Bore weld a cast excavator boom end

[Volvomad]

What is the most best way to repair worn out pin bosses made of cast something or other on the far end of an Ex 200-5 boom . My dipper has been getting wigglier year on year but and I had it on my to do list but now it has cracked outside the locating pin holes .
I asked on the forum before about expander pins and the responses were mostly negative .
Can I bore ,weld and rebore ?
I dont think there is enough material to bore and sleeve .
Should I fabricate a complete new boom end in steel ?

 

[funwithfuel]

Weld and bore. Just try and get factory dimensions. Also, find a constant to measure to. Otherwise you could wind up with a cattywampus bore. Thats a technical term btw lol.
Those cracks appear perpendicular to pin locating holes. Were you using your bucket for a hammer ? Its not a long reach, is it?

 

[Volvomad]

Thanks funwithfuel . Yes the cracks are outside the locating pin . It has a standard dipper but has placed a lot or rock armour up to 7 ton with a bucket , not a grab so it has had a tough time .
I have line bored twice in my life , both with homemade devices . I have carefully read as much as I could find here on this subject .
What do you mean by finding a constant to measure to ?
Is ER70S 1mm or 1.2mm wire suitable ? It is hard to get much else around here .
Is heat from continous welding a problem with so little parent material at 1 side of the bore ?

 

[funwithfuel]

I would contract an experienced vendor. The guy I use locally has done just about everything. He has a dedicated wire feed that has a very tight angled head for welding the perimeter of the bore continuously. Using the same bearings, he then bores the hole to spec. All i can remember was that the wire was a low hydrogen . But again, cast is not an issue if the right filler material is used.
I don't personally perform this work, so I cannot speak from experience. My experience is that it can be done, very well, and with trusted reliability.
The constant, that is a point that is undisturbed , equal on both sides and "true." That is the point all measuring must be made from. The last thing you would want to do is center up your boring bar 2-3* off center of boom. Then you would need spherical bearings instead of bushings in your dipper cylinder eye. You'd also dig goofy. Don't want that.

 

[Volvomad]

I dont spend much time on the seat so when I do ,my digging is abit goofy anyway . As for experience , the boring jobs I got professionaly done in the past were very dissapointing . It is just my mindset ,not quiet a god complex (yet) ,but if you want a job done right them where possible ,just do it yourself .

 

[ETER]

Your wire type and size would be fine (I have been using .030" up to 3" holes +/-), would not be worried about heat so much even if your welding by hand (small wire, lower heat and you can always walk away for a few minutes for a soda-pop if you think it's getting too warm)
I think you will know alot more about how your are going to fix it when it's dis-assembled, de-greased and the cracks are properly chased / ground out...would also be wondering how the pin bore is in the stick?
Regards, Bob

 

[Volvomad]

Thanks Bob . That sounds encouraging . I am going to have a stab at putting the welder spinning if I get a chance . I have a few weeks work ahead to get other stuff finished and out of the shop before I can bring in this one . I just like to plan ahead , not that I can ever stick to the plan .

 

[dabsfabs]

What machine manufacture. Ex probably Hitachi.

Do a few of the of them over the year just weld it with A18 1.00mm wire argon/co2 mix of gas will give low hydrogen wld deposit.

They are just a cast steel and weld prefectly fine. Renew the float colar and should be all fine once bored.

 

[Volvomad]

Thanks dabsfabs . I will have a look for A18 .

 

[Volvomad]

Didnt know I was using A18 all the time . I just look for ER70S -6 but it is the same thing .I think .