Bordfunker Posted August 14, 2019 Report Share Posted August 14, 2019 The aviation industry has been using glues instead of welding and rivets for over 40 years now, in order to not only save weight, but improve strength, so if it’s good enough for an Airbus, should be good enough for a Triumph. Lotus stopped welding the chassis for their cars a while ago, switching to bonded joints to reduce stress due to heating, so the industry has moved on on some levels, but not on others. Karl Link to comment Share on other sites More sharing options...
RogerH Posted August 14, 2019 Report Share Posted August 14, 2019 Hi Karl, go back another 30 years at least. Fokker were using bonded joints in the 1940. They lead the way for many years in perfecting methods of bonding Ali Alloys and then how to inspect them during their life. De Haviland were up and running with bonding in the late 50's. The DH121 TRident had quite a lot of bonded joints. Rivet holes are dangerous things and the less the better. I used some aerospace Araldite back in 2005 to bond the hinge to the flap of the TR4/4A air intake in front of the screen. These are Stainless Steel and still well stuck down and no rusting. Sadly aerospace Araldite is expensive wit a capitol E Roger Link to comment Share on other sites More sharing options...
Badwolf Posted August 14, 2019 Author Report Share Posted August 14, 2019 Karl/Roger - Thanks for the input on this. Quite an eye opener. Karl - Unbeknown to you, it was you indirectly that started me on this quest. I will try to find the post as you will, without doubt, be surprised. Link to comment Share on other sites More sharing options...
Badwolf Posted August 14, 2019 Author Report Share Posted August 14, 2019 Karl - Here they are, these are the links that started me off. You gave me the initial link to this site a long time ago for which I am very grateful I am incorporating many of the techniques used by this restorer into my work, as I believe are you. I actually met him at the Practical Classics restoration show in March (2019) and had a good chat. He certainly knows his stuff and puts it into practice, although more of a perfectionist than I will ever be. Door repair panel, about half way down the page..... http://forum.retro-rides.org/thread/204767/jowett-jupiter-accident-completed-delivered?page=6 .. discussion follows on to the following page Door 're-sizing' down when too big for the hole!!!.... http://forum.retro-rides.org/thread/204767/jowett-jupiter-accident-completed-delivered?page=7 Link to comment Share on other sites More sharing options...
Badwolf Posted August 20, 2019 Author Report Share Posted August 20, 2019 Right. So I have finally had a chance to do a destructive test on the adhesive Started with two pieces of 1inch square tubing and bonded them together at right angles. From one side from the other the joint area is the full width of the tube 1" x 1". Then the assembly was clamped into the workmate and a bucket of scrap metal weighing 31 pound (lb) hung from the horizontal arm 11 inches from the joint to start with and steadily moved along until it got to 18 inches away and on the 19th it finally failed after nearly pulling over the workmate and bending the bar a little in the jaws The faces looked liked this after breaking.. So, not sure exactly what this means in terms of force, torque, strength or whatever. I will leave it to those of you of greater proficiency in maths, force etc to work out what this rather basic experiment means in terms of the strength of the joint and whether it is stronger than say a spot weld. I suppose that this equates to about 46ft lb (31 x 1.5) of force but does the cross section of the joint come into the equation as well? Actually I found the results a little disappointing as I was hoping it would take more weight Link to comment Share on other sites More sharing options...
Pete Lewis Posted August 20, 2019 Report Share Posted August 20, 2019 Well to compare. ?.... you need to repeat the test with spot welded test peices Then we all know Pete Link to comment Share on other sites More sharing options...
Badwolf Posted August 21, 2019 Author Report Share Posted August 21, 2019 Good idea, but if I could spot weld.... I wouldn't have started this in the first place. 1 Link to comment Share on other sites More sharing options...
Pete Lewis Posted August 21, 2019 Report Share Posted August 21, 2019 Drill hole and a quick puddle might simulate to test if weld is better , how many table legs have you got ?? Pete Link to comment Share on other sites More sharing options...
