rebuilding CAT 345 bucket

By nevadanick (**)

Date 06-02-2008 03:43

are you reffering to the side cutters ?, or what ?

By aevald

Date 06-02-2008 07:19

Hello Jeffrey Compton, are you referring to the actual bottom of the bucket located behind the front cutting edge and the wear sections that are typically welded to the outside of this piece? Many of these buckets will have a multi-part composition that makes up the components of the bucket. What I refer to as the lip, is the heavy portion of the bucket that makes up the cutting edge and typically does the cutting while digging and also has tooth adapters welded onto it in many instances. On each end of this cutting lip there are heavy plates referred to as corner bits, they sometimes also have holes for bolting on replaceable cutting bits that are vertically positioned relative to the horizontal placement of the cutting lip. The end plates of the bucket will often have a 3 piece construction, the corner bits are positioned at the lower forward corner of the side plate and are the thicker portion of the side plate in many instances. There is another heavier piece that is tied to the top part of the corner bit and generally extends vertically to the top of the side plate to give reinforcement to the front edge of the bucket side plate. Behind these two pieces is the bulk of the side plate and it is generally made up of the thinnest part of the total package. All three of these pieces make up the side plate for most types of digging buckets. Directly behind the cutting lip is another fairly thin part of the bucket which is sometimes called the bottom or lower wrapper, it is welded to the back of the cutting edge/lip and generally extends straight back from this edge for a ways and then begins to bend at a radius up towards the upper portion of the bucket. Where the lower wrapper ends there is often a heavier piece of plate that is referred to as the top or upper wrapper, this piece generally is fitted in a lap joint orientation to the lower piece and starts being formed at roughly the same radius as the lower part and then straightens out again as it makes it's way to the top of the bucket. Many times wear plates or runners will also be applied starting at the back of the bottom cutting lip and following the straight portion of the bottom wrapper and then being bent to match the outside radius of the lower wrapper and extending upwards on the outside of the back of the bucket until they meet or end just shy of where the upper wrapper laps over the lower wrapper. These "fingers" don't completely cover the backside of the lower wrapper but instead act as wear surfaces for the bottom of the bucket and can be removed and changed as they wear(with an arc-air and welder), thus protecting the bottom of the bucket somewhat. The bucket mounting brackets, which generally also have the pin bosses welded to them, provide the mounts to attach the bucket to the machine. They are generally attached to the upper wrapper and welded prior to installing another wrapper that ties into the upper edge of the upper wrapper and then is formed to box in the pin boss mounts and stiffen the whole mounting assembly. If you survived reading my essay here try to better describe which portion of the bucket that you are working with and if possible try to include a sketch or some pictures. I am sure there are plenty of folks who can help out if you can give a little bit better description. Best regards, aevald

By Jeffrey Compton Date 06-02-2008 15:23

yes i am refering to actual bottom of the bucket (still working on my terminolgy) that starts behind the front cutting edge. i am useing a 2 peace replacement that has been pre rolled to the specs of the bucket the inner peace is 1" AR400 steel and the outer peace is 1/2" my real problem is that i cant weld to the cutting edge because i have to replace it to

By aevald

Date 06-02-2008 18:37 Edited 06-02-2008 18:41

Hello again Jeffrey, the use of AR400 as a welded component of this bucket seems just a bit odd to me. I say that because welding it can be a bit tricky and if it is subjected to heavy impacts I believe it would tend to be crack prone in the areas that it is attached with weld. Most of the buckets that I used to be involved with were built out of T-1, A-36, or A572 gr50 or 70. Nowadays there are many other alloyed plates available that have much better formability and weldability, I believe a couple of examples of this can be found under the Hardox or Weldox name, I know there are also others but I am not readily familiar with them.
As far as dealing with the job that you have before you, I am seeming to understand that you are removing the cutting edge and the bucket bottom and it's associated wear plate. You have a couple of options for how you can do this if you are concerned with shifting of the dimensions of the bucket. Start by applying X-bracing to the opening of the bucket leaving enough room near where the cutting edge attaches to allow you access for it's removal, this will help to maintain the shape of the bucket so that when you start cutting it apart you won't have anything move. You could possibly remove the cutting edge first, reinstall the new one and apply an internal strongback(this could be a piece of heavy flatbar or some other structural shape set on edge and tacked to the top of the cutting edge to hold it in place and keep it flat while you remove the bottom and it's doubler), just leave out any tacks on the edge where the cutting edge contacts the bottom plate. After you remove the bottom and it's doubler you could fit the bottom back in and tack it to the back of the edge of the cutting lip and the bucket sides as needed. If required you could then weld all of this out and then fit the wear plate in and weld it out. I say it that way because sometimes welding needs to occur before you apply other parts and once that welding has taken place those parts can then be fitted and welded as required. When making the welds that connect the bottom to the back of the cutting edge use a back-step type of weld progression to keep warpage to a minimum. There are many methods in use out in industry to describe this method, consider the way that engine heads are torqued and possibly come up with a weld progression that emulates this sort of skipping method. Make all of your welds start from the same end of the bucket for both the internal and external welds. Best of luck and regards, aevald.

By sbcmweb (****)

Date 06-03-2008 12:28

Man, Allen. You really know your stuff. Your students are very lucky to have such a knowledgeable & kind instructor! Always a pleasure to read your posts. S.W.

