Poured-in-place bronze bushes?

[Pete O]

As I progress through my tractor rebuild, thinking ahead to tasks that still need to be done, I have been contemplating how I might line-bore the bucket pivot holes for the front-end-loader. I'm too stingy (and the budget has already blown out too much) to pay someone to line-bore it. It occurred to me that I might be able to put a long shaft across the two arms and pour bronze bushes, similar to babbit bearings. I have in mind a setup and process that would make it possible, so that isn't my question; rather I'm wondering if this might produce an acceptable result, or is there some major drawback that I am not foreseeing?

[Mayhem]

You can line bore on your lathe.

[Pete O]

(01-03-2018, 11:25 PM)Mayhem Wrote: You can line bore on your lathe.

I'm talking about the pivot points at the front of the loader frame arms, the frame probably weighs about 300kg and the ends that need to be line-bored are about 1200mm apart. You could probably clamp it down to the carriage on your lathe Darren but it's a bit big for mine!

[Highpower]

Maybe something along these lines?  https://www.youtube.com/watch?v=f2saYF_FLgA

[Pete O]

Ok, the more I think about this idea the dumber it looks- I suspect that, at best, I would end up with a bronze sleeve shrunk so tight onto a dummy shaft that it would be impossible to remove. I guess there have got to be a plenty of reasons why everyone isn't doing it. So scrap the poured bush idea. I've seen the above clip, as well as a few others with homebrew line-boring setups but I've been stumped by how to drive and feed the boring shaft; a mag-base drill would be great but I don't have one and they are big $$$. I've come up with an idea to use the head off my drill press to turn and feed a shaft with a boring tool on the other end, might just be crazy enough to work.

[f350ca]

Its an interesting idea, just because its not done YET doesn't mean it wouldn't work. Could you make a core of sand or carbon or what ever that would break out after.

[randyc]

(01-04-2018, 03:50 AM)Pete O Wrote: ......I've come up with an idea to use the head off my drill press to turn and feed a shaft with a boring tool on the other end, might just be crazy enough to work...

I LOVE crazy ideas, even if they have 50% chance of working !  As a guy on YouTube, whose name I have now forgotten, said "Every day is a school day in the machine shop".

Will you use an outboard bearing for the drill press ?  Hope that you photograph and post the setup, Pete, even if it doesn't perform as well as you'd like.  Even partial successes (NOT implying that your idea will be anything but successful) are very useful as a learning tool !!!

Cheers !

[dallen]

this guy did it pretty simple, using a right angle drive as the powersource. probably used a VFD to control speed.

[randyc]

Now that is COOL ! The outboard bearing housing is simply tack-welded to convenient locations and the ratchet/pawl feed mechanism is simple and effective - probably all just stuff he had on hand.

(If I missed anything obvious in the video, sorry but I don't have any audio capability at present.)

[SteveG]

In a previous life, we used to replace the hard bronze bushings that attach the engines to the wing pylons on B747's.
The bushes were fitted using liquid nitrogen to shrink them then the machinists would line bore them in place.
My memory is a bit sketchy as its been 20+ years, but I don't recall the tooling being complex, and was just driven using large right angle pneumatic drill (slow speed and small head for access reasons). I don't recall any mechanical feed mechanism.

Since you're not looking at a high precision application, I don't see why you couldn't get away with making up a long boring bar with a HSS cutter, and mounting 2 guide blocks - one on the outside face of each bearing and simply driving it slowly with an electric drill.
If you make the boring bar so its longer than the whole setup by sufficient length that you can get the cutter to the space in between the faces to adjust for the next cut, and also have a second cutter hole in the bar in the appropriate place to let you bore the other bush without disturbing the setup I think the result should be plenty good enough.
I might be able to help you out with some bronze if you don't already have some. What size are the bushes?

Edit: re-reading you post, I think you were referring to line boring the steel pivot arms themselves. I was referring to line boring bronze bushes.
An option might be to bore the arms independently, fit bushes and then line bore them. As long as you make sure the bushes don't turn in operation the outcome should be the same.

Steve