On Sat, 20 May 2006 14:32:45 -0700, Larry Jaques
wrote:

On Sat, 20 May 2006 17:02:33 GMT, with neither quill nor qualm, Gunner
quickly quoth:

If that link doesn't work then go to MTD's home page, click on
"parts and accessories", and then "launch illustrated search engine".

http://www.mtdproducts.com/webapp/wc...rate/index.jsp


Btw..they are made in Chandler/Mesa Arizona.

Want the number for the plant supervisor or Sr. Engineer, so you can
bitch about the early failure? G

Bolens, Yard Machine, Cub Cadet, Troy-Built, and McCulloch products
are all THAT good, eh?


Gunner, vendor to MTD

Can you tell us what you vend to them?

Sure. Most of the pistons used in their engines are made from
castings, on OmniTurn CNC lathes.

Rather fascinating problems at first. The only way to hold the
piston casting..was from the inside..so needed an expanding collet
formed to fit the inside of the piston. Only problem was..3 out of 6
pistons would move during the operation Sometimes much..sometimes only
a smidge.. It was discovered that they have 6 die cast moulds..and 3
of them were out of spec enough that the custom expander would not
hold them rigidly. So I developed a way to hold even the loose ones.
Cant tell you about that..but it works. I had to sign a NDS.

The pistons come in, are held in the collet, and spun. The top is
domed slightly, the sides are turned, and the ring grooves are cut.
Then a drill motor comes in..and the C axis spindle turns the piston
and drills the wrist pin hole on one side, then spins 180', drills the
other hole, then a reamer comes in and reams the two holes seperately.
Test is when a gage pin with .0001 clearance is dropped into one
hole..it has to fall all the way through.

Not easy to do if the piston moved on the collet even a **** hair.
And of course all the other dimensions have to be within a certain
tolernce..surprisingly close for something of this nature.
Perpendicularity, parallelism, roundness, etc etc

Being aluminum..the piston cannot be held too loose by the internal
gripper, or it comes loose or moves, and cannot be expanded too much,
as the piston comes out 3 sided. A fine balance, complicated by the
die casting size issues. Took a while to quantify the problem and
then try various fixes.

Needless to say..they make good parts now. And coolant temperatures
both winter and summer made a fair amount of difference also..it being
in Aridzona next to Phoenix

Gunner



--
Music washes away from the soul the dust of everyday life.
---- --Unknown

"If thy pride is sorely vexed when others disparage your offering, be
as lamb's wool is to cold rain and the Gore-tex of Odin's raiment
is to gull**** in the gale, for thy angst shall vex them not at
all. Yea, they shall scorn thee all the more. Rejoice in
sharing what you have to share without expectation of adoration,
knowing that sharing your treasure does not diminish your treasure
but enriches it."

- Onni 1:33