How To Bending?!

hey there today I thought I'd talk about some stuff maybe let's stick around today's episode is brought to you by the letter beep and sponsored in part through the generosity of the metric system since 1792 the system trusted by 1516 so last night the missus and I were in Los Angeles for the world premiere of weld cart part 3 on the ride home she said this old Tony I loved it but he didn't really get much into the actual bending my jaw dropped it must have fell on the gas or got behind the brake pedal cuz I don't remember much after that a few days later after we came to in the ER she turned to me looked me straight in the eyes and said you really should make a follow-up video as our monitors beep tin that empty room I realized she was right this might upset a lot of tin knockers but there isn't too much - bending in theory anyway if you've ever tried it yourself tried to get good accurate bends well there's more to it than meets the eye bending can mean a lot of things to a lot of people in fact it's got 19 entries on dictionary.com could mean anything from this or this all the way to this now I wouldn't go so far as to say what we'll be doing here is precision bending this is still the guy in his garage I mean I can't do NASA level stuff out here but I'll try to put some thought into what we're doing just like anything else you make if you're making just one of something dimensions are usually relative part a needs to fit Part B with some level of acceptable tolerance that keeps the thing functional objective dimensions might not be super important kind of like the drawer I made in the last video finished size wasn't that critical as long as all the parts worked together satisfactorily for me anyway speaking of which yes I did cap the holes in the welding cart sometimes you make me wonder what channel you think you're watching here Stefan got the other end of that spectrum is making parts for other people there you don't have control over where that part you need to make will go or how it interacts with other parts in that case objective dimensions are law you make it to spec or it's trash no two ways about it anyway let's make a couple of bent parts work through the layout and see what we get shall we actually before we get into this just a word if I may I'll try to keep what you're about to see to an absolute minimum here but we're going to be getting into some math you want to bend stuff you got to do some math you tell me is it a contrived coincidence that reorganizing the letters in sheet metal spells mathletes but don't fret just addition and subtraction I promise if you're a little rusty please pause the video and brush up just like all good rulers throughout history I try to provide both inch and metric dimensions in my videos my channel is international the numbers will be thrown around working in both systems will get a little sloppy I'm gonna do this whole video in metric I know this is a controversial topic but since you brought it up let's talk about measurement systems take this block as an example in this universe's reference frame it has some width to it it has dimensions the block doesn't care if you call it 2 inches or 50 millimeters it's always whatever width it happens to be so let's not get caught up in labels shall we so 1980s would it be more convenient and cause less confusion if we all adopted the same system yeah maybe personally and I recommend you strive to do the same I have transcended labels when I look at a measuring device I see this which I'll grant you makes taking measurements a little hard sometimes now what was I even talking about and for my flagship phone here and see how it goes nothing fancy just something for out here in the garage since we're make pretend professionals we should probably start off with at least some attempt at a reasonable drawing so this phone is fifty point seven millimeters wide there's some curvature some kind of rounded champers but we'll call that fourteen point four make that about eleven it's about 70 up to the bottom of that camera bezel there two megapixel they make a quick drawing something like that is what I had in mind though to be honest i already forgot the dimensions though he took I think I said this return will be 11 phone is about ten point four make it ten point five so it actually fits in there seventy of the back and I don't know seventy on the return sort of for the kickstand let's do a quick flat pattern so that's 11 10 and 1/2 70 and 70 140 150 160 160 1.5 overall length let's do a chamfer to chamfer so it looks nice 45 should do it I've already checked and this is the squarest corner of this cut off my half I need a line at 11 then an additional 10 and 1/2 takes me to 21 and 1/2 it has a vernier scale on both sides if I add 72 that it takes me to 91 and a half and we said the overall length was 161 and a half okay I don't know if you could see those scribe lines but I'm ready to cut this happens to be one millimeter thick mild steel I haven't weighed my new phone but I think one millimeter should withstand the crippling forces we're dealing with okay hold the train had a little brain fart as I was scribing that sheet metal out this ten-and-a-half really bothered me this is essentially the thickness of the phone because it's not ten and a half it's essentially 15 it's 14 and a half plus some clearance 15 I mean come on I don't even think Samsung can get it down to 10 millimeters let alone an LG I'm just kidding that was