Folding a 4mm aluminium bar - Page 1
Forum section: electronics / projects

author: akis
author_rank: Frequent Contributor
timestamp: October 15, 2015, 11:21:49 am
content: I have a 4mm thickness 40cm length 6 cm width aluminium bar which has a small curvature along its length and it is so robust I have been unable to bend it even slightly. In addition I would like to fold it at the two ends so as to create a bracket but obviously this is impossible with the tools I have at home. I have called a hardware store but they also did not have the tools. Would anyone have any ideas how to do this?

author: Magicmushroom666
author_rank: Contributor
timestamp: October 15, 2015, 11:40:07 am
content: You can clamp it in a vice, then hammer it into a bend where it meets the vice.

author: Richard Crowley
author_rank: Super Contributor
timestamp: October 15, 2015, 11:42:26 am
content: The "proper" way to bend sheet metal is to use a "brake".But using the vice and hammer method is what most of us do for casual metalwork.Note that some types of aluminum don't lend themselves well to bending, and will crack and break.

author: Fungus
author_rank: Super Contributor
timestamp: October 15, 2015, 11:45:06 am
content: Quote from: Magicmushroom666 on October 15, 2015, 11:40:07 amHeating with a blowtorch would help a little bit, presumably.Quote from: Richard Crowley on October 15, 2015, 11:42:26 amHeat would probably help with this, too.

author: hayatepilot
author_rank: Frequent Contributor
timestamp: October 15, 2015, 11:51:09 am
content: You need to find a company that can process sheet metal e.g. laser cutting, bending etc.They will have the bending machines and know how to bend it. If you ask nicely they will probably do it for a little tip.Maybe a friend or relative works in the metal industry and can help you.If you often need to bend things, maybe something like this would be appropriate:http://www.warco.co.uk/box-pan-folders-sheet-metal-machinery-benders/89-vice-brake-adjustable-jaw-benders.htmlGreetings

author: madires
author_rank: Super Contributor
timestamp: October 15, 2015, 12:07:55 pm
content: I'd look for a company with a CNC folding machine. 2mm or 2.5mm is doable at home, but 4mm is a little bit too much.

author: GNU_Ninja
author_rank: Regular Contributor
timestamp: October 15, 2015, 12:10:16 pm
content: Read this ==>http://www.dbsheetmetals.co.uk/K%20Factors%20+%20Bending%20Info.pdfGood luck

author: KJDS
author_rank: Super Contributor
timestamp: October 15, 2015, 12:19:22 pm
content: A fly press would work, just need to find one.

author: Fungus
author_rank: Super Contributor
timestamp: October 15, 2015, 12:27:10 pm
content: Quote from: hayatepilot on October 15, 2015, 11:51:09 amYep.If I had to do a McGyver job I'd be thinking about cutting a 'V' groove in a piece of wood, put the aluminium across the groove where you want to bend it, lay a six inch nail across the top of the groove, and ... hammer time!It'll bounce around a lot, sure, but eventually you'll get a straight crease with a rounded corner that doesn't fracture.Once you get a decent starting bend it's easy to continue by other means.(4mmisquite thick though... and aluminumdoescrack...)

author: Ian.M
author_rank: Super Contributor
timestamp: October 15, 2015, 12:29:20 pm
content: Aluminium is what's known to metal workers as 'hot short', which means it looses most of its strength when heated. Bending it while hot will not go well - it will probably crack and tear badly. However many Aluminium alloys can readily be bent cold after annealing. To anneal aluminium, streak it with a bar of white soap, then flame heat it till the soap browns to a light tan colour. Remove from the flame and allow to air cool. Once cold it should be dead soft and bendable. If not, try a water quench instead of air cooling.You get ONE shot at bending it per annealing - if you don't bend it far enough or bend it too far, it work hardens at the bend line and will be likely to kink next to it or crack if you try to adjust the bend. Once you have it bent (and you may need to anneal it again to get a tight bend), it will slowly age harden over the next few weeks or months but may never fully regain its original hardness. Expect to ruin a few pieces learning annealing + bending.Hardening is faster if heated to between 100 and 200 deg C for a period of several hours - small clean parts could possibly be hardened in a domestic oven, but if you are getting more complex than simple flame annealing followed by natural age hardening, you *REALLY* need to research aluminium alloy heat treatment processes and the specific times and temperatures for the exact alloy you are using.