By aevald

Date 06-03-2008 13:47

Hello Steve, thank you for the kind words. I, like so many in industry, have been blessed with knowing and working with a number of highly skilled individuals who weren't afraid to answer a question, show me a trick, or help out with suggestions for making work easier and better. The thing about much of what we learn is that at the time this learning is taking place we often times don't realize the importance of it. I have run into challenges later in life that put to use some of what I have seen and been helped out with in the past by so many others. Best regards, Allan

By sbcmweb (****)

Date 06-03-2008 14:34

You said it perfect. Seriously. Had a lot of cool people take the time with me too. I sincerely appreciated it & still do when others, such as yourself so unselfishly give of their knowledge & experience. Learned something about welding on a bucket today too! (Really didn't know much to begin with!) :-) Look forward to more in the future. Thanks, Allen. S.W.

"Was many years ago that I left home and came that way, I was a young man full of hopes and dreams.." (Stranger in a Strange Land, Iron Maiden, Somewhere In Time LP)

By Wrench Tech (**)

Date 06-14-2008 04:57

Jeffery
If the sides are still on the bucket then sit the new floor on the existing cutting edge and fit it down between the sides and tack weld the other end to the existing piece of the floor that's left. Most of your trimming is done from this end anyway. Tack it well to your old cutting edge. If all looks well then weld it solid across the back, lay the bucket on it's side and weld the floor to the sides all the way ( lots of preheat first). Now you can wack the cutting edge off and nothing will move. The bucket floor should be dead even with the cutting edge on the inside of the bucket so it helps to weld a couple of tabs to the cutting edge on the inside for the floor to sit up against. Is you floor really 1 inch thick? On a bucket that size I usually use 5/8 - 100 plate for the floor and 5/8 hardox 400 for the liner inside. Hardox 400 for the wear bars on the back. Also if you have cut the bottom half of the sides off already ( which is quite often neccesary) you don't change your method much. Just attach to the old cutting edge with some good tacks and weld it good to the back. Then you add the side pieces - measure and fit all but the curve, hold the side piece against the bucket floor and mark the curve. Cut it out, tack everything good and weld it all up. Preheat everything well. The bucket floor fits down in between the sides. The real good weld needs to go on the inside - a single quick pass up the outside is good (covered with wear bars anyway). T100 for the sides. If you weld a doubler on top of that then Hardox 400 or your AR400. Treat changing the cutting edge like a separate job - I mean do everything structual first to the floor and sides and then wack the cutting edge. I've done quite a few of these jobs - a no brainer after the first couple. Hope this helps.

By vantage500man (**)

Date 06-05-2008 01:14

something like this

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By aevald

Date 06-05-2008 01:39

Yikes, vantage500man, that does bring back some memories of past challenges. Nice pictures by the way. Best regards, Allan

By MDG Custom Weld (***)

Date 06-05-2008 14:25

Hay Bear, one quick question on the bucket repairs: Are you using some type of wear resistant plate like Hardox/ Weldox, or are you just rebuilding with A-36 carbon steel?

We have done some of this work using both materials, and I'll say that wear plate sure takes some tonnage to form!

By vantage500man (**)

Date 06-06-2008 02:31

Yes both where with AR plate 1/2 and 1/2 AR where bars over and the company i did them for said they are holding up great and loved the work thank guys

By Wrench Tech (**)

Date 06-14-2008 13:44

I notice that you've put your wear bars across the bottom of the bucket parallel to the cutting edge. As far as I'm concerned this is the only way to go. I usually stick them on with 1 to 1 1/2 inches out past the sides for wear purposes. Having the bars across the bucket like that greatly adds to the strength of the bucket floor. They also last longer and protect the floor better than the formed strips. Way easier to put on, too. Some of the manufacturers around here put a formed strip up each side and weld bars crossways in between the strips. They save money by using mild steel for the floor. When working in blasted rock or boulders even a careful operator will wind up deforming the floor up towards the inside of the bucket with that arrangement. If I can talk my customers into it I will put new wear bars right over the top of everything. 1 inch by 4 inch hardox 400.

By makeithot (***)

Date 07-21-2008 05:35

Not that I'm critisizeing your work But I notice that some of your wear strips run paralell to your cutting edge ( which is the method of choice for me ) and on the other bucket they do not which for all intensive purpous means the bucket floor wears out before the wear strip. Is this how your customer wanted it?

By uphill

Date 07-21-2008 23:36

When you put your wear bars across the bucke your asking to snag every pipe, bolt and trench box you get close to. I imagine if the bucket were used for trenching or loading trux it would not come up. I cant say I have ever seen a bottom wear out before the wear strip. Sort of like an out of round tire, the high spot creates wear past itself.

By vantage500man (**)

Date 08-17-2008 16:46

They the customer wanted it back the way it came from the factory as close as possible.

By TIG Torch2008 Date 07-17-2008 01:34

i am 19 and work in a sheetmetal shop/ fab shop. i have had 5 years welding and metal work expierence. my best advice would be to measure the area that needs to be replaced. i am not fimiliar with loader buckets, but what i have done for a tractor was the cut a plate to fit on the bottom half, with 1/8" gap on each side to allow for good penetration. the top, here's a cool trick, clamp it in place, and weld it, or if clamps arent feesible, drill holes, bolt it in place, weld it, then removes the bolts and fill the holes with weld. im not sure the shape of the bucket but if i has a curve or any sort of radius, and you dont have a slip roller, you can use a press or shop brake and do what is called a brake roll. this is done by evenly marking break points along the material and putting a slight bend or break in the surface until it takes the shape you need. the more breaks, the smoother the bend will look. there are a few tips to remember. metal "grows" or lengthens when broke, and always aloow for material thickness and kerf with any cut or bend. a sure a nd tried and true method to nice, even, flush cuts....measure and measure again.