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Discussion in 'The Garage' started by KTM640Dakar, Mar 5, 2007.
You can use 5356 or 4043 filler. 5356 is stronger. 100% Argon gas TIG weld it.
Thanks for the input everyone. Mr. Dakar, I believe that the welder mentioned both of those rod types, so it sounds like he's right there along with you. He said the 5356 is trickier b'cause of the potential for fracture. My guess is just that he's not welded cast aluminum in a while. Would you too have discarded the broken off piece and just built up new metal to make the weld? The broken piece was small but I thought it could have saved quite a bit of trouble as far as providing the hole for the pin, even if it had to be rebored. Is TIG just too hot for a small piece of aluminum?
Here's the piece by itself:
I would have discarded as well. To achieve full penetration on a piece that thick you'd have to grind a bevel on all four sides of both pieces and make multiple passes which would be difficult in at least two directions due to space constraints. By discarding and building up you've got plenty of room to work. Were it not a stressed part I'd not worry about full penetration and reattach the old piece by beveling lightly and burning it in as hot as I can get away with.
As for my opinion, I'm only a semi-pro. I have (and still can) certify GTAW (TIG) and do weld professionally on occasion but not as a full time welder/fabricator. My advice is worth exactly what you've paid for it.
Yes sir, you are in complete agreement with Mike, and he's an extraordinary welder. I got to check out his shop and some of the projects he's working on today, and I feel lucky to have him working on my humble repair.
He knocked up a clever little jig using a machined (and then knurled) piece of copper rod with a center bore and a copper block and an aluminum block to offer both a heat sink, and something to weld up against as he builds up material for the new mount.
I wish I could be there to see it when he welds, but then again if he's like most people I know, even some masters don't like having someone look over their shoulders. I'm thinking I'm going to offer to clean up his shop 3 times a week for some lessons! Besides welding, I want to learn how to use this monster milling machine:
It looks like your in good hands for the repair.
I'm glad you appreciate the man's skills. Too many folk today would just complain about the cost, regardless of the skill and tools used for the repair. Weldors have far more skill than their profession allows them to charge.
I can weld at a hobby level and would be glad to show friends what I know; except that I completely fall apart and when someone is watching.......I can hardly solder. I have a very good friend that doesn't care how close I get when he's working on his lathe and mill. He can concentrate completely when I'm there, asking questions. :huh
Yep, I'd sweep his floor, just to be in the same room when he works.
We're of like minds then. I love your Garrison Keillor quote there at the bottom too. God I've been trying to sum things up that well for years. Thanks! Bookkeeping indeed.
I found that quote when I was married and clipped it out of the newspaper. Years later, I found it in a pile of papers, after my divorce.
It freaked me out. :eek1
The weld is complete, and I'm glad to say it looks pretty tough. I'm still cleaning it up a bit, and have some concern that the pin doesn't rotate as freely in the welded side as on the other side, but I'm still working on it. Mike used 4043 as Mr. Dakar suggested. I believe he is pleased with the result also. The price tag wasn't cheap, but I don't think I'll be worrying about it.... after the first few rides.... Here are the pics:
Thanks for all the replies!
Thanks for the follow-up pics. I love seeing alum repairs, it's like science fiction.
Does the pin need to rotate in the alum, or does that happen on the other piece? (steel pin in alum vs steel pin in steel)
Color the inside of the hole with a felt tip marker, gently push the pin into the hole until it rubs. Wiggle it a little, pull out, see where the marker is gone, and clearance that one spot, in the alum. I have several rat-tail files, very handy for this sort of thing: 1/4, 5/16, 3/8, 7/16 and 1/2".
Thanks man, yeah the pin rotates freely inside the lever, if that's what you mean. Wirespokes suggested snug was better than sloppy. Of course I don't want sloppy, just smooth resistance free rotation. My thought was that the original design was to allow all parts to rotate relative to one another freely. Of course we all know how well the design for this mechanism worked out, so maybe all bets are off. If people are really replacing the pin with through bolts that are threaded on the end and a locknut, I wonder just how much one of those would rotate freely.
I will do the marker trick as you suggest. Thanks!
just a thought, but if it truely does see rotation during riding then that steel pin will clearance itself in that aluminum within a couple miles of riding. I wouldn't sweat it too much.
I don't know about yours, but my R75/6 has a grease fitting.
That is a beautiful fix!
If I remember my R60/5 correctly, there is a grease fitting - on the arm. This implies to me that the pin stays put and the arm rotates on it. If the pin goes in, I think you're good.
And here's a question:
I need to weld aluminum (7075 specifically, to start). All my experience is with oxy/acetylene (mostly brazing, but I can do a good bead if I need to) and some stick/arc way back when.
I'm assuming that I should move to a TIG machine - but I don't know what level/features are really needed.