Badwolf Posted August 21, 2019 Author Report Share Posted August 21, 2019 Four but can reuse those already tested but still no welder to make puddle!! Link to comment Share on other sites More sharing options...
Pete Lewis Posted August 21, 2019 Report Share Posted August 21, 2019 Ive got a stick welder and a SiP mig all lost in the cupboard, the mig needs a new £25 gun fitting on the pipes , as old has blow a hole Looking for a new home , never bothered to repair it as welding is not my chosen hobby If you want to play ?? Pete Link to comment Share on other sites More sharing options...
Badwolf Posted August 21, 2019 Author Report Share Posted August 21, 2019 Thanks for the offer, very much appreciated, but I'm in the same boat with welding. For what I need to do, I don't want to start down that route. Looks like I may have to just do the job a see if it comes apart under real conditions. I really was hoping that the joint would take more load... like this one... https://m.youtube.com/watch?v=G6oLx4FjPVg https://m.youtube.com/watch?v=DqKj9iwg1Mk You can see the basis for my test but I can't find 3M dp420 to test in the uk. I may try dp490 which looks similar spec. Link to comment Share on other sites More sharing options...
Mjit Posted August 21, 2019 Report Share Posted August 21, 2019 A spot of back-of-the-fag-packet maths says: 31lb = 14kg / 18" = 0.46m (trying to do engineering calculations in imperial units is a form of Sadomasochism) 14kg under gravity exerts a force of 137N 137N on a 0.46m moment arm is a torque of 63Nm, or 46ft lb. To give that some context - 10 nuts torqued to 46lb ft is enough to keep an air tight seal between the engine block and head under the force of 200 little bombs going off every second (I THINK my maths is right there - 6,000RPM = 100RPS, and 2 cylinders fire every rvolution?) Link to comment Share on other sites More sharing options...
Badwolf Posted August 21, 2019 Author Report Share Posted August 21, 2019 Wow. I am impressed, with your fag packet!!! I assume that your calcs are right as 'I know nothing' about this stuff. Sorry about the imperial units though. So it does look that the bond was stronger than I thought. I have just whinged to the adhesive supplier... oh well, will see what they have to say!!! Link to comment Share on other sites More sharing options...
poppyman Posted August 21, 2019 Report Share Posted August 21, 2019 Instead of a blob of weld Badwolf, how about a couple of small nuts and bolts along with the adhesive? Tony. Link to comment Share on other sites More sharing options...
Pete Lewis Posted August 21, 2019 Report Share Posted August 21, 2019 dont we have enough nuts on here already ??? small ones and big ones Ha ! pete Link to comment Share on other sites More sharing options...
Badwolf Posted August 21, 2019 Author Report Share Posted August 21, 2019 Tony - The blob of weld was to simulate a spot weld, which in turn was to compare with the adhesive. The idea is to chemically bond the steel and pop rivet along the joints every 2 inches or so to hold the joint while the adhesive cures. I am open to most offers regarding the actual job. It is just the testing to get the correct adhesive for steel at the moment. I am even thinking about the difference between a simple self tapping screw and a spot weld etc. I am trying to evaluate all ideas so the more the merrier. Criticism, ideas, 'wouldn't do it that way', it all counts to helping me and so everyone on the forum. The comments already made to me both by an expert in speciality steel and about the length of time that bonding has been used has absolutely staggered me. If what I am trying helps anyone other than me, I will be well pleased. Link to comment Share on other sites More sharing options...
Pete Lewis Posted August 21, 2019 Report Share Posted August 21, 2019 looking at the surface area compared to a few spots i feel youre on pretty safe ground structural would be best left to welds but attachments could adhere with ease and from your simple test prove to be quite stable any fail would be progressive , where as welds juts fail, there;s no its going , just gone ask Kevin if they glue his rockets together ??? Pete Link to comment Share on other sites More sharing options...
