I can hold it in a vice quite firmly but the fan is quite flimsy so brute force rotation of that is rather difficult. -- Chris Green · |
Getting stuck aluminium collar off a steel shaft
On 29/11/2019 13:07, Chris Green wrote:
I have a small fan motor that I need to replace, the fan is mounted on an aluminium (I think) collar which is siezed on the shaft. So, what's a good approach to getting it unstuck? I've drilled out most of the grub screw that should be holding it, I doubt that's the issue now. It's just that the collar is very firmly stuck on the shaft. There's lots of "how to get steel studs out of aluminium cylinder blocks" advice I can find on the web but my problem is the other way around. Is there anything in particular that might help apart from all the usual things like soaking in penetrating oil, bashing it, etc.? Heat will do it. Also, try knocking the collar down the shaft a short way (perhaps with a suitable "socket" or box spanner) It's quite small, the shaft is about 7mm (possibly 1/4") diameter. The end protrudes only 1cm or so beyond the fan, I can hold it in a vice quite firmly but the fan is quite flimsy so brute force rotation of that is rather difficult. |
Getting stuck aluminium collar off a steel shaft
On 29/11/2019 13:07, Chris Green wrote:
I have a small fan motor that I need to replace, the fan is mounted on an aluminium (I think) collar which is siezed on the shaft. So, what's a good approach to getting it unstuck? I've drilled out most of the grub screw that should be holding it, I doubt that's the issue now. It's just that the collar is very firmly stuck on the shaft. snip The coefficient of thermal expansion of Aluminium is about twice that of steel, so I'd try heating it. Aluminium conducts much better too. Hot oil might do it. Cheers -- Clive |
Getting stuck aluminium collar off a steel shaft
On 29/11/2019 13:27, Clive Arthur wrote:
On 29/11/2019 13:07, Chris Green wrote: I have a small fan motor that I need to replace, the fan is mounted on an aluminium (I think) collar which is siezed on the shaft. So, what's a good approach to getting it unstuck?* I've drilled out most of the grub screw that should be holding it, I doubt that's the issue now.* It's just that the collar is very firmly stuck on the shaft. snip The coefficient of thermal expansion of Aluminium is about twice that of steel, so I'd try heating it.* Aluminium conducts much better too. Hot oil might do it. Cheers +1 and a puller is handy. -- Progress is precisely that which rules and regulations did not foresee, Ludwig von Mises |
Getting stuck aluminium collar off a steel shaft
Clive Arthur wrote:
On 29/11/2019 13:07, Chris Green wrote: I have a small fan motor that I need to replace, the fan is mounted on an aluminium (I think) collar which is siezed on the shaft. So, what's a good approach to getting it unstuck? I've drilled out most of the grub screw that should be holding it, I doubt that's the issue now. It's just that the collar is very firmly stuck on the shaft. snip The coefficient of thermal expansion of Aluminium is about twice that of steel, so I'd try heating it. Aluminium conducts much better too. Hot oil might do it. Sounds a good approach, I'll get my (relatively) new gas blow torch onto the job. -- Chris Green · |
Getting stuck aluminium collar off a steel shaft
The Natural Philosopher wrote:
On 29/11/2019 13:27, Clive Arthur wrote: On 29/11/2019 13:07, Chris Green wrote: I have a small fan motor that I need to replace, the fan is mounted on an aluminium (I think) collar which is siezed on the shaft. So, what's a good approach to getting it unstuck?* I've drilled out most of the grub screw that should be holding it, I doubt that's the issue now.* It's just that the collar is very firmly stuck on the shaft. snip The coefficient of thermal expansion of Aluminium is about twice that of steel, so I'd try heating it.* Aluminium conducts much better too. Hot oil might do it. Cheers +1 and a puller is handy. There's really nothing to get hold of with a puller, the fan is in the way. -- Chris Green · |
Getting stuck aluminium collar off a steel shaft
"Brian Gaff \(Sofa 2\)" wrote:
