My Garmin NUVI 500 for my bicycle uses a ball mount. The one that I
purchase from a third party is hollowed plastic and broke from
vibration. I adapted the broken piece to my light bar and it broke
again at the ball.
I toyed with several methods. One buy a ball turning tool, two find a
ball and mount it to a post. The ball was .670 inches and I didn't
find any one that size.
I decided to make a form tool for a section and move around the ball
shape. The critical section is smooth as the female move up to the
major diameter and that the major diameter size is maintained. The
down side also needs to be smooth for a short distance.
I Machined a rectangle piece of aluminum leaving the head 3/4 inches,
in three direction. The post section is 3/4 X 1/2 inches. Pictures are
here. http://www.billcotton.com/nuvi500.htm

On Sun, 24 Jan 2010 13:36:42 -0800 (PST), mac
wrote:

My Garmin NUVI 500 for my bicycle uses a ball mount. The one that I
purchase from a third party is hollowed plastic and broke from
vibration. I adapted the broken piece to my light bar and it broke
again at the ball.
I toyed with several methods. One buy a ball turning tool, two find a
ball and mount it to a post. The ball was .670 inches and I didn't
find any one that size.


It would have been 17mm


Mark Rand
RTFM

"mac" wrote in message
...
My Garmin NUVI 500 for my bicycle uses a ball mount. The one that I
purchase from a third party is hollowed plastic and broke from
vibration. I adapted the broken piece to my light bar and it broke
again at the ball.
I toyed with several methods. One buy a ball turning tool, two find a
ball and mount it to a post. The ball was .670 inches and I didn't
find any one that size.
I decided to make a form tool for a section and move around the ball
shape. The critical section is smooth as the female move up to the
major diameter and that the major diameter size is maintained. The
down side also needs to be smooth for a short distance.
I Machined a rectangle piece of aluminum leaving the head 3/4 inches,
in three direction. The post section is 3/4 X 1/2 inches. Pictures are
here. http://www.billcotton.com/nuvi500.htm

It looks like this worked well enough for you.

In the optical lens industry, spheres and spherical sections are generated
using a cup-shaped grinding tool. The workpiece is rotated, the tool axis is
at an angle to the workpiece and spun more quickly. The edge of the cup is
aligned over the apex of the workpiece, and then the tool is moved into the
work parallel to the workpiece axis. Here is a rough diagram of how it
works:
http://www.britannica.com/EBchecked/...ave-and-convex
The radius generated will depend on the diameter of the tool and the angle.
It can make very precise spheres that are the ready for (very) fine grinding
and final polishing. Perhaps you can do this with a tool post grinder on a
metal lathe.

On Jan 24, 5:39*pm, "anorton"
wrote:
"mac" wrote in message

...

My Garmin NUVI 500 for my bicycle uses a ball mount. The one that I
purchase from a third party is hollowed plastic and broke from
vibration. I adapted the broken piece to my light bar and it broke
again at the ball.
I toyed with several methods. One buy a ball turning tool, two find a
ball and mount it to a post. The ball was .670 inches and I didn't
find any one that size.
I decided to make a form tool for a section and move around the ball
shape. The critical section is smooth as the female move up to the
major diameter and that the major diameter size is maintained. The
down side also needs to be smooth for a short distance.
I Machined a rectangle piece of aluminum leaving the head 3/4 inches,
in three direction. The post section is 3/4 X 1/2 inches. Pictures are
here.http://www.billcotton.com/nuvi500.htm

It looks like this worked well enough for you.

In the optical lens industry, spheres and spherical sections are generated
using a cup-shaped grinding tool. The workpiece is rotated, the tool axis is
at an angle to the workpiece and spun more quickly. *The edge of the cup is
aligned over the apex of the workpiece, and then the tool is moved into the
work parallel to the workpiece axis. *Here is a rough diagram of how it
works:http://www.britannica.com/EBchecked/...68/Cross-secti...
The radius generated will depend on the diameter of the tool and the angle.
It can make very precise spheres that are the ready for (very) fine grinding
and final polishing. *Perhaps you can do this with a tool post grinder on a
metal lathe.

I serve my apprenticship at the Frankford Arsenal in Philadelphia PA.
Bldg 45 made the metel holderfor the lens blanks. The grinding was
done in Bldg 108, the optical shop.
Back in the old, old days, the military didn't just others to to
percision work. It was all done in house. When I came along in the
earlier fifty, work begun to be contracted out.

On Sun, 24 Jan 2010 13:36:42 -0800, mac wrote:

My Garmin NUVI 500 for my bicycle uses a ball mount. The one that I
purchase from a third party is hollowed plastic and broke from
vibration. I adapted the broken piece to my light bar and it broke again
at the ball.
I toyed with several methods. One buy a ball turning tool, two find a
ball and mount it to a post. The ball was .670 inches and I didn't find
any one that size.
I decided to make a form tool for a section and move around the ball
shape. The critical section is smooth as the female move up to the major
diameter and that the major diameter size is maintained. The down side
also needs to be smooth for a short distance. I Machined a rectangle
piece of aluminum leaving the head 3/4 inches, in three direction. The
post section is 3/4 X 1/2 inches. Pictures are here.
http://www.billcotton.com/nuvi500.htm

Making a bunch of taper cuts to rough out the sphere, then filing it
'round' on the lathe may work well, too.