author: Fungus
author_rank: Super Contributor
timestamp: October 15, 2015, 12:38:08 pm
content: How far do you want to bend it? 45 degrees? 90 degrees?90 degrees is going to be difficult.

author: akis
author_rank: Frequent Contributor
timestamp: October 15, 2015, 02:14:42 pm
content: I want it to be presicely 90 degrees. I cannot believe that pure Aluminium is so difficult to bend. In that case would stainless steel be easier to supply and bend? How about copper? Is 4mm copper easy to bend and is it strong enough?

author: Andy Watson
author_rank: Super Contributor
timestamp: October 15, 2015, 02:27:35 pm
content: It's the thickness that is the killer. Does it have to be 4mm?If you can't bend aluminium, stainless will be a non-starter.

author: KJDS
author_rank: Super Contributor
timestamp: October 15, 2015, 02:33:47 pm
content: The issue with bending isn't the angle but the internal radius. I suspect you'll struggle to have it less than the thickness, so 4mm material will need at least a 4mm internal radius.

author: Fungus
author_rank: Super Contributor
timestamp: October 15, 2015, 02:38:50 pm
content: Quote from: akis on October 15, 2015, 02:14:42 pmCopper is really easy.Strong enough for what??(How long is a piece of string?)

author: ONETEN
author_rank: Contributor
timestamp: October 15, 2015, 02:40:56 pm
content: This is something I have more experience in than electronics from years of building race carsYou say "bar" but what I think you mean is "tube". Bar is generally solid "bar", where as tube is obviously hollow.I think you have a snowballs chance of hand bending 4mm with diam of 60mm tube with hand tools! Your final center line radius will also need to be fairly generous depending on the angle you need to bend at to avoid crushing or stretching and ruining the tube.The only real way to bend aluminium of this size is with a mandrel bender, which is not something neighbor tom is likely to have in his shed. A press/brake is generally used more for sheet metal, not tube.You would be better off cutting the tube at 50% angle of the bend angle you wish to achieve and have it TIG welded back together. For example, cut at 45 degrees, rotate one end and weld back together to have a 90 degree.Also, Steel & stainless steel is significantly harder than Aluminium and you would have much less chance of bending that. The CAMS approved roll cage in my race car is CDS steel and 2mm thick, 50mm in diameter and they are proven to withstand bending and protect drivers in crashes at 250kmph!! If you watched bathurst last weekend, you would have seen this in action. You can imagine how futile it would be trying to bend tube like this with a vice or any hand tools.EDIT:After re-reading, I think I misunderstood and you meant flat bar? If so, this is much easier to bend than round bar/tube.I have bent it before in a serious bench vice giving it an almighty bashing with a 2kg mallet. I sometimes use it to make up brackets that are significantly weight bearing.

author: Fungus
author_rank: Super Contributor
timestamp: October 15, 2015, 02:41:57 pm
content: Quote from: akis on October 15, 2015, 02:14:42 pmQuote from: akis on October 15, 2015, 02:14:42 pmCopper is easy.Strong enough for what??(How long is a piece of string?)

author: Ian.M
author_rank: Super Contributor
timestamp: October 15, 2015, 02:45:45 pm
content: What makes you think its pure aluminium? If it was actually pure it would be soft enough to bend over your knee.A comparable size stainless bar will be far far harder to bend.Pure Copper will be very soft, even more so than annealed aluminium, but will work harden and is likely to require annealing to get a tight bend. Annealing copper is rather different from annealing aluminium, requires higher temperatures, and oxidisation is a significant problem. Copper alloys also tend to be hot short.

author: ONETEN
author_rank: Contributor
timestamp: October 15, 2015, 02:51:10 pm
content: Pure aluminium in 4mm thickness, 60mm wide and 400mm length will be very difficult to bend over a knee.Longer pieces would be a lot easier (1 meter or more) due to leverage, but they will always have a huge center line bend radius. Getting a tight CLR, like how I think the OP wants to make his bracket, is going to require some serious vice-mallet loving, but it is doable.

