My son, who is in graduate school, uses a high quality but no longer
made microscope for his home studies. Recently, one of the small brass
pinions broke in the focusing unit and he asked me if I could repair it.
I was able to disassemble to access the pinion which is on a rod.
Unfortunately, since the scope is no longer made, the exact part is no
longer available, but I have determined that a 64p 16T 0.4 modulus would
fit it almost exactly except that the bore is too small (it is 3mm and I
need it to be 4mm... actually a bit wider at #21 drill bit sized).
Unfortunately, web searching cannot locate a pinion of the proper bore
size (all are either 2 or 3mm bore), so I am thinking of getting one of
the 3mm ones and drilling it out to #21 sized. The problem is that this
needs to be very precise and if off by even a little will cause binding
and other problems in the focus mechanism. So I pose the question: How
would I go about drilling this out from 3 mm to #21 accurately using
ONLY hand drill, vice, etc as I have no access to lathes, presses, etc?
Thanks!

I'd go to Edmond Scientific site and you can get parts like all get-out!
They are an Optical leader for science.

Martin


On 2/19/2016 9:08 PM, Bill Baxter wrote:
My son, who is in graduate school, uses a high quality but no longer
made microscope for his home studies. Recently, one of the small brass
pinions broke in the focusing unit and he asked me if I could repair it.
I was able to disassemble to access the pinion which is on a rod.
Unfortunately, since the scope is no longer made, the exact part is no
longer available, but I have determined that a 64p 16T 0.4 modulus would
fit it almost exactly except that the bore is too small (it is 3mm and I
need it to be 4mm... actually a bit wider at #21 drill bit sized).
Unfortunately, web searching cannot locate a pinion of the proper bore
size (all are either 2 or 3mm bore), so I am thinking of getting one of
the 3mm ones and drilling it out to #21 sized. The problem is that this
needs to be very precise and if off by even a little will cause binding
and other problems in the focus mechanism. So I pose the question: How
would I go about drilling this out from 3 mm to #21 accurately using
ONLY hand drill, vice, etc as I have no access to lathes, presses, etc?
Thanks!

On 2/19/2016 10:08 PM, Bill Baxter wrote:
... The problem is that this
needs to be very precise and if off by even a little will cause binding
and other problems in the focus mechanism. So I pose the question: How
would I go about drilling this out from 3 mm to #21 accurately using
ONLY hand drill, vice, etc as I have no access to lathes, presses, etc?

Your _fundamental_ problem is that drilling is not "very precise" in any
context. It's due to the nature of the cutting action of a drill bit.
The hole diameter and shape aren't going to be closer than a few
thousandths and even the direction will be off, depending upon the ratio
of depth to diameter.

That said, "very precise" is not a very precise specification and for a
good answer, you will need to give tolerances. But you probably don't
have the ability to do that. So I would recommend that you just do it
as best you can free hand. There's a fair chance that it will work and
if it doesn't you're only out the cost of a pinion and you'll know
better what tolerances are required.

Good luck,
Bob

Bill Baxter wrote:

My son, who is in graduate school, uses a high quality but no longer
made microscope for his home studies. Recently, one of the small brass
pinions broke in the focusing unit and he asked me if I could repair it.
I was able to disassemble to access the pinion which is on a rod.
Unfortunately, since the scope is no longer made, the exact part is no
longer available, but I have determined that a 64p 16T 0.4 modulus would
fit it almost exactly except that the bore is too small (it is 3mm and I
need it to be 4mm... actually a bit wider at #21 drill bit sized).
Unfortunately, web searching cannot locate a pinion of the proper bore
size (all are either 2 or 3mm bore), so I am thinking of getting one of
the 3mm ones and drilling it out to #21 sized. The problem is that this
needs to be very precise and if off by even a little will cause binding
and other problems in the focus mechanism. So I pose the question: How
would I go about drilling this out from 3 mm to #21 accurately using
ONLY hand drill, vice, etc as I have no access to lathes, presses, etc?
Thanks!
If he's in graduate school, do they have a machine shop somewhere on campus?
In general, most campus machine shops will either do tiny jobs like this for
free, or can possibly charge his department for the fix. (Or a 6-pack of
beer might help it along.)

Take a piece of aluminum, bore approximately the OD of the gear, then slit
and grip the gear in a chuck. If they have a collet chuck with rubber-flex
collets, then this may not be needed. Then, bore the hole with a tiny
boring bar. This should be a 5 minute job for an experienced machinist, or
a 30 minute job for somebody in the student shop (but not too many
universities have student shops anymore due to liability and disinterest.)

Jon

Bill Baxter wrote:
My son, who is in graduate school, uses a high quality but no longer
made microscope for his home studies. Recently, one of the small brass
pinions broke in the focusing unit and he asked me if I could repair it.
I was able to disassemble to access the pinion which is on a rod.
Unfortunately, since the scope is no longer made, the exact part is no
longer available, but I have determined that a 64p 16T 0.4 modulus would
fit it almost exactly except that the bore is too small (it is 3mm and I
need it to be 4mm... actually a bit wider at #21 drill bit sized).
Unfortunately, web searching cannot locate a pinion of the proper bore
size (all are either 2 or 3mm bore), so I am thinking of getting one of
the 3mm ones and drilling it out to #21 sized. The problem is that this
needs to be very precise and if off by even a little will cause binding
and other problems in the focus mechanism. So I pose the question: How
would I go about drilling this out from 3 mm to #21 accurately using
ONLY hand drill, vice, etc as I have no access to lathes, presses, etc?
Thanks!

