Ever look inside a cotter?

A cotter is a mechanism like the quill lock on a bridgeport. Guy
Lautard describes them and how they work in one of his "Machinist's
Bedside Reader" books and I borrow the term "cotter" from him.

I've made and used them in a number of metal projects but I'd never
taken a close look inside. Now that I'm learning to use 3D modelling
I did that --and found it interesting. Perhaps a few readers here
will also, No news to many readers but it was interesting to me.

I've posted screenshots in the dropbox as cotter*.jpg. I was
contemplating making a cotter clamp for the LED ringlight I'm
building for my microscope. The mount for the ringlight to the scope
is made using PVC plumbing parts from Home Depot as raw material
costing less than 2 bux.

In the model, the large part is a (nominal) 2" PVC collar, cotter
barrel is (nominal) 1/2" PVC pipe, the slugs in the cotter would be
turned from delryn to slide easily in a .625 hole reamed into the
small pipe, the pinch screw would be 1/4-20 brass. The cotter barrel
is 2" long. PVC is neat stuff because it's cheap and because glue
works well.

I think I'll try a simple setscrew first, but if that isn't
satisfactory I'll have this as a fallback. I do like making cotters!

The thing that struck me in looking at the model was the double
mechanical advantage at work to pinch tight: screw plus wedge. No
wonder these things work so well!

On Fri, 16 Jan 2004 01:15:16 -0600, Don Foreman wrote:

Ever look inside a cotter?

A cotter is a mechanism like the quill lock on a bridgeport. Guy
Lautard describes them and how they work in one of his "Machinist's
Bedside Reader" books and I borrow the term "cotter" from him.
snip

Thanks for mentioning these. I want to make a really nice boring
bar holder for my lathe's toolpost (which I'm making) and have been
considering different bar clamping methods. I'm using 1/2" shank
boring bars. I wonder if a cotter clamp would be rigid enough.

--
"There cannot possibly be a god in heaven watching all of this calmly."
-- Revi Shankar




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Thanks for mentioning these. I want to make a really nice boring
bar holder for my lathe's toolpost (which I'm making) and have been
considering different bar clamping methods. I'm using 1/2" shank
boring bars. I wonder if a cotter clamp would be rigid enough.

The import quick-change toolposts come with a boring bar
holder that uses two screw activated wedges to lock the
bar in the bore. They look sort of like half cotters, if
you will. The screws are on the top and pull the wedges
up from the bottom. I would expect that a full cotter
(or two) would work even better. On my 200 series post,
this fits a 1" boring bar.

HTH,
--Glenn Lyford

Artemia Salina wrote:
... boring bar holder for my lathe's toolpost ...
I wonder if a cotter clamp would be rigid enough.

That's the way my Phase II boring bar holder works.

On Fri, 16 Jan 2004 10:04:04 -0500, Artemia Salina
wrote:

On Fri, 16 Jan 2004 01:15:16 -0600, Don Foreman wrote:

Ever look inside a cotter?

A cotter is a mechanism like the quill lock on a bridgeport. Guy
Lautard describes them and how they work in one of his "Machinist's
Bedside Reader" books and I borrow the term "cotter" from him.
snip

Thanks for mentioning these. I want to make a really nice boring
bar holder for my lathe's toolpost (which I'm making) and have been
considering different bar clamping methods. I'm using 1/2" shank
boring bars. I wonder if a cotter clamp would be rigid enough.

--
"There cannot possibly be a god in heaven watching all of this calmly."
-- Revi Shankar




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I made just such a boring bar holder and I found that it really works
well. Have a look at the following photos:

http://home.worldnet.att.net/~renner...cs/cotter1.JPG
http://home.worldnet.att.net/~renner...cs/cotter2.JPG
http://home.worldnet.att.net/~renner...cs/cotter3.JPG

HTH
Rick Renner

On Fri, 16 Jan 2004 17:18:27 GMT, (Rick
Renner) wrote:


I made just such a boring bar holder and I found that it really works
well. Have a look at the following photos:

http://home.worldnet.att.net/~renner...cs/cotter1.JPG
http://home.worldnet.att.net/~renner...cs/cotter2.JPG
http://home.worldnet.att.net/~renner...cs/cotter3.JPG

Very nice!

