how to ream a idler gear bushing

[socalrider]

I replaced the idler gear bushing to my 63 flh. I need to ream it to get it within specs (.555"). I cant locate a .555" reamer . What other methods are there to accomplish this? i want to attempt this myself and avoid any machine shops if possible. Im thinking I can get a reamer that is closest to the dimension i need (.546"). How would i get to .555" after i use the .546" reamer? Im thinking of doing this by hand. i have some wrenching skills but by no means am I a skilled machinist so any warnings or advice on this is very much appreciated.
gracias,
arnulfo

[RUBONE]

Don't bother looking for a .555. Just get an adjustable one!
Robbie

[Cotten]

Arnulfo!

Although I use a Sunnen hone,
If your bushing was a common pre-sized catalog piece, and it was not abused much when installed, then often the shaft will find a sweet fit with just a felt tip pen to mark the high spots, and a triangular machinist's scraper to take them off with a cross-hatch pattern.

If the hole is not concentric to the gear, then you are in trouble, but a reamer or hone wouldn't help that either.

Ideally, an undersized bushing would be installed, and then bored in a lathe, true to the run-out of the teeth. (Hand-shift tranny third-gears and kickclutch gears must be treated similarly..)

...Cotten

[Ohio-Rider]

Get the adjustable reamer as Robbie suggested, but don’t try to take it all in one cut. Sneak up on it, a couple thou at a time and use plenty of flushing oil.
Steve

[steinauge]

Rocker arm bushing reamer 94804-57 will get you right to size.It is a long pilot reamer and will fit nicely in a tailstock chuck or can be used by hand.An expansion reamer will work but I have never been particularly fond of them.Cotten the last few years the aftermarket bushings I have been getting are pretty undersize.

[Cotten]

Steinauge!

With two idlers and fresh bushings and shafts on the bench, I find that you are right!

Certainly too much to scrape, and enough to introduce wobble if taken all the way out with a hand-held ream or hone.

So we shall be boring them true to the gearteeth on the lathe, and finishing on the hone.

IDLERBOR.jpg

The three-jaw chuck resolves perfectly on the gear teeth, and the gear sits perfectly square upon it.

....Cotten

[PanPal]

I would not trust the three jaw to run true either. I know you can dial them in pretty close, but I would have tried grabbing that gear on the internal side in a four jaw and indicate the teeth and face. Even this is not perfect. Gear blanks are usually turned then later remounted in an indexing head to cut the teeth so the teeth are true to the bore moreso than the outside diameter of the gear. I suppose a pin gauge could be inserted between the teeth to check true runout and and have less change in backlash as it is rotated. Thats a lot of setup for trueing a bushing I know and several I have seen running are loose as a goose. I guess I don't understand why a reamer is not a good choice for this. They normally have more that 4 flutes and seem to create a very round hole. It's not like drilling through thin metal and ending up with a triangular hole.

[Cotten]

Panpal!

So how much more flat-rate should I charge to index in on a four-jaw, just to gain a couple of tenths" of accuracy on a gear that isn't that true to itself?

My Logan's three-jaw is miraculously true after all these years (1948), and hard as a diamond. After all, its a Cushman!

....Cotten

[Panshovevo]

Panpal!

So how much more flat-rate should I charge to index in on a four-jaw, just to gain a couple of tenths" of accuracy on a gear that isn't that true to itself?

My Logan's three-jaw is miraculously true after all these years (1948), and hard as a diamond. After all, its a Cushman!

....Cotten

You are fortunate to have an accurate three jaw. I have two lathes, an Atlas (Craftsman) and a Harrison, with a total of 3 three jaw chucks, and none of the three jaw chucks centers closer than .003".
I just use the four jaw chucks, as it's easier to dial them in.
Regards,
John

[Cotten]

John!

Have you considered boring your jaws to 'true'?

Three thou is enormous!

....Cotten

[Panshovevo]

Considered, but haven't done. How would you go about doing so?

Regards,
John

[socalrider]

thank you all very much for the replies. im going to go with steinauge's suggestion on the rocker arm reamer. if i had a lathe and the know how to use one i would go that route.unfortunately im not there yet. any advice or precautions on using a hand reamer? what kind of lubrication should i use? do i need to do a finish with a hone? what type hone, stone or brush/ball type?
gracias,
arnulfo

[Cotten]

Arnulfo!

Tapping oil or WD-40 would do for a lube.

If the reamer is accurate, then you could skip the hone and go straight to a plateau brush for a cross-hatch.

NYLOX.jpg

And John!
Boring the jaws requires an enormously hard boring tool, carbide at least, and a very sturdy toolpost. The indexed jaws are clamped tight on a brass or aluminum rod, which is then bored away, including the face of the jaw, until there is dangerously little support for the jaws. The remainder must be ground for clearance.
This produces jaws with a concave face, but at .003" run-out, you have little to lose.
Are you certain the chuck is properly mounted: does the back plate have similar runout? Are the jaws in their right slots? If they are the kind that can be flipped around, does it still have bad run-out?
Inspection may show that they just need to be re-mated upon a surface grinder. If you can determine that there is an offending jaw, you could possibly stone-dress it, or the others, by hand.

And one last question that I am compelled to ask; sorry:
When you clamp upon a workpiece, do you beat it into submission to make it spin true?

I do.

Good luck!

....Cotten

[PanPal]

When you clamp upon a workpiece, do you beat it into submission to make it spin true?

I do.

Cotten,
Sometimes I do also, but on something like this I would slowly creep in on face run out with a soft faced hammer and snug the jaws at the end and recheck. The face run out usually does not change when tightening the jaws and the OD run out is trued by jaws alone. They also do not need to be strong armed because we are boring soft material and very little at that. I understand that shop time doesn't make the use of a 4 jaw reasonable for this. A former Boss of mine use to say there are 100 ways to get there, pick a good one!

I would think during the first operation of turning this gear blank they faced the gear turned the inner hub and finish bored the gear. If the inner hub is turned close to a standard size, which most Harley parts are not, It may be able to be mounted in a standard Collet and run true. (they sell Bore to size collet blanks if not.) But one side only was turned when they also bored the gear. This would be the only side that is concentric with the bore. Bored soft jaws in a 3 jaw chuck is another option for clamping on the outer teeth.

My 3 jaw does not allow for soft jaws either. I myself do not have a 3 jaw that runs as true as yours. This is what surprised me when I saw your setup. All those jaws are in the way of checking run out. However Logan's are very fine chucks! Did all 3 jaws clamp on the top of a tooth? Meaning are there tooth tips 120 degrees apart around the circumference of the gear?

[1950Panhead]

John,
Cotton,

I have replaced the shafts and bushings for the idler gears on two panheads and carefully reamed to .001" clearance using an adjustable reamer. On both panheads the idler gears spun free and did not bind. I also check clearance by rocking the gears back and forth.
Initial clearance was .011" between shaft and bushing on one bike.

I understand that using a lathe, if the chuck is centered, you can put the bushing exactly in the center. Thanks for the posts and pictures, it is interesting to see how others do this.

Jerry