What make and model scope, It might have a twin out there.

How did the pinion break? Through the bore? sheared teeth?
What is the shaft made from? How is the pinion secured to the shaft?

Does the replacement have to be brass? I'm wondering if a delrin/nylon
or similar plastic one would work as well.

Or find a 4mm ream and ream the hole out.

--
Steve W.

On Fri, 19 Feb 2016 22:08:11 -0500, Bill Baxter wrote:

My son, who is in graduate school, uses a high quality but no longer
made microscope for his home studies. Recently, one of the small brass
pinions broke in the focusing unit and he asked me if I could repair it.
I was able to disassemble to access the pinion which is on a rod.
Unfortunately, since the scope is no longer made, the exact part is no
longer available, but I have determined that a 64p 16T 0.4 modulus would
fit it almost exactly except that the bore is too small (it is 3mm and I
need it to be 4mm... actually a bit wider at #21 drill bit sized).
Unfortunately, web searching cannot locate a pinion of the proper bore
size (all are either 2 or 3mm bore), so I am thinking of getting one of
the 3mm ones and drilling it out to #21 sized. The problem is that this
needs to be very precise and if off by even a little will cause binding
and other problems in the focus mechanism. So I pose the question: How
would I go about drilling this out from 3 mm to #21 accurately using
ONLY hand drill, vice, etc as I have no access to lathes, presses, etc?
Thanks!

Given your constraints I would make a split sleeve of soft aluminium and
grip the gear+sleeve in the drill chuck - and spin it to check visually
if the hole is centred. If not, loosen, shift, check again. If at all
possible I would put a pin that fit the existing bore in it; dab of hot
glue, check the spinning end of the pin.

Then I'd set up a mirror beside the vice and grab a drillbit in the vice,
probably horizontal (my vice has a horizontal V-slot at one end for this;
if your does not, put a bit of soft wood on one side of the drill and bed
the shank in it when you tighten the vice). I'd get the best drill I had
- sharp and evenly ground. Look at it with a magnifying glass.

Then I'd drill it. I like horizontal because I can support the spinning
chuck with my fingers and feel as well as see (x2; that's what the mirror
is for) if it is wandering.

Don't make the drill free end short. You are hoping it will follow the
hole, so let it.

I would VERY much like not to have to do this right the first time, so
replacement pinions to modify - especially cheap ones - would be very
helpful. I'd bet with five tries I would get at least one good enough to
work.


Are you sure it is .4 module?

Because this one

http://www.surplusshed.com/pages/item/m4203.html

is 9mm outside 16T .5module 4mm bore if you trust their measurements.

At 20 cents each the fact that they are plastic becomes less important.

If yours is .4 it should measure 7.2mm outside.

64p 16t .4mm pinions are available in the rc/slot car world but they
usually have smaller bores. They are also (relatively) cheap, and some
are even aluminium so drilling them freehand will be easier.

"Bill Baxter" wrote in message
...
My son, who is in graduate school, uses a high quality but no longer
made microscope for his home studies. Recently, one of the small
brass
pinions broke in the focusing unit and he asked me if I could repair
it.
I was able to disassemble to access the pinion which is on a rod.
Unfortunately, since the scope is no longer made, the exact part is
no
longer available, but I have determined that a 64p 16T 0.4 modulus
would
fit it almost exactly except that the bore is too small (it is 3mm
and I
need it to be 4mm... actually a bit wider at #21 drill bit sized).
Unfortunately, web searching cannot locate a pinion of the proper
bore
size (all are either 2 or 3mm bore), so I am thinking of getting
one of
the 3mm ones and drilling it out to #21 sized. The problem is that
this
needs to be very precise and if off by even a little will cause
binding
and other problems in the focus mechanism. So I pose the question:
How
would I go about drilling this out from 3 mm to #21 accurately using
ONLY hand drill, vice, etc as I have no access to lathes, presses,
etc?
Thanks!

That's a tricky job even with a lathe, since the outer surface of the
pinion may not be "precisely" concentric with the pitch diameter which
controls smoothness of engagement.

Without a lathe you might at best achieve the accuracy of a clockmaker
from the 1700's.
http://www.ronellclock.com/Broaches_c208.htm

Our tech was little better than the Greeks' and Romans' until the
modern lathe was invented around 1800, enabling the Industrial
Revolution.
https://en.wikipedia.org/wiki/Antikythera_mechanism
"After the knowledge of this technology was lost at some point in
Antiquity, technological artifacts approaching its complexity and
workmanship did not appear again until the development of mechanical
astronomical clocks in Europe in the fourteenth century."

