John wrote:

"Steve W." wrote in message
...
David R.Birch wrote:

Fortunately, they can be had cheap, so it's a good idea to buy two good
ones and use one for parts, as the price of certain replacements are as
much as a used machine. Other parts are just not available.

David

You know I often hear folks who have fully equipped machine shops
complain about the lack of replacement parts for machines.

What parts could not be made in house?
Why?


The only parts in a machine that I can think of which are likely out of
the abilities of most shops would be semiconductors and other electronic
components.


--
Steve W.


Most shops lack the ability to make replacement parts. The shop is run
as a production shop where a high machinst skill level is not
necessary.

That is one of the problems IMO. One of my friends works in a similar
shop. His entire job consists of swapping out raw stock/finished parts
from a CNC center. If a machine fails they call a repair tech in.

It doesn't take much time to make a spur gear. If you
order the same part from the mfgr. you are usually hit with a lead time
of a couple of weeks, and a price that is sky high. A screw for a G&L
350T horizontal boring mill runs about 7 grand with the nut and the lead
time was quoted as 4 weeks. Our shop did the screw and nut in about 3
days. Anyone know how to cut a 3 1/3 pitch acme lead screw on a manual
lathe

Cutting a spur gear is not that hard if you have a dividing head. The
math for setting up the hole plate is pretty straight forward and is in
many of the older machining books. The actual setup of the dividing
head takes about an hour, cutting the gear teeth on a 4 inch gear would
take another hour or two depending on how strong your machine is and how
many cuts you do on each tooth. it takes longer to order the right
involute cutter if you don't have the right one in stock than to cut the
gear itself. I have a repair gear to do that is metric 3.5 module 37
teeth. The gear has an inside spline with a long hub. I cheat a little
and do most of the gear stuff on our 4 axis horizontal machining center
that is faster than doing it manually but the dividing head is on the
shelf waiting to be used.

I just grind and harden a profile tool and set up the OLD shaper.
Splines, gear teeth, sprocket teeth and many other items are easily cut.
Slower while cutting BUT I don't have to order special tooling or wait
for delivery either.


Spline cutting on a shaft is also very easy to do with the dividing
head. You will need two ( left and right) 60 degree cutters on an arbor
with the proper shims to get your spline width. Then just cut the
splines and rough out the metal between the splines with a slab mill.

On the K&T and Cincinatti manual machines the hardest part to make is
the clutch plates. I never had to make them but I bet you could buy the
sheet material ( steel coated with brass?) and have them waterjetted.
The older US made machines are a dream to work on compared with some of
the imported stuff. The whole knee of the K &T pulls out in one piece
after taking a couple of bolts out.

Here are pictures of a K&T 205-12 that I had apart. The one engage
lever set screw had shifted due to a loose set screw.

htttp:userweb.intergrafix.net/amdinc/0714081256.jpg

htttp:userweb.intergrafix.net/amdinc/0714081256a.jpg


All these machines were designed and built before there was CAD,
everything was designed on a drafting board with pencil and paper. I
have five machines like this in the shop, one we have set up to do
keyways on shafts.


John



--
Steve W.