Your technique works, obviously, and would be the way to go if you need
to make a ton of parts. Probably makes a more precise ball, too, if you
get the contour of the tool correct. (In fact, this may be a good way to
make something like a Cox engine connecting rod).

--
www.wescottdesign.com

On Sun, 24 Jan 2010 14:39:01 -0800, "anorton"
wrote:


"mac" wrote in message
...
My Garmin NUVI 500 for my bicycle uses a ball mount. The one that I
purchase from a third party is hollowed plastic and broke from
vibration. I adapted the broken piece to my light bar and it broke
again at the ball.
I toyed with several methods. One buy a ball turning tool, two find a
ball and mount it to a post. The ball was .670 inches and I didn't
find any one that size.
I decided to make a form tool for a section and move around the ball
shape. The critical section is smooth as the female move up to the
major diameter and that the major diameter size is maintained. The
down side also needs to be smooth for a short distance.
I Machined a rectangle piece of aluminum leaving the head 3/4 inches,
in three direction. The post section is 3/4 X 1/2 inches. Pictures are
here. http://www.billcotton.com/nuvi500.htm

It looks like this worked well enough for you.

In the optical lens industry, spheres and spherical sections are generated
using a cup-shaped grinding tool. The workpiece is rotated, the tool axis is
at an angle to the workpiece and spun more quickly. The edge of the cup is
aligned over the apex of the workpiece, and then the tool is moved into the
work parallel to the workpiece axis. Here is a rough diagram of how it
works:
http://www.britannica.com/EBchecked/...ave-and-convex
The radius generated will depend on the diameter of the tool and the angle.
It can make very precise spheres that are the ready for (very) fine grinding
and final polishing. Perhaps you can do this with a tool post grinder on a
metal lathe.

=========
or see
http://littlemachineshop.com/product...1970&category=
and
http://littlemachineshop.com/product...2568&category=
for some ideas on how to make your own.


Unka George (George McDuffee)
...............................
The past is a foreign country;
they do things differently there.
L. P. Hartley (1895-1972), British author.
The Go-Between, Prologue (1953).

On Sun, 24 Jan 2010 14:39:01 -0800, "anorton"
wrote:


"mac" wrote in message
...
My Garmin NUVI 500 for my bicycle uses a ball mount. The one that I
purchase from a third party is hollowed plastic and broke from
vibration. I adapted the broken piece to my light bar and it broke
again at the ball.
I toyed with several methods. One buy a ball turning tool, two find a
ball and mount it to a post. The ball was .670 inches and I didn't
find any one that size.
I decided to make a form tool for a section and move around the ball
shape. The critical section is smooth as the female move up to the
major diameter and that the major diameter size is maintained. The
down side also needs to be smooth for a short distance.
I Machined a rectangle piece of aluminum leaving the head 3/4 inches,
in three direction. The post section is 3/4 X 1/2 inches. Pictures are
here. http://www.billcotton.com/nuvi500.htm

It looks like this worked well enough for you.

In the optical lens industry, spheres and spherical sections are generated
using a cup-shaped grinding tool. The workpiece is rotated, the tool axis is
at an angle to the workpiece and spun more quickly. The edge of the cup is
aligned over the apex of the workpiece, and then the tool is moved into the
work parallel to the workpiece axis. Here is a rough diagram of how it
works:
http://www.britannica.com/EBchecked/...ave-and-convex
The radius generated will depend on the diameter of the tool and the angle.
It can make very precise spheres that are the ready for (very) fine grinding
and final polishing. Perhaps you can do this with a tool post grinder on a
metal lathe.

Om a metal lathe..CNC..it can be done in one simple operation.

http://www.omni-turn.com/Pages/Examp...el%20ball.html

If you think there may ba a market for your new mount..Id be happy to
turn you onto people who could make these and other parts cheaply and
quickly. You might have a new product!!!

Gunner

Whenever a Liberal utters the term "Common Sense approach"....grab your
wallet, your ass, and your guns because the sombitch is about to do
something damned nasty to all three of them.

mac wrote:


I serve my apprenticship at the Frankford Arsenal in Philadelphia PA.
Bldg 45 made the metel holderfor the lens blanks. The grinding was
done in Bldg 108, the optical shop.
Back in the old, old days, the military didn't just others to to
percision work. It was all done in house. When I came along in the
earlier fifty, work begun to be contracted out.

I enjoyed your link. I used a couple Avocet 50's for many years to get a trip altimeter
using barometric pressure. Finally, I ran out of units to piece a working one out of.