If precision metalworking by hand was easy we wouldn't need the
expensive machine tools. Lacking them you could look up the old manual
clockmaking and gunsmithing methods. I didn't find very much useful
there, though

--jsw

On Sat, 20 Feb 2016 09:27:24 -0500, "Jim Wilkins"
wrote:

"Bill Baxter" wrote in message
...
My son, who is in graduate school, uses a high quality but no longer
made microscope for his home studies. Recently, one of the small
brass
pinions broke in the focusing unit and he asked me if I could repair
it.
I was able to disassemble to access the pinion which is on a rod.
Unfortunately, since the scope is no longer made, the exact part is
no
longer available, but I have determined that a 64p 16T 0.4 modulus
would
fit it almost exactly except that the bore is too small (it is 3mm
and I
need it to be 4mm... actually a bit wider at #21 drill bit sized).
Unfortunately, web searching cannot locate a pinion of the proper
bore
size (all are either 2 or 3mm bore), so I am thinking of getting
one of
the 3mm ones and drilling it out to #21 sized. The problem is that
this
needs to be very precise and if off by even a little will cause
binding
and other problems in the focus mechanism. So I pose the question:
How
would I go about drilling this out from 3 mm to #21 accurately using
ONLY hand drill, vice, etc as I have no access to lathes, presses,
etc?
Thanks!

That's a tricky job even with a lathe, since the outer surface of the
pinion may not be "precisely" concentric with the pitch diameter which
controls smoothness of engagement.

Without a lathe you might at best achieve the accuracy of a clockmaker
from the 1700's.
http://www.ronellclock.com/Broaches_c208.htm

Our tech was little better than the Greeks' and Romans' until the
modern lathe was invented around 1800, enabling the Industrial
Revolution.
https://en.wikipedia.org/wiki/Antikythera_mechanism
"After the knowledge of this technology was lost at some point in
Antiquity, technological artifacts approaching its complexity and
workmanship did not appear again until the development of mechanical
astronomical clocks in Europe in the fourteenth century."

If precision metalworking by hand was easy we wouldn't need the
expensive machine tools. Lacking them you could look up the old manual
clockmaking and gunsmithing methods. I didn't find very much useful
there, though

--jsw


FWIW (and this will be of little use to the OP), fixturing used for
boring center holes in pinions sometimes uses a set of round pins that
engage the teeth. The idea is that you want to locate off of a
consistent location on the gear flanks, rather than the tips of the
teeth. And you want to average those locations, so you use pins on a
lot of the teeth.

When I was at Wasino (now Amada Machine Tools), we designed such
fixtures for DeWalt, to bore the bevel gears used in their angle-head
grinders. The final design actually used wedges -- one for each tooth
-- rather than pins, but the idea was the same.

You get much smoother running of the finished gear set that way.

--
Ed Huntress

"Ed Huntress" wrote in message
...
On Sat, 20 Feb 2016 09:27:24 -0500, "Jim Wilkins"
wrote:

"Bill Baxter" wrote in message
...
My son, who is in graduate school, uses a high quality but no
longer
made microscope for his home studies. Recently, one of the small
brass
pinions broke in the focusing unit and he asked me if I could
repair
it.
I was able to disassemble to access the pinion which is on a
rod.
Unfortunately, since the scope is no longer made, the exact part
is
no
longer available, but I have determined that a 64p 16T 0.4 modulus
would
fit it almost exactly except that the bore is too small (it is 3mm
and I
need it to be 4mm... actually a bit wider at #21 drill bit sized).
Unfortunately, web searching cannot locate a pinion of the proper
bore
size (all are either 2 or 3mm bore), so I am thinking of getting
one of
the 3mm ones and drilling it out to #21 sized. The problem is
that
this
needs to be very precise and if off by even a little will cause
binding
and other problems in the focus mechanism. So I pose the
question:
How
would I go about drilling this out from 3 mm to #21 accurately
using
ONLY hand drill, vice, etc as I have no access to lathes, presses,
etc?
Thanks!

That's a tricky job even with a lathe, since the outer surface of
the
pinion may not be "precisely" concentric with the pitch diameter
which
controls smoothness of engagement.

Without a lathe you might at best achieve the accuracy of a
clockmaker
from the 1700's.
http://www.ronellclock.com/Broaches_c208.htm

Our tech was little better than the Greeks' and Romans' until the
modern lathe was invented around 1800, enabling the Industrial
Revolution.
https://en.wikipedia.org/wiki/Antikythera_mechanism
"After the knowledge of this technology was lost at some point in
Antiquity, technological artifacts approaching its complexity and
workmanship did not appear again until the development of mechanical
astronomical clocks in Europe in the fourteenth century."

If precision metalworking by hand was easy we wouldn't need the
expensive machine tools. Lacking them you could look up the old
manual
clockmaking and gunsmithing methods. I didn't find very much useful
there, though

--jsw


FWIW (and this will be of little use to the OP), fixturing used for
boring center holes in pinions sometimes uses a set of round pins
that
engage the teeth. The idea is that you want to locate off of a
consistent location on the gear flanks, rather than the tips of the
teeth. And you want to average those locations, so you use pins on a
lot of the teeth.

When I was at Wasino (now Amada Machine Tools), we designed such
fixtures for DeWalt, to bore the bevel gears used in their
angle-head
grinders. The final design actually used wedges -- one for each
tooth
-- rather than pins, but the idea was the same.

