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[DPRG] help making a dual threaded shaft?

Subject: [DPRG] help making a dual threaded shaft?
From: RoboVac robovac at mninter.net
Date: Tue Sep 9 23:49:08 CDT 2003

A third method is to check with an industrial supply store for a rod already
made with left hand threads on one end and right hand threads on the other.
That is what I have done in the past.  This is assuming you are using a
common size thread and it does not have to be too long.  The most common
thread for this seems to be 1/4 - 20 and they are about a foot long.

William Crolley

----- Original Message ----- 
>From: "Earl Bollinger" <earlwbollinger at comcast.net>
To: "'Clay Timmons'" <ctimmons at cadence.com>
Cc: <dprglist at dprg.org>
Sent: Tuesday, September 09, 2003 8:28 PM
Subject: RE: [DPRG] help making a dual threaded shaft?

> Actually you'll need to do what I do, get a set of "rare" left hand
> thread taps and dies for the thread size you want.
> I am using 4-40 or 6-32 myself for a small gripper.
> There are two ways that I see.
> One: Take a bras or aluminum or mild steel rod of the size you need.
>    Cut it a little longer than needed.
>    Then thread one side right threaded, thread the other side left
> threaded, leave a small unthreaded portion in the center. Then tap one
> arm right handed and tap the other arm left handed.
> Two: A bit less work, use a threaded rod for one side, then left hand
> thread another rod for the right. Then drill and tap a short joiner rod
> for both left and right hand threads and join the two threaded rods
> together.
> I intend to use a short piece of both L and R hand threaded rods to
> screw onto the outer ends and use these as bushings or bearings on the
> support truss for the grippers. I feel the raw threaded ends would ream
> out the holes on the support trusses too quickly if I don't.
> You can get the "rare" left hand taps and dies from
> http://www.jtsmach.com/jtswebshop/asp/home.asp
> Regards,
> Earl

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