Just before winter I bought a Garmin Colorado, the cadence sensor, and the heart rate
monitor. It will be spring before I give it a test ride. The Colorado I have has topo
maps and not street routable cartography though I'm told I can but that at extra cost.

Wes
--
"Additionally as a security officer, I carry a gun to protect
government officials but my life isn't worth protecting at home
in their eyes." Dick Anthony Heller

On Sun, 24 Jan 2010 17:02:36 -0600, Tim Wescott
wrote:

On Sun, 24 Jan 2010 13:36:42 -0800, mac wrote:

My Garmin NUVI 500 for my bicycle uses a ball mount. The one that I
purchase from a third party is hollowed plastic and broke from
vibration. I adapted the broken piece to my light bar and it broke again
at the ball.
I toyed with several methods. One buy a ball turning tool, two find a
ball and mount it to a post. The ball was .670 inches and I didn't find
any one that size.
I decided to make a form tool for a section and move around the ball
shape. The critical section is smooth as the female move up to the major
diameter and that the major diameter size is maintained. The down side
also needs to be smooth for a short distance. I Machined a rectangle
piece of aluminum leaving the head 3/4 inches, in three direction. The
post section is 3/4 X 1/2 inches. Pictures are here.
http://www.billcotton.com/nuvi500.htm

Making a bunch of taper cuts to rough out the sphere, then filing it
'round' on the lathe may work well, too.

That's exactly how I did it. It's not a precision thing, doesn't even
have to be very round. Mine is still a bit oversize and tight. I'll
whittle it down a bit more if I find that it needs it.

Wayne

On Jan 24, 6:24*pm, Gunner Asch wrote:
On Sun, 24 Jan 2010 14:39:01 -0800, "anorton"





wrote:

"mac" wrote in message
...
My Garmin NUVI 500 for my bicycle uses a ball mount. The one that I
purchase from a third party is hollowed plastic and broke from
vibration. I adapted the broken piece to my light bar and it broke
again at the ball.
I toyed with several methods. One buy a ball turning tool, two find a
ball and mount it to a post. The ball was .670 inches and I didn't
find any one that size.
I decided to make a form tool for a section and move around the ball
shape. The critical section is smooth as the female move up to the
major diameter and that the major diameter size is maintained. The
down side also needs to be smooth for a short distance.
I Machined a rectangle piece of aluminum leaving the head 3/4 inches,
in three direction. The post section is 3/4 X 1/2 inches. Pictures are
here.http://www.billcotton.com/nuvi500.htm

It looks like this worked well enough for you.

In the optical lens industry, spheres and spherical sections are generated
using a cup-shaped grinding tool. The workpiece is rotated, the tool axis is
at an angle to the workpiece and spun more quickly. *The edge of the cup is
aligned over the apex of the workpiece, and then the tool is moved into the
work parallel to the workpiece axis. *Here is a rough diagram of how it
works:
http://www.britannica.com/EBchecked/...68/Cross-secti...
The radius generated will depend on the diameter of the tool and the angle.
It can make very precise spheres that are the ready for (very) fine grinding
and final polishing. *Perhaps you can do this with a tool post grinder on a
metal lathe.

Om a metal lathe..CNC..it can be done in one simple operation.

http://www.omni-turn.com/Pages/Examp...el%20ball.html
Yes if happen to have a CNC around, that would've been my choice.
The history of my home machine shop, It was a belt sander and drill
press with a cross slide vise. I had help a friend set up his three in
one machine. I thought that if I could come up was a reason I would
buy one also. A little while later I read about a free coasting
gearing for a tandem bicycle. I shopped around for a unit to modify
our tandem bicycle. A bicycle shop wrench, that the name they go by,
said that this type is just a couple of BMX free wheeler mounted. The
shop wanted 500 dollars for the set of gears. That was my excuse to
spend 1500 dollars for the three in one. Bolt circles and other
calculation made for a fun take off for my shop.
I docketed many of the projects on my web page and posting on in this
group.

If you think there may ba a market for your new mount..Id be happy to
turn you onto people who could make these and other parts cheaply and
quickly. *You might have a new product!!!

Gunner
Thanks, but I don't see a market, Several are made for motorcycle that
are stronger.
*Whenever a Liberal utters the term "Common Sense approach"....grab your
*wallet, your ass, and your guns because the sombitch is about to do
*something damned nasty to all three of them.- Hide quoted text -

- Show quoted text -

mac explained on 1/24/2010 :
My Garmin NUVI 500 for my bicycle uses a ball mount. The one that I
purchase from a third party is hollowed plastic and broke from
vibration. I adapted the broken piece to my light bar and it broke
again at the ball.
I toyed with several methods. One buy a ball turning tool, two find a
ball and mount it to a post. The ball was .670 inches and I didn't
find any one that size.
I decided to make a form tool for a section and move around the ball
shape. The critical section is smooth as the female move up to the
major diameter and that the major diameter size is maintained. The
down side also needs to be smooth for a short distance.
I Machined a rectangle piece of aluminum leaving the head 3/4 inches,
in three direction. The post section is 3/4 X 1/2 inches. Pictures are
here. http://www.billcotton.com/nuvi500.htm

Get a good mount?
http://www.touratech-usa.com/shop/sh...o?SKU=065-0015
I've used their mounts for a different model.
I did make an addition so the mount could rotate on the bars

Wayne D.