On Fri, 16 Jan 2004 17:18:27 +0000, rennerr_nospam wrote:

On Fri, 16 Jan 2004 10:04:04 -0500, Artemia Salina
wrote:

I wonder if a cotter clamp would be rigid enough.

I made just such a boring bar holder and I found that it really works
well. Have a look at the following photos:

http://home.worldnet.att.net/~renner...cs/cotter1.JPG
http://home.worldnet.att.net/~renner...cs/cotter2.JPG
http://home.worldnet.att.net/~renner...cs/cotter3.JPG

Nice job Rick. One thing that concerns me is the possibility of the
boring bar wanting to roll a bit as the cotter clamp is tightened.
Have you experienced anything like that in your holder? Anything
you would have done differently after using it for a while?

Thanks


--
"There cannot possibly be a god in heaven watching all of this calmly."
-- Revi Shankar




----== Posted via Newsfeed.Com - Unlimited-Uncensored-Secure Usenet News==----
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---= 19 East/West-Coast Specialized Servers - Total Privacy via Encryption =---

A'int CAD cool?!

Actually, I'd be interested in details on your ringlight. I've been
considering exactly this project for a while. How many LED's did you use?
How are you powering them? How much light do you get compared to a fiber
optic ringlight (with e.g. a 150W EKE bulb)? Other construction details?

-- Greg

http://www.depmco.com

"Don Foreman" wrote in message
...
Ever look inside a cotter?

A cotter is a mechanism like the quill lock on a bridgeport. Guy
Lautard describes them and how they work in one of his "Machinist's
Bedside Reader" books and I borrow the term "cotter" from him.

I've made and used them in a number of metal projects but I'd never
taken a close look inside. Now that I'm learning to use 3D modelling
I did that --and found it interesting. Perhaps a few readers here
will also, No news to many readers but it was interesting to me.

I've posted screenshots in the dropbox as cotter*.jpg. I was
contemplating making a cotter clamp for the LED ringlight I'm
building for my microscope. The mount for the ringlight to the scope
is made using PVC plumbing parts from Home Depot as raw material
costing less than 2 bux.

In the model, the large part is a (nominal) 2" PVC collar, cotter
barrel is (nominal) 1/2" PVC pipe, the slugs in the cotter would be
turned from delryn to slide easily in a .625 hole reamed into the
small pipe, the pinch screw would be 1/4-20 brass. The cotter barrel
is 2" long. PVC is neat stuff because it's cheap and because glue
works well.

I think I'll try a simple setscrew first, but if that isn't
satisfactory I'll have this as a fallback. I do like making cotters!

The thing that struck me in looking at the model was the double
mechanical advantage at work to pinch tight: screw plus wedge. No
wonder these things work so well!

Hey Rick.

I like it !!

Take care.

Brian Lawson,
Bothwell, Ontario.
XXXXXXXXXXXXXXXXXXXX
On Fri, 16 Jan 2004 17:18:27 GMT, (Rick
Renner) wrote:

On Fri, 16 Jan 2004 10:04:04 -0500, Artemia Salina
wrote:

On Fri, 16 Jan 2004 01:15:16 -0600, Don Foreman wrote:

Ever look inside a cotter?

A cotter is a mechanism like the quill lock on a bridgeport. Guy
Lautard describes them and how they work in one of his "Machinist's
Bedside Reader" books and I borrow the term "cotter" from him.
snip

Thanks for mentioning these. I want to make a really nice boring
bar holder for my lathe's toolpost (which I'm making) and have been
considering different bar clamping methods. I'm using 1/2" shank
boring bars. I wonder if a cotter clamp would be rigid enough.

