Re: Ball Screw Machining

John, Any steel that has been hardened must be reheated to above the
critcal (nonmagnetic) point, about 1400� F(800�C), and then allowed
to cool very slowly. This would be a bright red heat. place the item
in wood ashes, lime or ceramic blanket until cool. Works fer me.
Rich Dean

John Ross wrote:

>
> From: John Ross <johnr@...>
>
> Hi I'm new (as of today) to this list, and I have a question about
> machining hardened ball screws. I have been converting my Mill Drill to
> ball screws as the article in HSM. Dan Falck has been giving me some advice
> on how he did this conversion. As Dan had did on his conversion I heated
> the ball screw in a lathe at its slowest speed (60 RPM), to a Straw color
> then let it cool before machining them. They are still extremely hard.
> I've tried reheating them but have had no better luck. Drilling the #7
> hole for a 1/4 20 center screw was darn near impossible and my tap won't
> even start to cut a thread. The ball screws I'm trying to use are from
> McMaster Car and they list them as "induction hardened to Rockwell 56-60C".
> Does anybody have any ideas as to how to soften these up so I can machine
> these beasts. My fathers suggestion to grind them is a little pricey
> considering I don't own a tool post grinder.
>
> John Ross
>
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