Anyone welded the centre shift ball on to the big cast saddle on a G series grader? We had one break off, through the weld, today. Simple enough job if you have the knowledge, unfortunately, welding cast is not one my strong points.:crying
I'm not a professional welder, but I know some things about cast. Everything has to be heated up slowly and thoroughly, and then welded with nickel rod. Then, after welding, it has to cool very slowly, preferably in an oven. All this means nothing if it's machinable cast though. I would talk to Cat. They probably have instructions for replacement of the ball.
If it was welded originally it's more likely cast steel? Yes, CAT will have a procedure they can print out.
Let's see a photo of the one that's failed please. I'm trawling through the system to find a welding procedure but drawn a blank so far - that leads me to believe it's nothing special to weld on a replacement. Looking at a 16H drawbar the welding of the ball is just a standard weld using 7018 if electrodes are used.
I believe the saddle is cast steel and only requires enough heat to drive off the moisture. As I recall the procedure is much the same as welding a new trunnion ball on a D8H or D9G.
It failed about twelve months ago and we welded it with some rods that were supposed to be the ducks nuts on cast. Very expensive and difficult to use, even after preheating. Iam leaning towards the WIA 16TC rods we have here, similar to the 7018 I believe. Could another option be flux cored mig wire ?
Correction.. The 16tc is actually a 7016, the WIA Austarc77 is 7018-1H8, and 18TC is 7018-1, there is also a 7018-1H4R. Iam in the big smoke tomorrow, so Iam able to easily get any of these.
Yair . . . Queenslander. In the old days most "cast" components on Cats, or Allis's were cast steel and were weldable with low hydrogen rods. In the CIG range they were known as Multicraft or Ferrocraft. They were not particularly user friendly but would run reasonable with a "tractor-pac" or similar machine . . . ours ran off the PTO on the Blitz. It was important to heat them to drive off any moisture and I had a piece of pipe welded to the exhaust and used to poke them in there to get the buggers hot. I guess you are jammed for room/short of material but with your present problem I would try to put a wedge point to the base of that ball and/or space it out as much as possible to get more weld in there with a good multi-pass vertical up on each side. Finish of top and bottom and then spend some time with the grinder and sanding disk to get a nice smooth radius on the weld . . . if that socket that fits over the ball hangs up, makes a mark or catches you have a stress riser straight away. You will find it easier to tack in position and get voids filled with ordinary old GP's for starters. Cheers.
I have seen many of those welded with hard wire MIG or just plain old WIA TC16's.Cat says a bit of preheat if its a cold day.I would go to 100 to 150C just to be sure.
It's hard to tell from looking at that photo but is part of the ball (inside the ring of weld that's left) still attached to the bracket or is that dark area inside actually the centreshift bracket..? I have scoured everywhere I could think of and come up with nothing, so based on experience and what information I can find about about welding these balls on the frame parts here's what I'd suggest. Firstly I need to state that it's very unusual for Cat to use any sort of special welding procedures or materials to join structural components. Apart from a very few cases the welds for pretty much everything are specified as 7018 or the equivalent in all-position flux-cored or gas-shielded wire. Here's my suggested procedure: - 1. Take the ball and clean up all the failed weld from it. Once you have the ball clean you need to machine or grind a bevel on the end that butts up to the centreshift housing that is about 10mm x 45 degrees in profile. A bit like the diagram below. The final weld will be in 2 stages, first a 10mm x 45-degree groove weld followed by a 12mm x 45-degree fillet weld. 2. Clean up the cast housing so the ball sits square and butts up tight on it. Once you are ready to weld preheat the housing in the area around where the ball is to be welded and the ball itself to around 100-120 DegC and locate the ball in position with 2 small tack welds 180 degrees opposite each other in approximately the 4:30 & 10:30 clock positions. You'll see why when we get to the next step. 3. Keep the temperature of the assembly up around the 100-degree mark from this point forward and using 7018 electrodes (I don't think a wire-feeder torch will get in the root satisfactorily, or at least it won't be very manoeuverable) weld the root pass of the 10mm groove starting from the 12 o'clock position to the 3 o'clock position. Then weld the root pass starting from the 6 o'clock position and to the 9 o'clock position. The size of electrode used in the first few passes will be determined to a large extent by what diameter will comfortably fit into the root of the joint. Once you have those 2 root passes in place clean the slag and stress-relieve the weld using a needle peening gun. NOTE: This procedure will be at least a 2-man job - one to weld and the other to handle the needle-peening gun. 4. Grind out the tack welds from Step 2. Inspect both ends of the two root pass welds from Step 3 and if necessary grind one or both ends of them to expose good weld metal. On a job like this you can easily expect to remove up to 50% of the metal you just laid in not 2 minutes ago if you want a good quality weld. 5. Weld from the 3 o'clock to the 6 o'clock and from the 9 o'clock to the 12 o'clock positions. Clean the slag and stress-relieve as per Step 3. Any weld that you're not happy about at any point then grind it out and do it again. 