Boring excavator boom

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wreckman

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I have loose bushings in the end of my excavator boom. I need to bore out the end of the boom and press in a sleeve. What is the best way to enlarge this hole for a sleeve. I really did not want to have a machine shop do it as I have a mill and a lathe. Can I use a core bit and a mag drill to true up a larger bore dia so I can sleeve it for new bushings. Its not a big excavator so it is about 4 ".
 
Look at line boring , 2 flange bearings plus a bar fitted with cutting tools you could power with your mag drill just weld a piece of plate to your bucket to mount it to and grind off later. Might need a 2.5" bar or so to reduce chatter. If you do them one at a time you may run into binding issues or way off on alignment. Lots of youtube videos on it. Good luck
 
pineyfolks said:
Look at line boring , 2 flange bearings plus a bar fitted with cutting tools you could power with your mag drill just weld a piece of plate to your bucket to mount it to and grind off later. Might need a 2.5" bar or so to reduce chatter. If you do them one at a time you may run into binding issues or way off on alignment. Lots of youtube videos on it. Good luck
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This!! I used to work in the strip mines as a weldor. Seen this a bunch. What we would do is, make sure your bore is clean (old bushing is out of there) preheat, then weld up with 7018. Then line bore it to fit the new Caterpillar bushing. I think we left eith .005 or .010 press on them. I cant honestly remember now.

Chris
 
I work in the the mining industry and would agree that you need a boring bar set up. I like to set up the bar and true up the bore before welding them up.
But that would also depend on how long it's been ran with a bad bushing. I saw online that Climax will rent boring bar setup's.
Here is a link to they're site http://climaxportable.com/products/?rentals
 
Its a Kubota excavator so I guess I could take it off the machine and set it up on the mill. I just didnt want to have to take the boom off and muscle it and crib it to the mill.
 
Check out Keith Fenner on you tube. He has I think 2 videos on line boring. Explains it well in my opinion.

Chris
 
Hello Wreckman,
Are you aware of HeavyEquipmentForums.com ? Lotsa good examples of how this work is done.
Typically a boring bar is used.Even if going oversize,the boring bar is used to get to a finished dimension and assures parrellelism (sp.)
HTH
Jay.
 
A portable line boring tool is the way to go. You can rebuild the hole and bore it back to original dimensions, but it is kind of pricey and does require a fair bit of skill when building up the hole with metal. I use a Mig in spray mode and do the build up with the part as hot as I can get it with a torch then allow it to cool completely and do the bore then. Everywhere I ever worked had the machine in the tool room because the average truck based tech could not afford one of their own. It's a great tool to use but pricey and easy to mess up if your welding skills are subpar and you fail to remove all of the grease and grime before you start. Depending on the use of the machine the sleeve idea may also not be an approved repair so be carefull there if your doing it for somebody else. If it's your stuff, you can do whatever you are comfortable with but watch for liability issues if you have heavy habded employees. The ambulance chasers look for that kind of stuff to make a big deal out of anymore. Just sayin... Hope it doesn't apply to you. Good luck and look to Cat or Volvo service centers for a place to locate the tool and get a price.
Bob
 
last year i had to do this to a skidder in a muddy hole. I basically made two steady rests with large brass bars for fingers. i welded these on the top and bottom of the area to be bored. i took a piece of 2" shafting and drilled holes for tool steel and set screws where both bushes would be bored. i also made a fixture to measure and set the tool stick out. i ran this with a mag drill. worked great and saved the day. use the fingers to adjust the bar for center. sorry no pics but the setup is buried in the snow somewhere with all the other scrap. if your bar has to span a long distance just add more steady rests. unless you have some very good laser alignment equipment i would try to do all holes with one long bar. hope this is clear as mud, if you have any questions feel free to ask.
 
The way that we set up the bore was with "centering cones". At least thats what I called them. They were cones that went into each side of the bore, then you inserted your bar in the cones, bingo centered up! Is there a technical term for them?

Chris
 
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