On Mon, 8 Dec 2008 15:25:43 -0800 (PST), andy
wrote:

Hi folks:
I am trying to make a skeg-mount rudder for a lobsterboat.
the rudder is made from a 1/4" thick piece of 316 stainless steel.
The rudder stock (shaft) is 1-1/4" diameter 316 stainless steel rod,
cut into two pieces and slotted to accept the rudder plate which is
then welded in. The two pieces of rudderstock are arranged so that
the lower one is held in a bearing (on the skeg for all you boat
folks), and the upper one penetrates the bottom of the boat through a
packing gland and has a keyway to attach the tiller.

My question is how do I cut the slots? they need to be through the
round stock and maybe 6 inches along the long axis of the rod. (2
pieces, top and bottom)

I have access to a Bridgeport mill with unknown tooling, so I will
have to buy a cutter for the job.
My plan is using something similar to a keyway cutter and attacking
the work from each side. Maybe leaving the very end "un-slotted" to
remain rigid before hacksawing out the last bit?

That should work just fine.


Plan B may be an 1/4" endmill attacking from the top? although this
seems like it would be too flexy for a 1-1/4" cut.

Nah... you'll be fine. I would drill, say, 7/32" holes all the way
through the bar. Use a 2-flue end mill.


As you can probably tell, I am not a machinist. Although I do read
RCM regularly. I also understand 316 stainless is not easy to work
with.

I would love to hear what you folks think of my plan,including lubes,
speeds, what the cutter is called at Enco or wherever.

Plenty (and I mean PLENTY) of heavy duty synthetic (or old sulfurized
oil) lube would be my pick. (problem is.... you're looking at about
$30 for a 1 gallon bottle and about $110 for 5 gals, if the gal isn't
available) Stainless steels conduct heat poorly, therefore the heat
will be concentrated in the cutter. Lots of cutting fluid will counter
this effect. Take light cuts, but never let the cutter just ride in
the cut without cutting. (Work hardening will be the inevitable
result.)


Thanks,
Andy
Lynn, MA

PS
Make sure all of this assembly is 316.... and that includes the rudder
and weld filler metal.
--

Forté Agent 5.00 Build 1163

"When a work lifts your spirits and inspires bold and
noble thoughts in you, do not look for any other standard
to judge by: the work is good, the product of a master
craftsman." - Jean de la Bruyere (1645-1696)

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