The failure of the BFH testing method

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This is for all the newbies to welding and for the hobbiest looking for a project.  The project is to build a weighted pendulum.  It would be where you would be able to add weight to a striker and it would strike a coupon with a measurable weight.  Then you would be able to test coupon after coupon against each other and you would be able to determine with far greater accuracy which weld was better stronger and tougher than the rest.The failure of the BFH testing method is you can not deliver the same umph with each blow nor can you maintain the same angle and impact point.When I was a carpenter we had a contest of who could drive the most 16d nails in with one lick. They were started online a 1/4 inch.  The old trim carpenter with his 16 oz hammer beat all us framers with our 22 and 28 ouncers.  He didn't even have a large swing.  Problem was not how many we drove perfectly, but rather how many we messed up!That said it is fun to beat things and break them, but determining strength from coupon to coupon with beating it with a hammer is like describing the ocean from holding a thimble full of water.
Reply:Scott YoungWhat is the length of your moment-arm,and how fat is Bob?Opus
Reply:I haven't built one yet, but the idea for it has been bouncing around in my head for a while.  I shared this idea before with someone who was "testing" a lot of coupons but it fell on deaf ears.  I just moved and as soon as I get my welders set back up, I plan to build one. I figure I am going to make it 6' tall with a simple A frame.  So the moment arm will be roughly 6 and Bob will be a head off of a sledge.  If this proves to be too light then a couple weight plates donated from a weight lifting set can be slid down the arm and rested on Bob.
Reply:Scott,What you're describing is almost exactly the machine used in a Charpy or Izod impact test.This measures impact toughness in ft-lbs or joules of energy absorbed by the weld before breaking.  Do a search on these machines, and you'll see some photos.Meaningful results come from precisely machined specimens with very tight tolerances on their size/shape and the location of a machined notch.The machine records how high the hammer swings after breaking the test piece.  With this information and a fixed starting height, radius for the arm, and weight of the head, it's fairly easy to calculate how much energy the hammer head lost in breaking the test piece.I supect you'll need the added weights to the machine you described in the original post..  The Charpy test machines I've seen have a bob or head weight of 40 or so lbs, I'd guess.  This is used for breaking standard test pieces measuring 10mmx10mmx about 40mm long.  bigger test pieces will need a longer radius arm or more weight in the striker to reliably break good welds.  If the hammer doesn't break the test piece, if it stops upon impact, then you don't know for sure how tough the weld is.  You just know that it's tougher than XXX.Benson's Mobile Welding - Dayton, OH metro area - AWS Certified Welding Inspector
Reply:DabI got to go see one of those machines in use when I younger.  It is pretty neat.  My machine is a crude comparison, but for a guy comparing coupons against one another it will do nicely.  I sold all my scrap steel when I moved and I need to find some to replace it.  The more I think about it the more I am going to make this a project for my son and daughter to do.
Reply:They have YouTube videos of a charpy test.  It gives you an appreciation for what all goes into certification.
Reply:good idea! is this in response to Lanse's latest video? I was wondering just how evenly hammer blows impact the failure of a weld. Too many variables.Miller diversion 165Miller mig 211Hypertherm pm 30Milwaukee 6230 14 inch chop sawMd 45 mag drill (RIP; fell on its head)New MD 45! Thanks to the esposa!Finally got an O/A setup
Reply:Originally Posted by [email protected] idea! is this in response to Lanse's latest video? I was wondering just how evenly hammer blows impact the failure of a weld. Too many variables.
