Barry Gardner wrote:

Paul,

Here's a question to pass to Butch, the maker of the last batch of Wiggins
couplings.

I'm working on making a few of these in the machine shop of my local
community college. My question is whether Butch made them on an engine lathe
and, if so, how he held them? Did he have an expanding mandrel on centers
that gripped the aluminum tubing from the inside as he machined the outside?
Or did he make some other kind of home-brew contraption to grip them (and
hopefully would be willing to sketch for the benefit of those of us lacking
his experience and imagination)?

Armed with your blueprint, Paul, a bunch of us in my shop class were
puzzling over the best type of fixture to do this.

Barry Gardner
Wheaton, IL

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Hi Barry;

    First of, my batch was made in a high speed CNC Lathe, and believe it or
not it was cheaper and faster to turn them out of SOLID round stock instead of
aluminum tubing.........A length of material (12 ft. long) is fed through the
spindle and all the turning, grooving and boring operations are performed with
the last one being the parting (cutting of the part from the al. bar), so when
the part is mandrel caught, (catched), it's completely finished....."Piece-O-
Cake" :)

You can do the same thing in an manual lathe, just takes a little longer :) If
your lathe is not big enough to feed the bar thru the Spindle, cut lengths of
material which is determined by how far the stock will go into the chuck (3jaw)
and add 2 inches from the jaws, this means there will be 2 inches sticking out
from the chuck's jaws.......Face off the stock, center drill, step rough drill
the bore, do not finish bore. Move on to the outside turnings, grooving,
vebeling etc. to finish sizes. Go back to the bore and using a single point
boring bar bore to finished size. You can now part the piece by using a parting
tool, make sure you leave the piece about 1/32 oversize. Next UN-chuck and pull
the stock out and repeat operations.....If you have, and know how to use a 4
pos tool turret, and took note of your dial numbers, you wouldn't have to break
up your set-ups and can repeat this over and over again with no problems at
all. For facing the parts afterwards, the best thing is to use a collet, if you
don't, the best next thing I find is to remove the hardened jaws from the chuck
(I would imagine they are removable for reversing purposes), and mill, drill to
mount aluminum rectangular blocks in their place, face-off and bore out a hole
same as the O.D. of the part you want to chuck for facing........This is a
great project for anybody who want's to learn machining skills.
As a rule, in most machined jobs, fixtures should be avoided as they actually
take longer to do than the actual parts, even if you're planning to do hundreds
since you can get a CNC shop to make them for you cheaper.......RIGHT, Jerry? :)

                                    If I can be of further help, let me know.
                                                   Butch

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