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Bending aluminium
I want to make up some bent aluminium components.
The items will be 'U" shape brackets. I intend to start with aluminium strip that's about 250mm long and 50mm wide and then bend the last 50mm at each end to stand up at 90 deg. The thing I don't know is how thick can the strip be and still be sensibly bent without special tools ? For my purposes, the thicker the better as it needs to have holes tapped in it, but I still need to bend the stuff. I don't know exactly what grade it's going to be as it's just the ali strip I get from my ironmonger. As far as bending is concerned, I usually use an old Workmate with angle iron as jaw protectors/strengtheners. I mark the bend point, clamp it up, place a hardwood block against it and belt it with the hammer ( 2kg ish ). So my question is really three questions What's the thickest 50mm wide strip that I'm likely to successfully bend this way ? Is there a better way of doing it without buying special tools ? I assume that hot bending isn't appropriate for ali, neither is any form of heat softening or hardening a practical proposition. If all else fails, how much might I have to pay to get four items like that made for me in 6mm thick strip ? |
#3
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In article .com,
Roly wrote: I want to make up some bent aluminium components. The items will be 'U" shape brackets. I intend to start with aluminium strip that's about 250mm long and 50mm wide and then bend the last 50mm at each end to stand up at 90 deg. You might find you can get 'U' section ally near enough for what you need. And at 50mm wide, it wouldn't cost a fortune for offcuts. George King Metals in Colliers Wood would be my first call if you're anywhere close - they sell by weight and of course a cutting charge. The thing I don't know is how thick can the strip be and still be sensibly bent without special tools ? For my purposes, the thicker the better as it needs to have holes tapped in it, but I still need to bend the stuff. I don't know exactly what grade it's going to be as it's just the ali strip I get from my ironmonger. As far as bending is concerned, I usually use an old Workmate with angle iron as jaw protectors/strengtheners. I mark the bend point, clamp it up, place a hardwood block against it and belt it with the hammer ( 2kg ish ). So my question is really three questions What's the thickest 50mm wide strip that I'm likely to successfully bend this way ? Is there a better way of doing it without buying special tools ? I assume that hot bending isn't appropriate for ali, neither is any form of heat softening or hardening a practical proposition. Annealing ally is easy. Wipe it with soap - the sort you clean your face with - and heat it 'till the soap turns black. Then quench in water. If all else fails, how much might I have to pay to get four items like that made for me in 6mm thick strip ? I'd first try to find suitable U section extruded. It's a delight to work with. I use it for making up things that have to fit in a 19" bay, etc, and it comes in various heights. I've not needed anything 250mm high, but with a bit of luck... -- *Frankly, scallop, I don't give a clam Dave Plowman London SW To e-mail, change noise into sound. |
#4
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4mm would do, 6mm would be better. There's no significant load on the
threads, the threaded part just hold another minor part in place. Inserts would stick out the other side and I need the front & back to be flat so that it can slide into alternative fixing positions - where it's fastened by a bolt through a hole into something more solid. I don't have a heavy enough bench for a decent vice. I do have a tool for setting threaded inserts. I don't much like it as the inserts don't always bite very well and sometimes work loose enough to rotate in their hole. The tool looks much like the one you linked to. I get better results by doing what I previously used to do. Cinch nuts, a ball bearing and a hammer ! |
#5
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Dave Plowman said -
You might find you can get 'U' section ally near enough for what you need. I rather doubt it. The width needs to fit an existing part and it's not a convenient round figure either. Extrusions always seem to be whole inch or cm multiples. That's why I reckon I'll need to make something the right size. |
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#7
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Thanks to the two of you for the info about annealing and hardening.