Reply:Yes, I believe that passive note was directed at me...When I do experimental videos, including the one that probably sparked this thread, I'm not looking for scientific numbers, I really couldnt care less about those...What I'm after is an answer to the question, is "A" stronger than "B"?If the welds categorized as "A" took an average of 50 hits to break,and those categorized as "B" took 30 on average, than "A" is the stronger method/process/filler metal/etcIt may not be the most scientific method in the world, but its perfectly adequate for answering the "Is this stronger than that" question.I generally dont swing that hammar very hard in order to keep from tiring myself out, and I always use a number of samples so I can get a more accurate average. It works for me [Account Abandoned 8/8/16 Please Do Not Attempt Contact Or Expect A Reply]. See you on YouTube! -ChuckE2009
Reply:Lanse while it is true I suggested this to you a while back before your feelings got hurt. I did not direct this towards you.  As it is clearly labeled it is for newbies and hobbiest, both of which you clearly feel you are not.  I did not watch your latest video as that was your advise to me.  I am sorry you feel this is directed at you; it clearly wasn't my intent.  Looking back it was in post #3 that I made my mistake and mentioned telling someone and yes I had mentioned this to you. And yes it had fallen on deaf ears.  I was pm'd and asked if you were the one and I replied "was it that obvious?"  Had I wanted to aim it at you I would have mentioned your name.  Go back and read, I don't take cowardly shots!  I call it like I see it and typically address who it is I am calling out. Again I do apologize if you feel this was directed at you.  People (newbies) are always looking for projects and they are going to be wanting to "test" coupons.  That was my intent.  I have had my share of using a hammer destroying coupons enough to know it is a foolish waste of time except to see if you were able to penetrate deep enough to reach the root of the joint.
Reply:Scott, it's all good man my feelings aren't hurt or anything. My method works for what I do, just thought I'd clarify that.. Thanks for the response [Account Abandoned 8/8/16 Please Do Not Attempt Contact Or Expect A Reply]. See you on YouTube! -ChuckE2009
Reply:Simplest method to test welds is a simple compact bender.  CEP posted up a good example using one, and I've got picts of using mine to do some basic bends awhile back somewhere. The biggest issue is most actual tests are based using 3/8" or thicker samples. My guess is to get decent results on thinner material like 1/8", you'd have to use a narrower center pin to get the smaller weld stressed enough. Same thing applies with hammer tests. Usually with thinner materials like 1/8", the material will bend before the weld gets stressed. That really doesn't give you any solid data. I've also noticed that newer welders tend to pile on way too much material in general. That also won't give you the results you need for decent feed back on your welds.Doing some bend tests on 1/8" materials is on my "around to" list. I can get plenty of 1/8" coupons at the tech school to do some trails with different pin diameters to see if there's a decent size that stresses the material well. The problem with thicker material is that guys with small machines can't do conclusive tests because the material is simply too thick for what their machine can handle.There's a "project" for you Lanse. See if any of your instructors have any suggestions for test data for bends on say 1/8"..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:I remember that post and like you it is on my "around to" list.  I have too many honey dos at the moment for much playing.
Reply:Torchmate 2x2 CNC with Flashcut CNC controlsHypertherm Powermax45 Esab ET220i Razorweld 195 MigRazorweld 200ac/dc TigTormach 770, Tormach xstechRazorweld, Vipercut/Vipermig, SSC Foot Pedal Dealer
Reply:Originally Posted by Gamble
Reply:you could even do the math to calculate velocity and then obtain the energy delivered at impact.However - and I'm just spitballing here - Why not just cut the weld crosswise? Then file or sand it smooth and inspect with a good  glass.Wouldn't that tell you everything you need to know about penetration and bonding with the substrate? Here's an interesting story about Hammers:I worked for a while in a machine shop that Inter Alia serviced a  tube bending shop.  the tube benders were all these Brazilian Italian guys many of whom spoke almost no English.The tubes were bent in a variety of machines ( no CNC benders)  and then placed in Jigs that we made  to fine tune them.  The shapes were often quite complex.  Mostly we made tube jobs for Aerospace and especially US military jet aircraft.  Anyway  I when I started working there I noticed that all the tube benders had little carts  each was festooned with a whole slew of hammers of different shapes and sizes.  So I had to ask.The answer: "Well-a dis my 10-thou hammah an dis-a one my 5-thou hammah" and like that. Every hammer was used to produce a unique energy when delivered with the practiced skill of the tube bender guy whose swing  was so consistent that he could move  a piece  of pipe the same amount over and over again  across a whole production run.Talk about lost arts.Hey~!! It's a hobby. It's not supposed to make sense~!!
