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 get 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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