The commercial version of this idea is "full grip soft jaws". 1/3 of a
circle wedges with chuck interfaces, made to be machined down.
On Thu, Dec 6, 2018 at 7:22 PM Peter Fairbrother <peter@xxxxxxxxxx> wrote:
A technique I have used for outside gripping is:
Turn a couple of inches of the work to the final diameter using a fixed
steady.
Get a bit of plate about 3/4" thick and a bit bigger than the final work
to make an adapter. Chuck it, bore a hole accurately to the final
diameter. Mark the adapter for position in the chuck, then remove and
cut a slit in it, rechuck (or cut a slit in it in situ).
Loosen the chuck a little, insert the turned end of the work into the
hole, tighten down fairly hard. The turned end will be accurately
centered. No lobes, no jaw marks.
Bore etc as usual.
-- Peter Fairbrother
On 06/12/18 20:54, William Claybaugh wrote:
Wyatt:
In my experience it is necessary to put a disk of the tube ID inside a
tube when gripping w/ a chuck, otherwise one gets a three or four or six
lobe shape depending on the number of jaws in the chuck.
Carl:
Have you talked to Garboden? His TOS lathe is plenty big enough to do
this job.
Bill
On Thu, Dec 6, 2018 at 1:46 PM Wyatt Rehder <wyatt.rehder@xxxxxxxxx
<mailto:wyatt.rehder@xxxxxxxxx>> wrote:
This seems like it should be a fairly conventional operation, 24"
isn't too long and 8" is plenty large of diameter to work inside.
Expensive bit would be the semi-custom boring bar to mount to the
compound. Could just braze on an insert to the end of a 3" or so bar.
Grab it on the outside, and put it in a steady rest. Bore the inside
with your boring bar. Once you get it to dimension, flip your jaws
around, perhaps use a 6 jaw chuck and grab it from the inside. I would
go a little long on the tube initially, and put a taper in the
tailstock side and put a "oil-country" livecenter in your tail stock.
Bring the OD to spec. Lop off the extra length.
There should definitely be a shop around that can do this for you.
Many might not have the extra-big boring bars, or live-centers on
hand. Shops that do Oil-field or mining work would likely have them.
On Thu, Dec 6, 2018 at 11:10 AM Norman Yarvin <yarvin@xxxxxxxxxxxx
<mailto:yarvin@xxxxxxxxxxxx>> wrote:
>
> The request was for 0.300", though, not 0.030". If this is for a
> rocket, presumably it's a high pressure one.
>
> On Thu, Dec 06, 2018 at 01:36:24AM -0800, George Herbert wrote:
> >If it doesn't have to be actually a pipe, just approximately
cylindrical,
> >true, and 0.030" wall... consider a mandrel like Paul suggested
and just
> >grease the mandrel and wrap 0.030 sheet around it with a bit of
lap joint,
> >and glue. Wait for glue to dry, just slip it off.
> >
> >Not hard to get glued joint stronger than 0.030 Al.
> >
> >Also easier to get some alloys which are better than 6061-T6
that way.
> >
> >That said, not knowing what you're doing exactly in terms of joining
> >endcaps and so forth, that might not be a useful form for your
next steps.
> >
> >On Thu, Dec 6, 2018 at 12:01 AM Michael Clive <zeinin@xxxxxxxxx
<mailto:zeinin@xxxxxxxxx>> wrote:
> >
> >> Magorian hone in la
> >>
> >> On Wed, Dec 5, 2018, 7:05 PM Carl Tedesco
<ctedesco@xxxxxxxxxxxxxx <mailto:ctedesco@xxxxxxxxxxxxxx> wrote:
> >>
> >>> All,
> >>>
> >>>
> >>>
> >>> Does anyone have a recommendation for a shop (preferably in
the Southern
> >>> California area) that can machine aluminum pipe (modify OD &
ID and make
> >>> round)?
> >>>
> >>>
> >>>
> >>> I want to take a 24” length of 8” diameter 6061-T6 pipe and
machine the
> >>> OD to 7.708” with the wall thickness at 0.300”. A local shop
wants to
> >>> lathe it from both ends, but cannot guarantee there will be a
step in the
> >>> middle.
> >>>
> >>>
> >>>
> >>> Thanks in advance,
> >>>
> >>>
> >>>
> >>> Carl Tedesco
> >>>
> >>>
> >>>
> >>
> >
> >--
> >-george william herbert
> >george.herbert@xxxxxxxxx <mailto:george.herbert@xxxxxxxxx>
>