Re: Zass question


"Steve Ackman" <steve@xxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:slrndfcen9.mgf.steve@xxxxxxxxxxxxxxxxxxxx
> On Thu, 4 Aug 2005 23:10:47 -0700, Johnny wrote:
> >
>
> > I recently bought a zass 169dg and yes it does exactly as you describe.
It
> > was so bad I looked into why and was unimpressed with the machining of
the
> > rotor burr in 2 ways. Firstly the the thread was not tapped axially in
the
> > burr and secondly the burr plane is offset from the plane of the burr
body.
> > Seems to me this would cause the end to wobble although I don't see why
one
> > edge wouldn't always contact tyhe stator burr.
> > My old zass 151 did the same a little but the new 169 is way worse.
Looks
> > like about a 0.020 inch run-out. Sigh.
> > I've put some photos on the web at
> > http://members.cox.net/fullcity/zassburr/ some of which compare a 12
yr
> > old zass 151 rotor burr with the new 169 burr.
> >: Johnny
>
> The short version: If it was assembled first
> and then machined, (much of) the runout could be an
> optical illusion.
>
> The longer version:
> Most likely the internal threads were drilled and
> tapped before the burr was milled and the shaft used
> in a collet while the burr was machined.
> Since the hole was either not centered, or not
> parallel to the axis of the burr body, then the
> machined cutting edges on the burr (even though
> concentric with the shaft) would appear to be much
> farther out than they actually are.
> This would be quite common, and even almost
> expected when starting out with a casting.
>
> If you really wanted to see what's what, you
> could put the shaft in a V-block (or pair of them),
> and rotate it with a reference (pointer, plane, or
> dial indicator) on/near the the cutting edges of the
> burr.
>
> - Steve "precision grinding for nuclear submarine
> reactor parts, and aircraft landing gear were us"
> Ackman
yep I like that explanation which is why I don't want to indite xass (yet)
however it doesn't explain the contact for only part of the rotatation.
Don't have any V-blocks here at home right now but may have soon (excuse for
a trip down to harbor freight...)
will report back
Johnny


.

Relevant Pages

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    ... >> I recently bought a zass 169dg and yes it does exactly as you describe. ... >> rotor burr in 2 ways. ... >> edge wouldn't always contact tyhe stator burr. ... > to cosmetic imperfection of the machining. ...
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  • Re: Zass question
    ... > I recently bought a zass 169dg and yes it does exactly as you describe. ... > was so bad I looked into why and was unimpressed with the machining of the ... > burr and secondly the burr plane is offset from the plane of the burr body. ... tapped before the burr was milled and the shaft used ...
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