6. Continue to weld the 10mm groove weld, but for the next pass start at the 1 o'clock position and weld to 4, then from 7 to 10, etc, etc. You get my drift - all the joints between succesive weld passes are going to be in different places. Don't weld more than 90 degrees of the circumference of the ball at a time. Oh, and keep an eye on the temperature and whack a bit of heat into it every once in a while to keep it well up. Did I mention that ..? 7. As you get further up the groove it becomes easier and there will be a tendency to want to weave the electrode to fill the groove - Don't ....!! Weld using stringer beads and keep them as narrow as practical. If necessary lay 2 beads alongside each other then lay a 3rd bead over the centre of the first two but remember to de-slag and stress relieve after welding each bead. 8. Once the 10mm groove weld is completed, de-slagged, & stress-relieved then grind everything smooth and start the 12mm fillet weld the exact same way as per Steps 3 to 7. Don't weld more than 90 degrees of circumference at a time and stagger the start of each weld segment so that they overlap one another as per Step 6. 9. When the fillet weld is completed beat the bejasus out of it with the needle gun for at least 10 minutes then grind the whole surface of the weld smooth. Then using maybe a small burr wheel blend the fillet weld into both the centreshift bracket and the ball so that the surface is 100% smooth and by smoothing off the surface you have eliminated most if not all stress risers.
Thanks once again Nige, I think it would be impossible to find a more comprehensive description anywhere. The ball will clean up very well, similar to your drawing, but with bigger bevel, maybe 20 mm x 45 deg. Thanks also to others for your suggestions, Iam sure Iam on the right track now. Cheers, Greg
I have no problem with a 20mm bevel, just be aware that with the larger size of bevel throat as you get away from the root you will need to be even more careful about not weaving the electrode when welding. You may find that starting with 3.2mm electrode in the root then going to the next size larger as you get closer to the surface may be a solution. Just don't be tempted to go too big on the electrode diameter in an attempt to "fill the hole" too fast. With the small amount of weld (relatively speaking) that will go in this repair it's doubly important to make sure the area gets neither too cool or too hot while the welding is taking place. Whatever temperature you start at, try to maintain it pretty much right at that level right the way through the process. I can't emphasise enough the need for the needle peening to stress-relieve the weld as it is being done to avoid creating stress risers once everything cools. Beat it with the gun, then beat it some more, then when you think it's been beaten enough beat it some more ...........
I've been thinking again about that weld. If your groove weld is going to be 20mm x 45deg then that would make the fillet weld to go over the top of it 22mm x 45 deg because the fillet has to overlap the end of the groove by a couple of millmetres. 22mm x 45deg is an awful big weld and brings it's own problems of stress-relieving (did I mention a needle peening gun..?), maybe it might be better to make an unequal leg fillet weld of something like 22 x 12 or 22 x15. It all depends what looks right when you start to do it. Just be aware of that fact and modify your fillet weld design to suit, something like a cardboard template cut to size will help you visualise what the final weld will look like. Decide what your fillet weld design will be before starting to burn rods. Either way when it's done grind it all smooth and radius all sharp edges.
I just read RayF's post #9 above and I agree with him. You can go as high as 150C on the preheat without doing any damage, maybe that would be even better than the 100-120 I suggested. The only thing you need to do is to keep it at whatever temperature you preheat it to right throughout the process and only start to let it cool once you have finished with your needle-peening & grinding after completing Step 2 of the weld (external fillet).
I know nothing about welding but I found this a very interesting topic. Thanks
Yair . . . Hank R. Well said, it is interesting and I have a couple of questions for Nige. Nige. To me the design concept of welding a piece of (say) three inch round onto a flat surface is a bit naff and I'm surprised to see it on a Cat. Most times there is a machined recess into which the component is pressed or driven. This effectively takes the thrust and the component can then be held in place by a (relatively) small weld all around. If the component is going to be welded all round as opposed to a full weld where it becomes part of the structure why is it preferable to introduce the awkwidity of the initial forty five degree slag trap versus machining the component off flat and putting in a larger version of your step two fillet all around? Thinking about it further if I was Queenslander I would even look into the feasibility (clearance wise) of welding the ball into a nice shaped piece of three quarter plate on the bench and then sticking it on there with a simple positional fillet all round. Not trying to be a smart azz, just throwing a few thoughts out there for discussion . . . . Cheers.