You get much smoother running of the finished gear set that way.

--
Ed Huntress

As a one-off approach I'd put a snug-fitting shaft in the pinion's
center hole and do whatever was needed to make it run true as the
chucked pinion rotates, then remove it and bore larger. A reamer or
broach might cut straight enough if you spin the work and ensure that
the reamer doesn't start to wobble. Bob Engelhardt gave you the sad
truth about drill bit accuracy. They also tend to grab and break in
brass.

This is the cheapest type of tool I know of that approximates a lathe
headstock:
http://www.grizzly.com/products/5-C-Spin-Index/G5649

--jsw

On Sat, 20 Feb 2016 10:20:38 -0500, "Jim Wilkins"
wrote:

"Ed Huntress" wrote in message
.. .
On Sat, 20 Feb 2016 09:27:24 -0500, "Jim Wilkins"
wrote:

"Bill Baxter" wrote in message
...
My son, who is in graduate school, uses a high quality but no
longer
made microscope for his home studies. Recently, one of the small
brass
pinions broke in the focusing unit and he asked me if I could
repair
it.
I was able to disassemble to access the pinion which is on a
rod.
Unfortunately, since the scope is no longer made, the exact part
is
no
longer available, but I have determined that a 64p 16T 0.4 modulus
would
fit it almost exactly except that the bore is too small (it is 3mm
and I
need it to be 4mm... actually a bit wider at #21 drill bit sized).
Unfortunately, web searching cannot locate a pinion of the proper
bore
size (all are either 2 or 3mm bore), so I am thinking of getting
one of
the 3mm ones and drilling it out to #21 sized. The problem is
that
this
needs to be very precise and if off by even a little will cause
binding
and other problems in the focus mechanism. So I pose the
question:
How
would I go about drilling this out from 3 mm to #21 accurately
using
ONLY hand drill, vice, etc as I have no access to lathes, presses,
etc?
Thanks!

That's a tricky job even with a lathe, since the outer surface of
the
pinion may not be "precisely" concentric with the pitch diameter
which
controls smoothness of engagement.

Without a lathe you might at best achieve the accuracy of a
clockmaker
from the 1700's.
http://www.ronellclock.com/Broaches_c208.htm

Our tech was little better than the Greeks' and Romans' until the
modern lathe was invented around 1800, enabling the Industrial
Revolution.
https://en.wikipedia.org/wiki/Antikythera_mechanism
"After the knowledge of this technology was lost at some point in
Antiquity, technological artifacts approaching its complexity and
workmanship did not appear again until the development of mechanical
astronomical clocks in Europe in the fourteenth century."

If precision metalworking by hand was easy we wouldn't need the
expensive machine tools. Lacking them you could look up the old
manual
clockmaking and gunsmithing methods. I didn't find very much useful
there, though

--jsw


FWIW (and this will be of little use to the OP), fixturing used for
boring center holes in pinions sometimes uses a set of round pins
that
engage the teeth. The idea is that you want to locate off of a
consistent location on the gear flanks, rather than the tips of the
teeth. And you want to average those locations, so you use pins on a
lot of the teeth.

When I was at Wasino (now Amada Machine Tools), we designed such
fixtures for DeWalt, to bore the bevel gears used in their
angle-head
grinders. The final design actually used wedges -- one for each
tooth
-- rather than pins, but the idea was the same.

You get much smoother running of the finished gear set that way.

--
Ed Huntress

As a one-off approach I'd put a snug-fitting shaft in the pinion's
center hole and do whatever was needed to make it run true as the
chucked pinion rotates, then remove it and bore larger. A reamer or
broach might cut straight enough if you spin the work and ensure that
the reamer doesn't start to wobble. Bob Engelhardt gave you the sad
truth about drill bit accuracy. They also tend to grab and break in
brass.

This is the cheapest type of tool I know of that approximates a lathe
headstock:
http://www.grizzly.com/products/5-C-Spin-Index/G5649

--jsw

Wow, I've never seen a spin fixture for $50 before. They're usually
hundreds, or even over $1,000.

Also FWIW, those DeWalt bevel gears were bored with single-point PCBN
boring tools. Diametral accuracy was +/- 50 microinches, and the
tendency for PCBN to fail in a very rapid progression, once they
reached a certain amount of wear, meant that the tools had to be
changed when the air gage said that accuracy was slipping beyond 20
microinches either way. The gears were (and probably still are) iron
alloy PM infiltrated with copper.

--
Ed Huntress

"Ed Huntress" wrote in message
...
On Sat, 20 Feb 2016 10:20:38 -0500, "Jim Wilkins"
wrote:


This is the cheapest type of tool I know of that approximates a
lathe
headstock:
http://www.grizzly.com/products/5-C-Spin-Index/G5649

--jsw

Wow, I've never seen a spin fixture for $50 before. They're usually
hundreds, or even over $1,000.

Also FWIW, those DeWalt bevel gears were bored with single-point
PCBN
boring tools. Diametral accuracy was +/- 50 microinches, and the
tendency for PCBN to fail in a very rapid progression, once they
reached a certain amount of wear, meant that the tools had to be
changed when the air gage said that accuracy was slipping beyond 20
microinches either way. The gears were (and probably still are) iron
alloy PM infiltrated with copper.