On Sun, 24 Jan 2010 13:36:42 -0800 (PST), mac
wrote:

My Garmin NUVI 500 for my bicycle uses a ball mount. The one that I
purchase from a third party is hollowed plastic and broke from
vibration. I adapted the broken piece to my light bar and it broke
again at the ball.
I toyed with several methods. One buy a ball turning tool, two find a
ball and mount it to a post. The ball was .670 inches and I didn't
find any one that size.
I decided to make a form tool for a section and move around the ball
shape. The critical section is smooth as the female move up to the
major diameter and that the major diameter size is maintained. The
down side also needs to be smooth for a short distance.
I Machined a rectangle piece of aluminum leaving the head 3/4 inches,
in three direction. The post section is 3/4 X 1/2 inches. Pictures are
here. http://www.billcotton.com/nuvi500.htm

Neat Bill, and good to hear from you. It's been a while.

On Jan 25, 2:01*am, Don Foreman wrote:
On Sun, 24 Jan 2010 13:36:42 -0800 (PST), mac

wrote:
My Garmin NUVI 500 for my bicycle uses a ball mount. The one that I
purchase from a third party is hollowed plastic and broke from
vibration. I adapted the broken piece to my light bar and it broke
again at the ball.
I toyed with several methods. One buy a ball turning tool, two find a
ball and mount it to a post. The ball was .670 inches and I didn't
find any one that size.
I decided to make a form tool for a section and move around the ball
shape. The critical section is smooth as the female move up to the
major diameter and that the major diameter size is maintained. The
down side also needs to be smooth for a short distance.
I Machined a rectangle piece of aluminum leaving the head 3/4 inches,
in three direction. The post section is 3/4 X 1/2 inches. Pictures are
here.http://www.billcotton.com/nuvi500.htm

Neat Bill, and good to hear from you. *It's been a while.

Thanks Don;
Good to see your ping also.

On Sun, 24 Jan 2010 14:39:01 -0800, "anorton"
wrote:


"mac" wrote in message
...
My Garmin NUVI 500 for my bicycle uses a ball mount. The one that I
purchase from a third party is hollowed plastic and broke from
vibration. I adapted the broken piece to my light bar and it broke
again at the ball.
I toyed with several methods. One buy a ball turning tool, two find a
ball and mount it to a post. The ball was .670 inches and I didn't
find any one that size.
I decided to make a form tool for a section and move around the ball
shape. The critical section is smooth as the female move up to the
major diameter and that the major diameter size is maintained. The
down side also needs to be smooth for a short distance.
I Machined a rectangle piece of aluminum leaving the head 3/4 inches,
in three direction. The post section is 3/4 X 1/2 inches. Pictures are
here. http://www.billcotton.com/nuvi500.htm

It looks like this worked well enough for you.

In the optical lens industry, spheres and spherical sections are generated
using a cup-shaped grinding tool. The workpiece is rotated, the tool axis is
at an angle to the workpiece and spun more quickly. The edge of the cup is
aligned over the apex of the workpiece, and then the tool is moved into the
work parallel to the workpiece axis. Here is a rough diagram of how it
works:
http://www.britannica.com/EBchecked/...ave-and-convex
The radius generated will depend on the diameter of the tool and the angle.
It can make very precise spheres that are the ready for (very) fine grinding
and final polishing. Perhaps you can do this with a tool post grinder on a
metal lathe.

A long time ago in American Machinist, there was an article that
showed how to make a perfect ball on a Bridgeport (actually half a
ball). Tilt the head at 45 deg. Put in a fly tool with exactly the
radius you want, mount the part on a rotary table and start moving the
tool to the part very slowly, while turning the table. Said to make
near perfect hemispheres. In a small size, wouldn't take all that
long, I'd guess.

Karl Pearson

On Tue, 02 Feb 2010 16:08:40 -0500, wrote:

On Sun, 24 Jan 2010 14:39:01 -0800, "anorton"
wrote:


"mac" wrote in message
...
My Garmin NUVI 500 for my bicycle uses a ball mount. The one that I
purchase from a third party is hollowed plastic and broke from
vibration. I adapted the broken piece to my light bar and it broke
again at the ball.
I toyed with several methods. One buy a ball turning tool, two find a
ball and mount it to a post. The ball was .670 inches and I didn't
find any one that size.
I decided to make a form tool for a section and move around the ball
shape. The critical section is smooth as the female move up to the
major diameter and that the major diameter size is maintained. The
down side also needs to be smooth for a short distance.
I Machined a rectangle piece of aluminum leaving the head 3/4 inches,
in three direction. The post section is 3/4 X 1/2 inches. Pictures are
here. http://www.billcotton.com/nuvi500.htm

It looks like this worked well enough for you.

