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Re: Ball bearing life why so short?

 

I have purchased the ABEC-9 class for rebuilding a mill head. The ball bearings companies low that class. I think I could buy new lathe cheaper.?

Dave?
Re: Ball bearing life why so short?

 

I've always thought it was from improper pre-load! Getting the pre-load right is finicky & usually requires several iterations to get right, something not done by the factory.? What you want is no measurable axial play & minimal bearing heating at full speed.

A reasonable upgrade is to replace the bearings with 7206, an angular contact bearing that's the same size as the 6206 deep groove bearings originally installed. They're available sealed,? to keep crud out. They can handle a higher axial load than their deep groove counterparts without the hassle of converting to unsealed taper? roller bearings.

?<??>

Roy (retired M.E.)
Re: Linear Digital Readout Scales

 

If look at photo of my mill I used a low cost digital caliper from Harbor Freight?

Dave?
Re: Linear Digital Readout Scales

 

Try my thread on portable DRO'S.??
/g/7x12MiniLathe/message/118787

I have mounted a temp DRO'S to lathe pass for primary dealing with snap rings.
Low cost digital caliper can used too.

Dave?
Re: Ball bearing life why so short?

 


?
Just the quality of mini lathe if spent $10.00 lathe upgrade on Spindle bearings 4" crosss feed travel and DC power feed?

The wholesale price of lathe is $300.00 retail is $600.0 a incress the retail to $620.00

What difference in the lathe

Dave?




mike allen
Feb 14???

??? ??? Cause its probably the cheapest 6206 bearing they could find .

??? animal
Linear Digital Readout Scales

 

I am looking for some short linear digital scales to mount on a small lathe like a Shereline. I am hoping to find something on the order of ¡°cut-off¡± digital caliper.
Could anyone suggest a good source? I want to avoid any wires and prefer a button battery type.
Dick
Re: Ball bearing life why so short?

 

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??? Spindle bearings in the ABEC-9 class are one of the best ya can get , & the price confirms it .

??? animal

On 2/15/24 5:03 PM, davesmith1800 wrote:

I agree they use cheapest they can find.

Dave?

mike allen
Feb 14? ?
? ? ? ? Cause its probably the cheapest 6206 bearing they could find .
? ? animal
Re: Ball bearing life why so short?

 

I agree they use cheapest they can find.

Dave?

mike allen
Feb 14? ?
? ? ? ? Cause its probably the cheapest 6206 bearing they could find .
? ? animal
Re: Ball bearing life why so short?

 

There are downside tapper roller bearings. I have used and designed a lot of tapper roller bearings?

They are a pain to seal.
This group per load is not problem but it is with most.
Most forget about Lubrication of any bearing. This problem with lathes too. No or low lubrication kills lathes?

I seal for life deep groove ball bearing can fix most problems and should last 20,000 hours. It sounds like quality is problem.?


Bill Williams
9:55am? ?
If the necessary preloading is the cause of ball bearing failure then that makes a strong case for replacing with tapered roller bearings designed for preloading
Re: Ball bearing life why so short?

 

If the necessary?preloading is the cause of ball bearing failure then that makes a strong case for replacing with tapered roller?bearings designed?for preloading.


On Thu, Feb 15, 2024 at 10:46?AM Ralph Lehotsky <ralphlehotsky@...> wrote:
I totally agree - replace with a good 6206 from a competent manufacturer.

Re: Ball bearing life why so short?

 

I totally agree - replace with a good 6206 from a competent manufacturer.
Re: Ball bearing life why so short?

 

¿ªÔÆÌåÓý

I would offer that "DEEP GROOVE" bearings do NOT have good axial load potential.
?
plus?
The fact that the bearing 6206 seems to be big and chunky in your hand and by human force standards, when the machine is applying load to the bearing in the axial direction, it may still be being overloaded by the massive mechanical advantage the lathe can generate.

plus
Cheap bearings.

Maybe switch to sealed 7206 Angular Contact bearings similar to --> ? , installed in opposing directions.

Good Luck with your continued research in this matter.


