To grind a perfectly round shaft. Hone, cliyndrical or centerless.

I have 3 Sunnen honing machines but have never OD honed. Does it offer any advantages over cylindrical or center-less grinding if you want to make a part (very hard) as round as possible? The area to be ground is only 1" long and 13/16" diameter. I was going to cylindrical grind it (don't have a center less grinder)but was wondering if honing may be better? I only need to grind off a couple thou but need it as perfect as possible and a good surface finish. The OD when done needs to be +/- .0002"

OD hones are crazy expensive but do they do a better job or should I stick to the grinder I have which works great?

Just wondering about OD honing as I know nothing about it. I am probably over thinking this and should just put the part in the cylindrical grinder and be done with it.

If an OD hone can be applied, you’ve got the best solution with it.

Second best is revolving grind disc, part between centres. Third best is centerless which is principally useful with serial work. Endless grind belts are used on crank shafts and cam shafts, something quite special.

Have you not got to watch for lobed finish, I remember clocking a part I thought was round but wasn’t, it was trilobular, only showed up between centres
Mark

Since you seem to be going crazy on this let me toss this out there. The hot ticket with roller bearing big ends is hollow rollers and a shrink fit between the races and the rollers. Less mass to accelerate and decelerate (which happens every revolution) and the interference helps to avoid skidding. And silver-plated lightweight steel cages.

You could add titanium rods if you like ...

Go for it !

Does the diameter to be finished have any runout callouts to other features? After heat treatment a bowed shaft is a given, at some tolerance level. OD grinding can correct this, honing can't.

EmanuelGoldstein said:

Since you seem to be going crazy on this let me toss this out there. The hot ticket with roller bearing big ends is hollow rollers and a shrink fit between the races and the rollers. Less mass to accelerate and decelerate (which happens every revolution) and the interference helps to avoid skidding. And silver-plated lightweight steel cages.

You could add titanium rods if you like ...

Go for it !

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??? Too much celebrating the 100th anniversary?

A "big end" has constant rotation, it's the little end that waggles and (de)accelerates back and forth. And a Ti rod makes a terrible rubbing surface for a roller bearing, it would need a hardened steel liner to get any life out of it.

I do agree skidding is bad, unless you're a featured player in one of the F&F movies.

Laverda,
I would look at buying a class X Gage pin the exact size that you need. It would then only need to be cut and ground to length. OD honing would be tricky on a piece that short. Class X Gage pin 60/62 RC, .00004 tolerance and 10 micro finish, any diameter you want. Probably about 30.00.
spaeth

Milland said:

??? Too much celebrating the 100th anniversary?

A "big end" has constant rotation, it's the little end that waggles and (de)accelerates back and forth.

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Omigawd ! I get to correct Milland on a technical matter ! Woo-hoo !

Nope The pin rotates at a constant (more or less) speed but think of rod angularity and direction. The outer race, in relation to the inner race, is moving at a constantly varying speed and direction. That's what makes roller bearing big ends less than ideal. The biggest problem is the inertia of the rollers and the cage at high rpm.

Kind of funny that Porsche went to such extremes with Hirth cranks when a plain bearing big end is better. The Germs aren't infallible after all

And a Ti rod makes a terrible rubbing surface for a roller bearing, it would need a hardened steel liner to get any life out of it.

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Even steel rods on motorcycles almost all have a pressed-in race, it's a given. The one exception I know of are XR rods : they go out of round very badly because of the knife-and-fork setup and you can't make them fatter without interference, so the newer (newer than 1972, anyhow) style is one-piece, with the race being a hardened section of rod. Gave them a little more mass to resist distortion. But that means instead of replacing the race, you buy a new set of rods. Guess which is more expensive

They turn those at 9,000 rpm now, btw. That is way beyond insane.

The Sunnen OD hone is very good and isn't prone to lobing. Too expensive, but if you look at the thing, it would be very easy to make one. Glue up your own stones from silicon carbide toolmakers sticks. OD grinding between centers will get you where you need to go. Or a collet or chuck for that matter. So will cast iron laps from American Lap- External Laps and Holders 0.0002" should be easy. Maybe cylindrical grind and finish with the lap for surface finish.

Conrad Hoffman said:

Maybe cylindrical grind and finish with the lap for surface finish.

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Where's Buck when we need him ? What do they do on big rolls to get that finish ? Pretty sure they aren't lapped.

Related question : is a really shiny finish actually better than a matte one ? And which is best for a roller bearing ? Why ?

AFAIK, big rolls are OD ground with wheels made especially for the purpose. As for best finish for a bearing, I've no idea!

IF ya got the grinder, grind it, but if you need good geometry, lap the centers after heat treat. Yes, they do distort. In a pinch, 60 degree carbide center reamers do a pretty good job.