a joke don't start setting me lg8 male so that ten and a half is really 15 that's 26 and 140 takes us to 166 I've already gone ahead and laid that out on the backside of this piece so this should be correct now when it comes to sheet metal you've got some options each one is worse than the last but you have some options it could use your psychic powers but then you'd be laid up in bed for a couple of days and you'd have to wait to finish the project ideally what you'd have is a full-sized CNC hydraulic shear in your garage it's like an artificially intelligent giant paper cutter on steroids but try to pitch that one to your significant other oh wait next down the wish list might be a compact to mechanical shear that'd be pretty nice I've always wanted one stick the metal in stomp on the pedal perfect cut most of the time anyway but unless you've got a lot of space or maybe you do this a lot even the compact shears tend to take up quite a bit of space now sure there's plasma and freakin lasers and that sort of stuff but let's look at some perhaps more traditional items stuff you might expect and shears are likely the first thing that come to mind in this case with one millimeter stock that's probably fine any more than that and you'll be staring down the barrel of a serious workout then there are power shears this is a Makita it's pretty old but I love this thing gets a lot of use down here could stand to be sharpened but we'll have a closer look at this in a minute and then of course there's Old Faithful the angle grinder with a cut-off wheel I'm also showing cold chisels technically they do cut sheet metal I wouldn't use them for a project like this but they do cut for the sake of sharing I'll show you what a cold chisel does and these aren't called cold just because they're heartless they're called that because they cut metal cold as in cold working basically with both this and the air chisel we'll see in a minute there can openers cutting sheet metal with one of these is akin to doing surgery with la chisel I guess usually not very pretty this might be more adapt at cold cutting small bolts or splitting rusted nuts that sort of thing this one's actually seen better days but let's give it a try not pretty actually if the chisel were a little sharper and I was using a smooth backer like not these serrated vise jaws I bet that had come out a lot cleaner in fact let's try it that's just a block of cold-rolled steel with I guess a sharper edge a more continuous edge all right it's a lot better this here is a sheet metal trimmer it's a very close cousin to the cold chisel just on the end of an air hammer and it does basically the same thing it'll do two cuts and pull out a center strip I haven't actually used this in a while I hope it still cuts it's not really the highest quality cheap metal trimmer there is I think I just got it with the set that came with the air hammer this is the kind of thing I might use to cut a like a 55-gallon drum in half something you don't want hot sparks getting into and you're not really that concerned with the quality of the cut I'm actually quite surprised that's quite a clean cut I may have to start using that a little more often there is sort of the chip it just kind of bulldozes ahead of itself despite me not even trying that looks like it actually went pretty straight too and here's the electric version of what we just saw except here that's got a moveable jaw that actually does the cutting it's more like power shears than a cold chisel this isn't really all that sharp so the lines are blurred I think you can get these as add-ons to like a cordless drill or a corded drill this you can run up against a straightedge should measure the offset clamp down a straightedge and get the nice clean cuts of course you can also do this with a cut-off wheel set up a straight edge cut your way through this is probably the lowest barrier to entry not counting shears of course but it does make a heck of a racket dust and dirt and all that kind of stuff anyway let me cut this out and we'll talk about bending hi Bigsby can you give me an to bend this for me I'm sorry Dave I'm afraid I can't do that so this is my sheet metal bender if you're a usual you'll have seen this before I use this for thin sheets it'll do up to I think 36 inch bends that's almost a meter not quite but of course the longer the bend the harder it is to do as you saw this bender is a bit of a compromise there's no built-in clamping there's no back stops there's nothing I just make do with cut-offs I have on hand block the part up clamp it down and pull the bend it does a fair amount reasonably well without taking up a lot of precious garage space I know someone's gonna ask but unfortunately I don't have plans for this thing if you want to make one you'll have to do with me and every other cheapskate has since the dawn of time build five of them until you lose the will to bend and just make do the rest your life with the last one you made I'm just kidding there's tons of plans around of every shape style and size what they usually come down to is two pieces of heavy angle iron with a hinge at each end make it as long as you think you need as beefy as you think you need cut out some material and weld in a hinge one side would get some sort of a base or a way to attach it to your bench or garage floor and the other side gets a handle and then once your material is clamped down you just simply rotate it around the two hinges here I've got