Re: [PSUBS-MAILIST] Fabricating T-bars (was: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 -----

From: Daniel Lance

To: personal_submersibles@psubs.org

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 You Yahoo!?
Tired of spam? Yahoo! Mail has the best spam protection around
http://mail.yahoo.com

__________________________________________________
Do You Yahoo!?
Tired of spam? Yahoo! Mail has the best spam protection around
http://mail.yahoo.com