Portable Line Boring

Ed - remember the conditions these plain bush bearings work under. Vast load and in a mixture of concrete dust / earth etc. The welded in bushes a usually pretty hard. The daily greasing does push the gunge out but it'll be back as soon as the bucket goes in the muck!

AWEM

Reply to
Andrew Mawson
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I didn't verbalize really good so here is a picture of a home made boring bar.

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The drawing is using a 1" shaft, 1/4" HSS lathe bit, and tapped for a 5/16 set screw to push the tool out.

You don't need fancy bearings. Plates with close fitting holes tacked to each side to center bar, use lots of lube.

Look at Bill Marrs link, specifically,

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You don't have a big pin hole so the cutter head shown isn't going to work but I think what I drew would work for you.

Wes

Reply to
Wes

'Fraid not. This is joints in hydrualic construction machinery - steel pins running in hardened steel bushings is typical construction. If the bore for the bush is not hosed, maintenance is pretty simple, for moderate values of simple - yank pins (swear), remove bushings (swear more), new bushings (and pins, if needed) (swear a little, but most of the swearing is for removal). Keep it greased...

If you were to pour up a nice Babbit bearing, then go use the machine, it would be: hook onto a rock, squeeze the Babbit out like toothpaste. The joints would have to be made much larger to get the pressures down where bearing materials like Babbit hold up.

Very low velocity, very high pressure, plus a filthy and abrasive working environment.

For a vague idea of what's involved, consider that my bucket is rated to produce 9000 lbs of force at the edge - which is about 2 feet from the pivot. The cylinder is less than a foot away on the other side, so it has to be putting 18,000 lbs into the bucket pins, and the pivot itself gets some large force that's not immediately obvious, but might be as much as 27,000 lbs...on a pin that's about and inch and half diameter, with the bearing on the bucket only 1-1/4 inch long on either side of the dipper-stick.

Reply to
Ecnerwal

The stones are mounted on rods with a rack cut into them , the center rod of the hone assembly is a pinion that fits into a square block that has holes for the rack rods . There is a small planetary gearset built into the drive/center rod to extend or retract the stones . Two stones and two wipers constitute a set . At least that's how my Sunnen cylinder hone is made . And yes , they will straighten an oval/tapered hole . I've used mine more than once to bore motorcycle cylinders to the next oversize ... also works very well to lightly scuff a cylinder and remove the ridge at the top in preparation for new rings .

Reply to
Terry Coombs

18000 / (1.5 * 2.5) =3D 4800 PSI. When I designed my front end loader I looked for examples of bearing pressure and found as much as 9000, on a swinging bridge pivot. I kept mine to 2000 to allow brass pipe bushings, the max for sintered oilite is lower. It operates at half the design load which blew the front tires.

Jim Wilkins

Reply to
Jim Wilkins

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