Crude live tooling

[JRouche]

Longitudinal grease grooves in 932 bronze bearing bores 7 1/ 2" long.




Asked my employer if they had done this job in the past, indeed they had and he finds a right angle die grinder hose clamped to a holder under a bench.

Chatter City and a slow process but they are only lubricant grooves so are not measured by the customer.
Crude but effective (-:

I think you nailed it!

What a deep cut. Well, it worked. . It looks nice, does it flow??

Kidding!! JR

[JoeCB]

If you really want to do it with a shaper....extend the tool bar so that it hits a ramp and lifts the tool at the end of the stroke.

See, another example of what can be learned from the guys here that know

Joe B

[nickel-city-fab]

I make many parts for this customer per year, many are larger diameter and have no grooves.

1 I have zero knowledge of what they do in use.

2 I make them as the drawing indicates even if it is wrong, trying to explain to an engineer that they are wrong works equally as well as telling a Catholic that God does not exist.


Last week I made 3 parts from a tabulated drawing, same part diameters at different lengths, the customer ordered the wrong length part, hilarity ensued.

.... and they still had to pay you.

[Doozer]

In my experience, for a shaft that's periodically loaded, good designers (or installers if it's not a split bearing) generally place the oil grooves so that they are providing oil at the point just before the load begins. From there it's pulled out of the grooves and into the loaded zone. These grooves should not have sharp edges either. They should either have a bevel that's about 15° from tangent or a convex radiused edge. This helps the oil get pulled out of the groove. If the load is non periodic, it's best to have at least one of the grooves on top so at a halt or very low speed gravity will pull oil down from there instead of holding it at the bottom and having it leak out. At higher speed the oil will cover the bearing as the shaft drags it around.

That is correct. Something Zora Arkus Duntov kept in mind when designing the small block Chevy crankshaft.

-Doozer

[Bented]

I make many parts for this customer per year, many are larger diameter and have no grooves.

1 I have zero knowledge of what they do in use.

2 I make them as the drawing indicates even if it is wrong, trying to explain to an engineer that they are wrong works equally as well as telling a Catholic that God does not exist.


Last week I made 3 parts from a tabulated drawing, same part diameters at different lengths, the customer ordered the wrong length part, hilarity ensued.

[The Artful Bodger]

If you really want to do it with a shaper....extend the tool bar so that it hits a ramp and lifts the tool at the end of the stroke.

[Richard P Wilson]

Yes, but Bented said in the first post that its a grease bearing, not an oil one. I don't think he's said what its actually for. I suspect something low speed, maybe even an excavator bucket pin bush. Presumably the lubricant feeds into that central circular groove under pressure, then from there into the 4 long grooves and generally smears itself around.

[eKretz]

Yes, I understand that but the straight grooves have lessened the load carrying capability of the bearing especially if the load is directly over the slot.

JL...............

In my experience, for a shaft that's periodically loaded, good designers (or installers if it's not a split bearing) generally place the oil grooves so that they are providing oil at the point just before the load begins. From there it's pulled out of the grooves and into the loaded zone. These grooves should not have sharp edges either. They should either have a bevel that's about 15° from tangent or a convex radiused edge. This helps the oil get pulled out of the groove. If the load is non periodic, it's best to have at least one of the grooves on top so at a halt or very low speed gravity will pull oil down from there instead of holding it at the bottom and having it leak out. At higher speed the oil will cover the bearing as the shaft drags it around.

[Dan Dubeau]

facts before criticizing

What a crazy concept. 🤪

[Doozer]

Yes, I understand that but the straight grooves have lessened the load carrying capability of the bearing especially if the load is directly over the slot.

JL...............

Unless fed by oil.
Then the load capacity is more.
You need all the facts before criticizing a design.

-D

[Dan Dubeau]

"If it looks stupid, but it works, it ain't stupid"

Sometimes there no times for coming up with the best theoretically possible solution to every problem. There's only time to make due with what you've got.

Probably could have got away with a straight grinder too, with a ball endmill on a skew. I love the ingenuity to get the job done.

[Doozer]

4 oil grooves makes me think of Cincinnati Filmatic bearings.
The hydrostatic action makes the grind spindle self-center
being fed oil at 4 points. I know you said grease, so it is not going
to exactly work that way. But that is the concept.

--Doozer

[Richard P Wilson]

Yes, I understand that but the straight grooves have lessened the load carrying capability of the bearing especially if the load is directly over the slot.

JL...............

Its still the customers problem, as is how he installs the bushings and in what orientation. Customers don't need to expect contract machinists to point out where their precious design could be better. For that they'd have to pay for the advice and be prepared to pay any additional cost of the part. Very, very few will do that. IMHO.

[eKretz]

I have done these a few different ways. With a boring bar and the tool mounted sideways. With a 90° mounted air grinder as shown here, and even with a straight air grinder by hand. (For this last it pays dividends to clamp a piece of flat bar in the bore to act as a template, letting the grinder ride along it in a manner such that the tool rotates in a direction that pulls it toward the guide bar).

[JoeCB]

Good thought mickeyt about "start" holes.. looking at the bushing, the grooves start close enough to the end that one could drill the start holes at an angle from outside the bushing, just drill same depth as the oil groove. ... Problem solver, shapers rule ( sometimes !)

Joe B