--
"There cannot possibly be a god in heaven watching all of this calmly."
-- Revi Shankar




----== Posted via Newsfeed.Com - Unlimited-Uncensored-Secure Usenet News==----
http://www.newsfeed.com The #1 Newsgroup Service in the World! 100,000 Newsgroups
---= 19 East/West-Coast Specialized Servers - Total Privacy via Encryption =---

I made just such a boring bar holder and I found that it really works
well. Have a look at the following photos:

http://home.worldnet.att.net/~renner...cs/cotter1.JPG
http://home.worldnet.att.net/~renner...cs/cotter2.JPG
http://home.worldnet.att.net/~renner...cs/cotter3.JPG

HTH
Rick Renner

On Fri, 16 Jan 2004 13:46:19 -0500, Artemia Salina
wrote:

On Fri, 16 Jan 2004 17:18:27 +0000, rennerr_nospam wrote:

On Fri, 16 Jan 2004 10:04:04 -0500, Artemia Salina
wrote:

I wonder if a cotter clamp would be rigid enough.

I made just such a boring bar holder and I found that it really works
well. Have a look at the following photos:

http://home.worldnet.att.net/~renner...cs/cotter1.JPG
http://home.worldnet.att.net/~renner...cs/cotter2.JPG
http://home.worldnet.att.net/~renner...cs/cotter3.JPG

Nice job Rick. One thing that concerns me is the possibility of the
boring bar wanting to roll a bit as the cotter clamp is tightened.
Have you experienced anything like that in your holder? Anything
you would have done differently after using it for a while?

Thanks


--
"There cannot possibly be a god in heaven watching all of this calmly."
-- Revi Shankar




----== Posted via Newsfeed.Com - Unlimited-Uncensored-Secure Usenet News==----
http://www.newsfeed.com The #1 Newsgroup Service in the World! 100,000 Newsgroups
---= 19 East/West-Coast Specialized Servers - Total Privacy via Encryption =---

Thanks for the kind words. Regarding the issue of boring bar rotation,
I haven't detected any in the dozens of job set ups I've done with
this holder. I can't think of anything I'd change about this holder.

Rick Renner

On Fri, 16 Jan 2004 13:36:26 -0800, "Greg Dermer"
wrote:

A'int CAD cool?!

Actually, I'd be interested in details on your ringlight. I've been
considering exactly this project for a while. How many LED's did you use?
How are you powering them? How much light do you get compared to a fiber
optic ringlight (with e.g. a 150W EKE bulb)? Other construction details?

I don't know how much light a 150W fiberoptic ringlight throws, but
I'd expect it to be a lot brighter than 10 LEDs running about 0.2 to
0.4 watts each. Experiments lead me to believe that I'll have ample
light for the low (3.5x to 22.5x) magnifications I use, but 150 watts
it emphatically is not.

I'm using 10 large (10mm) white LED's, arrayed in a circular array
about 5" in dia. Each LED is in a little "projector" about 1.5" long
and 0.5 dia with a ball nose set in a round hole to facilitate aiming.
There's a little 0.5"dia lens in each projector that images the
glowing phosphor surface inside the LED onto the worksurface. The
result is a very well-defined and evenly-illuminated disc of light
about 2.5" dia with no rings or dark spots like you get from an
incandescant flashlight. It looks almost like a white disc cut out
of paper. LED flashlights spray light all over the place so they're
less efficient. Light not illuminating the microscope's limited field
of view is wasted.

All 10 "projectors" will be aimed at the same spot, Because they all
impinge at an 18 degree angle from vertical but from various
directions, I'm expecting very shadow-free but high-contrast
lighting, and little problem with specular reflections because no
specular reflection would glint from more than one or maybe 2 of the10
projectors. It's high-contrast because the light from each projector
is well-collimated, not diffuse as from a fluorescent ringlight and
possibly from a fiberoptic ringlight. (I've never used a f.o.
ringlight) .

Power supply will be a 45 or 50 volt DC supply current-regulated to
50 to 100 mA. (adjustable) to run all 10 LED's in series. That'll
ensure that they're all running the same current so should be about
the same brightness. No dropping resistors. The LED's are rated
at 30 mA but they'll take considerably more, though with consequent
degradation in lifetime. I may only get 5000 hours out of them.
I'll "relamp" with the much better LED's available then, if I should
live so long.