On 2/15/2024 10:45 AM, davesmith1800 wrote:

It is a deep groove ball bearing?
This type has very good axial load?
They use type of deep groove on live centers too.?

Dave?
Craig Hopewell
5:08am? ?
They are not designed for heavy axial loads - like heavy (for a mini-lathe) cuts.
--
Lone Tree, Colorado USA
Re: Ball bearing life why so short?

 

Probably the problem quality?
How cheap can you go?

Dave?

Agreed.
Go for a known quality brand. SKF or NSK as a couple of examples.
Dave
The Emerald Isle
Re: Ball bearing life why so short?

 

It is a deep groove ball bearing?
This type has very good axial load?
They use type of deep groove on live centers too.?

Dave?

Craig Hopewell
5:08am? ?
They are not designed for heavy axial loads - like heavy (for a mini-lathe) cuts.
--
Lone Tree, Colorado USA
Re: Ball bearing life why so short?

 

They are not designed for heavy axial loads - like heavy (for a mini-lathe) cuts.
--
Lone Tree, Colorado? ?USA
Re: Ball bearing life why so short?

 

Agreed.
Go for a known quality brand.? SKF or NSK as a couple of examples.

Dave
The Emerald Isle


On Thursday, 15 February 2024, 03:08:15 UTC, mike allen <animal@...> wrote:

??? ??? Cause its probably the cheapest 6206 bearing they could find .

??? animal

On 2/14/24 6:41 PM, davesmith1800 wrote:
I have the 6206 bearing in motors and doors. The life for a seal 6206 ball bearing is 20,000 to 60,000 hours.
In a mini lathe a lot shorter.?
Why is it so short?

Dave?

Re: Ball bearing life why so short?

 

Possibly because the bearing isn't the best match for the application.? Preload will eliminate all free play, axially speaking, and it is all too easy to over-do it.? Angular contact or tapered roller bearings would be better suited for spindle bearings.
Re: Ball bearing life why so short?

 

I am not an engineer, but I believe that it has to do with preloading and heat. A motor may be exposed to a substantial amount of heat, but they have some free play to it, essentially allowing the shaft?to float a bit. The life may be shortened due to the combination of loading and friction from the preloading of the bearing to eliminate?all movement. Just a?thought I had while reading through this thread.


On Wed, Feb 14, 2024 at 6:51?PM chrisser via <chris.kucia=[email protected]> wrote:
Maybe the axial loading when machining on a lathe?

Of course, all the drill presses I've been inside of have ball bearings and most of their load is axial in spite of that.? But maybe the axial forces involved in using a drill press aren't as large as those when using a lathe.

Or it could just be cheap bearings or even cheap lubricant.
On Wednesday, February 14th, 2024 at 9:42 PM, davesmith1800 <davesmith1@...> wrote:

[Edited Message Follows]

I have used the 6206 bearing in motors and doors. The life for a seal 6206 ball bearing is 20,000 to 60,000 hours.
In a mini lathe a lot shorter.?
Why is it so short?

Dave

Re: Ball bearing life why so short?

 

¿ªÔÆÌåÓý

??? ??? Cause its probably the cheapest 6206 bearing they could find .

??? animal

On 2/14/24 6:41 PM, davesmith1800 wrote:

I have the 6206 bearing in motors and doors. The life for a seal 6206 ball bearing is 20,000 to 60,000 hours.
In a mini lathe a lot shorter.?
Why is it so short?

Dave?

Re: Ball bearing life why so short?

 

Maybe the axial loading when machining on a lathe?

Of course, all the drill presses I've been inside of have ball bearings and most of their load is axial in spite of that.? But maybe the axial forces involved in using a drill press aren't as large as those when using a lathe.

Or it could just be cheap bearings or even cheap lubricant.
On Wednesday, February 14th, 2024 at 9:42 PM, davesmith1800 <davesmith1@...> wrote:

[Edited Message Follows]

I have used the 6206 bearing in motors and doors. The life for a seal 6206 ball bearing is 20,000 to 60,000 hours.
In a mini lathe a lot shorter.?
Why is it so short?

Dave

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