author: AF6LJ
author_rank: Unknown
timestamp: October 15, 2015, 02:55:59 pm
content: Quote from: akis on October 15, 2015, 02:14:42 pmBelieve me it is problematic to bend especially if you are trying to bend the wrong alloy.Also; aluminum has a bending radius you have to take into account.

author: AF6LJ
author_rank: Unknown
timestamp: October 15, 2015, 03:01:04 pm
content: Quote from: Ian.M on October 15, 2015, 02:45:45 pmNot to mention you anneal copper by quenching, same as fine silver.

author: Fungus
author_rank: Super Contributor
timestamp: October 15, 2015, 03:14:07 pm
content: Quote from: AF6LJ on October 15, 2015, 02:55:59 pmThe hardest part is bending it neatly and only where you want it to bend.

author: Bud
author_rank: Super Contributor
timestamp: October 15, 2015, 03:14:33 pm
content: Cant you use a piece of aluminum angle stock and screw the flat plate to it? Perfect 90 degree assembly.

author: AF6LJ
author_rank: Unknown
timestamp: October 15, 2015, 03:18:03 pm
content: Quote from: Fungus on October 15, 2015, 03:14:07 pmNot my favorite material to bend.Give me fine silver any day, I can deal with that.I use to make jewelry until my eyesight went from bad to more bad.

author: Kleinstein
author_rank: Super Contributor
timestamp: October 15, 2015, 04:16:52 pm
content: Pure aluminum (like that used for conductors) is very soft, especially if not work hardend. This would be rather easy to bend - even easier than soft copper. Depending on purity and annealing it can be as soft as butter - so a foot long 4 mm bar could slowly bend under it's own weight.Aluminium alloys can be much harder, but there are quite different alloys - so without knowing the alloy type it's hard to tell which type of heating is right. Some alloys get soft after annealing and slowly harden over time - others would need bending in the hot state. So one could try heating to anneal first - if then bends easy, this is OK. If still to much force is needed, the next try would be bending in the hot state.As stainless steel is also quite variable, there are Al alloys that are considerably harder than some versions of stainless steel, though not as hard as the more usual hard form of stainless.

author: xReM1x
author_rank: Regular Contributor
timestamp: October 15, 2015, 05:30:14 pm
content: how about heating up the aluminium and then bending it?

author: Richard Crowley
author_rank: Super Contributor
timestamp: October 15, 2015, 05:39:25 pm
content: Quote from: xReM1x on October 15, 2015, 05:30:14 pmRecommend reading through the discussion. This has already been covered in detail.It would appear that the OP doesn't know what alloy he has, so heat may be beneficial, or it may make things much worse.

author: KJDS
author_rank: Super Contributor
timestamp: October 15, 2015, 06:21:10 pm
content: Further to my previous suggestion, lay it on the lawn and hit it with an axe.What can possibly go wrong?

author: DimitriP
author_rank: Super Contributor
timestamp: October 15, 2015, 07:04:01 pm
content: Quote from: akis on October 15, 2015, 11:21:49 amJust a couple of ideas, not necessarily good ones:You sandwich it between two planks of wood and drive over it.Folding the ends is another story.Instead of bending the ends you could cut them off and weld them on.

author: calzap
author_rank: Frequent Contributor
timestamp: October 15, 2015, 07:20:11 pm
content: There are many grades and alloys of Al. McMaster-Carr, a popular supplier in the US, sells 19 types. Some are incredibly tough, some are incredibly soft, some are very brittle and crack with even a few degrees of bending, some will work-harden or work-soften. Torching it may help, but some alloys will melt easily, and high magnesium alloys will ignite. Cutting and welding will work, but you have to have the skills and equipment (gas-flooded MIG or TIG). Not all alloys of Al can be welded.The piece apparently has some curvature along its length, which make it even more difficult. If you have some wood-working skills and tools you can make some jigs that will help. Cut grooves just wide enough for the Al strip to slip into sideways in two timbers. Put them on the ground with a few cm between them. Slip the Al strip into them with the bend point centered in the gap. Put your weight on one timber, pull up on the end of other, and hope for the best. Instead of wood, a couple of pieces of iron pipe with the right ID could be used.Mike in California