--
Ed Huntress

The two low-cost spin fixtures I have were machined to $50 tolerances.
Lapping might make the spindles more cylindrical and carefully
adjusted rounded-end setscrews might take out the play to the housing.
They let me move work between the lathe and mill without losing
registration, and are good enough to machine keyways and wrench flats.
http://www.sherline.com/1045pg.htm

I used a 3-jaw one to hold the split clamp I just made, to face off
the bandsawed side. My larger 3-jaw wouldn't fit into the 1.30" ID.

--jsw

On 2/20/2016 10:25 AM, Jim Wilkins wrote:
"Ed Huntress" wrote in message
...
On Sat, 20 Feb 2016 10:20:38 -0500, "Jim Wilkins"
wrote:


This is the cheapest type of tool I know of that approximates a
lathe
headstock:
http://www.grizzly.com/products/5-C-Spin-Index/G5649

--jsw

Wow, I've never seen a spin fixture for $50 before. They're usually
hundreds, or even over $1,000.

Also FWIW, those DeWalt bevel gears were bored with single-point
PCBN
boring tools. Diametral accuracy was +/- 50 microinches, and the
tendency for PCBN to fail in a very rapid progression, once they
reached a certain amount of wear, meant that the tools had to be
changed when the air gage said that accuracy was slipping beyond 20
microinches either way. The gears were (and probably still are) iron
alloy PM infiltrated with copper.

--
Ed Huntress

The two low-cost spin fixtures I have were machined to $50 tolerances.
Lapping might make the spindles more cylindrical and carefully
adjusted rounded-end setscrews might take out the play to the housing.
They let me move work between the lathe and mill without losing
registration, and are good enough to machine keyways and wrench flats.
http://www.sherline.com/1045pg.htm

I used a 3-jaw one to hold the split clamp I just made, to face off
the bandsawed side. My larger 3-jaw wouldn't fit into the 1.30" ID.

--jsw


Here's a fellow the brought his $50 spindexer up to tighter spec's.
https://www.youtube.com/watch?v=Rg7h...#t=1281.237593
First of 4 videos.
Mikek

On 20/02/16 16:25, Jim Wilkins wrote:
"Ed Huntress" wrote in message
...
On Sat, 20 Feb 2016 10:20:38 -0500, "Jim Wilkins"
wrote:

This is the cheapest type of tool I know of that approximates a
lathe
headstock:
http://www.grizzly.com/products/5-C-Spin-Index/G5649

--jsw
Wow, I've never seen a spin fixture for $50 before. They're usually
hundreds, or even over $1,000.

Also FWIW, those DeWalt bevel gears were bored with single-point
PCBN
boring tools. Diametral accuracy was +/- 50 microinches, and the
tendency for PCBN to fail in a very rapid progression, once they
reached a certain amount of wear, meant that the tools had to be
changed when the air gage said that accuracy was slipping beyond 20
microinches either way. The gears were (and probably still are) iron
alloy PM infiltrated with copper.

--
Ed Huntress
The two low-cost spin fixtures I have were machined to $50 tolerances.
Lapping might make the spindles more cylindrical and carefully
adjusted rounded-end setscrews might take out the play to the housing.
They let me move work between the lathe and mill without losing
registration, and are good enough to machine keyways and wrench flats.
http://www.sherline.com/1045pg.htm

I used a 3-jaw one to hold the split clamp I just made, to face off
the bandsawed side. My larger 3-jaw wouldn't fit into the 1.30" ID.

--jsw


Both the cheap 5C spin indexers I have were not machined on the base
sides so that was the first job to do by accurately locating the bore
and machining the base sides parallel to the bore. I remembered this as
one of the high school shops I learned some machining in had a Suburban
Tools 5C indexer (expensive, accurate, US made) and that came as
standard with accurately machined/ground sides apparently. The
instructor mentioned this and it meant for most applications you could
place a 5/8" flat in the BP T slots and place the indexer up against
that and you were good to go with the indexer axis parallel to the table
axis. Works for me with the stuff I do and the initial machining time is
more than offset by the increased ease of set-up.

In article ,
Bill Baxter wrote:

How
would I go about drilling this out from 3 mm to #21 accurately using
ONLY hand drill, vice, etc as I have no access to lathes, presses, etc?

Ream it, don't drill it.

--
Cats, coffee, chocolate...vices to live by
Please don't feed the trolls. Killfile and ignore them so they will go away.

"David Billington" wrote in message
...
On 20/02/16 16:25, Jim Wilkins wrote:
"Ed Huntress" wrote in message
...
On Sat, 20 Feb 2016 10:20:38 -0500, "Jim Wilkins"
wrote:

This is the cheapest type of tool I know of that approximates a
lathe
headstock:
http://www.grizzly.com/products/5-C-Spin-Index/G5649

--jsw
Wow, I've never seen a spin fixture for $50 before. They're
usually
hundreds, or even over $1,000.

Also FWIW, those DeWalt bevel gears were bored with single-point
PCBN
boring tools. Diametral accuracy was +/- 50 microinches, and the
tendency for PCBN to fail in a very rapid progression, once they
reached a certain amount of wear, meant that the tools had to be
changed when the air gage said that accuracy was slipping beyond
20
microinches either way. The gears were (and probably still are)
iron
alloy PM infiltrated with copper.