In the optical lens industry, spheres and spherical sections are generated
using a cup-shaped grinding tool. The workpiece is rotated, the tool axis is
at an angle to the workpiece and spun more quickly. The edge of the cup is
aligned over the apex of the workpiece, and then the tool is moved into the
work parallel to the workpiece axis. Here is a rough diagram of how it
works:
http://www.britannica.com/EBchecked/...ave-and-convex
The radius generated will depend on the diameter of the tool and the angle.
It can make very precise spheres that are the ready for (very) fine grinding
and final polishing. Perhaps you can do this with a tool post grinder on a
metal lathe.

A long time ago in American Machinist, there was an article that
showed how to make a perfect ball on a Bridgeport (actually half a
ball). Tilt the head at 45 deg. Put in a fly tool with exactly the
radius you want, mount the part on a rotary table and start moving the
tool to the part very slowly, while turning the table. Said to make
near perfect hemispheres. In a small size, wouldn't take all that
long, I'd guess.

Karl Pearson

I developed and expanded on this in an article I wrote to go into a
next version of Guy Lautard's "Machinist's Bedside Reader" which never
happened. It's mine to share, ping me if you'd like a PDF of it by
email.

On Sun, 24 Jan 2010 17:09:17 -0700, wrote:

On Sun, 24 Jan 2010 17:02:36 -0600, Tim Wescott
wrote:

On Sun, 24 Jan 2010 13:36:42 -0800, mac wrote:

My Garmin NUVI 500 for my bicycle uses a ball mount. The one that I
purchase from a third party is hollowed plastic and broke from
vibration. I adapted the broken piece to my light bar and it broke again
at the ball.
I toyed with several methods. One buy a ball turning tool, two find a
ball and mount it to a post. The ball was .670 inches and I didn't find
any one that size.
I decided to make a form tool for a section and move around the ball
shape. The critical section is smooth as the female move up to the major
diameter and that the major diameter size is maintained. The down side
also needs to be smooth for a short distance. I Machined a rectangle
piece of aluminum leaving the head 3/4 inches, in three direction. The
post section is 3/4 X 1/2 inches. Pictures are here.
http://www.billcotton.com/nuvi500.htm

Making a bunch of taper cuts to rough out the sphere, then filing it
'round' on the lathe may work well, too.

That's exactly how I did it. It's not a precision thing, doesn't even
have to be very round. Mine is still a bit oversize and tight. I'll
whittle it down a bit more if I find that it needs it.

Wayne

If you have a mill, a tiltable indexing head or rotary table and care
to provide a valid email addy, I'll send you an article I wrote, in
PDF format, about making balls and spherical cavities with a
flycutter. I didn't invent this technique and I acknowledge and
credit the previous article mentioned by another poster. I merely
tried to discover and teach how to do it since previous documentation
was vague. I derived the various formulae I presented, and verified
them both theoretically and in the shop.

I have reported examples of my work with this technique to RCM by
reference to my website. I've since removed in favor of more current
activities but will rehost if anyone is interested.

On 2/2/2010 10:59 PM, Don Foreman wrote:

I have reported examples of my work with this technique to RCM by
reference to my website. I've since removed in favor of more current
activities but will rehost if anyone is interested.

Yes, please.

--Winston

--
Support the blind and deaf. Hire a building contractor today!

In article ,
Don Foreman wrote:

On Tue, 02 Feb 2010 16:08:40 -0500, wrote:

On Sun, 24 Jan 2010 14:39:01 -0800, "anorton"
wrote:


"mac" wrote in message
...
My Garmin NUVI 500 for my bicycle uses a ball mount. The one that I
purchase from a third party is hollowed plastic and broke from
vibration. I adapted the broken piece to my light bar and it broke
again at the ball.
I toyed with several methods. One buy a ball turning tool, two find a
ball and mount it to a post. The ball was .670 inches and I didn't
find any one that size.
I decided to make a form tool for a section and move around the ball
shape. The critical section is smooth as the female move up to the
major diameter and that the major diameter size is maintained. The
down side also needs to be smooth for a short distance.
I Machined a rectangle piece of aluminum leaving the head 3/4 inches,
in three direction. The post section is 3/4 X 1/2 inches. Pictures are
here. http://www.billcotton.com/nuvi500.htm

It looks like this worked well enough for you.

In the optical lens industry, spheres and spherical sections are generated
using a cup-shaped grinding tool. The workpiece is rotated, the tool axis
is
at an angle to the workpiece and spun more quickly. The edge of the cup is
aligned over the apex of the workpiece, and then the tool is moved into the
work parallel to the workpiece axis. Here is a rough diagram of how it
works:
http://www.britannica.com/EBchecked/...s-section-of-a
-curve-generator-for-concave-and-convex
The radius generated will depend on the diameter of the tool and the angle.
It can make very precise spheres that are the ready for (very) fine
grinding
and final polishing. Perhaps you can do this with a tool post grinder on a
metal lathe.

