Square bar through bearing? 1

[FredFlatstone]

I have a project that calls for an 8mm rod through a number of bearings. The bearings use a set screw, which means that ideally a flat edge is called for to give the set screw something to hold to. I'm wondering, rather than go through the extra machining costs, could I use a square bar, or would the very small contact area cause problems for the bearings?

Thank you.

 

[SnTMan]

FredFlatstone (Computer), To ask the question is to answer it...

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[FredFlatstone]

Yes, perhaps you are correct there Mike! I'm not too well versed with MechEng so wasn't quite sure.

Thanks for your input.

 

[3DDave]

It's unlikely that doing so would not make everything else worse. The reduction of section area, the reduction of polar moment of inertia, the reduction of bending resistance between bearings.

There are some bearings made specifically for square shaft, but I recall that it is much much larger and done to allow some item to be relocated along the shaft while maintaining high torque/clocking capacity, making up for reduction of section properties by making the shaft larger.

There are some single component shaft locking compounds that produce significant capacity.

 

[JohnRBaker]

I think you'll find that most all square-bore bearings do not even have a set screw, as seen in these examples:

https://www.thebigbearingstore.com/square-bore-disc-bearings/

https://www.grainger.com/category/p...earing+Type|Flanged+Square+Bore&filters=attrs

https://www.rexnord.com/Products/Be...rings/Square-Bore-Cylindrical-Outer-Ring-O-D-

https://www.amazon.com/Spherical-Square-BORE-Harrow-Bearings/dp/B00N1X0Q3Y

http://www.peerbearing.com/agricultural-bearings.html

John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without

 

[dvd]

You may have better luck finding hex-bore bearings. These are used on conveyor rollers extensively. 8mm may not go so well, I am familiar with imperial sizes. (A pic of what you are trying to accomplish would allow critics to comment with greater authority, and may even bring some valid suggestions.)

 

[Jboggs]

The manufacturer of the bearings anticipated a round shaft, and intended for the set screw to contact the round surface of the shaft. The set screw is not intended to transmit a lot of torque. Its only purpose is to engage the inner race and the shaft so that they rotate together and there is no slippage. Its ok as is.

 

[DAVIDSTECKER]

Many of the bear set screws have an end designed to "Bite" into the shaft.
If you want a flat spot you could fit the baring and shaft, tighten the set screw to leave a mark, then file a flat on the shaft.

 

[SwinnyGG]

Jboggs has it.

The set screw is only there to eliminate slip between the shaft and inner race. It has to absorb a very small amount of force. Use round shafting, you'll be fine.

 

[Strong]

If your shaft has low speed and minimal thermal expansion then a single set screw should be okay.

Walt