--
Ed Huntress
The two low-cost spin fixtures I have were machined to $50
tolerances.
Lapping might make the spindles more cylindrical and carefully
adjusted rounded-end setscrews might take out the play to the
housing.
They let me move work between the lathe and mill without losing
registration, and are good enough to machine keyways and wrench
flats.
http://www.sherline.com/1045pg.htm

I used a 3-jaw one to hold the split clamp I just made, to face off
the bandsawed side. My larger 3-jaw wouldn't fit into the 1.30" ID.

--jsw


Both the cheap 5C spin indexers I have were not machined on the base
sides so that was the first job to do by accurately locating the
bore and machining the base sides parallel to the bore. I remembered
this as one of the high school shops I learned some machining in had
a Suburban Tools 5C indexer (expensive, accurate, US made) and that
came as standard with accurately machined/ground sides apparently.
The instructor mentioned this and it meant for most applications you
could place a 5/8" flat in the BP T slots and place the indexer up
against that and you were good to go with the indexer axis parallel
to the table axis. Works for me with the stuff I do and the initial
machining time is more than offset by the increased ease of set-up.

I also lucked onto a lightly used one of these for about the same
price as the spin index:
http://www.use-enco.com/1/1/35195-co...-indexers.html
It's more rigid and better for milling, limited mainly by work
slipping in the collet.

Like you I milled the base parallel to the bore axis, and clamp it
horizontally in the milling vise or upright on an angle plate

It costs a lot more new and unlike the spin index wouldn't allow the
OP to rotate the chucked pinion while advancing it onto a reamer.

--jsw

Ed Huntress wrote:
On Sat, 20 Feb 2016 09:27:24 -0500, "Jim Wilkins"
wrote:

"Bill Baxter" wrote in message
...
My son, who is in graduate school, uses a high quality but no longer
made microscope for his home studies. Recently, one of the small
brass
pinions broke in the focusing unit and he asked me if I could repair
it.
I was able to disassemble to access the pinion which is on a rod.
Unfortunately, since the scope is no longer made, the exact part is
no
longer available, but I have determined that a 64p 16T 0.4 modulus
would
fit it almost exactly except that the bore is too small (it is 3mm
and I
need it to be 4mm... actually a bit wider at #21 drill bit sized).
Unfortunately, web searching cannot locate a pinion of the proper
bore
size (all are either 2 or 3mm bore), so I am thinking of getting
one of
the 3mm ones and drilling it out to #21 sized. The problem is that
this
needs to be very precise and if off by even a little will cause
binding
and other problems in the focus mechanism. So I pose the question:
How
would I go about drilling this out from 3 mm to #21 accurately using
ONLY hand drill, vice, etc as I have no access to lathes, presses,
etc?
Thanks!

That's a tricky job even with a lathe, since the outer surface of the
pinion may not be "precisely" concentric with the pitch diameter which
controls smoothness of engagement.

Without a lathe you might at best achieve the accuracy of a clockmaker
from the 1700's.
http://www.ronellclock.com/Broaches_c208.htm

Our tech was little better than the Greeks' and Romans' until the
modern lathe was invented around 1800, enabling the Industrial
Revolution.
https://en.wikipedia.org/wiki/Antikythera_mechanism
"After the knowledge of this technology was lost at some point in
Antiquity, technological artifacts approaching its complexity and
workmanship did not appear again until the development of mechanical
astronomical clocks in Europe in the fourteenth century."

If precision metalworking by hand was easy we wouldn't need the
expensive machine tools. Lacking them you could look up the old manual
clockmaking and gunsmithing methods. I didn't find very much useful
there, though

--jsw


FWIW (and this will be of little use to the OP), fixturing used for
boring center holes in pinions sometimes uses a set of round pins that
engage the teeth. The idea is that you want to locate off of a
consistent location on the gear flanks, rather than the tips of the
teeth. And you want to average those locations, so you use pins on a
lot of the teeth.

When I was at Wasino (now Amada Machine Tools), we designed such
fixtures for DeWalt, to bore the bevel gears used in their angle-head
grinders. The final design actually used wedges -- one for each tooth
-- rather than pins, but the idea was the same.

You get much smoother running of the finished gear set that way.

Wouldn't the original hole (3mm) in the replacement pinion be good enough
to use as the reference? If the replacement pinion is all wonky well, then
that sucks and the microscope runs a bit rough, vs. being broken.

If I had to do this on my sherline, this is how I'd proceed-

Fixture the new 3mm bore pinion in bored out Al scrap with a slit like
suggested by somebody, put it in the the 4 jaw chuck, locate the center
with an inserted 3mm shaft next to the pinion and inch or so away to make
sure it's straight, then drill undersize and then with the #21 using the
tailstock.

