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Rick
It is possible to role without a flat spot.
After running the material through the rolls turn it end for end and role it
through again. The flat spot is on the leading edge first trip through the
rolls. The rolls form true to the last fraction if an inch on the trailing
edge. Turning the material around finishes what was the leading edge the
first time through.
Dan H.
----- Original Message -----
Sent: Thursday, November 10, 2005 1:58
PM
Subject: Re: [PSUBS-MAILIST] Inner /
Outer support ribs.
the problem with installing support frames is
that when rolling plate the first three to four inches can not be bent .
giving you a flat spot at the weld line in the tube.the easliest way to get
around this is to pre weld the frames inner web and true up to final size.
tack the outer web in place. do not weld the tube seam yet. Weld in
lifting eyes along the inside of the hull along the seam line and at
opposing points along the hull. set the frames inplace, and using chain
hoists pull the hull into roundness against the frames. note some triming of
the hull seam may be required for final fit.
rick
m
----- Original Message -----
Sent: Thursday, November 10, 2005 10:02
AM
Subject: RE: [PSUBS-MAILIST] Inner /
Outer support ribs.
Myles I should tell you getting those stiffeners in was far and away
the hardest part of building Solo. It took me three months of work to get
the first ring in. But it certainly worked as a method for stretching the
hull into roundness. This is a 3/8 thick hull of only 31" outside diameter,
so not very stretchy. If I remember correctly, the out of roundness prior to
inserting the stiffeners was about half an inch difference between maximum
and minimum diameters. With stiffeners in, I can't detect any out of
roundness.
My method was as follows: Roll the ring in along the
greater diameter, then try to straighten it until normal to the hull. I
tried hydraulics and failed. I tried icing the rings and heating the hull,
but that failed too. The latter is what Phil Nuytten does, but I presume his
hull cylinders are much higher quality (rounder) than mine. What worked
for me in the end was a very long lever built to hook onto the end of the
hull cylinder, chained to 1/2" holes drilled in the stiffener web. I built a
motorized table for my mill-drill machine, with which I could gradually
reduce the diameter of the stiffener by a few thousandths after each
unsuccessful attempt. I did this lots of times, on each iteration getting
closer to straightening the stiffener all the way. Of course, the hard one
is the first stiffener, and after that they go
fast.
rgds,
Alec
Dan,
The point I never considered was
using the rings to force the hull into roundness. I can definately
see where this would be easier when putting them on the inside as they
could be pounded / hammered / tapped into place, spot welded, and then
secured when all was well. That answers another question in that the
rings are to be pre made and not welded onto the pressure hull when
building them. In that way, the roundness of the rings could be made
true before installing. As for attaching things to the rings inside
the hull, is it safe to drill 1/4" holes for bolts or is that comprimising
the integretity of the ring too much ? ...or would welding mounting
brackets to the rings and then drilling the holes be preferable
?
On the K350, does the design
just eliminate the ring where the tower is, the tower collar providing the
strength in that area ?
Thanks for making my mind up for
me Dan.
Myles.
----- Original Message -----
Sent: Wednesday, November 09, 2005
9:10 PM
Subject: Re: [PSUBS-MAILIST] Inner
/ Outer support ribs.
Myles,
A K-350 has ribs spaced 12 inches apart,
and at the ends where the hull tube meets the end caps, they are 10
inches apart leaving two inches of hull tube sticking past the last
frames to weld the end caps to.
True, the frame would be easier to
apply to the outside of the hull, for convenience of working, but it's
easier to spring the hull into better roundness when working from the
inside. No rolled tube is perfect round. You have to
work it as your installing the framing.
Ribs on the outside give you more places
for corrosion to attack, but do increase the inside room. Ribs on
the inside cramp the space in the sub, but are a convenient place to
clamp things that you want to add later on, without welding on the
finished sub hull.
Dan H.
----- Original Message -----
Sent: Wednesday, November 09,
2005 6:11 PM
Subject: [PSUBS-MAILIST] Inner /
Outer support ribs.
I understand that support ribs offer the
same strength increase whether they are on the inside or outside of
the pressure hull. As I am planning on adding fairing, I am also
considering puting the ribs on the outside to free up interior
space. Is this a good idea ? In other words, is it easier
to install the ribs when they are on the outside ? Are the ribs
pre-made and then welded on or built right onto the pressure
hull ? I can't seem to figure out the ribs, how they are made,
and the best way to install them. My pressure hull is of a
similar design as the K350 36" x 1/4 " x 8'. I am
considering a rib spacing of 18".
Myles.
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