A long time ago in American Machinist, there was an article that
showed how to make a perfect ball on a Bridgeport (actually half a
ball). Tilt the head at 45 deg. Put in a fly tool with exactly the
radius you want, mount the part on a rotary table and start moving the
tool to the part very slowly, while turning the table. Said to make
near perfect hemispheres. In a small size, wouldn't take all that
long, I'd guess.

Karl Pearson

I developed and expanded on this in an article I wrote to go into a
next version of Guy Lautard's "Machinist's Bedside Reader" which never
happened. It's mine to share, ping me if you'd like a PDF of it by
email.

I's like a copy. The above email is real.

Perhaps it would make a good addition to the Dropbox?

Thanks,

Joe Gwinn

On Tue, 02 Feb 2010 23:25:39 -0800, Winston
wrote:

On 2/2/2010 10:59 PM, Don Foreman wrote:

I have reported examples of my work with this technique to RCM by
reference to my website. I've since removed in favor of more current
activities but will rehost if anyone is interested.

Yes, please.

--Winston

OK
http://members.goldengate.net/dforeman/balls

I'll leave it up for a couple of weeks.

On Wed, 03 Feb 2010 21:44:23 -0500, Joseph Gwinn
wrote:

In article ,
Don Foreman wrote:

On Tue, 02 Feb 2010 16:08:40 -0500, wrote:

On Sun, 24 Jan 2010 14:39:01 -0800, "anorton"
wrote:


"mac" wrote in message
...
My Garmin NUVI 500 for my bicycle uses a ball mount. The one that I
purchase from a third party is hollowed plastic and broke from
vibration. I adapted the broken piece to my light bar and it broke
again at the ball.
I toyed with several methods. One buy a ball turning tool, two find a
ball and mount it to a post. The ball was .670 inches and I didn't
find any one that size.
I decided to make a form tool for a section and move around the ball
shape. The critical section is smooth as the female move up to the
major diameter and that the major diameter size is maintained. The
down side also needs to be smooth for a short distance.
I Machined a rectangle piece of aluminum leaving the head 3/4 inches,
in three direction. The post section is 3/4 X 1/2 inches. Pictures are
here. http://www.billcotton.com/nuvi500.htm

It looks like this worked well enough for you.

In the optical lens industry, spheres and spherical sections are generated
using a cup-shaped grinding tool. The workpiece is rotated, the tool axis
is
at an angle to the workpiece and spun more quickly. The edge of the cup is
aligned over the apex of the workpiece, and then the tool is moved into the
work parallel to the workpiece axis. Here is a rough diagram of how it
works:
http://www.britannica.com/EBchecked/...s-section-of-a
-curve-generator-for-concave-and-convex
The radius generated will depend on the diameter of the tool and the angle.
It can make very precise spheres that are the ready for (very) fine
grinding
and final polishing. Perhaps you can do this with a tool post grinder on a
metal lathe.

A long time ago in American Machinist, there was an article that
showed how to make a perfect ball on a Bridgeport (actually half a
ball). Tilt the head at 45 deg. Put in a fly tool with exactly the
radius you want, mount the part on a rotary table and start moving the
tool to the part very slowly, while turning the table. Said to make
near perfect hemispheres. In a small size, wouldn't take all that
long, I'd guess.

Karl Pearson

I developed and expanded on this in an article I wrote to go into a
next version of Guy Lautard's "Machinist's Bedside Reader" which never
happened. It's mine to share, ping me if you'd like a PDF of it by
email.

I's like a copy. The above email is real.

Perhaps it would make a good addition to the Dropbox?

Thanks,

Joe Gwinn

I'll respond by email. I don't want to put it out on the internet
because I want to respect Guy here. I wrote it, gratis, for him to
include in a forthcoming Machinist's Bedside Reader -- but that was a
decade ago and TMBR4 still hasn't happened. The only version I still
have contains some editing by him, though no material content. He did
tell me he had no objection to my sharing it with individual
interested metalworkers. I've not heard from him for several years
now but he's still alive, his website is current.

On 2/3/2010 7:56 PM, Don Foreman wrote:
On Tue, 02 Feb 2010 23:25:39 -0800,
wrote:

On 2/2/2010 10:59 PM, Don Foreman wrote:

I have reported examples of my work with this technique to RCM by
reference to my website. I've since removed in favor of more current
activities but will rehost if anyone is interested.

Yes, please.

--Winston

OK
http://members.goldengate.net/dforeman/balls

I'll leave it up for a couple of weeks.

Extremely cool.

Thanks Don!

--Winston

--
Support the blind and deaf. Hire a building contractor today!

