"andy" wrote in message
oups.com...
Hello folks.
I am writing to get some suggestions for making an aluminum deck hatch
for a boat.
These hatches are mounted flush with the floor (deck) of a boat and are
watertight.

I am just in the thinking it out stage, but would appretiate any input
the group may have.
The product I am trying to duplicate is:
http://store.hamiltonmarine.com/browse.cfm/4,224.htm
It is basically a piece of 1/4" diamond tread aluminum plate. This
plate has a series of "dogs" or latches which secure the hatch into a
stainless steel frame. the dogs are pieces of stainless flat stock
attached to a nut which is operated from above the hatch with a socket.
each dog has a corresponding divot in the hatch which serves to recess
the operating nut flush with the top of the hatch. The divots are
approximately 3" in diameter and 3/16" deep.


This advice is worth exactly what you paid, but...

You'll probably run into issues with wrinkling, basically. A shop hydraulic
press could probably do it, but anything just beyond the radius of your
divots will probably wrinkle unless you have a binder on the die (perhaps
called a "draw ring" or something similar. We call them binders).

Also, you'll have to do any other forming (for the diamond pattern, for
instance) after the divots are made unless you don't mind the binder/draw
ring leaving a ringed mark around each divot.

Lastly, and of least importance, you'll have to create your outside edges
last as you will probably get a least some "draw" effect, even if your die
is mostly stretching the material. Essentially your square blank will not be
square after the divots and diamond patters have been produced as material
will be drawn into these forms.

I'd wager the manufacturer uses a draw die to create the divots and pattern
in one operation (maybe two) and then uses a pierce and trim die to complete
the part. You would not be able to run the draw die on a shop press. Chances
are you'd need a punch press (perhaps with a draw cushion for the binder) of
over 100 tons, although I could be wrong with that number.

Boats are holes in the water into which you pour money. Didn't anyone tell
you before you bought?

Regards,

Robin