author: Muttley Snickers
author_rank: Unknown
timestamp: October 15, 2015, 08:20:09 pm
content: One of my customers is a large manufacturer and fabricator of aluminium truck trailers and every time I am over there the scrap bin gets raided, ironically my task over there generally is to maintain the security and surveillance systems to make sure nothing gets knocked off. I do ask for stuff before taking anything by the way and they are always happy to supply whatever I need.For bending up to about 6mm plate I made up a jig for my 2 tonne arbor press which has two 25mm adjustable parallel solid steel bars on the base plate and a 25mm supported tee bar that I made for the press head itself, It's only good for up to 100mm wide and anything bigger that I need will be done by another customer locally that has a huge automated press brake.I agree with the other posters that a bit of heat goes a long way and practice makes perfect but some materias are just plain difficult to manipulate and can become brittle or tear, the arbor press gives me a good start with a radius and sometimes it needs finishing off in the vise again with some solid bar for the radius.On a side note I picked up this vise below at a flea market for $40 and it initially looked a bit sad so I spent a whole day cleaning it up to almost new condition, unfortunately a couple of the interchangeable jaws are missing along with the top of the lever pedal and both were readily available and cheap from Travers Tools in the US but shipping was a problem and I can no longer find the listing of the replacement parts on their site, it's a shame really.Mine is labeled as Duoneng and they were also sold under the T&O and Dake brands mainly in the US, a brilliant vise and work station if you can find one.Best RegardsMuttley

author: ConKbot
author_rank: Super Contributor
timestamp: October 16, 2015, 12:04:42 am
content: Quote from: akis on October 15, 2015, 02:14:42 pmAhh the the great green engineer assumption. Learnded in school that gold, copper, silver, aluminum are all ductile metals are flexible etc. When in practice probably the only thing less desirable to bend then aluminum is anything cast. I've seen this exact situation before. After a week or two the strips turned up and were made from hot rolled steel because the aluminum kept cracking when trying to get a sharp inside radius. If you can drop in thickness because it's stronger, either mild steel or stainless would be a lot easier to work with. Stainless work hardens like aluminum, but it's a lot easier to anneal or just heat and bend if needed. It needs more heat but it's less sensitive to overheat. Aluminum melts with only dull red heat, and the part will just collapse. Steel and stainless have a few colors to go through before melting.

author: free_electron
author_rank: Super Contributor
timestamp: October 16, 2015, 02:38:25 am
content: Why would aluminum be hard to bend without tearing?soda cans are even spun from aluminum.. drawn and then spunJust use one of these :I just checked my car. not a crack in any bend in sight

author: alsetalokin4017
author_rank: Super Contributor
timestamp: October 16, 2015, 02:56:56 am
content: Quote from: Bud on October 15, 2015, 03:14:33 pmBest answer so far.because:1. The workpiece is unlikely to be "pure aluminum" and the actual alloy + heat treatment is not known. The workpiece is more likely to crack than it is to take a perfect, sharp 90-degree bend, even with a proper bending brake, heating/annealing/etc.2. You can buy aluminum (alloy) angle stock at the local big-box hardware store. These bits are extruded, not bent into their shape, and so have nice sharp and precise angles that are not stressed.Of course, the end-shape desired may not be compatible with the corner profile produced by using angle stock to join the bottom with the sides of the 'U', and the required fasteners may also interfere. But depending on the use and desired end-shape, one may even be able to get away with simply gluing the angle stock to the bottom and uprights of the 'U' shape (using the right kind of adhesive of course.)

author: ConKbot
author_rank: Super Contributor
timestamp: October 16, 2015, 03:01:50 am
content: Quote from: free_electron on October 16, 2015, 02:38:25 amGive me a sharp bend in a piece of 'generic go to' 6061-t6 1/8" or 3/16" strip that a shop may have a variety of in stock.with the right alloy in a fully annealed state, it obviously is super ductile and able to be stamped and deep drawn well. But the post stamping metallurgy is probably just as interesting as the stamping process.