Badwolf Posted August 21, 2019 Author Report Share Posted August 21, 2019 Pete - Kevin's rockets are supposed to go whizz bang all gone in a blue light... that's what I'm trying to avoid, but point taken I wasn't sure exactly how the area of bond (in this case 1 square inch - sorry mjit) related to the strength calculations. Greater area, greater strength, so a seam 6 inches long by 1/2 inch wide (sorry again) should be stronger than the test piece but, is the total of 3 sq inches (I give up, its imperial, I have to live with it) significatly stronger than the 1 sq inch and by how much. Answers on a postcard or any other method please. Link to comment Share on other sites More sharing options...
Pete Lewis Posted August 21, 2019 Report Share Posted August 21, 2019 this has got me ..............riveted size matters... more to some than others Pete Link to comment Share on other sites More sharing options...
poppyman Posted August 21, 2019 Report Share Posted August 21, 2019 2 hours ago, Badwolf said: Tony - The blob of weld was to simulate a spot weld, which in turn was to compare with the adhesive. The idea is to chemically bond the steel and pop rivet along the joints every 2 inches or so to hold the joint while the adhesive cures. I am open to most offers regarding the actual job. It is just the testing to get the correct adhesive for steel at the moment. I am even thinking about the difference between a simple self tapping screw and a spot weld etc. I am trying to evaluate all ideas so the more the merrier. Criticism, ideas, 'wouldn't do it that way', it all counts to helping me and so everyone on the forum. The comments already made to me both by an expert in speciality steel and about the length of time that bonding has been used has absolutely staggered me. If what I am trying helps anyone other than me, I will be well pleased. I see what you mean now i have read the post fully Duuuuh. It is going to be an interesting outcome Badwolf. It is of intrest to me about the different types of bonding agents there are, so i will keep watching and learning. It was good to know in one of your tests how brittle an adhesive is as some are strong but very brittle. Keep up the good work Tony. Link to comment Share on other sites More sharing options...
poppyman Posted August 21, 2019 Report Share Posted August 21, 2019 3 hours ago, Pete Lewis said: dont we have enough nuts on here already ??? small ones and big ones Ha ! pete Agreed Tony. Link to comment Share on other sites More sharing options...
Badwolf Posted August 21, 2019 Author Report Share Posted August 21, 2019 I have had an interesting email correspondence with Fastmovers. The adhesive that they sent me had a sell by date of 01/07/19. On examining the test very closely I notice that the bond appears to have 'torn', rather than fractured, which makes me think that the bond has not cured properly even though it was well mixed and left to cure for about 5 days.. The adhesive has stuck well to the metal but has failed 'within itself' so to speak. I did notice on mixing that one of the components appeared to be a little on the thick side. I took up the date thing with Fastmovers who apologised and told me that they did not have any 'new supply' (!!!) and was there anything else that I would like to try or they could give me a full refund. They are sending me another type of adhesive and I will do similar tests on that. Sorry if this is getting boring, but it may be that the final bond is actually stronger than the tests give credit for. As mentioned in previous posts I was very impressed with the reported strength of 3M dp420 but it does not appear to be available in the UK for some reason. Probably something nasty in it which the EU doesn't like, which makes it really, really good. Link to comment Share on other sites More sharing options...
poppyman Posted August 21, 2019 Report Share Posted August 21, 2019 1 hour ago, Badwolf said: Probably something nasty in it which the EU doesn't like, which makes it really, really good. Why not wait till 31st October Badwolf, it might become available ? Tony. Link to comment Share on other sites More sharing options...
Pete Lewis Posted August 21, 2019 Report Share Posted August 21, 2019 Dont start!!!! Link to comment Share on other sites More sharing options...
Mjit Posted August 22, 2019 Report Share Posted August 22, 2019 20 hours ago, Badwolf said: Tony - The blob of weld was to simulate a spot weld, which in turn was to compare with the adhesive. And of course while you'd use a series of spot welds along a joint you wouldn't use a series of adhesive blobs, rather a continual line, meaning a greater joining area and a stronger joint. 20 hours ago, Pete Lewis said: structural would be best left to welds Lotus have been using structural bonding on their cars since the Elise was released in '96... Link to comment Share on other sites More sharing options...
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