I can remember doing that as a kid when I used to make model aircraft undercarts, but had long forgotten the details. But the aluminium I used to use was an alloy that's much stiffer than the aluminium I usually find in shops. Is there an easy ( and cheap ) source of an alloy that's more suitable than bog-standard soft ali ? |
#8
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On Mon, 04 Apr 2005 00:37:02 +0100, The Natural Philosopher
wrote: Heating and fast cooling re-hardens. Not on aluminium (or most non-ferrous metals, for that matter). Annealing of aluminium or copper is a different process from steel. For steel you're trying to change the crystal structure of the metal, either by heating it to a temperature where the desired structure is stable, then freezing it in place (hardening) or by slowly reducing it in temperature so that it can re-align to the structure that's stable at low temperatures (annealing). For aluminium (and pure unalloyed metals in general), you're just shaking the dislocations out of the crystal lattice and putting it back the way it was. |
#9
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"The Natural Philosopher" wrote in message ... wrote: .... Is there a better way of doing it without buying special tools ? I assume that hot bending isn't appropriate for ali, neither is any form of heat softening or hardening a practical proposition. Actually, they are. Heating and slow cooling anneals. Heating and fast cooling re-hardens.... It does, however, normally require a temperature controlled oven to do it in. For example, the annealing information I have for one fairly common free-machining age-hardening alloy is to hold at 410C for 2-3 hours, reduce at 10C per hour down to 260C, then air cool. Age hardening, for T4 temper is soak at 510C for 3 hours, then water quench. Hardening for optimum strength (T8 temper) requires 510C for an adequate time to heat the piece through, water quench, cold working to shape, then holding at 160C for 15 hours before air cooling. Colin Bignell |
#10
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"The Natural Philosopher" wrote in message ... I assume that hot bending isn't appropriate for ali, neither is any form of heat softening or hardening a practical proposition. Actually, they are. Heating and slow cooling anneals. Heating and fast cooling re-hardens. NONONO! Not with Al! Mary |
#11
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In article . com,
Roly wrote: You might find you can get 'U' section ally near enough for what you need. I rather doubt it. The width needs to fit an existing part and it's not a convenient round figure either. Extrusions always seem to be whole inch or cm multiples. That's why I reckon I'll need to make something the right size. Ah - right. Your original post suggested the size wasn't critical. -- *I used up all my sick days so I called in dead Dave Plowman London SW To e-mail, change noise into sound. |
#12
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In article ,
Andy Dingley writes: For aluminium (and pure unalloyed metals in general), you're just shaking the dislocations out of the crystal lattice and putting it back the way it was. I think you're describing work hardening. Annealing (heating) is the opposite, breaking the lattice up into small crystal domains with lots of dislocation boundaries so it bends more easily (at the more dislocation boundaries). -- Andrew Gabriel |
#13
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wrote in message oups.com... I want to make up some bent aluminium components. The items will be 'U" shape brackets. I intend to start with aluminium strip that's about 250mm long and 50mm wide and then bend the last 50mm at each end to stand up at 90 deg. The thing I don't know is how thick can the strip be and still be sensibly bent without special tools ? For my purposes, the thicker the better as it needs to have holes tapped in it, but I still need to bend the stuff. I don't know exactly what grade it's going to be as it's just the ali strip I get from my ironmonger. As far as bending is concerned, I usually use an old Workmate with angle iron as jaw protectors/strengtheners. I mark the bend point, clamp it up, place a hardwood block against it and belt it with the hammer ( 2kg ish ). So my question is really three questions What's the thickest 50mm wide strip that I'm likely to successfully bend this way ? Is there a better way of doing it without buying special tools ? I assume that hot bending isn't appropriate for ali, neither is any form of heat softening or hardening a practical proposition. If all else fails, how much might I have to pay to get four items like that made for me in 6mm thick strip ? Dave Plowmans method for Annealing is the way to go. "Annealing ally is easy. Wipe it with soap - the sort you clean your face with - and heat it 'till the soap turns black. Then quench in water." Baz |
