Tapmatic and equivalent heads suggest retracting from the hole at 120% of
the original feed. No torque to retract vs torque to thread; retraction at
the
same feed as threading provides no thrust on the clutch. Your tap stalls
and strips the threads.
----- Original Message -----
From: "Tuffy" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Friday, April 28, 2000 7:19 PM
Subject: Re: [mfg-smartcam] here's one for you real machine heads ...
> Are you using syschronis or rigid tapping?
> Are you using a "Tapmatic" type head?
>
> Several years ago we had a problem of stripping holes in mild steel,
> it turn out the Tapmatic heads were binding during the spindle
> reversal, thus not allowing the tap to follow the helix of the thread.
> The problem was most prevalant with high helix taps. Purchasing new
> tapping heads was the short term cure, buy new machines with rigid
> tapping was the final solution.
>
> Something to remember, rigid tapping does not gaurantee the tap
> follows the helix perfectly. Ask any machine tool manufacturer if they
> will gaurantee perfect syschronization of the spindle rotation and
> the Z-axis. I'm sure they will not. Don't get me wrong, for 99.9% of
> the stuff you tap, it will work just fine.
>
>
> On Fri, 28 Apr 2000 11:28:59 -0400, you wrote:
>
> >... speaking of tapping
> >.05 wall thickness of Invar (free cut) waveguide
> >(if you don't know what waveguide is, it's just rectangular tube)
> >it appears that my 2-56 tap retains the chip once it goes through the
wall
> >and on it's exit, the chip (not the tap) is stripping the thread off!
> >
> >( T6 H6 2-56 GH3 TAP)
> >N770 T6 M06
> >N772 G00 G90 G55 X0.068 Y0.17
> >N774 G43 H6 Z0.1 M08
> >N776 M29 S700
> >N778 G99 G84 Z-0.18 R0.1 F12.5
> >N780 Y-0.17
> >
> >
> >
> >
> >also, the 4-40 holes are tapping just fine.
> >i've tried special goop ("walter" stick compound) and the problem
persists.
> >the tap is still fine (in fact, eight pieces tapped just fine before this
> >started happening), everything is fine ... EXCEPT THE HOLES ARE
STRIPPED!!!
> >any guesses?
> >Ernie Gemmel
> >CNC Supervisor
> >Apollo Microwaves Ltd.
> >Tel (514)426-5959
> >Fax (514)426-3747
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> >send the message "info mfg-smartcam" to [EMAIL PROTECTED]
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