Other construction details (including a cad model and photos)
available, just send me an email. Warning, though: I made no attempt
to be "practical" or even "sensible" on this project, though I was
"cheap". I'm retired, can spend my time any way I want, and
that's often in the shop. It was fun just seeing if I could build
this somewhat fanciful design. The 10-facet conical metal ring was
an interesting challenge.

On Fri, 16 Jan 2004 13:36:26 -0800, "Greg Dermer"
wrote:

A'int CAD cool?!

Actually, I'd be interested in details on your ringlight.

OK, see
http://www.goldengate.net/~dforeman/ledring/

On Sat, 17 Jan 2004 17:33:43 -0600, Don Foreman
wrote:

On Fri, 16 Jan 2004 13:36:26 -0800, "Greg Dermer"
wrote:

A'int CAD cool?!

Actually, I'd be interested in details on your ringlight.

OK, see
http://www.goldengate.net/~dforeman/ledring/

Boy Don, that's cool. I like the way you did the balls. I have tools
and cnc to do this easily but your method is a good one to know.
Especially if the lathes are full and you just gotta have that part.
And all the detail on that page. gives me something to strive for if I
ever manage to get mine up and running.
Cheers,
Eric R Snow

Don,

Thanks for the response and for the writeup. Of course it's not 150W, but
on the other hand I expect that the efficiencies of the LED's are higher
than the incandescent bulb, and then there is a little loss in the fiber...
So the disparity might not be as much as one might guess. Who knows?

It looks like a great project. Congrats!

-- Greg

"Don Foreman" wrote in message
...
On Fri, 16 Jan 2004 13:36:26 -0800, "Greg Dermer"
wrote:

A'int CAD cool?!

Actually, I'd be interested in details on your ringlight. I've been
considering exactly this project for a while. How many LED's did you
use?
How are you powering them? How much light do you get compared to a fiber
optic ringlight (with e.g. a 150W EKE bulb)? Other construction details?

I don't know how much light a 150W fiberoptic ringlight throws, but
I'd expect it to be a lot brighter than 10 LEDs running about 0.2 to
0.4 watts each. Experiments lead me to believe that I'll have ample
light for the low (3.5x to 22.5x) magnifications I use, but 150 watts
it emphatically is not.

I'm using 10 large (10mm) white LED's, arrayed in a circular array
about 5" in dia. Each LED is in a little "projector" about 1.5" long
and 0.5 dia with a ball nose set in a round hole to facilitate aiming.
There's a little 0.5"dia lens in each projector that images the
glowing phosphor surface inside the LED onto the worksurface. The
result is a very well-defined and evenly-illuminated disc of light
about 2.5" dia with no rings or dark spots like you get from an
incandescant flashlight. It looks almost like a white disc cut out
of paper. LED flashlights spray light all over the place so they're
less efficient. Light not illuminating the microscope's limited field
of view is wasted.

All 10 "projectors" will be aimed at the same spot, Because they all
impinge at an 18 degree angle from vertical but from various
directions, I'm expecting very shadow-free but high-contrast
lighting, and little problem with specular reflections because no
specular reflection would glint from more than one or maybe 2 of the10
projectors. It's high-contrast because the light from each projector
is well-collimated, not diffuse as from a fluorescent ringlight and
possibly from a fiberoptic ringlight. (I've never used a f.o.
ringlight) .

Power supply will be a 45 or 50 volt DC supply current-regulated to
50 to 100 mA. (adjustable) to run all 10 LED's in series. That'll
ensure that they're all running the same current so should be about
the same brightness. No dropping resistors. The LED's are rated
at 30 mA but they'll take considerably more, though with consequent
degradation in lifetime. I may only get 5000 hours out of them.
I'll "relamp" with the much better LED's available then, if I should
live so long.

Other construction details (including a cad model and photos)
available, just send me an email. Warning, though: I made no attempt
to be "practical" or even "sensible" on this project, though I was
"cheap". I'm retired, can spend my time any way I want, and
that's often in the shop. It was fun just seeing if I could build
this somewhat fanciful design. The 10-facet conical metal ring was
an interesting challenge.