[TheForge] Krause/Nazel type air hammer

Wed Dec 4 08:10:03 2002

I'm not sure what is being referred to as "lapping" here, but valve
lapping is not generally done in automotive machines shops much
anymore. The valve grinding benches everyone seems to have, have
progressively finer stones with the correct angles on them, it's just
a matter of sticking the air motor on the next stone and using it,
doesn't even take two hands to change a stone.  That does the seat,
the valve is done in a grinder set to do the angles to match the
stones and the bench has a stone dresser to keep the angle on the
stones correct.
   When lapping was common it was done because the machines weren't
capable of making perfect seat/valve matches. The machinist would
finish by actually putting the valve in it's hole and using several
different grit compounds between the faces.  There are little
"handles" with suction cups at each end, stick the suction cup on the
valve head face and start spinning it back and forth, like trying to
friction start a fire without a bow.  Not hard to do, just very time
consuming.  Last I knew NAPA still offered a couple of grades of grit
and a handle in their small engine parts line.  If I had only a few to
do and wanted perfect fits, I'd certainly lap them.  VERY OLD
technology, most automotive machinists today have never done it
because they didn't have to.

   Jeff   ><>

----- Original Message -----
From: "Larry and Pat Brown" <[email protected]>
To: <[email protected]>
Sent: Wednesday, December 04, 2002 5:16 AM
Subject: Re: [TheForge] Krause/Nazel type air hammer

> The valves only move with the treadle as the air flow is created by
the
> rear piston
>
> The machining part that slowed me down quickly was lapping the
valves in
> place(Unfamiliar territory as far as experience and tools). The two
guys
> with machine tools I talked to didn't want to get involved
> L Brown
>
>
> At 09:38 PM 12/3/2002 -0600, you wrote:
>
> >----- Original Message -----
> >From: "Gladish Family" <[email protected]>
> >
> >
> > > I decided not to build one of these because of how much time I
don't have,
> > > but after gazing at Mark's book and my sketch pad for hours, I
concluded
> > > that the job could be done by a linkage that activates two ball
valves.
> >One
> > > opens as the other closes.
> > > Times two, of course, for upper and lower air passages.
> > > Get the proportions of the levers right for the treadle travel,
and you've
> > > got it with components you can buy at Ace Hardware.
> > > Simple, huh?
> > > Not as cute as Mark's, but it would work.
> > >
> > > Andy G.
> > >
> >
> >I would be concerned that the ball valves that you would buy at a
"Home
> >Depot" type store would nt hold up to the rate of cycling that you
want from
> >a air hammer. Haveing build a few test fixtures that I had to run
at cycle
> >rates 12 to 120 cycles/minute I don't think the valve stims could
take it
> >for long.
> >
> >Dan Rathburn
> >Elgin, IL USA
> >
> >
> >
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