author: promacjoe
author_rank: Regular Contributor
timestamp: October 16, 2015, 04:01:46 am
content: depending on the type of Aluminum that you have, You will need to heated to between 400°F and 800°F Before bending. It can be done without heating but, it will keep the bar from tearing on the outside of the bend. You also need a fairly decent Break or metal bender. if done improperly, you will wind up with a piece of scrap metal. a professional company that does aluminum bending is your best bet. You also might try finding a metalworking users group in your area, and see if someone close to you is willing to help.good luck.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: October 16, 2015, 04:42:04 am
content: Watching electronickers talk about materials properties, heat treatment and fabrication is like watching mechanical engineers talk about semiconductor properties, transfer functions and PWB layout. Both disciplines depend on basic physical principals and pros in one field seem to think they know everything about the other. There are a few who really do know both fields, and a few more that recognize their limitations, but the rest are pure entertainment. As I think about it, this situation probably explains a lot of audiophoolery. Hopefully I am one of those who knows that he knows enough to leave real work and advice to the pros. If I have to bend something in my home shop I try it, but with aluminum I fail more often than succeed. That is in spite of large vises, multi-ton presses, electric and gas welding equipment and other tools that can be brought to bear. If I had to build something the shape as I understand you want it I would use copper for ease of fabrication, or steel if strength was an issue. Iron and steel bend very nicely when heated enough, and are easy to judge temperature by the color. Also easy to weld back up again if they crack during the bend process.To the original poster. If you can explain what you are trying to accomplish the folks here who actually know their stuff can give you better advice on how to get to the answer. Things like how strong it has to be, how accurate the size and shape needs to be, and whether using up material on hand is one of the goals are the kinds of things that can help inform an answer.For those that want a little intro into the scope of the problem a widely available online resource is MIL-HDBK-5 "Metallic Materials and Elements for Aerospace Vehicle Structures". The handbook is now obsolete, replaced by an international standard, and doesn't cover all metals, just those actually used in airplane, rocket and missile structures, but will fully saturate anyone who wants just a surface understanding.

author: akis
author_rank: Frequent Contributor
timestamp: October 16, 2015, 12:10:46 pm
content: Thanks for all the replies.As you can see on the pictures the purpose of the aluminium bars are to brace together opposite glass panels of an aquarium because they bulge out when filled with water.The aquarium already has a plastic bar/brace as can be seen in the picture, but the glue used to attach the bar to the inside glass has expanded/given and the glass bulges out.As you can see on the first picture I made two aluminium bars/braces and glued them on either side of the original plastic bar, but after a few months the glue has come off the glass.The internal braces were made with two aluminium bars, 4mm thick, 60mm wide, with two galvanised steel brackets attached at their ends. The aluminium bars were half-drilled with plenty of indentations to create more surface area for the glue to take. I have removed one bar and tested the strength of the bond and it is perfect. Unfortunately the bond between brackets and glass was not as good.The solution now is to bite the bullet and use a similar construction but longer so I can fit it outside the glass, I will simply place it on top of the aquarium bracing the two sides together, and that will not need any glue on the glass. But because it will be outside it will be hightly visible and it needs to look nice.So I was thinking to use a longer aluminium bar and instead of attaching the very ugly steel brackets at the ends, to instead fold it so it is one piece. That would look nice. By the way on the photos the aluminum bar looks ditry from all the water that has fallen on it, when new it is nice and shiny.

author: Ian.M
author_rank: Super Contributor
timestamp: October 16, 2015, 12:43:54 pm
content: It doesn't need to be 60mm wide or 4mm thick. 12mm wide, 3mm thick stainless strip would be plenty strong enough. As its going over the tank edges, bonding area isn't an issue - just get the glass totally clean and freshly sand and degrease the bent ends then bed on neutral cure clear silicone to stop them slipping out of place and take up any small length errors. Don't use aluminium - its never going to stay looking nice and it will be very difficult to get the bends to look good and not be weak.Also its one of the worst choices for glueing.Hint: Cut it too long so you have plenty of end to grip in a vice while bending then cut the bent end to size afterwards.

