"Tom Gardner" mars@tacks wrote in message
...
On 5/10/2012 12:02 AM, Dennis wrote:
"DoN. wrote in message
...
On 2012-05-09, Bob La wrote:
"Tom Gardner"mars@tacks wrote in message
...
We use 2" x .049 wall tube cut 4" and deburred. We also use three
shorter
lengths but in small quantities. I usually get 200' and send it out.
For
the short lengths, we cut the tube on a bandsaw then deburr each end,
inner and outer, in a lathe.
Would it work if I slide 1' pieces onto a mandrel in the lathe and
used
a
pizza cutter type wheel in the cross slide to part the tube? Kind of
like
a pipe cutter.
You could use your lathe as a pipe drive I suppose with a regular pipe
cutter. A pipe drive is basically just a big lathe chuck with a couple
stop
posts to keep the tubing cutter from spinning instead of cutting. I
made
thousands of cuts with one when I was growing up and helping out in my
dad's
hardware store. I don't think the cutter wheel would work by itself,
but
no
reason you couldn't use the whole tubing/pipe cutter. If your lathe
will
feed 2" pipe I'm sure there is room for the cutter.
Actually -- I don't think that the pipe cutter would work well
with walls that thin. And if the mandrel is just barely a slip fit on
the mandrel, I think that could work well -- even without gripping the
tubing with the chuck. Use a wheel out of a pipe cutter, not a pizza
cutter which is too large an OD and too thin.
The only problems that I see with this a
1) The mandrel will probably get burred fairly quickly, unless
you have the infeed stop just before the cutter wheel touches
the mandrel.
2) The tubing might want to walk. Orient one end against a step
in mandrel diameter, and use a live center supported pusher for
the other end -- with the tailstock moved every time you take
another bite off the length. This suggests that you may want to
make a first cut on a batch of your 4" stock, and then shift the
tailstock to make the next batch of cuts.
Or -- add a threaded end to the mandrel, and a spin-on nut to
lock it against the step.
Alternatively if you just wanted to play and get creative...
How about an eccentric drive power hacksaw with a guide mounted on your
lathe? I use a hand powered hacksaw on the lathe sometimes.
If you do that -- turn a groove where the hacksaw blade will
hit, using a parting tool. With the cutter wheel, you need the backing
of the mandrel, but not with the hacksaw blade.
Good Luck,
DoN.
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I form up some stainless steel woven cloth into a "beanie" shape using a
mandrel in the chuck and a matching cup mounted on the tailstock.
I've used a cutting wheel from a pipe cutter and run that in from the
side,
it cuts nicely. Maybe if the thin tube was supported on such a mandrel
it'd
work ok.
Otherwise just hack em out with a chop saw... 
I was thinking of a brass "anvil" for the cutting wheel. Your job tells
me this might work.
For the mandrel I've used an old bit of stainless I had lying around. I cut
a small groove say 0.8mm wide x 0.5mm deep x on the mandrel where the
cutting wheel runs in. The wheel effectively does not touch the manrell.
I also do a job where I cut 100mm diamter PVC tube into 50mm long pieces. I
part these off using a bit of HSS. I have a turned wooden mandrel in the
chuck that supports the parted off bit of the tube. I also have another
wooden mandrel in the tailstock with an old bearing & bolt to support the
other part of the tube when its "cut free".
To mount the cutting wheel I just have an off the shelf hex head shoulder
screw that suits the ID of the cutting wheel.