RMweb Premium mezzoman253 Posted October 3, 2015 RMweb Premium Share Posted October 3, 2015 Hi, I've got a piece of flat 3mm thick ali' strip, 30mm wide by 200mm long. I need to bend it to form a shape like a handle. Like this, but obviously right angles! I've got a bench vice, but I'm looking for any advice on how to bend it to keep it square and keep the dimensions. Any tips gratefully received. Rob Link to post Share on other sites More sharing options...
Rabs Posted October 3, 2015 Share Posted October 3, 2015 How accurate do you need the 100mm length to be? If you can tolerate +/- 1mm or so then the simplest method is to place the part in the vice with the nominal bend line sitting about 1/2 the material thickness above the jaws. Then place a piece of hardwood or plywood in front of the protruding length and either push this wooden part by hand or use a soft mallet: http://www.bbc.co.uk/schools/gcsebitesize/design/resistantmaterials/processtechniquesrev6.shtml If you need more precision then I think you'd need to invest in something like one of these: https://www.machinemart.co.uk/shop/product/details/cmf24-sheet-metal-folder or these http://www.warco.co.uk/box-pan-folders-sheet-metal-machinery-benders/89-vice-brake-adjustable-jaw-benders.html but that seems OTT if you only have one job for them If the aluminium cracks or splits when you try to bend it you have two options. One is to heat it with a blowtorch before trying to bend it. The other is to put a round bar on one of the vice jaws so that the metal is bent around the bar when you fold it. This keeps the bend radius to the size of the bar rather than forming a sharp corner. Link to post Share on other sites More sharing options...
34theletterbetweenB&D Posted October 3, 2015 Share Posted October 3, 2015 Supplementary to Rabs' advice: this is 'suck it and see' territory, is the alloy you have able to bend to this extent while remaining strong enough for purpose? Do you have some surplus material to try forming the bends to get the hang of how the bend position, squareness, and end dimensions come out; and on which formed bends you can then do a strength test to see if it will stand up to the intended use? Duty of care; is there any safety issue if what you make subsequently breaks? The tricky element is the 10mm between bends dimension. It may be best to start the bend adjacent the 100mm end taking it to 45 degrees, then form the end bend fully, then complete the first bend. I'd not try the blowtorch heating myself! It'll quite probably go from stiff to a pasty oxidised mess very easily. Link to post Share on other sites More sharing options...
JeffP Posted October 3, 2015 Share Posted October 3, 2015 Use a longer piece and cut off for the 10 mm..better to waste a bit than the whole lot. Link to post Share on other sites More sharing options...
RMweb Premium dhjgreen Posted October 3, 2015 RMweb Premium Share Posted October 3, 2015 To anneal rub with toilet soap, heat with wide spread blow torch; when the film turns brown, it is hot enough, then quench in water. (Try a small sample first, it is 50 years since I last did this!!!) Link to post Share on other sites More sharing options...
RMweb Premium mezzoman253 Posted October 3, 2015 Author RMweb Premium Share Posted October 3, 2015 Hi, The piece I have is the only piece, so I don't want to mess it up. Hence asking questions first. The 100mm length is not absolute, but needs to be fairly close. The short ends need to fit in a space between to protrusions on the back panel of a radio. There are no safety implications to its use after forming. When I've done it I'll post a picture for you. It'll be next week though. Thanks for all the advice. Rob Link to post Share on other sites More sharing options...
PenrithBeacon Posted October 3, 2015 Share Posted October 3, 2015 Most grades of aluminium shrink when being bent but some get longer. This would very noticeable with 3mm thick material. I think I'd prefer to buy a proprietary handle. Link to post Share on other sites More sharing options...
RMweb Premium mezzoman253 Posted October 4, 2015 Author RMweb Premium Share Posted October 4, 2015 Most grades of aluminium shrink when being bent but some get longer. This would very noticeable with 3mm thick material. I think I'd prefer to buy a proprietary handle. Hi, This is a custom fit and the 100mm flat will carry 4 connectors for the antenna sockets. So finding a suitable handle would be difficult, but not impossible. It may come to that if I can't get this to work. Thanks for the suggestion, I hadn't considered a handle, but it could work. Rob Link to post Share on other sites More sharing options...
Middlesea John Posted October 4, 2015 Share Posted October 4, 2015 It will depend what alloy of aluminium it is. Some alloys are designed intentionally not to bend and if you apply a lot of pressure they will snap with painful and/or costly consequences. Link to post Share on other sites More sharing options...
RMweb Premium mezzoman253 Posted October 4, 2015 Author RMweb Premium Share Posted October 4, 2015 It will depend what alloy of aluminium it is. Some alloys are designed intentionally not to bend and if you apply a lot of pressure they will snap with painful and/or costly consequences. Hi, This is the description from eBay "Aluminium Flat Bar, Alloy 6082T6, 3mm thick". A Google turned up this http://www.aalco.co.uk/datasheets/Aluminium-Alloy_6082-T6~T651_148.ashx Rob Link to post Share on other sites More sharing options...