On Mon, 22 Feb 2016 22:01:01 +0000 (UTC), Cydrome Leader
wrote:

Ed Huntress wrote:
On Sat, 20 Feb 2016 09:27:24 -0500, "Jim Wilkins"
wrote:

"Bill Baxter" wrote in message
...
My son, who is in graduate school, uses a high quality but no longer
made microscope for his home studies. Recently, one of the small
brass
pinions broke in the focusing unit and he asked me if I could repair
it.
I was able to disassemble to access the pinion which is on a rod.
Unfortunately, since the scope is no longer made, the exact part is
no
longer available, but I have determined that a 64p 16T 0.4 modulus
would
fit it almost exactly except that the bore is too small (it is 3mm
and I
need it to be 4mm... actually a bit wider at #21 drill bit sized).
Unfortunately, web searching cannot locate a pinion of the proper
bore
size (all are either 2 or 3mm bore), so I am thinking of getting
one of
the 3mm ones and drilling it out to #21 sized. The problem is that
this
needs to be very precise and if off by even a little will cause
binding
and other problems in the focus mechanism. So I pose the question:
How
would I go about drilling this out from 3 mm to #21 accurately using
ONLY hand drill, vice, etc as I have no access to lathes, presses,
etc?
Thanks!

That's a tricky job even with a lathe, since the outer surface of the
pinion may not be "precisely" concentric with the pitch diameter which
controls smoothness of engagement.

Without a lathe you might at best achieve the accuracy of a clockmaker
from the 1700's.
http://www.ronellclock.com/Broaches_c208.htm

Our tech was little better than the Greeks' and Romans' until the
modern lathe was invented around 1800, enabling the Industrial
Revolution.
https://en.wikipedia.org/wiki/Antikythera_mechanism
"After the knowledge of this technology was lost at some point in
Antiquity, technological artifacts approaching its complexity and
workmanship did not appear again until the development of mechanical
astronomical clocks in Europe in the fourteenth century."

If precision metalworking by hand was easy we wouldn't need the
expensive machine tools. Lacking them you could look up the old manual
clockmaking and gunsmithing methods. I didn't find very much useful
there, though

--jsw


FWIW (and this will be of little use to the OP), fixturing used for
boring center holes in pinions sometimes uses a set of round pins that
engage the teeth. The idea is that you want to locate off of a
consistent location on the gear flanks, rather than the tips of the
teeth. And you want to average those locations, so you use pins on a
lot of the teeth.

When I was at Wasino (now Amada Machine Tools), we designed such
fixtures for DeWalt, to bore the bevel gears used in their angle-head
grinders. The final design actually used wedges -- one for each tooth
-- rather than pins, but the idea was the same.

You get much smoother running of the finished gear set that way.

Wouldn't the original hole (3mm) in the replacement pinion be good enough
to use as the reference? If the replacement pinion is all wonky well, then
that sucks and the microscope runs a bit rough, vs. being broken.

If I had to do this on my sherline, this is how I'd proceed-

Fixture the new 3mm bore pinion in bored out Al scrap with a slit like
suggested by somebody, put it in the the 4 jaw chuck, locate the center
with an inserted 3mm shaft next to the pinion and inch or so away to make
sure it's straight, then drill undersize and then with the #21 using the
tailstock.

Assuming that the original center hole was accurate (and it probably
is), then drilling it out will almost certainly make it *inaccurate*.
Whether it will be out-of-concntric or out-of-round by enough to
matter is questionable, but unknown until you do it.

Conventional drill bits do not drill straight holes, and the holes are
always at least a little bit trilobal. The two lips fight each other
for dominance; there is nothing to guide the drill bit. The
interaction of two lips on a hole-drilling cutter produces, believe it
or not, a trilobal hole. If you grind your drill bits by hand, you
often can measure the trilobal innacuracy with a dial indicator.

The way to do it would be with a single-lip cutter; ideally, in a
lathe or a really good mill, with a boring bar. Then the force is
equal all around the cut. A single-lip D-bit will do the same thing.

--
Ed Huntress

Ed Huntress wrote:
On Mon, 22 Feb 2016 22:01:01 +0000 (UTC), Cydrome Leader
wrote:

Ed Huntress wrote:
On Sat, 20 Feb 2016 09:27:24 -0500, "Jim Wilkins"
wrote:

"Bill Baxter" wrote in message
...
My son, who is in graduate school, uses a high quality but no longer
made microscope for his home studies. Recently, one of the small
brass
pinions broke in the focusing unit and he asked me if I could repair
it.
I was able to disassemble to access the pinion which is on a rod.
Unfortunately, since the scope is no longer made, the exact part is
no
longer available, but I have determined that a 64p 16T 0.4 modulus
would
fit it almost exactly except that the bore is too small (it is 3mm
and I
need it to be 4mm... actually a bit wider at #21 drill bit sized).
Unfortunately, web searching cannot locate a pinion of the proper
bore
size (all are either 2 or 3mm bore), so I am thinking of getting
one of
the 3mm ones and drilling it out to #21 sized. The problem is that
this
needs to be very precise and if off by even a little will cause
binding
and other problems in the focus mechanism. So I pose the question:
How
would I go about drilling this out from 3 mm to #21 accurately using
ONLY hand drill, vice, etc as I have no access to lathes, presses,
etc?
Thanks!

That's a tricky job even with a lathe, since the outer surface of the
pinion may not be "precisely" concentric with the pitch diameter which
controls smoothness of engagement.