long handles on either end just to help give me some leverage let's get back to our little phone stand appears to work the phone fits it's not falling over and there's no creaking sound let's have a closer look the phone is a little bit loose in there again it works fine but I was shooting for a little bit of a snugger fit now we wanted marked off and bent at 15 millimeters this is the front edge that's the flat the phone sits in that's the back and that's the kickstand measure what we got that is almost 16 millimeters same thing on the other side let me grab a school yeah the bends all look reasonably square how curious where did that extra millimeter come from if I bring you in really tight you can see the bends happen right on the scribe lines which are 15 millimeters apart and we saw both bends or square so why isn't this inside pocket 15 millimeters this part if we were making it for someone else would now be trash it just failed inspection now the reasons why this isn't a size are staring us right in the face but it's hard to see because this material is so thin it'll be easier to talk through on something bigger something thicker I happen to have this block that's 2 inches thick my bender can't handle stock this thick but luckily it's only mild steel the first thing you might notice is that the bend isn't sharp there's a bend radius state the obvious the material is deforming all of the material on the inside of our Bend has compressed it's sort of bunched up the material on the outside of the bend has stretched for that to happen the material needs some breathing room it can't just turn on a dime that breathing room becomes the bend radius just like me if you don't give it breathing room it'll snap usually US hobby folks don't have the kind of muscle around to see that happening steel but maybe you've seen it happen in aluminum it has a larger minimum Bend radius if you've ever tried to force a really tight Bend on aluminum you'll know that it breaks for steel that minimum safe Bend radius is usually smaller than aluminum in fact it can be quite small it depends on the thickness of course the grade of material trying to bend its heat treat how you're gonna try to bend it etc you can look all that info up in our case with one millimeter sheet it's not very much but it still needs accounting for in my particular case with this scrappy bender here I don't have too much control over Bend radius or a minimum Bend radius that is to say I can make larger radius bends if I use a rounded top die like this tubing for example it's got much bigger radii that I can bend stock around but if I use a sharp corner tool like this cold rolled flat stock and try to force a smaller Bend radius on the material one of two things will happen either and most likely my clamps will slip see the amount of force can get very high and the way this bender works it just can't take the heat as I try to pull the bend those forces will transfer onto the clamp and if it slips the bend radius will get larger basically the clamps will slip until the forces are equal and I can pull a Bend option number two I've got 55 clamps across 24 inches of bender the clamps don't slip but either the material would crack or my bender would break so in a way this bender has an auto minimum Bend radius feature if you go back and watch the weld card video where I'm bending the drawer and that material was thicker I was getting large Bend radii off of this bender and had to do some cleanup on the hydraulic press since the inside dimension here on the phone holder is 16 and set a 15 that we intended it's evident that we picked up a half a millimeter Bend radius on each side had we known that ahead of time we could have scribe the lines 14 millimeters apart instead of 15 in order to end up with a finished feature that was 15 millimeters you have to account for what will happen during the bending when you're laying out the flat pattern you have to think about it before you cut your blank or you might scrap your part the amount of material you need to account for before making a bend is called the bend allowance and just like it says on the tin it's the allowance you'll need to make for the bend you're about to pull of course you'll also need to be careful of where these dimensions refer to where on the bend line or at the bend allowance that 70 millimeters in this case refers to also where this Bend allowance goes with respect to your Bend line sort of depends on the equipment you're using like if it's a press break or like a box or a pan break and what the intention of your final dimensions are is the important dimension of that Bend the inside or the outside including the sheet metal thickness like if you were to clamp on this line here all of your Bend allowance would happen outside obviously after that clamp if you were to clamp here this whole Bend allowance would shift up a bit you can't allow to bend something that's clamped down in a big machine bottom line you look this stuff up it's usually presented based on your material thickness T so for a certain material say mild steel in this case you google it and it'll tell you that the Bend allowance is going to be one or two or three times the thickness of the metal that you're working with add that to your flat pattern before you develop the overall size of the part then cut it out but to give you the 30,000 foot view I'm going to throw some definitions at you so if you do look it up you might have a better understanding