In article ,
Harold and Susan Vordos wrote:

"Mark Mossberg" wrote in message
m...
Steve,

Turning a 4" long diameter in a 6" long square bar isn't that big of a
deal.
All you need is a lathe with a 5C collet closer, a 1" square collet (I
think
this as big as a 5C goes),


Wrong! 5C collets are available in (round) sizes up to 1-1/8", but there's
no chance in hell you can buy one large enough to hold 1" square material.
The material exceeds collet size across the corners. You could buy a step
chuck (2" diameter or larger) and mill the configuration with some care,
however.

That -- or a 4-jaw chuck. A regular one could be used, but this
kind of job would be nicer in a 4-jaw universal (scroll-back) chuck.
Yes, they are rare, but they do exist. I've got two at present for
different machines.

Cutting fancy features lengthwise in the round portion can get
complicated.
If the features are 90 or 180 degrees apart you can use the remaining
square
ends as references. Any more than that and your looking at a 4th axis set
up. Maybe even 4 axis surfacing.

Not true. If the parts are machined by holding with a step chuck, an
indexing head and tailstock center would be adequate for holding and
indexing for flutes.

He said *no* machining on the ends, but you would at least need
to center drill one end, and ideally should face both ends, too.

One could machine them easily @ 30 degree or 45
degree intervals, using a small (radiused) side cutter,

Or -- a ball-end mill, which would have less trouble staying
clear of the square ends. It could not cut as fast as a half-round side
milling cutter, but ... :-)

And if six flutes would be sufficient, one end of the workpiece
could be held in the machinable collet in a hex collet block held in a
vise.

either on a
horizontal or a vertical mill. The biggest problem here would be using a
small enough cutter so it didn't interfere with the square portion.

The ball end mill seems to be called for here.

A
Woodruff cutter might be a solution. This would be an excellent operation
for a hand mill, a Nichols, for example.

Agreed -- the lever X-axis feed would be nice for the fluting.
I would prefer to have a universal 4-jaw chuck on a proper dividing
head, however, as it would be more rigid than the spin indexer. You
would have to spend a lot of time turning cranks on the dividing head,
however.

Hard to give you an idea of the cost without seeing it. One thing's for
sure, the material cost will be insignificant compared to the labor.

[ ... ]

Absolutely. This would be a relatively labor intensive part to make, even
without difficult tolerances, which are not a concern from all indications.
At today's shop prices, I wouldn't be surprised to see a part of this nature
go for $45 each.

And for this, without CNC to do the work, I would tend to say
that the fixturing to do fifty of them efficiently would boost the price
significantly.

Enjoy,
DoN.
--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---