author: akis
author_rank: Frequent Contributor
timestamp: October 16, 2015, 01:15:08 pm
content: How about mild steel they sell it on ebay, 3mm thick and 5mm at various widths. I could get a bar, bend it as you said and then cut off the excess on both sides with the hacksaw. But how wide/thick? I have plenty of options see here:http://www.ebay.co.uk/itm/Mild-Steel-Flat-Bar-flat-bar-steel-welding-fabrication-ironworks-metal-works-/111200307900?var=410229542274&hash=item19e40e0abc:m:mi2BDywf_XHEZ2KDYgnsr0Q

author: KJDS
author_rank: Super Contributor
timestamp: October 16, 2015, 01:23:15 pm
content: Mild steel will rust, stainless is the best option here.

author: Ian.M
author_rank: Super Contributor
timestamp: October 16, 2015, 02:04:16 pm
content: Mild steel will *NOT* be satisfactory unless you pay to have it powder coated after bending. However it would be good to practice bending to an exact length on before getting more expensive stainless strip. It has similar stiffness and bending properties except that it wont work-harden to anywhere near the same degree.Hint: Mark the bend line with a marker before bending, and mark another line on the long part of the bar a fixed distance away. Then you can easily measure how far off the desired position the bend was and compensate for the loss of or excess length when marking out the bend at the other end. Don't scribe the lines as that's likely to start a crack if its on the outside of the bend.

author: free_electron
author_rank: Super Contributor
timestamp: October 16, 2015, 02:10:08 pm
content: your glass BULGES when the aquarium is filled ?methinks you need thicker glass... ( or transparent aluminum)

author: Ian.M
author_rank: Super Contributor
timestamp: October 16, 2015, 02:16:44 pm
content: There's a lot of force on the sides of a long deep aquarium tank, and if the top tank edge isn't supported by a frame, bulging can be a real problem.

author: akis
author_rank: Frequent Contributor
timestamp: October 16, 2015, 02:27:32 pm
content: It is a wellknown issue affecting this particular brand and model - Jewel Rio 180. The German manufacturers swear that the glass can take it, but you know they are talking rubbish because the swealling distorts the rectangular shape nad causes all sorts of stress on the seams.I bought an stainless steel bar, 3mm/30mm and I will visit a shop to have it bent for me where they have machines.The bending does not have to be dead accurate (40.5cm presicely) because it can be larger and then I can fill the gap on the back side of the aquarium with a plastic insert or something.

author: Ian.M
author_rank: Super Contributor
timestamp: October 16, 2015, 02:33:46 pm
content: As I said earlier, bed the ends on a dab of clear silicone sealent. It stops the brace slipping and cushions what would otherwise be a point loading on the edge of the glass, but wont be visually intrusive. If you are trying to fit the brace to a full tank, you'll need two well padded sash clamps either side of the brace to hold the sides in straight for 24H while the silicone cures.

author: ConKbot
author_rank: Super Contributor
timestamp: October 16, 2015, 03:46:34 pm
content: Ah, since your application is tension only, If you can attach a bracket to the outside of the tank in a satisfactory manner (stainless channel?) , string across some stainless wires between the brackets, tension them, and it should be a bit cleaner (imo) then big brackets. But there's many ways to skin a cat.

author: KJDS
author_rank: Super Contributor
timestamp: October 16, 2015, 03:59:33 pm
content: I like the idea of wires, some careful design and you could have a dual purpose fish tank / harp

author: nctnico
author_rank: Super Contributor
timestamp: October 16, 2015, 04:09:45 pm
content: Quote from: madires on October 15, 2015, 12:07:55 pmI bend 50x10 mm stainless steel in my shedAluminium is no problem. What would be necessary is some heat treatment otherwise aluminum may crack later on.

author: SeanB
author_rank: Super Contributor
timestamp: October 16, 2015, 05:00:37 pm
content: Place a glass top brace there, probably a 10mm thick strip of glass 150mm wide and the length of the top, held to the top glass with a generous bead of aquarium grade silicone sealer. Glass strip will need to have all corners ground and the edges ground flat, so that there is no stress risers that will break it. This will provide the needed support and the glass will be nicely in compression after the silicone has cured.