Reply:most noob welders will have so much variation in results that such a test would be meaningless.being consistent takes a lot of hours.miller thunderbolt 250vlincoln square wave tig 175 prolincoln idealarc mig sp250everlast tig 210EXTeverlast power plasma 50chicago electric (hf) 130 tig/90 arcchicago electric 90 amp flux wire3 sets oxy/acet
Reply:If you want i can get you some pictures of sharpy break tester we made at the collegethere is alot too it sensors software and what notMiller Xmt 350Lincoln Ln-25Ahp 200xSmith Gas Mixer AR/HTig is my Kung FuThrowing down dimes and weaving aboutInstagram http://instagram.com/[email protected]
Reply:Wilkie, that would be cool to see.
Reply:Other than getting a kick out of watching Lanse's AWESOME videos, what's the purpose of the rest of us for making these tests in the first place?  Especially when there's been countless studies, tests, books and periodicals already published, telling us what we already know; that is that 7018's are stronger than 6010, 6011, 6013, 7014 and 7024's.  Or that 6010's are stronger than 6013's and 70-series has more tensile strength than 60-series electrodes. Kinda silly for the average joe to waste money and bend pieces of steel, when anyone can read a book  (ie.  Lincoln's "Procedure handbook of arc welding") to find out what stick, rod or electrode is the "best" to suit one's particular needs.  Publications have already taken the guess work outa "type A weld is better than type B." Lincoln Power Mig 216Lincoln AC/DC-225/125Miller  625 X-Treme PlasmaMiller 211 Forney 95FI-A 301HF 91110Victor Journeyman O/PMilwaukee DaytonMakita  Baileigh NRA Life Member
Reply:Originally Posted by SuperArcOther than getting a kick out of watching Lanse's AWESOME videos, what's the purpose of the rest of us for making these tests in the first place?  Especially when there's been countless studies, tests, books and periodicals already published, telling us what we already know; that is that 7018's are stronger than 6010, 6011, 6013, 7014 and 7024's.  Or that 6010's are stronger than 6013's and 70-series has more tensile strength than 60-series electrodes. Kinda silly for the average joe to waste money and bend pieces of steel, when anyone can read a book  (ie.  Lincoln's "Procedure handbook of arc welding") to find out what stick, rod or electrode is the "best" to suit one's particular needs.  Publications have already taken the guess work outa "type A weld is better than type B."
Reply:Superarc,My intent was for a hobbiest to have a project that could help him accurately measure the strength of one coupon against another instead of using a hammer.  I agree we can all read a book.  But as you know some like to see for themselves.  As for cost what is the cost of 3 joints and some hardware?  I will be using this as time well spent teaching my kids.
Reply:Originally Posted by Scott YoungWhen I was a carpenter we had a contest of who could drive the most 16d nails in with one lick. They were started online a 1/4 inch.  The old trim carpenter with his 16 oz hammer beat all us framers with our 22 and 28 ouncers.  He didn't even have a large swing.  Problem was not how many we drove perfectly, but rather how many we messed up!
Reply:Originally Posted by SuperArc, what's the purpose of the rest of us for making these tests in the first place?  Especially when there's been countless studies, tests, books and periodicals already published, telling us what we already know; that is that 7018's are stronger than 6010, 6011, 6013, 7014 and 7024's.  Or that 6010's are stronger than 6013's and 70-series has more tensile strength than 60-series electrodes. Kinda silly for the average joe to waste money and bend pieces of steel, when anyone can read a book  (ie.  Lincoln's "Procedure handbook of arc welding") to find out what stick, rod or electrode is the "best" to suit one's particular needs.  Publications have already taken the guess work outa "type A weld is better than type B."