Scrub, you're quite right. The best way would be to have what is effectively a stub shaft on the ball that fit into a bore and then simply fillet weld the outside. However that costs additional money as regards machining. What happens today is that generally the inside weld is what's known as a J-groove (as opposed to a V-groove in this particular case) where effectively the bottom of the groove is much more accessible. To all intents & purposes the groove is parallel-sided with a radius at the bottom. I've put a diagram below comparing the 2 groove shapes. In fact if the OP could machine the ball to produce a J-groove it would be much easier to weld. You have to remember that I'm pulling information from sources some of which are 20+ years old and things have moved on since then, although as my late grandfather would often say - "we're advancing backwards" .......
Yair . . . Gotcha Nige. I'm afraid my thinking and methodology goes back further than twenty years with a bit of bush lore thrown in . . . mostly though it works. (big grin) As always, I and most folks here appreciate your knowledge and contributions to this forum. Cheers.
It's interesting to note that, although the saddle is a different design, on the H series the ball is pinned through it rather than welded on to it, a much better idea. I must say Iam beginning to get a little nervous with so much attention about to be focused on my, very average, welding ability. Iam going to try the WIA 18TC rods, which are 7018-1 I've used plenty of 16TC in the past, they are excellent it you are burning the whole rod in one pass but can be a little difficult to re strike a partly burnt rod. The 18 is supposed to be better.
TAKE your time and know fully what and how your are going to to weld and preheat the whole process before you start and have plenty of time to do the job and you will be done before you know it. I do like the idea of welding to a larger plate on the bench at least 3/4 to 1" thick then weld the plate to the machine but you still have to preheat and post heat it with a slow cool down period
G'day, While you are planning. I never had any joy in welding cast but I am only a backyard self taught. Last advices (not yet tested by me) I read about were to use 'stainless' wire with MIG. Advice I read was based on stainless not creating a carbon rich bond like other Mig wire which does not apparently work with cast. Of at least equal importance as senior members have mentioned is to 'peen' the weld immediately after the weld to take the contraction out of it on cooling, ie to stretch it. While the advice here is to keep the heat in it the advice I read about was to do short welds so it did not get too hot? Sorry the information is somewhat contrary apparently but maybe the better informed can make sense of this before you start to get to the bottom of it. Hate for you to start and have it fall off? I would for sure be tempted to have a mechanical fix to the inside of the ball to take pressure off the weld? Rod drilled right through? Welded at the ends? High tensile bolt recessed? I could have muddied the waters but better you are not stuck there doing a job twice, Regards, MX45
I think maybe we are confusing "cast" with "cast"........ Cat castings are generally cast steel rather than something even like SG iron and so are reasonably easy to weld something to, provided you do the correct preheat, stres relief and post heat. Getting into the tehcnicalities of it regarding temperature you have "preheat temperature" which is the temperature to which you heat the workpiece before starting to weld and "maximum interpass temperature" which is the maximum temperature which should not be exceeded just after you've stopped welding and are preparing to remove slag and needle peen. If the preheat temperature is 150 then the maximum interpass temperature would be something like 165-170. That's the reason to keep each weld short and to weld only 90 degrees of circumference at a time. TBH with the relatively small size of this component and the small volume of weld metal being deposited I would be more worried about the temperature dropping below the preheat value rather than exceeding the maximum interpass temperature. An infra-red thermometer is a vital tool in a procedure like this one.
Well, got it stuck back on this afternoon, may not be the perfect welding job, but I feel a whole lot more comfortable with it than our previous attempt twelve months ago. Was impressed with the 18TCs, nice to work with and easier to restrike than the 16s
That looks very good indeed, and grinding all the welds smooth will improve fatigue resistance no end. I would however suggest that you go back and grind out a few of the imperfections that are visible in the photos, each one of them is a potential stress-riser and crack initiation site. I've ringed a couple of them in red. Also I'd suggest after doing that to lay another bead right around the ball at the junction between the existing welding and the machine frame then re-grind. That extra bead will help smooth the radius of the weld/frame transition even more. I think the fact that you are happier with this repair than the one you did a year ago is the best indication that it's a good job.
Yair . . . Good one Queenslander . As suggested by Nige though another couple of hours dabbing and grinding would be time well spent. Ideally you should end up with a smooth radius with no surface marks or imperfections . . . not always possible or practical. I used to be a rough YOUNG b*****d and thought this smooth radiused weld caper was bull-****e. The first big rakes we built to go on eights were a poor design with the two inch thick Assab teeth butt welded to the ten inch by ten inch bottom member. Within about a month they started shedding teeth in stumpy going . . . weld them on and they'd fall off again. The boss had a CIG welding consultant come out and he spaced the tooth away from the bottom member (rake off tractor and upside down) with three pieces of sixteenth gas welding wire. After some preheat he had me weld about a twelve pass unwoven fillet around the tooth with Multi's then he radiused the weld with coarse and then fine stones run with a flexible drive on a Villiers engine . . . this was before the days of angle grinders. Well, as mentioned it seemed like bull****e but those teeth never came off. The welding wire apparently introduced a bit of "give" into the joint to help prevent initial cracking and smoothing the welds particularly around the front of the tooth prevented the stress risers occurring. As the rake accumulated hours the welds became polished and the teeth and bottom member appeared to be a casting with no visible weld. The problem was fixed on later rakes by profiling the teeth with a substantial "tab" which extended six inches or so up the front of the bottom member. Since that experience I have evolved into a rough OLD b*****d who (somewhat) understands the importance of eliminating stress risers in the welds of components subject to shock and intermittent loads. (big grin) Cheers
I'm a decent welder, my first impression was I would have thought the base metal would be way more discolored if kept at 150C for the duration. Looks great otherwise.
