Subject: turning down bolts

From: [email-masked] (kenneth.b.reber)
Date: Mon, 27 Sep 1993 20:42:34 GMT

I have a need to reduce the dia. of a bolt.  Actually starting with a
1/2 dia, I need to cut it down to 3/8 fine leaving a 1/2 dia shoulder.
that is 1/2 long as measured from the head.
(It's a restoration project requiring a bolt with large hex head in relation to
the thread.)

What is the best way to chuck it up?  Can't use a center as the threaded
end also needs turned. Will the three jaw hold on the head tight enough
to allowing cuts down to 3/8 dia.?

I need to make 10 of these.

Suggestions?

Thanks,
Ken

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From: [email-masked] (Ken Moonitz)
Date: Tue, 28 Sep 1993 18:31:19 GMT

>I need to make 10 of these.

There is no reason why you can't use a center on this operation,
I've done it several times.  Chuck up the hex head in a three jaw,
center drill the threaded end (obviously under 3/8") and turn away.
the only trick is getting close to the center.  If you start with
an extra long bolt you can machine a grove just ahead of the center
and turn from the grove towards the head stock.        

Another Ken

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From: [email-masked] (Stuart Friedberg)
Date: Tue, 28 Sep 93 18:46:30 GMT

In article <[email-masked]> [email-masked] (kenneth.b.reber) writes:
>I need to cut it down to 3/8 fine leaving a 1/2 dia shoulder.
>end also needs turned.

Hmmm.  Why can't you use a center on the threaded end, gripping
the hex head in a 3 jaw chuck?  A small center drill shouldn't
affect the threads any, and a center would add a great deal of
stability to an otherwise shaky (3 jaw only) setup.

I have a cheap carbon steel dead center that I ground nearly half
away so I have lots more clearance between cutting tool and center
than with a normal center on small stock

> Will the three jaw hold on the head tight enough to allowing cuts down
> to 3/8 dia.?

This probably won't work very well alone.

Stu Friedberg  ([email-masked])

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From: [email-masked] (John Kopf, X6305)
Date: 28 Sep 1993 19:35:44 GMT

> I need to make 10 of these.

I'd install the tailstock drill-chuck, and use it to hold the threaded portion
in alignment while clamping the bolt head in the 3-jaw chuck.  Then back off
the drill-chuck and turn off the threads (shallow cuts should be OK) until
down to the diameter.  Tnen proceed to thread it.

JK