He only wants to go down 3/16" of an inch on a 3" diameter divot. I was
figuring that as a 3/16" offset over an inch or so span. Total bend of
20 degrees with 1/2" inside radius.

I agree that the beat it down with a wood block has possibilites, even
if it is just for a quick sample. Making up the stock is probably a
foregone conclusion though.

john wrote:


RoyJ wrote:

I can't say I've done that one but the principle is pretty easy: just
use a suitable male and female die. Tonnage will vary with the exact
shape of the angles and clearances you put in there. Large clearances
will reduce the tonnage but make it more difficult to get the clean
lines you would like. A quick calc for 6061-T6 says that it should be
easy with a 50 ton shop press, suspect less would work
http://www.harborfreight.com/cpi/cta...emnumber=46768

Die design is a bit tricky. You need to have a retainer ring to hold
the plate flat while you extrude though the center of the ring. If you
don't hold it flat the plate will 'pucker'

andy wrote:

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.

My question is this: is it possible to make these divots using a
hydraulic press (the sort with the hydraulic jack) and some dies? or
does this type of forming require a punch-press type of sudden impact
to get the desired results?
I have acess to a lathe to make the dies. I would like to produce say 8
hatches with 4 divots each.

any suggestions would be appretiated (including "go buy them you cheap
p.....")
Andy Hall
Lynn, MA



6061 t6 will most likely crack before you complete the forming. If
you anneal it it will eliminate the problem, but then you will have to
get it retempered.

A cheap and dirty way of making them is to make a form out of hard oak
wood and pound it out with a ball-peen hammer into the form. Start from
the middle and work outwards. You may have to anneal the metal as you
go if you workharden it too much. Make sure you polish the end of the
hammer so it will not leave marks in the aluminum.


John