"Lloyd E. Sponenburgh" lloydspinsidemindspring.com wrote in message
. 3.70...
"Bob La Londe" fired this volley in
:


Ok shiny was probably not the best term. Smooth is more important.
It will have a low pressure pneumatic seal with am o-ring and piston.
The raw tube works ok, but I was thinking with a better than mill
finish the o-rings might last longer.

So far I have not worn out an o-ring with the existing units, but I
would like to make future ones "better."

How long are these tubes, Bob?

Finished working length may vary from 10-12 inches.

It takes darned near forever with a long boring bar, but with the right
speeds and the right rake on an HSS boring bit, you can get a pretty nice
finish.

Yeah, I thought about a round face boring bit, but supporting and doing a
12" internal finish is beyond my skills and equipment. I was just hoping to
improve the finish "some"

Get it turned to "round" (sans weld), then use a small flap hone if you
want to clean it up.

I may "just" do a flap wheel down the bore and see how that works out.
perfectly round is not super critical. it's a low pressure o-ring fit after
all.

Remember, I went through this recently with a customer's project, and
finally ended up buying an aluminum air cylinder long enough to cut what
I needed. But mine was 18" long and 6" i.d. That made it kind of hard
to bore with a conventional setup, and I didn't have the time to jig the
lathe to mount the work on the cross-slide, and the bit in the spindle,
supported by the tailstock.


I recall your project. I read quite a bit on that thread. Glad you got it
worked out.


Bob