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Brian, I’m not sure whether it was you who
was inquiring recently about the method I used for preventing warp (I made the
last 4 inches of the hull a separate cylinder, and machined the hatch seat with
those 4 inches attached). Anyway, what I can now add is that it worked! I had
done it a long time ago, but until I got to the present final assembly stage
had not taken the time to do fine adjustments of the hatch mounts. This was
quite a job, involving very fine shims of hundredths of an inch thickness, because
there are 8 linear bearings that have to be reasonably aligned if the whole
thing is to slide freely. I can now say it does in fact meet the hull reasonably
evenly all the way around. I’m quite relieved not to have found distortion.
But if I had, you would have just made my day with this post! I had a very hard time finding anyone who
could machine a ring 31” in diameter. If at all possible I wanted it done
on a lathe, rather than a mill, because it would be so much faster (hence
cheaper). No machine shop could handle the diameter, with two exceptions: the
power company, who need to turn large turbine components, and a railroad repair
yard who need to true train wheels. A power company
machinist ended up doing the job as a private after-hours endeavor for a couple
of hundred bucks, even though it took him about 12 hours to do, and took such
pride in the work that the window seat cavity diameter is accurate within a
thousandth of an inch. You might just want to ask around local shops like that
before laying out $2K. Thanks,
-----Original Message----- I just
solved my hatch ring milling problem ! I found a company in
Sacramento that rents flange facing equipment. This equipment is made to
secure either inside or outside on the ring. Comes in two pieces and
weights about 125 lbs. Rents for $2000.00/ wk. This will eliminate
the warp factor problem as when the ring is welded to the main body of the sub. Brian
Cox |