Unless the fan itself is plastic, in which case it will be a mess. A bit of oil down the grub hole and either end, then gentle tapping of the spindle to see if it moves after a few hours. However if you have drilled the grub screw hole, how are you going to re attach the fan to a new motor? By drilling and tapping a new grub screw hole. :-) Or by cleaning out the existing one, I haven't drilled it out so far that the thread has gone, however I'm not sure I'll be able to clean out the remains of old grub screw. -- Chris Green · |
Getting stuck aluminium collar off a steel shaft
On 29/11/19 13:07, Chris Green wrote:
I have a small fan motor that I need to replace, the fan is mounted on an aluminium (I think) collar which is siezed on the shaft. So, what's a good approach to getting it unstuck? I've drilled out most of the grub screw that should be holding it, I doubt that's the issue now. It's just that the collar is very firmly stuck on the shaft. There's lots of "how to get steel studs out of aluminium cylinder blocks" advice I can find on the web but my problem is the other way around. Is there anything in particular that might help apart from all the usual things like soaking in penetrating oil, bashing it, etc.? It's quite small, the shaft is about 7mm (possibly 1/4") diameter. The end protrudes only 1cm or so beyond the fan, I can hold it in a vice quite firmly but the fan is quite flimsy so brute force rotation of that is rather difficult. If the other methods don't work, and the collar really is aluminium and the shaft steel, then immersing it in concentrated caustic soda will dissolve the aluminium and leave the steel untouched. It is unlikely that the plastic will be affected (unless it's polycarbonate or PETE, although these would be unlikely to be used as fan blades), but it might melt if the reaction gets too hot. A note of caution, however; it isn't called "caustic soda" for nothing. Eye protection is essential, and so are decent length gloves. -- Jeff |
Getting stuck aluminium collar off a steel shaft
On Fri, 29 Nov 2019 14:00:38 +0000, Chris Green wrote:
Sounds a good approach, I'll get my (relatively) new gas blow torch onto the job. Alternatively, use cold. There's a variety of "rust shock" sprays that combine oil and some gas that cools on contact. Even if the ally gets tighter on steel with cold, it may help as it may stretch, and then be looser as it warms up again, IYSWIM. And less chance of melting the nearby plastic... Thomas Prufer |
Getting stuck aluminium collar off a steel shaft
In article ,
Chris Green wrote: The coefficient of thermal expansion of Aluminium is about twice that of steel, so I'd try heating it. Aluminium conducts much better too. Hot oil might do it. Sounds a good approach, I'll get my (relatively) new gas blow torch onto the job. You could try putting the whole thing in boiling water first. That won't melt anything. ;-) -- *I used up all my sick days so I called in dead Dave Plowman London SW To e-mail, change noise into sound. |
Getting stuck aluminium collar off a steel shaft
On 29/11/2019 13:07, Chris Green wrote:
I have a small fan motor that I need to replace, the fan is mounted on an aluminium (I think) collar which is siezed on the shaft. So, what's a good approach to getting it unstuck? I've drilled out most of the grub screw that should be holding it, I doubt that's the issue now. It's just that the collar is very firmly stuck on the shaft. There's lots of "how to get steel studs out of aluminium cylinder blocks" advice I can find on the web but my problem is the other way around. Is there anything in particular that might help apart from all the usual things like soaking in penetrating oil, bashing it, etc.? It's quite small, the shaft is about 7mm (possibly 1/4") diameter. The end protrudes only 1cm or so beyond the fan, I can hold it in a vice quite firmly but the fan is quite flimsy so brute force rotation of that is rather difficult. Steel on aluminium can be a bugger. If the motor is dead, I'd be inclined to destroy the motor in an attempt to save the fan. Angle grinder, dremel, etc. depending on the size. Once you have the fan with just an inch of motor spindle it becomes comparatively easy, I'd start by removing the grub screw, soaking the lot in penetrating fluid of your preference, and then finding suitable spacers to let you push the spindle out in a press, or a pillar drill, or a vice. Once it has moved a bit it should be easier to remove e.g. with a mole wrench. |
Getting stuck aluminium collar off a steel shaft
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