In article ,
Don Foreman wrote:

On Wed, 03 Feb 2010 21:44:23 -0500, Joseph Gwinn
wrote:

In article ,
Don Foreman wrote:

On Tue, 02 Feb 2010 16:08:40 -0500, wrote:

On Sun, 24 Jan 2010 14:39:01 -0800, "anorton"
wrote:


"mac" wrote in message
...
My Garmin NUVI 500 for my bicycle uses a ball mount. The one that I
purchase from a third party is hollowed plastic and broke from
vibration. I adapted the broken piece to my light bar and it broke
again at the ball.
I toyed with several methods. One buy a ball turning tool, two find a
ball and mount it to a post. The ball was .670 inches and I didn't
find any one that size.
I decided to make a form tool for a section and move around the ball
shape. The critical section is smooth as the female move up to the
major diameter and that the major diameter size is maintained. The
down side also needs to be smooth for a short distance.
I Machined a rectangle piece of aluminum leaving the head 3/4 inches,
in three direction. The post section is 3/4 X 1/2 inches. Pictures are
here. http://www.billcotton.com/nuvi500.htm

It looks like this worked well enough for you.

In the optical lens industry, spheres and spherical sections are
generated
using a cup-shaped grinding tool. The workpiece is rotated, the tool
axis
is
at an angle to the workpiece and spun more quickly. The edge of the cup
is
aligned over the apex of the workpiece, and then the tool is moved into
the
work parallel to the workpiece axis. Here is a rough diagram of how it
works:
http://www.britannica.com/EBchecked/...ross-section-o
f-a
-curve-generator-for-concave-and-convex
The radius generated will depend on the diameter of the tool and the
angle.
It can make very precise spheres that are the ready for (very) fine
grinding
and final polishing. Perhaps you can do this with a tool post grinder
on a
metal lathe.

A long time ago in American Machinist, there was an article that
showed how to make a perfect ball on a Bridgeport (actually half a
ball). Tilt the head at 45 deg. Put in a fly tool with exactly the
radius you want, mount the part on a rotary table and start moving the
tool to the part very slowly, while turning the table. Said to make
near perfect hemispheres. In a small size, wouldn't take all that
long, I'd guess.

Karl Pearson

I developed and expanded on this in an article I wrote to go into a
next version of Guy Lautard's "Machinist's Bedside Reader" which never
happened. It's mine to share, ping me if you'd like a PDF of it by
email.

I's like a copy. The above email is real.

Perhaps it would make a good addition to the Dropbox?

Thanks,

Joe Gwinn

I'll respond by email.

I got it; thanks.


I don't want to put it out on the internet
because I want to respect Guy here. I wrote it, gratis, for him to
include in a forthcoming Machinist's Bedside Reader -- but that was a
decade ago and TMBR4 still hasn't happened. The only version I still
have contains some editing by him, though no material content. He did
tell me he had no objection to my sharing it with individual
interested metalworkers. I've not heard from him for several years
now but he's still alive, his website is current.

Understood.

Joe Gwinn

On Wed, 03 Feb 2010 00:32:41 -0600, Don Foreman
wrote:

On Tue, 02 Feb 2010 16:08:40 -0500, wrote:

On Sun, 24 Jan 2010 14:39:01 -0800, "anorton"
wrote:


"mac" wrote in message
...
My Garmin NUVI 500 for my bicycle uses a ball mount. The one that I
purchase from a third party is hollowed plastic and broke from
vibration. I adapted the broken piece to my light bar and it broke
again at the ball.
I toyed with several methods. One buy a ball turning tool, two find a
ball and mount it to a post. The ball was .670 inches and I didn't
find any one that size.
I decided to make a form tool for a section and move around the ball
shape. The critical section is smooth as the female move up to the
major diameter and that the major diameter size is maintained. The
down side also needs to be smooth for a short distance.
I Machined a rectangle piece of aluminum leaving the head 3/4 inches,
in three direction. The post section is 3/4 X 1/2 inches. Pictures are
here. http://www.billcotton.com/nuvi500.htm

It looks like this worked well enough for you.

In the optical lens industry, spheres and spherical sections are generated
using a cup-shaped grinding tool. The workpiece is rotated, the tool axis is
at an angle to the workpiece and spun more quickly. The edge of the cup is
aligned over the apex of the workpiece, and then the tool is moved into the
work parallel to the workpiece axis. Here is a rough diagram of how it
works:
http://www.britannica.com/EBchecked/...ave-and-convex
The radius generated will depend on the diameter of the tool and the angle.
It can make very precise spheres that are the ready for (very) fine grinding
and final polishing. Perhaps you can do this with a tool post grinder on a
metal lathe.

A long time ago in American Machinist, there was an article that
showed how to make a perfect ball on a Bridgeport (actually half a
ball). Tilt the head at 45 deg. Put in a fly tool with exactly the
radius you want, mount the part on a rotary table and start moving the
tool to the part very slowly, while turning the table. Said to make
near perfect hemispheres. In a small size, wouldn't take all that
long, I'd guess.

Karl Pearson

I developed and expanded on this in an article I wrote to go into a
next version of Guy Lautard's "Machinist's Bedside Reader" which never
happened. It's mine to share, ping me if you'd like a PDF of it by
email.