Certainly appreciate the advice fellas. The job only received minimal finish grinding because I was running out of daylight. Seems I didn't anticipate how much time I would spend walking from side to side around the grader to get access over the circle, must have covered a mile and a half. We do have a temp gun and we're able to keep it at 120+ for most of the time. I gave it a rub with a sanding disc, hence the shiny appearance. Cheers, Greg
After you got it preheated did it stay at 120+ just with the heat of the welding or did you have to occasionally keep heating it in order to keep the temperature up..? My vote's on the latter due to the volume of weld being so small. Obviously if you ran out of daylight then that explains a lot. When you go back to start again you need to remember that you're now heating a lot more volume of metal because of the volume of weld you put in there so it will take longer to get the temperature up and if you're "dabbing & grinding" as Scrub puts it you'll put even less heat into the workpiece therefore your heating torch will become even more important.
We had to put the torch on it half a dozen times. Kept my offsider hopping as well, swapping sides with the needle gun.
Did it surprise you just how much you can pockmark a recently laid-down weld with a needle gun..? I'm pleased it went so well after you were obviously having second thoughts about the job part way through this discussion.
Yes it did a little, turns a nice smooth weld into something that appears, on the surface, to be a little ordinary. Sure beats a chipping hammer for removing slag.
That pockmarked look means it's done its job. That's why you grind the weld and smooth everything off afterwards, and not just to make it look pretty. I can't see why anyone would want to use a chipping hammer if you have a needle peening gun available, and the best part it is performing a two-fold function by removing the slag and stress-relieving at the same time.
I'm not a professional welder but I welded two of the cast steel ears on the boom of my Cat 235 excavator. It was 100+ outside and I gauged the metal about 1" deep with my plasma cutter so it was scorching hot. Then welded it with my MIG, going back and forth between the two sides to create a good bond. I used the 300A setting with 0.045 wire. This was about 8 years ago and it's still holding. So it is possible to weld cast steel with a MIG.
About 25 years ago, we broke the ball off our old Cat No. 12 grader. This was about an early 60's model. My dad bought a replacement ball from Cat and while we were scratching our heads trying to figure out how to weld it, I noticed that there was an unused ball on the other side of the tilt mechanism. So we just unbolted the arm, swapped it to the other side, and have been using it ever since. (On the farm, not commercially.) I still have that brand new ball that Daddy bought. I wonder how much that Cat ball cost back then, and what the money that it cost would have grown to by now had it been invested wisely. On the other hand, the old grader is probably still worth what he paid for it used back in the early 70s. I could be wrong on that, though, I don't guess I've seen one of these sell in a long while.
Queenslander, any update. How's the weld repair holding up..?
It's holding up fine Nige. I went back and tidied it up as you suggested and it looks,almost, a professional job. I guess though, given that the original factory weld failed after twenty years, it will have a finite lifespan.
Come on then, we need photos......!! The thing is that a lot of posters are coming to HEF these days with questions about repair welding and it's nice to be able to direct them to case studies showing how it should be done. Saves re-inventing the wheel.
Welding question for ya Nige. Thinking about welding a little "C Hook" w/safety on to the H Link on my little KX 121-3 Kubota Excavator for lifting crap around the farm. Do I need to pre-heat the cast steel "H Link" & all the peening & such ... or can I just buzz it on there with some 7014 ? I don't really want to burn up the rubber dirt seals on the pins. If I need to pre-heat .. then I think I'll just weld the hook to a bucket. Thanks ~Glenn
Best thing to do is start your own thread and post some pictures of the parts in question so that we don't get all messed up on this thread. You'll find on here that opinions are like a$$holes, everyone's got their own .......
Sorry ... I'll get some pix & start a new thread. g
Nige, Oy, I resemble that remark! LOL
Well... I did say, "almost" a professional job, still a few imperfections, the bloody things are easier to spot in a photo than with the naked eye. Had to give it another buff with a sanding disc, as it had developed a patina of rust since the repair.
As per the famous one-liner - "turned out nice again" ........ If the inside is as good as what's in the photos that looks really good.