Tips/Techniques Unique uses for ball bearings

[Johnwa]

 

[Ironman]

Nice use for a ball bearing to build a burnishing tool. I often work with hot rolled and it is hard to get a nice finish with HR material. I'd like to try this. I wonder how much burnishing changes the dimension.

 

[Matt-Aburg]

Nice use for a ball bearing to build a burnishing tool. I often work with hot rolled and it is hard to get a nice finish with HR material. I'd like to try this. I wonder how much burnishing changes the dimension.

That is sweet. I would think you could figure out exactly how much compression to get exact size. It probably adds surface hardness also... Goodbye emery paper !!

 

[DavidR8]

Dang I wonder if that would work on my 12x37....

 

[Susquatch]

Dang I wonder if that would work on my 12x37....

I bet it would.

I'd love to see a high magnification video of what is happening under that ball.....

 

[DavidR8]

I bet it would.

I'd love to see a high magnification video of what is happening under that ball.....

Would have to be reducing the diameter right?

 

[whydontu]

I bet it would.

I'd love to see a high magnification video of what is happening under that ball.....

Can’t find a macro video, but here’s some numbers:

https://cogsdill.com/products/burnishing-tools/

My math says dimensions won’t change much. 125uRa roughness is pretty gross, and if the cogsdill description is accurate, smoothing out a 125uRa machining finish would squish down the peaks and fill in the valleys, so maybe reduce the O.D. of a cylindrical piece by half of the Ra value. 62 millionths of an inch?

 

[Matt-Aburg]

 

[DavidR8]

Can’t find a macro video, but here’s some numbers:

https://cogsdill.com/products/burnishing-tools/

My math says dimensions won’t change much. 125uRa roughness is pretty gross, and if the cogsdill description is accurate, smoothing out a 125uRa machining finish would squish down the peaks and fill in the valleys, so maybe reduce the O.D. of a cylindrical piece by half of the Ra value. 62 millionths of an inch?

Oh that’s way less than I expected.
Thanks!

 

[Susquatch]

Would have to be reducing the diameter right?

I don't really think it would be much of anything. The only reduction would be associated with the surface roughness peaks normalizing to the average by filling in the valleys. That won't be 100%, but I'd still expect that to be the trend.

Edit - didn't see @whydontu 's post till after posting the above. I agree with his comments.

Fundamentally, you can't compress the bar. You can only even out the bumps and valleys.

 

[Janger]

That is awesome! I didn't know about this at all. And definitely on the to do list now! What a cool project and he is an excellent machinist.

There is a tricky bit though. The nut which holds the ball bearing captive I have a few questions... What size is the hole to keep the bearing in place? Why dosen't the bearing rub on the housing? The nut seems to cinch down to the bottom of the threads yet the ball can still move around. What might the clearance be?

Would this work on aluminium too?

@Johnwa thanks for posting this.

@johnnielsen did you use this technique?

 

[Janger]

I see in another one of the vids you can burnish flat stock in a mill. What would a shop made tool to do that look like? Kind of a fly cutter like device?

 

[DavidR8]

That is awesome! I didn't know about this at all. And definitely on the to do list now! What a cool project and he is an excellent machinist.

There is a tricky bit though. The nut which holds the ball bearing captive I have a few questions... What size is the hole to keep the bearing in place? Why dosen't the bearing rub on the housing? The nut seems to cinch down to the bottom of the threads yet the ball can still move around. What might the clearance be?

Would this work on aluminium too?

Obviously I know next to nothing but it seems to me that the hole only needs to be small enough contain the steel ball bearing.
I suspect there may be washers holding the captive ball bearing in the middle of the slot?
I think the bore for the bearing needs to be close tolerance so that it’s not rattling around.

 

[Janger]

Obviously I know next to nothing but it seems to me that the hole only needs to be small enough contain the ball bearing.
I suspect there may be washers holding the bearing in the middle of the slot?
I think the bore for the bearing needs to be close tolerance so that it’s not rattling around.

Not that bearing. The steel ball. definitions .... argh I don't have clear words.

This is a ball bearing says google:



from https://www.theengineerspost.com/types-of-bearings/

McMaster says these are steel balls.

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.

www.mcmaster.com

Ok I'll rephrase now that I know what the names are.

Questions:
There is a tricky bit though. The nut which holds the Steel ball captive I have a few questions... What size is the hole to keep the ball in place? Why dosen't the ball rub on the housing? The nut seems to cinch down to the bottom of the threads yet the ball can still move around. What might the clearance be?

 

[DavidR8]

Not that bearing. The steel ball. definitions .... argh I don't have clear words.

This is a ball bearing says google:
View attachment 41538


from https://www.theengineerspost.com/types-of-bearings/

McMaster says these are steel balls.

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.

www.mcmaster.com

Ok I'll rephrase now that I know what the names are.

Questions:
There is a tricky bit though. The nut which holds the Steel ball captive I have a few questions... What size is the hole to keep the ball in place? Why dosen't the ball rub on the housing? The nut seems to cinch down to the bottom of the threads yet the ball can still move around. What might the clearance be?

Sorry my explanation mixed metaphors or at least balls and bearings

 

[Ironman]

I think there is nothing critical here. The ball is captured by the end cap and the ball bearing behind it takes the thrust pressure. He never gave dimensions because it will depend on the size of the ball and the ball bearing size will depend on the size of your tool post slot. Actually you could let the ball bearing hang out each side as well.

 

[Susquatch]

I find myself wondering if a simple knurling tool wouldn't do exactly the same thing. Just replace the knurling wheels with smooth curved surfaces..... Not flat. Could be one or two wheels.

If they exist, a round sided bearing would be perfect!

I bet this process is really hard on the cross-slide screw and nut. Not something I'd want to do very often. I like my lathe too much to do that to it.

Also thinking that I wouldn't use that without a follow rest.

I recently received and tried some round Inserts for cutting Aluminium. I was blown away by the improved finish on hot-rolled steel. I have more experimenting to do but for right now I'm just plain amazed.

 

[RobinHood]

I recently received and tried some round Inserts for cutting Aluminium. I was blown away by the improved finish on hot-rolled steel. I have more experimenting to do but for right now I'm just plain amazed.

That’s what I found when I just for laughs and giggles tried one out a long time ago; actually I was too lazy to change the insert back to steel after working in ALU. I only had one tool holder at the time…
If you try inserts for SS on hot rolled steel, you will also see an improvement vs a regular steel insert (when taking light cuts).

 

[RobinHood]

I bet this process is really hard on the cross-slide screw and nut. Not something I'd want to do very often. I like my lathe too much to do that to it.

I am not sure about that: depending on the ball size, there is a very small contact area that does the work. I would be surprised if the forces are any higher than during regular medium to heavy turning.

As far as using a knurling tool with two crowned, smooth wheels: that should work perfectly. The forces would be larger than using just a ball because of the larger contact area.

 

[Susquatch]

I am not sure about that: depending on the ball size, there is a very small contact area that does the work.

The forces would be larger than using just a ball because of the larger contact area.

That's where I started too. It is good to question these things.

Isn't the balls working area strictly determined by its diameter? And wouldn't a torrus of the same major diameter have a much smaller working area because of the much smaller cylinder radius?

Edit - above torrus description revised for clarity.