Geeez...a bean counter. Look, if you want ot make the thing, do it in a
way that excersizes your abilities and produces the result you want. The
nicklels and dimes approach will spoil the project.
JR
Dweller in the cellar
Bernard Arnest wrote:
Hi,
Back in December I inquired about making a ball vise. I have been
practicing some simpler machining since, and now would like to begin.
I never did have any luck finding 7-10" diameter steel balls or even
solid rod at scrap yards.
I can buy 6" rod stock from the campus machine shop for ~$60, or
$1.10/lb I believe it was (although my calculator is predicting that it
should be $48, so it might have been more...), and machine it into one
hemisphere and one clipped-off cone shape. The hemisphere is doable; I
have access to a CNC lathe. Off campus, inquiring about 8" diameter
rod stock, they wanted $1.75/lb!
Alternatively, I can cast. I asked a local club, and they'll help
me cast it for $1.20/lb if I provide the steel. I can find random
scrap steel for $.10/lb. This at first had great appeal when I learned
of the low cost of scrap steel, but it makes me recoil some to think
that I'll end up paying more per pound because of casting costs! AND,
coming out of the cupola, it will be cast iron, which while quite
functional, is inferior to steel for this application.
The two benefits of this would be that a sphere is 2/3 the volume of
the smallest cylinder that will contain that sphere, so even though
it's $1.30/lb and not $1.10/lb, it costs $.23/lb less to cast in a
sphere than to purchase a solid cylinder and machine off 1/3 of its
weight in making it a sphere. Also, while I still want to program the
lathe to machine a sphere, it will have to machine off far less
material, saving not an insignificant amount of work.
What do you advise? Cast an iron sphere, or machine from a solid
steel cylinder, assuming the former to cost 23cents/lb less? I want a
100-lb vise (trust that I do intend to make a 4.5" vise from all scrap
first, before investing in this), so this is expensive for me :-(
Is it possible that, if I shop around, I may be able to have it cast
for less than the $1.20/lb quoted me, or is that a bargain...?
thanks!
-Bernard
Arnest
--
--------------------------------------------------------------
Home Page:
http://www.seanet.com/~jasonrnorth
If you're not the lead dog, the view never changes
Doubt yourself, and the real world will eat you alive
The world doesn't revolve around you, it revolves around me
No skeletons in the closet; just decomposing corpses
--------------------------------------------------------------
Dependence is Vulnerability:
--------------------------------------------------------------
"Open the Pod Bay Doors please, Hal"
"I'm sorry, Dave, I'm afraid I can't do that.."