Proper reamer to fix egg shaped hole?

climb.on · Jun 22, 2020

I have only a little experience with an handheld adjustable reamer and none with a bridge reamer . Will these reamers take care of a 1" diameter x 1-1/4" deep egg shaped or out of round hole in ductile iron? Is one preferable over the other? I'd do it by hand, as I don't have a mill, but would need to do 12 holes (4 plates with 3 holes each). I do have a decent drill press though.

More background....

I'm working through replacing the pins and bushings on my Case 1845c skid loader. I'm currently working on these triangular plates on the boom. The triangular plates themselves don't have bushings and are wallowed about .03". The egg shaped holes are 1.030 (at narrow point) 1.060 (at wide point).

I'm considering using either a hex head bridge reamer or an adjustable reamer to bore out these holes to 1-1/6" which is 1/16" oversize and very close to what the maximum oval hole dimension is at (1.060). Then I can work on oversize pins.

Limy Sami · Jun 22, 2020

IME - I sincerely doubt it, plus you will have problems over which part of the hole the reamer centres on

I know it'd not what you want to hear, but in an oval situation, single point boring is the only solution - have you got access to a mag drill rig - (like a Rotabroach)

Joe Miranda · Jun 22, 2020

Like Limy said - you really need to line bore those holes. It is not difficult to make a line-boring rig if you have a mag drill.

climb.on · Jun 22, 2020

Thanks for the reply guys. I suspected it would be a pretty simple answer one way or the other. I don't have a mag drill, but I have some machinist friends who I can hit up for a favor.

DDoug · Jun 22, 2020

"Egg shaped Bushings"....

climb.on · Jun 22, 2020

Had to think about that for a second... :nutter:

I bet McMaster has those, right?

ChipSplitter · Jun 22, 2020

climb.on said:
Had to think about that for a second...

I bet McMaster has those, right?

Not quite....

But they do have these. They work great. McMaster-Carr

bhigdog · Jun 22, 2020

Looks like they come off the machine pretty easily. Within reason actual hole location isn't as important as the pairs being alike. A BP would work fine just bore them so pairs are matched on hole location. I'd say if the bushings are hard you're looking at new plates.........Bob

trevj · Jun 22, 2020

bhigdog said:
Looks like they come off the machine pretty easily. Within reason actual hole location isn't as important as the pairs being alike. A BP would work fine just bore them so pairs are matched on hole location. I'd say if the bushings are hard you're looking at new plates.........Bob

Christ yes! This!

Put the effin thing on a mill table and bore the hole to a convenient oversize.

If the bushings are supposed to be hard, like as not a torch and then bore out the mess remaining, and press/weld in a replacement bush.

ChipSplitter · Jun 22, 2020

I have yet to figure out why heavy equipment manufacturers don't weld in hardened bosses. Use a hard boss (50-60 Rc case .05 deep) and a soft (25-30 Rc) pin.
We do it all the time and have documented testing to over a million cycles with zero wear on the boss.

Conspiracy? :confused:

pavt · Jun 22, 2020

ChipSplitter said:
I have yet to figure out why heavy equipment manufacturers don't weld in hardened bosses. Use a hard boss (50-60 Rc case .05 deep) and a soft (25-30 Rc) pin.
We do it all the time and have documented testing to over a million cycles with zero wear on the boss.

Conspiracy?

Was your million cycles done while submerged in mud with a helper that wasn't greasing it because he was too busy getting stoned? With a 50-ton load? Also, wouldn't welding it in change the heat treat? I know, I worked in a heavy equipment shop back in the 90's... went thru 180 lbs of 7018 one winter, welding up pin holes for the line borer. Cat used hardened bushings that press in, but when the bushing hole itself gets wallowed out, yer screwed. Hence 180 lbs of rod....

ratbldr427 · Jun 22, 2020

It looks like the pins are cross bolted so unless someone did that as a kludge ,the pins are supposed to be a press fit in the triangle pieces and the other elements pivot on the fixed pins.Dosen't look like much length for a bushing anyway.
If that is the case you probably have to keep the original cenetrs(go bigger then bush oe pin size) or else you would have to make all the elements oversize.

Don't know jack about that unit and can't tell for sure by the pictures so maybe wrong.Just a thought.

gbent · Jun 22, 2020

Take the parts off and have them bored and bushings made to fit. Price replacement parts first. Note the part, like a lot of Case parts, says "Warning, ductile iron. Do not weld".

72bwhite · Jun 22, 2020

find a guy with a portable boring set up.
much like line boring the mains on an engine

Phil in Montana · Jun 22, 2020

Tear down and take the parts to a shop with a hbm...Phil

thermite · Jun 23, 2020

Phil in Montana said:
Tear down and take the parts to a shop with a hbm...Phil

LOL! Yah welll. that's one way of "generating" them rare egg-shaped Bronze bushings!

Guy running a small bar off one of the the 3-inchers got pushed a tad out of round off the nasty corn-cob stick weld build-up he wuz cutting back. Or so I surmised, common as it was.

"MY" bushing, previous day's second-shift. Foreman QC'ed it, knowed it was true as could be. Before they pressed it in. A hand scraper took care of it. Woz only three thou oval on somewhere around a 3-inch bore.

Would have WORKED OK. Coal and rock dust opened 'em up all too DAMNED quickly at the coal-face. Just first had to pass assembled inspection and test to get TF out of the machine-hall and onto a rail-car to the mine.

Yah didn't exactly drive one of these down the highway, even with pilot vehicles.

Joy 1CM Continuous Miner

All electric, and lots OF it. 100 HP main, I'm sure of. Made plenty of armature shafts, new bearing-fits in end-bells for 'em. ISTR 600 Volts, DC?

Figure the average plug-in extension cord would sorta "detonate".

Mechanola · Jun 23, 2020

You can push a broach through the egg-oval shaped holes. Main time about five seconds. Only the setup will take longer time. Maybe you want to go more into servicing of those machines.

Limy Sami · Jun 23, 2020

Mechanola said:
You can push a broach through the egg-oval shaped holes. Main time about five seconds. Only the setup will take longer time. Maybe you want to go more into servicing of those machines.

You can,????????????? but a 1'' dia broach (with 3.142'' of cutting length) is going to take a lot of pushing, ………...and you aren't going to clean up over 0.060 in one pass - so that's at least an extra broach if not more, ….and that's without going in to the cost of the tooling.

EOLSON · Jun 23, 2020

If it were my machine I'd weld in a sleeve (with a hole lined up with grease fitting) and use a smaller pin. No boring, reaming, drilling, etc.

72bwhite · Jun 24, 2020

defiantly take em off and have them bored over size.
then press in a bushing.
what probably happened is bubba didn't keep them greased
sheared the bolts off and they wore the holes out of round.
you see it often in hoe buckets, lower bushings on loader buckets...
happens a lot with stuff with more then one operator, and no one
in particular responsible for things like greasing the pins

Proper reamer to fix egg shaped hole?

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