#14
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Mary Fisher wrote:
"The Natural Philosopher" wrote in message ... I assume that hot bending isn't appropriate for ali, neither is any form of heat softening or hardening a practical proposition. Actually, they are. Heating and slow cooling anneals. Heating and fast cooling re-hardens. NONONO! Not with Al! Yes, with Al. Mary |
#15
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Baz wrote:
wrote in message oups.com... I want to make up some bent aluminium components. The items will be 'U" shape brackets. I intend to start with aluminium strip that's about 250mm long and 50mm wide and then bend the last 50mm at each end to stand up at 90 deg. The thing I don't know is how thick can the strip be and still be sensibly bent without special tools ? For my purposes, the thicker the better as it needs to have holes tapped in it, but I still need to bend the stuff. I don't know exactly what grade it's going to be as it's just the ali strip I get from my ironmonger. As far as bending is concerned, I usually use an old Workmate with angle iron as jaw protectors/strengtheners. I mark the bend point, clamp it up, place a hardwood block against it and belt it with the hammer ( 2kg ish ). So my question is really three questions What's the thickest 50mm wide strip that I'm likely to successfully bend this way ? Is there a better way of doing it without buying special tools ? I assume that hot bending isn't appropriate for ali, neither is any form of heat softening or hardening a practical proposition. If all else fails, how much might I have to pay to get four items like that made for me in 6mm thick strip ? Dave Plowmans method for Annealing is the way to go. "Annealing ally is easy. Wipe it with soap - the sort you clean your face with - and heat it 'till the soap turns black. Then quench in water." That's the one! Baz |
#16
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#17
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On Mon, 04 Apr 2005 11:30:47 +0100, The Natural Philosopher
wrote: Actually, they are. Heating and slow cooling anneals. Heating and fast cooling re-hardens. NONONO! Not with Al! Yes, with Al. Baz wrote (and you followed up): "Annealing ally is easy. Wipe it with soap - the sort you clean your face with - and heat it 'till the soap turns black. Then quench in water." That's the one! So which is it ? Does heating and quenching harden aluminium or soften it ? The answer is of course both. There _are_ quenching processes for aluminium that strengthen it, and coincidentally make it less ductile. They're not useful "hardening" processes though. If your bike frame is in 6065-T6 alloy, then that "T6" refers to just such a process. But for all practical home workshop processes, any heating of aluminium anneals, normalises and softens it - whether you quench it afterwards or not. |
#18
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"Mary Fisher" wrote in message . net... "The Natural Philosopher" wrote in message ... I assume that hot bending isn't appropriate for ali, neither is any form of heat softening or hardening a practical proposition. Actually, they are. Heating and slow cooling anneals. Heating and fast cooling re-hardens. NONONO! Not with Al! Yes, given the right alloy, equipment and procedures, (see my other post). It is not, however, a home project. Even with a professional metal workshop, I send the stuff away to a specialist heat treatment company. Colin Bignell |
#19
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"Baz" wrote in message ... .... Dave Plowmans method for Annealing is the way to go. "Annealing ally is easy. Wipe it with soap - the sort you clean your face with - and heat it 'till the soap turns black. Then quench in water." However, if you want to put a thread in annealed aluminium, use a three-lobe displacement tap, not a convential tap that cuts the threads. Three-lobe taps work harden the material locally, making the thread stronger than if you cut it. Colin Bignell |
#20
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In article .com,
wrote: As far as bending is concerned, I usually use an old Workmate with angle iron as jaw protectors/strengtheners. I mark the bend point, clamp it up, place a hardwood block against it and belt it with the hammer ( 2kg ish ). [snip] What's the thickest 50mm wide strip that I'm likely to successfully bend this way ? The Radiospares 3mm 'bending grade' soft aluminium sheet would bend ok, but with a small amount of crystallisation on the outer of the bend. Trouble is, a thread in soft aluminium would not be very strong. Perhaps consider using self tappers. -- Tony Williams. |
#21
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#22
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