http://www.mcmaster.com/#steel-bearing-balls/=j14m3n

I found these ball bearings for use in rebuuilding my blacksmith forge blower. I need .248 inch dia. and they offer 1/4" and I am quite sure they will work.

I don't know what would be best for use in a old forge blower (high speed fan with little lubrication). I don't really understand the Rockwell hardness. The S2 is C55 and the 1020 carbon is C60. Also listing an E52100

Interesting..I have a rockwell tester and have never seen 1020 steel rleach 60 on the C scale.

Rockwell testers that I am familiar with have a diamond tip that is pressed into the metal and the machine can measure the impression that it makes with a certain pressure applied. The results allowo us to somewot predict wot a steel will do for us..Like yoiu are doing, WE can base thta decision on wot we know has worked in the past in similiar applications. For wot you are asking I would like to know wot the bearing rides in,, How hard that is? most bearings ride in hardened races, both inner and outer. My gut feeling is that any of the bearings you listed will work just fine. I just am not sure about the 1020. That of couirse does not mean that it is not that hard,,I just have not been able to reach that with mild steel.

It is very hard to get any real hardness form less than 40 points of carbon.

I would expect 1020 to reach that hardness only in a case-hardened condition.

The link does indicate that the balls are case hardened.

For those unfamiliar with the process, case-hardening is a process by which additional carbon diffuses into the surface, at high temperature, from a carbon-rich packing medium. The entire article can then be quenched, but only the surface, with a high enough carbon content to form Martensite, will harden.

Given the low speed and low force nature of a hand crank blower, a case hardened bearing should last quite a long time indeed!

Wear those bearings out and then replace.I bet you they would outlive you in that situation. Most bearings are abused to death and not worn out from protected usage. So unless your blower is out of the rain and snow it quite well will be still operating when the kids sell it.
Of course there are exception.
Carry on

Many times, you'll find that Bearing Balls are Chrome plated, to enhance their SURFACE hardness, and wear characteristics.

Plain Carbon Steel balls, lubed with a bit of Graphite Grease ( Never-Seize ) will work like a charm.


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420 is a stainless ball bearing steel.