In my ignorance, it looks like a Lincoln square wave 175 or equivalent is it.
Too much? Or not enough?
That looks an awfully complicated and costly way to do a repair job, which should have taken 30 minutes at most and certainly didnt need any of those copper pieces making!
Al that was required here was to clean up broken part, fit a piece of steel rod (an old bolt would do) to take the place of the OE pivot pin, and weld using 4043 5%Mg rod. There would be a need for a bit of work to shape the repair properly, and cost of the welding would be around $50.
I googled "welding 7075". From ESAB (competes with Miller and Lincoln)
How Do I Weld 2024 and 7075?
Q - I come into contact with two aluminum alloys of which I have found difficulty in obtaining information about arc welding. These alloys are 2024 and 7075. Can you provide me with information on how to weld these alloys with either the GMAW or GTAW process?
A The reason you are having difficulty finding information on welding 2024 and 7075 is that both of these materials belong to a small group of aluminum alloys that are generally considered as being unweldable by the arc welding process. These materials are often found on aircraft, sporting equipment and other types of high-performance, safety-critical equipment and are not usually arc welded on the original component. Probably, the two most commonly found aluminum alloys within this category are 2024, which is an aluminum, copper, magnesium alloy, and 7075, which is an aluminum, zinc, copper, magnesium alloy. Both of these materials can become susceptible to stress corrosion cracking after welding. This phenomenon is particularly dangerous because it is not detectable immediately after welding, and usually develops at a later date when the component is in service. The completed weld joint can appear to be of excellent quality immediately after welding. However, changes which occur within the base material adjacent to the weld during the welding process, can produce a metallurgical condition within these materials which can result in intergranular micro cracking, which may be susceptible to propagation and eventual failure of the welded component. The probability of failure can be high, and the time to failure is generally unpredictable and dependent on variables such as tensile stress applied to the joint, environmental conditions, and the period of time which the component is subjected to these variables.
It is strongly recommended that great care be taken when considering the repair of components made from these materials. It must be stressed that if there is any possibility of a weld failure becoming the cause of damage or injury to person or property, do not perform repair work by arc welding on these alloys and then return them to service.
Well I don't know how to respond to that except to say that the guy I found was the only person in the area who would even take the job, so I wasn't in much position to dictate prices (nor do I know enough about welding aluminum to dictate method). I'm glad he took the time to do it carefully and ultimately the piece is likely better than it was prior to the break. I told him up front that I would dress the weld and make it pretty/fit the bolt, and he took it upon himself to make the jig. Unfortunately that part took an hour, but I probably would have messed it up had he not done it for me. I don't even have a drill press.
He's not a motorcyclist, so I'm glad that he took very seriously the fact that our lives literally depend on our machines not failing us at critical times. I know I do. To me it's worth it to know he didn't just slap on some metal haphazardly. I know it's not just one or the other, but who would know if you didn't have someone like him who was willing to let me see what he was doing, and doing it carefully? Everything I've read about welding cast aluminum is that it's always a risky enterprise, and particularly so when it's a part that experiences constant stress, vibration, temp changes, is soaked in oil, etc., etc. You tell me. Was I taken for a ride? :huh
By the way, when was the last time you performed this exact repair?
Yes, and that was the "common" knowledge for me as well - until I found some information from Easton, a mfg of aluminum tubing for frames:
Weld beads should be done in one pass. Starting and stopping should be kept to a minimum. The starting and stopping point of weld beads should be on the sides of the frames, never on the vertical axes.
Avoid welding over a previously welded joint. This will further weaken the joint by building stress and damage the tube by creating a larger heat affected zone. Welding over tacks is acceptable. Tacks should be small and on the sides of the frame never on the vertical axis of the frame. Keep the weld beads to reasonable size. Extra large weld fillets require excessive heat and damage the tube. Weld fillets should blend smoothly into the tubes.
Welds should not burn through tubes as this will always weaken the joints. This damage is easily visible from the inside. Some distortion is to be expected. If burn through is unavoidable, due to thin sections being welded, a secondary continuous purge attachment is necessary to provide a gas shield on interior of tube.
Weld fillers for 7005:
Use 5356, 5180 or 5183 fillers for welding 7005 frames.
Alignment of 7005 frames:
Minor alignment after welding should be performed as soon as possible while material adjacent to the weld is in its softest state. 7005 age-hardens rapidly making alignment much more difficult as time advances. As tubes re-age-harden the force necessary to straighten the frame increases. This can lead to damage to either the tube or the weld
that will not be easily detected and can shorten the life of the frame. Less than 6 hours is the recommend time frame for alignment. If frames are built in subassemblies, alignment should be done on each subassembly within6 hours."
I will also note that many bicycle frames (such as the one I want to modify) are welded of 7075.
So - for welding of Aluminum in general: Squarewave 175 - too much, or not enough?