Reply:Originally Posted by KelvinUm, ever heard of destructive testing to check for weld integrity? Apparently not. I guess someone named "SuperArc" doesn't NEED no stinking testing.Your "Procedure Handbook of Arc Welding" probably has an entire chapter or two devoted to the subject, along with diagrams and/or plans for the very testing apparatus the OP is talking about.You can use the strongest welding electrode in the world, but if your weldment has all kinds of discontinuities, it's not going to be worth a darn. That's why becoming a certified welder usually involves a lot of test coupons and destructive testing.So I'm thinking Wook should bring one of those testing contraptions to Weld-o-Rama!!! The only thing I have is a BFH single jack!
Reply:Sorry, Superarc, I guess I misread you.I got the feeling you were saying that there was no point to destructive testing – with a BFH or otherwise – and that books could tell you all you needed to know about how good a particular weld specimen was.IMHO, destructive testing is especially important for hobbyists/amateurs because it will reveal a lot of bad welds and teach new guys that you can't always tell if a weld is acceptable just by looking.Carry on.
Reply:Personally I think you need both types of testing, bend, and impact. I welded up a V-butt plate with 6013, it bent just fine! Latter I did a 6013 fillet break test with hammer, and it broke with only 3 blows of a 4-pound hammer. Attached ImagesDon’t pay any attention to meI’m just a hobbyist!CarlDynasty 300V350-Pro w/pulseSG Spool gun1937 IdealArc-300PowerArc 200ST3 SA-200sVantage 400
Reply:Originally Posted by KelvinSorry, Superarc, I guess I misread you.I got the feeling you were saying that there was no point to destructive testing – with a BFH or otherwise – and that books could tell you all you needed to know about how good a particular weld specimen was.IMHO, destructive testing is especially important for hobbyists/amateurs because it will reveal a lot of bad welds and teach new guys that you can't always tell if a weld is acceptable just by looking.Carry on.
Reply:Originally Posted by KelvinSorry, Superarc, I guess I misread you.I got the feeling you were saying that there was no point to destructive testing – with a BFH or otherwise – and that books could tell you all you needed to know about how good a particular weld specimen was.IMHO, destructive testing is especially important for hobbyists/amateurs because it will reveal a lot of bad welds and teach new guys that you can't always tell if a weld is acceptable just by looking.Carry on.
Reply:How about a jig that holds the test coupon in a certain position to be set on a press with a pressure gauge? I think that as long as the test pieces are all shaped equal and the jig is stout enough to staty put during the whole process... it should provide acurate data.Coupons will probably bend before breaking, due to the nature of the force applied to the coupon... but will provide good data anyway.Mikel
Reply:I believe Kelvin was making the point of his message that testing the weld joint is a way to check the quality of the weld as it relates to the welders skill, and not necessarily if the material used was best for the application.  Superarc seems to have been slightly blinded to the intended idea by his perception of Kelvin’s lack of respect in his response, and felt the need to defend himself.  But often when we miss the initial concept or idea, and choose to defend the intellect rather then address the initial idea, we do more damage to our own reputation then the perceived damage done by others.  We do best to avoid the piece of dung that is thrown at us, neither "letting it get to us" by catching it, nor "going out of our way" to produce more to throw back, thereby keeping ourselves clean.  But we all come short from time to time when it comes to the proper application of wisdom (I know I do), and so we need to be generous with one another and learn from one another rather then rip each other apart.In school last week, using 7018 in the flat position, I welded a 3/8-inch plate (45 degree bevel, ¼-inch gap), using a backing plate. After multiple passes I then removed the backing plate and cut the plate into five sections to bend test.  The test pieces will be bend tested at the end of this week.  The purpose of the test is not to teach me which rod is best for this or that application as a book may suggest, but rather to see if my welding “skill” is such that the weld joint will maintain its integrity when stressed.  If time permits, I will post a write up with pictures this weekend.Peace,GarLincoln Electric, Power MIG 256Hypertherm Powermax 45 Miller Dynasty 280DXSmith O/A torchGenesis of a welding table
