Stupid question here...
Does the stress from a rolled ring affect it's
strenght? Would a water cut ring be stronger then a rolled
one?
Pierre Poulin
----- Original Message -----
Sent: Saturday, August 13, 2005 9:40
AM
Subject: Re: [PSUBS-MAILIST]
extendair
No,,,your not understanding what I'm saying. Take the
plate and have the rings water jet cut in 4 sections then weld the sections
together to form the hole ring. You take 4 "C" sections to build 1
ring. You don't need to cut the hole ring at one time. And if you
have them cut from say 3/8 plate then just forget about the flange all
together. Make the web thicker and have it water jet cut so it's
perfectly round. ( within 4 to 5 thousands true ) In theory you
could build a pressure vessel from aluminum foil and if it was a perfect
sphere you could send it to the Trench and it would not collapse. The
increase in out of round tolerance would be a great advantage. You
should not be building the rings to match the plate,,,,the plate should
be rolled to match the rings.
With all the sections cut you can clamp them down to a sheet
of 3/4 plywood and have the ends beveled so they end up very ,,very
round. Have them TIG welded
together...DJB
"Dan H."
<jmachine@adelphia.net> wrote:
Dan,
I agree with you. Why use nine square
feet of plate for a three foot diameter ring, and pay for having it water
jet cut, when you can purchase a sheet of plate for the hull and have the
strips sheared from the drop then role it. The only thing to be
cautious of when using sheared strips is to be sure the strips are sheared
the same width from end to end. Apparently the back stop on the shear
where mine was cut was a bit farther back on one end then the other. I
had to fool with them to make exact circles.
If you find a shop with roles grooved for
the thickness of the material you need to role on the jack, of course have
them do it but I couldn't so I devised a simple rolling machine out of junk
I had around. It wasn't that difficult to do. The shop I had
role the hull had huge roles and did a very good job with it. They
even rolled the 3/4 thick collar I needed for the intersection of the
conning tower and the hull, but they couldn't role the flat strips on the
jack. They didn't have grooved roles, so I spent a few hours making
the wheels and gathering my junk.
The rings warp so much with the heat of
welding, water cut rings aren't going to be round within a thousandth of an
inch when your finished anyway. The welding jig I used, and stagger
welding, got my frames it within a 1/16 out or round. When your
welding the frames in the hull they move anyway and can be
adjusted by jacking the hull as your welding and by choosing where to weld
when.
There are many ways to do the same job
and get the same result for the same effort. A lot depends
on what you have available and what skills you poses, but then,
Dave does this for a living so he probably knows best.
Dan H.
----- Original Message -----
Sent: Friday, August 12, 2005 6:10
PM
Subject: Re: [PSUBS-MAILIST]
extendair
Dave, With the high cost of steel these days, especially
SA 516 GR 70 can you justify that much scrap ? You still have to shear the
strips for the flange part of the "T" and roll them. It doesn't take that
much more time to shear & roll 6 pcs the hard way ? DL
From: Dave Banks <noperiscope@yahoo.com> Reply-To:
personal_submersibles@psubs.org Date:
Fri, 12 Aug 2005 12:16:08 -0700 (PDT) To:
personal_submersibles@psubs.org Subject: Re:
[PSUBS-MAILIST] extendair
Cliff,,,
You really don't need to build a
rolling machine for 1.5 by .25 steel. I'm sure there are a few
weld shops near you that have one and just have them roll the flat bar
for you. Yes, you have it cut long and then trim the
ends. But you also need to understand that having them cut in a circular
form and welding them together will give you truer circles. This
is very important to the integrity of the pressure vessel. I do
this for a living and you don't need to have the web rolled on edge, the
flange, yes, but not the web. I would not roll them, I would have them
water jet cut and then weld them together. Then they would be within 5
or 6 thousands of an inch true. Also would appreciate anyone with
pictures or dimensions and specifications on the rolling fixtures.
This ! sounds like something that?s going to take a little time to
put together and get used to working with. Of course, it would
have to be something that has to be done early in the project and can?t
wait till later. I do, however, appreciate the fact that I
will be doing it myself and learning another aspect of metal-smithing in
the process. Thanks as Always and Kind Regards,
Cliff
McDonald
Hello
psubbers, Thanks everyone for the replies. I?ll go with the
rings one way or another. I have a question about making them.
When you start with the flat bar, how do you get the ends to curl
on the same radius as the rest of the band? I?m thinking I will
have to come up with rollers at least 6? OD. That would mean both
ends of the bar will have a couple of inches that aren?t rolled.
Do you cut the bar extra long, roll it to desired radius and then
trim it to length to g! et a fully rolled piece? Daniel I sure
would appreciate! any pictures you may have of the rings, especially if
you took any during the process of making them. Also would
appreciate anyone with pictures or dimensions and specifications on the
rolling fixtures. This sounds like something that?s going to take
a little time to put together and get used to working with. Of
course, it would have to be something that has to be done early in the
project and can?t wait till later. I do, however, appreciate
the fact that I will be doing it myself and learning another aspect of
metal-smithing in the process.
Thanks as Always and Kind
Regards,
Cliff
McDonald __________________________________________________ Do
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