RMweb Gold 57xx Posted October 4, 2015 RMweb Gold Share Posted October 4, 2015 I'd not try the blowtorch heating myself! It'll quite probably go from stiff to a pasty oxidised mess very easily. You would need a very powerful "blow torch" or be very cack-handed to do that! To anneal rub with toilet soap, heat with wide spread blow torch; when the film turns brown, it is hot enough, then quench in water. (Try a small sample first, it is 50 years since I last did this!!!) This is the way I was taught to do it in school metalwork classes too. Cold bending ally can fatigue and crack it if you make the bends too sharp so make sure if you do go the cold forming route to make the corners at least 4 x thickness in radius. Annoyingly they don't have the bend radius for T6 temper on that chart but it will be similar to T4. Link to post Share on other sites More sharing options...
RMweb Premium mezzoman253 Posted October 5, 2015 Author RMweb Premium Share Posted October 5, 2015 Hi, Had a rethink on this after looking at the back of the radio. I think I can use existing holes to support the aluminium without all those bends, allowing me to bend only once, possibly twice. That would stop the need to do the short end bends. Watch this space. Rob Link to post Share on other sites More sharing options...
34theletterbetweenB&D Posted October 5, 2015 Share Posted October 5, 2015 You would need a very powerful "blow torch" or be very cack-handed to do that! ... Never underestimate what members of the awkward squad such as myself can do. I was carelessly confusing a butane torch with a blow torch admittedly (evidence of being prone to error, exhibit one) , but have found it all too easy to make copper go runny with one of those. Link to post Share on other sites More sharing options...
RMweb Premium Siberian Snooper Posted October 5, 2015 RMweb Premium Share Posted October 5, 2015 For better accuracy at the bends, if the line is on the inside of the bend subtract 1/2 the thickness of the metal before marking it, on the other hand if the line is on the outside add 1/2 the thickness of the metal. So taking the 100mm if you mark it at that and bend on the lines you will be 3mm to big or small depending which way you bend the metal. If the lines are on the inside mark them at 97mm, if on the outside at 103mm. Then mark the 35mm lines these will be 33.5mm inside or 36.5 outside etc. Etc. And as others have said anneal the ally first otherwise it will crack, been there and done it more than once trying to cut corners. Link to post Share on other sites More sharing options...
RMweb Premium dhjgreen Posted October 5, 2015 RMweb Premium Share Posted October 5, 2015 Hi, Had a rethink on this after looking at the back of the radio. I think I can use existing holes to support the aluminium without all those bends, allowing me to bend only once, possibly twice. That would stop the need to do the short end bends. Watch this space. Rob Rob, With this description 6082 is typically used in: ~ Highly stressed applications ~ Trusses ~ Bridges ~ Cranes ~ Transport applications ~ Ore skips ~ Beer barrels ~ Milk churns I personally would not try to bend it even after annealing. I would definitely expect it to crack without annealing. Link to post Share on other sites More sharing options...
Jeff Smith Posted October 5, 2015 Share Posted October 5, 2015 What is the actual purpose of this bracket? Is it just to house antenna sockets? Will you be drilling holes? Will it be carrying much load, could a thinner material do the same job, say 1mm? Do the corners have to be right angles or would say a 5mm corner radius be ok? Its a long time since I did any aluminium bending but larger radii are a lot easier and less likely to crack, you just have to allow for the bend radii to get the required 100mm length after bending... Link to post Share on other sites More sharing options...
RMweb Premium mezzoman253 Posted October 5, 2015 Author RMweb Premium Share Posted October 5, 2015 Hi, Bracket will carry large sockets for antenna connectors only, nothing else. See link for connector type. http://www.ebay.co.uk/itm/120837359795?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT There will be larger holes to take the connectors and smaller ones to fix those to the ali''. The connectors have 25mm flanges with 4 holes, at 18mm centres, for the fixing of same. The load is the plug and cable for 2 of those connectors, the other 2 aren't used unless the sockets are connected in pairs with small jumper cables. I think 1mm would be too thin, perhaps 2mm would work. Corners don't have to be right angles, but it would be preferable, as to get 4 connectors in the space available would be tight. Thanks for the interest. Rob Link to post Share on other sites More sharing options...
RMweb Premium mezzoman253 Posted November 16, 2015 Author RMweb Premium Share Posted November 16, 2015 Update on this. I decided that the bending would be too complex for me with simple tools, so had a rethink and came up with a plate supported by two pieces of the bar I'd got already. One on the right and one below. The holes will take 4 "N" type connectors, similar to the connector on the top RHS of the transceiver. This will enable splitting of the transmit and receive paths, and, by two jumper cables across the connectors, enable straight through working should I need to revert. The connectors are in 2 pairs, one pair each for the 144 & 432MHz bands. The plate is very sturdy and utilises some mounting threads on the rig. So no alterations were need to the chassis. Ideally the frame could be cut and bent from one piece of plate, but as a one off this seems OK. Rob Link to post Share on other sites More sharing options...
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