Crude live tooling

[Richard P Wilson]

I can see why that die grinder chattered. It's hanging out there quite a ways.

Also, wouldn't it have been better to cut spiral grease groove ?? Since your straight grooves are spaced at 90 deg. the only part carrying the load in line with the grooves are the ends where the grooves stop.

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

He made them to the customers drawing. If the customer specifies straight grooves, that what he gets, and if theres a problem with this, its the customer's problem, not Benteds problem.

[Bented]

Indeed, if they draw lubrication grooves in the part bore of any shape that is what they get.
I could have used a CNC lathe and made many different groove shapes, at a much higher cost of course.

If I ever have to do more of these I will put them in a CNC lathe after the finish boring, the steady feed rate will make it a breeze.

After 10 years of using NC lathes I truly dislike the monotony of hand wheels especially when single point threading.
Close 1/2 nuts, open 1/2 nuts, back tool out, return carriage to start position, infeed cross slide and repeat as required.

This is the year 2021 not 1941.

Threading on a 1995 Bridgeport lathe.


Threading on a 2021 Trak lathe.
3/8 NPT thread, turn profile and thread, can't help the fingerprints it is a touch screen control (-:

[nickel-city-fab]

Annoyingly loud, over ear headphones recommended, I use Marshall headphones connected by bluetooth to a tablet or laptop, small and light weight.
Excellent ear protection, however they cost more then $0.00,

Sometimes I'm glad that I became legally deaf. Believe it or not, I use my fingertips to feel for chatter before it sets in. Its actually quite sensitive. There's nothing I can do about having to use a needle scaler on an old dumpster in a cement building though. Yeah there are days like that.

[JoeLee]

He made them to the customers drawing. If the customer specifies straight grooves, that what he gets, and if theres a problem with this, its the customer's problem, not Benteds problem.

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...............

[JoeCB]

Oh, I'm back... Yes could do it on the shaper.... would be slow, but do-able. Looking at the bushing a little closer, there is an annular groove at the mid point of the bushing. So the shaper could cut the long groove from each end to the annular groove. The start would have to be stepped down with each successive cut.

Joe B

[mickeyf]

So the shaper could cut the long groove from each end to the annular groove. The start would have to be stepped down with each successive cut.

Or... Drill holes from the outside of the bushing, at each end of where the oil groove will go before pressing the bushing in. Yes, the hole would then go all the way through the bushing to the containing piece, but I'm not immediately seeing how that would cause a problem. (Other than not being on the original drawing...)

[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

[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).

[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.

[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

[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]

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]

facts before criticizing

What a crazy concept. 🤪

[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.

[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.