of what you're reading let's go back to that big block I bent for you earlier Bend allowance is this material here all of the material that went into making the bend its length of that arc basically but if you look closely the material has thickness to it in this case quite a bit of thickness so how long is that Bend if we measure on the inside of the bend we'll have a much shorter been allowance than we would at the outside right so what gives remember earlier we said when you bend something the inside will compress and the outside will stretch well if that's true that means somewhere in between those two extremes the material is seeing no stress right if one side is all in compression and the other side is all in tension there must be a place where that changes from one to the other and that place is usually about the center line of your material thickness the inside of the bend got shorter the outside of the bend got longer but somewhere in the middle here the length didn't change at all and fun fact that place is called the neutral axis that arc the length of that arc through the part of the metal that didn't deform is the bend allowance that's the number we need to account for in our flat pattern before we cut the sheet stock so easy enough right for a 90 degree Bend it's just a quarter of a circle pi times the diameter is the circumference divide that by four and you have your Bend allowance but not so fast there partner what is that diameter if we assume the neutral axis is at half the material thickness it's easy right take the bend radius which is always measured on the inside of the bend and add half of the material thickness bingo bango you can now calculate the been deloused but the neutral axis isn't always in the middle in fact it's usually a bit closer to the inside maybe 45 percent of the way in instead of 50 might not sound like a lot but if you're doing a lot of bends you can bet it'll add up and it won't add up to profit you can be sure that the location of that neutral axis is called the K factor well the K factor tells you where that neutral axis really is it's like the x factor but way cooler if you do a lot of sheetmetal work in 3d cad like fusion or SolidWorks or what have you you may recognize that term that K factor every bend you do in CAD wants to know what factor you want to use because well frankly it's important now the software will usually have a built in database of what that should but it's always smart to double-check just before clicking that okay okay whatever let's just get on with it button alright anyway this rabbit hole has gotten deep enough bottom line for kids like us either look up the k-factor and figure out the bend allowance for the material you're working with or do a few test bends and keep a close eye on what you marked out versus what you got and just figure that into the part you need to make holy smokes what a mouthful but just one more thing well actually there are a lot one more things when it comes to bending but one last point for now and I'm done I swear it's not really a point even I just want to put what you just saw in a different light a quick example of why this is important let's say we're laying out a simple part with 90 degree Bend lines something like this the way a well-adjusted person would likely dimension that is by giving you the length of the two sides maybe one inch on one leg and two inch on the other pretty straightforward right but how would you bend this you really can't lay this out on flat sheet metal have a close look at how it's dimension then you'll see it's quite sinister the dimensions span from a simple reference edge the one you cut presumably to the outside of an already bent corner it's just brushing over everything that happens in that Bend what we'd really like if we're the ones making the part are the flat lengths the dimensions just up to where the bend will start or finish simply because that's how we're going to bend it right you'd maybe clamp this line here and the break and pull the bend but the person that made the drawing doesn't really care they just want a part that's to size and that's where all the math comes in based on these dimensions you'd need to calculate what they call the setback in this case it's an outside setback just looking at it for a 90 degree Bend it's the bend radius plus the material thickness that's where you'd clamp the material and the bend allowance we saw earlier tells you how much metal you need to fill that bend in how much metal you need to actually make that Bend if you give it too little the leg on the Left will end up short give it too much and the leg will end up long okay well I think that's all I got I mean what we did changes a little with different types of bends that you're making the equipment you're using and there's stuff like material spring back error accumulation you have to watch out for if you're making a big part with a lot of consecutive bends but at the core of it it's really not that complicated just take a deep breath and thing get through before you start actually bending metal it really wasn't my intention to make a mountain out of a molehill you know what I'm saying right Bigsby [Music] thanks for watching

Channel: This Old Tony

Views: 1,139,757

Rating: 4.9431953 out of 5

Keywords: bending, sheet metal, bending sheet metal, k factor, bend allowance, set back, setback, sheet metal setback

Id: FyXpCPVOr8s

Length: 22min 30sec (1350 seconds)

Published: Fri Nov 24 2017