Hi,
I'm interested in making a graver's ball for myself. It is basically
a 4, 6, or 8" sphere of solid mild steel with a wooden ring on bottom
for it to rotate in, a vise stuck on top, and several bearings inside
so that it can rotate at the equator. I'm fairly new to machining, so
a 4" ball vise will be good practice if nothing else, and still useful
for small items, although what I'm really interested in is machining a
larger 6-9" diameter ball for myself. Most parts are fairly basic.
But where can I get either a 6-9" ball (i.e., if anything on earth
might use ball bearings of that size, which I could scavenge?) or 6-9"
solid mild steel rod from which to machine the ball in separate
hemispheres? I'm building it half for fun, but half to save money, so
if it costs me $2+/lb for the steel it's not worth it. Any ideas on
where to find stock, perhaps some sort of scrap, of such a dimension,
and affordably? I live in Cambridge, MA.


thanks!
-Bernard Arnest

On 15 Nov 2005 17:45:11 -0800, "Bernard Arnest"
wrote:

Hi,
I'm interested in making a graver's ball for myself. It is basically
a 4, 6, or 8" sphere of solid mild steel with a wooden ring on bottom
for it to rotate in, a vise stuck on top, and several bearings inside
so that it can rotate at the equator. I'm fairly new to machining, so
a 4" ball vise will be good practice if nothing else, and still useful
for small items, although what I'm really interested in is machining a
larger 6-9" diameter ball for myself. Most parts are fairly basic.
But where can I get either a 6-9" ball (i.e., if anything on earth
might use ball bearings of that size, which I could scavenge?) or 6-9"
solid mild steel rod from which to machine the ball in separate
hemispheres? I'm building it half for fun, but half to save money, so
if it costs me $2+/lb for the steel it's not worth it. Any ideas on
where to find stock, perhaps some sort of scrap, of such a dimension,
and affordably? I live in Cambridge, MA.


thanks!
-Bernard Arnest

http://www.logansteelinc.com/ in Meriden CT. I was there a couple of
weekends ago and they have a large selection of steel in the odds and
ends building. I don't recall if there was any stock in as large size
as you are interested in but it might be worth a call or email. Their
price was $.75 per pound.

Errol Groff

Instructor, Machine Tool Department

H.H. Ellis Technical High School
643 Upper Maple Street
Danielson, CT 06239

New England Model Engineering Society
www.neme-s.org

Try a large dealer in heavy duty construction equipment. A vibratory
compactor used for compacting highway subgrade material uses a pair of very
large diameter steel balls rotating inside a pair of ball bearing races -
one on each end . The balls are free inside the race, and come up to speed
to produce a eccentric force that is transmitted to the ground. Dave

"Errol Groff" wrote in message
...
On 15 Nov 2005 17:45:11 -0800, "Bernard Arnest"
wrote:

Hi,
I'm interested in making a graver's ball for myself. It is basically
a 4, 6, or 8" sphere of solid mild steel with a wooden ring on bottom
for it to rotate in, a vise stuck on top, and several bearings inside
so that it can rotate at the equator. I'm fairly new to machining, so
a 4" ball vise will be good practice if nothing else, and still useful
for small items, although what I'm really interested in is machining a
larger 6-9" diameter ball for myself. Most parts are fairly basic.
But where can I get either a 6-9" ball (i.e., if anything on earth
might use ball bearings of that size, which I could scavenge?) or 6-9"
solid mild steel rod from which to machine the ball in separate
hemispheres? I'm building it half for fun, but half to save money, so
if it costs me $2+/lb for the steel it's not worth it. Any ideas on
where to find stock, perhaps some sort of scrap, of such a dimension,
and affordably? I live in Cambridge, MA.


thanks!
-Bernard Arnest

http://www.logansteelinc.com/ in Meriden CT. I was there a couple of
weekends ago and they have a large selection of steel in the odds and
ends building. I don't recall if there was any stock in as large size
as you are interested in but it might be worth a call or email. Their
price was $.75 per pound.

Errol Groff

Instructor, Machine Tool Department

H.H. Ellis Technical High School
643 Upper Maple Street
Danielson, CT 06239

New England Model Engineering Society
www.neme-s.org

On 15 Nov 2005 17:45:11 -0800, "Bernard Arnest"
wrote:

Hi,
I'm interested in making a graver's ball for myself. It is basically
a 4, 6, or 8" sphere of solid mild steel with a wooden ring on bottom
for it to rotate in, a vise stuck on top, and several bearings inside
so that it can rotate at the equator. I'm fairly new to machining, so
a 4" ball vise will be good practice if nothing else, and still useful
for small items, although what I'm really interested in is machining a
larger 6-9" diameter ball for myself. Most parts are fairly basic.
But where can I get either a 6-9" ball (i.e., if anything on earth
might use ball bearings of that size, which I could scavenge?) or 6-9"
solid mild steel rod from which to machine the ball in separate
hemispheres? I'm building it half for fun, but half to save money, so
if it costs me $2+/lb for the steel it's not worth it. Any ideas on
where to find stock, perhaps some sort of scrap, of such a dimension,
and affordably? I live in Cambridge, MA.


thanks!
-Bernard Arnest

Just a heads up...old bowling balls get used a lot for this sort of
work. And its easy to mill a flat in it for the vise, tap well, and
may be dropped into a small trailer tire sans wheel for stability.

And you can pick em up at the Goodwill for $5

Gunner

"Pax Americana is a philosophy. Hardly an empire.
Making sure other people play nice and dont kill each other (and us)
off in job lots is hardly empire building, particularly when you give
them self determination under "play nice" rules.

Think of it as having your older brother knock the **** out of you
for torturing the cat." Gunner