This is a good e-mail also. I'd appreciate a copy. Love to see neat
ideas like that preserved and explained.

Karl

I made a mount for my Nuvi using a standard ball bearing for the ball -
heated it up to remove some of the temper and drilled it and threaded it,
and then made a shaft to fit and appropriate mounting bracketry to hold it
where I wanted it. I can't imagine any reason to make the ball - you can
order bearing balls in brass or various other materials as well off of ebay
or any of the usual suppliers

"Joseph Gwinn" wrote in message
...
In article ,
Don Foreman wrote:

On Tue, 02 Feb 2010 16:08:40 -0500, wrote:

On Sun, 24 Jan 2010 14:39:01 -0800, "anorton"
wrote:


"mac" wrote in message
...
My Garmin NUVI 500 for my bicycle uses a ball mount. The one that I
purchase from a third party is hollowed plastic and broke from
vibration. I adapted the broken piece to my light bar and it broke
again at the ball.


snip

On Thu, 04 Feb 2010 17:22:53 -0500, wrote:

On Wed, 03 Feb 2010 00:32:41 -0600, Don Foreman
wrote:

On Tue, 02 Feb 2010 16:08:40 -0500, wrote:

On Sun, 24 Jan 2010 14:39:01 -0800, "anorton"
wrote:


"mac" wrote in message
...
My Garmin NUVI 500 for my bicycle uses a ball mount. The one that I
purchase from a third party is hollowed plastic and broke from
vibration. I adapted the broken piece to my light bar and it broke
again at the ball.
I toyed with several methods. One buy a ball turning tool, two find a
ball and mount it to a post. The ball was .670 inches and I didn't
find any one that size.
I decided to make a form tool for a section and move around the ball
shape. The critical section is smooth as the female move up to the
major diameter and that the major diameter size is maintained. The
down side also needs to be smooth for a short distance.
I Machined a rectangle piece of aluminum leaving the head 3/4 inches,
in three direction. The post section is 3/4 X 1/2 inches. Pictures are
here. http://www.billcotton.com/nuvi500.htm

It looks like this worked well enough for you.

In the optical lens industry, spheres and spherical sections are generated
using a cup-shaped grinding tool. The workpiece is rotated, the tool axis is
at an angle to the workpiece and spun more quickly. The edge of the cup is
aligned over the apex of the workpiece, and then the tool is moved into the
work parallel to the workpiece axis. Here is a rough diagram of how it
works:
http://www.britannica.com/EBchecked/...ave-and-convex
The radius generated will depend on the diameter of the tool and the angle.
It can make very precise spheres that are the ready for (very) fine grinding
and final polishing. Perhaps you can do this with a tool post grinder on a
metal lathe.

A long time ago in American Machinist, there was an article that
showed how to make a perfect ball on a Bridgeport (actually half a
ball). Tilt the head at 45 deg. Put in a fly tool with exactly the
radius you want, mount the part on a rotary table and start moving the
tool to the part very slowly, while turning the table. Said to make
near perfect hemispheres. In a small size, wouldn't take all that
long, I'd guess.

Karl Pearson

I developed and expanded on this in an article I wrote to go into a
next version of Guy Lautard's "Machinist's Bedside Reader" which never
happened. It's mine to share, ping me if you'd like a PDF of it by
email.

This is a good e-mail also. I'd appreciate a copy. Love to see neat
ideas like that preserved and explained.

Karl

Done

On Thu, 4 Feb 2010 20:34:09 -0800, "Bill Noble"
wrote:

I made a mount for my Nuvi using a standard ball bearing for the ball -
heated it up to remove some of the temper and drilled it and threaded it,
and then made a shaft to fit and appropriate mounting bracketry to hold it
where I wanted it. I can't imagine any reason to make the ball - you can
order bearing balls in brass or various other materials as well off of ebay
or any of the usual suppliers

I've done that too. Sometimes I don't want to pay $7 shipping and wait
a week for something I can make in less than an hour. Being retired
does tend to change one's attitude about time vs $$$.

On Thu, 4 Feb 2010 20:34:09 -0800, "Bill Noble"
wrote:

I made a mount for my Nuvi using a standard ball bearing for the ball -
heated it up to remove some of the temper and drilled it and threaded it,
and then made a shaft to fit and appropriate mounting bracketry to hold it
where I wanted it. I can't imagine any reason to make the ball - you can
order bearing balls in brass or various other materials as well off of ebay
or any of the usual suppliers

Here's why I made my own ball - turning an aluminum ball to the
accuracy needed for this job is fast and easy. I made the entire mount
from scraps I had in stock, in about 2 hours, and that included a lot
of getting in and out of the car for test fitting. The mount is an
1/8" plate about 2" square and curved slightly in both dimensions.
Welded to that at an angle is a 3/8" coupling nut drilled and tapped
for a locking screw. The ball shaft telescopes in the coupling nut.
The plate is attached in the perfect spot with two-sided tape to some
dash plastic.

Wayne