author: @rt
author_rank: Super Contributor
timestamp: October 16, 2015, 07:18:29 pm
content: Brass sheet is easier to bend straight by hand and ruler than copper, and maybe easier than aluminium.You score both sides of the brass with a Stanley knife using a steel ruler in exactly the same line on both sides,then use a pair of tiles to clamp one side of the line, and fold with another tile.Brass sheet is also the easier to cut straight by hand and ruler over copper.Just do the same thing as above and keep bending in opposite directions until it fatigues and breaks.Brass, copper, and aluminium can also have folds etched into them by masking all but the line,and using anything from vinegar to Septone to etch the line, then fold the same way as above.

author: @rt
author_rank: Super Contributor
timestamp: October 16, 2015, 07:23:37 pm
content: I only read it was for aquarium.We used to use strips of glass the entire length of the aquarium fixed perpendicular to the top front and back,and then also fix glass bracing across the two strips to also form the resting parts for the lids.We used Selley’s Glass & Window sealant on the inside (the one that says it’s ok for aquariums on the label),and structural sealant for the outside and all bracing.

author: akis
author_rank: Frequent Contributor
timestamp: October 16, 2015, 07:30:35 pm
content: Did someone mention a clamp? :-)The top of the aquarium is two clear polycarbonate panels, they are not structural.I will place the stainless stell bar in the middle and it will attach on the plastic/wood imitation top collar that you see in the picture.The small aquarium with the problem is 3ft/180L and the large one is 4ft/350L. The lights are hand made powerful LED strips inside clear acrylic tubes and sealed on boath sides, with a 12V/6A PSU (1.5A each strip).

author: akis
author_rank: Frequent Contributor
timestamp: October 16, 2015, 07:40:49 pm
content: Quote from: @rt on October 16, 2015, 07:23:37 pmAh funny you should say that. I was inspecting another 4ft/350L tank and it had been customised exactly as you described. There were two long strips of glass running across the length, on the front and the back glass, mounted perpendicularly forming two shelves. There was another strip of glass mounted across from front to back secured on those two shelves. The work was shoddy. There was what appeared to be grey coloured cement bonding all the glass pieces together, it was clearly done by hand, sloppy and ugly to look at, it looked like a 5 year old was left to play with clay. Whereas the seams on the glass panels are done at the factory and are perfect.But I could not understand the need for all this customisation and the guy selling it did not know either.

author: AF6LJ
author_rank: Unknown
timestamp: October 16, 2015, 11:50:41 pm
content: I have had 4' tanks of the 238 liter (60 gallon type)The glass was tempered and at least a quarter of an inch thick.It would flex about a sixteenth of an inch.What I don't understand is why you...1. concerned with a couple of cm worth of flex.or maybe your glass is not thick enough or the wrong alloy.

author: akis
author_rank: Frequent Contributor
timestamp: October 18, 2015, 10:05:22 am
content: The flex is 5mm on each pane total of 1cm. This is with the central brace still holding on somewhat after the glue has deteriorated.

author: G7PSK
author_rank: Super Contributor
timestamp: October 18, 2015, 03:55:41 pm
content: Some one mentioned letting the aluminium air cool after heating it, as aluminium age hardens this will result in it getting hard again. To anneal aluminium rub it with bar soap any type will do then heat it until the soap turns brown and then plunge it into water, this traps the crystals in the soft state before they can revert to the hard, but if you leave the aluminium long enough after annealing it will go hard again so you pretty well need to work it immediately.

author: Ian.M
author_rank: Super Contributor
timestamp: October 18, 2015, 04:02:25 pm
content: Depends on the alloy and the thickness. I've had good results with air cooling aluminium sheet I needed to anneal. I did point out that it may need quenching if air cooling doesn't result in a soft enough end state. Finally quenching thin sections frequently results in distortion.

author: G7PSK
author_rank: Super Contributor
timestamp: October 18, 2015, 04:27:14 pm
content: In all the years I have been working aluminium (over 40) I have never found the need to anneal sheet only plate or bar stock.