Re: Ball Screw Machining

rtr@...

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> From: John Ross <johnr@...>
> To: 'CAD_CAM_EDM_DRO@...'
> Subject: [CAD_CAM_EDM_DRO] Ball Screw Machining
> Date: Thursday, July 01, 1999 1:20 PM
>
> 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
>All the induction hardened Ball Screws I have ever worked on have been

quite soft where the center drill was. Induction hardening doesn't go very
deep. Before you heated it you probably could have ground a few
thousandths off of where you wanted to drill a hole and gotten to the more
ductile metal.
they don't usually induction harden very far because that part is as
brittle as it is hard. The rest isn't hard, but it isn't brittle either.
Hopefully, one of the old machinist types can shed some light on this.
Ted Robbins

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