Reply:Originally Posted by GarI believe Kelvin was making the point of his message that testing the weld joint is a way to check the quality of the weld as it relates to the welders skill, and not necessarily if the material used was best for the application.  Superarc seems to have been slightly blinded to the intended idea by his perception of Kelvin’s lack of respect in his response, and felt the need to defend himself.  But often when we miss the initial concept or idea, and choose to defend the intellect rather then address the initial idea, we do more damage to our own reputation then the perceived damage done by others.  We do best to avoid the piece of dung that is thrown at us, neither "letting it get to us" by catching it, nor "going out of our way" to produce more to throw back, thereby keeping ourselves clean.  But we all come short from time to time when it comes to the proper application of wisdom (I know I do), and so we need to be generous with one another and learn from one another rather then rip each other apart.In school last week, using 7018 in the flat position, I welded a 3/8-inch plate (45 degree bevel, ¼-inch gap), using a backing plate. After multiple passes I then removed the backing plate and cut the plate into five sections to bend test.  The test pieces will be bend tested at the end of this week.  The purpose of the test is not to teach me which rod is best for this or that application as a book may suggest, but rather to see if my welding “skill” is such that the weld joint will maintain its integrity when stressed.  If time permits, I will post a write up with pictures this weekend.Peace,Gar
Reply:Originally Posted by SuperArcGar, I believe Kelvin and I already worked out our differences and the issue was closed.  Why are you stirring the pot???  That's called being a "troll."   Perhaps you need to pay attention a little bit more in "school," there Son.  Maybe take a critical thinking class or two while you're at it.
Reply:[QUOTE=Scott Young;2559661]The failure of the BFH testing method is you can not deliver the same umph with each blow nor can you maintain the same angle and impact point.i would suggest you do not use the bfh system correctly, so you call it a failure.it is not about quantification. it requires repeated blows from varying angles. it provides information that permits a level of confidence or says grind it out.
Reply:Originally Posted by GarForgive me sir, but while I was typing my response, no one else had said anything (at the very least I had not seen it).  After I posted it, you two had already kissed and made up. But looking at the time posted comparatively I'm not sure what happened, but know this, had I seen the information you mentioned, I would not have posted. GarEdit: It appears I read only page one of the original post and did not realize there was a page two where the conversation continued and resolved itself. Wow, don't I look stupid. In addition to the "critical thinking" classes you so graciously recommended, I'll work on my observation skills as well.
Reply:Hi, I don't suppose the tensile strength testing of a steel test piece would indicate any results?Given that the tensile strength of mild steel is approx, give or take a pound or two, 27 tons per sq inch.If you welded two pieces of plate together with a butt weld, then tried to pull them apart length ways....the plate should break at any point other than the weld, but if it consistently broke at the weld joint for a number of test pieces, then you can't weld for toffee.1 sq inch is 1" X 1", but for a test, if the plate was .375" thick you would need a piece 2.667" wide and as long as you want, put in a press with a pulling jig and pulled till it broke, monitoring the tonnage all the while.Is this a viable test result?If not, why not?Would the heat of the weld anneal the plate and make it soft in the weld zone?Ian.
Reply:Weldbead, it is of value as you described.  My point was it is of little value comparing coupon to coupon as the variables are to many to control.  To say x electrode is better/stronger/tougher than y electrode because x electrode took 10% more blows from a hammer if inherently flawed? Each blow is different in ftlbs.  The angle of force is different and the leverage is different with each impact due to differing impact locations.It is also a simple project someone can build that will utilize their fitting and welding skills.  When I was younger I scrounged for projects.This is just my opinion though.Last edited by Scott Young; 04-30-2013 at 07:49 AM.