Without a lathe you might at best achieve the accuracy of a clockmaker
from the 1700's.
http://www.ronellclock.com/Broaches_c208.htm

Our tech was little better than the Greeks' and Romans' until the
modern lathe was invented around 1800, enabling the Industrial
Revolution.
https://en.wikipedia.org/wiki/Antikythera_mechanism
"After the knowledge of this technology was lost at some point in
Antiquity, technological artifacts approaching its complexity and
workmanship did not appear again until the development of mechanical
astronomical clocks in Europe in the fourteenth century."

If precision metalworking by hand was easy we wouldn't need the
expensive machine tools. Lacking them you could look up the old manual
clockmaking and gunsmithing methods. I didn't find very much useful
there, though

--jsw


FWIW (and this will be of little use to the OP), fixturing used for
boring center holes in pinions sometimes uses a set of round pins that
engage the teeth. The idea is that you want to locate off of a
consistent location on the gear flanks, rather than the tips of the
teeth. And you want to average those locations, so you use pins on a
lot of the teeth.

When I was at Wasino (now Amada Machine Tools), we designed such
fixtures for DeWalt, to bore the bevel gears used in their angle-head
grinders. The final design actually used wedges -- one for each tooth
-- rather than pins, but the idea was the same.

You get much smoother running of the finished gear set that way.

Wouldn't the original hole (3mm) in the replacement pinion be good enough
to use as the reference? If the replacement pinion is all wonky well, then
that sucks and the microscope runs a bit rough, vs. being broken.

If I had to do this on my sherline, this is how I'd proceed-

Fixture the new 3mm bore pinion in bored out Al scrap with a slit like
suggested by somebody, put it in the the 4 jaw chuck, locate the center
with an inserted 3mm shaft next to the pinion and inch or so away to make
sure it's straight, then drill undersize and then with the #21 using the
tailstock.

Assuming that the original center hole was accurate (and it probably
is), then drilling it out will almost certainly make it *inaccurate*.
Whether it will be out-of-concntric or out-of-round by enough to
matter is questionable, but unknown until you do it.

Conventional drill bits do not drill straight holes, and the holes are
always at least a little bit trilobal. The two lips fight each other
for dominance; there is nothing to guide the drill bit. The
interaction of two lips on a hole-drilling cutter produces, believe it
or not, a trilobal hole. If you grind your drill bits by hand, you
often can measure the trilobal innacuracy with a dial indicator.

The very first hole I drilled on a lathe was a big fat triangle. Though a
1/4 inch hole in brass would be child's play. Wrong.

The way to do it would be with a single-lip cutter; ideally, in a
lathe or a really good mill, with a boring bar. Then the force is
equal all around the cut. A single-lip D-bit will do the same thing.

It sounds like the part just runs a gear rack on a microscope. How precise
does it even need to be in the first place?

I have an overbuilt (it's German) camera macro focus rail that has a
helican rack and pinion. It even has a hidden eccentric bushing to be used
for adjusting the play between the pinion and rack. Maybe the microscope
has this as well to make up for tolerances of parts and wear too.

"Ed Huntress" wrote in message
...
On Mon, 22 Feb 2016 22:01:01 +0000 (UTC), Cydrome Leader
wrote:

Ed Huntress wrote:
On Sat, 20 Feb 2016 09:27:24 -0500, "Jim Wilkins"
wrote:

"Bill Baxter" wrote in message
...
My son, who is in graduate school, uses a high quality but no
longer
made microscope for his home studies. Recently, one of the
small
brass
pinions broke in the focusing unit and he asked me if I could
repair
it.
I was able to disassemble to access the pinion which is on a
rod.
Unfortunately, since the scope is no longer made, the exact part
is
no
longer available, but I have determined that a 64p 16T 0.4
modulus
would
fit it almost exactly except that the bore is too small (it is
3mm
and I
need it to be 4mm... actually a bit wider at #21 drill bit
sized).
Unfortunately, web searching cannot locate a pinion of the
proper
bore
size (all are either 2 or 3mm bore), so I am thinking of getting
one of
the 3mm ones and drilling it out to #21 sized. The problem is
that
this
needs to be very precise and if off by even a little will cause
binding
and other problems in the focus mechanism. So I pose the
question:
How
would I go about drilling this out from 3 mm to #21 accurately
using
ONLY hand drill, vice, etc as I have no access to lathes,
presses,
etc?
Thanks!

That's a tricky job even with a lathe, since the outer surface of
the
pinion may not be "precisely" concentric with the pitch diameter
which
controls smoothness of engagement.

Without a lathe you might at best achieve the accuracy of a
clockmaker
from the 1700's.
http://www.ronellclock.com/Broaches_c208.htm

Our tech was little better than the Greeks' and Romans' until the
modern lathe was invented around 1800, enabling the Industrial
Revolution.
https://en.wikipedia.org/wiki/Antikythera_mechanism
"After the knowledge of this technology was lost at some point in
Antiquity, technological artifacts approaching its complexity and
workmanship did not appear again until the development of
mechanical
astronomical clocks in Europe in the fourteenth century."

If precision metalworking by hand was easy we wouldn't need the
expensive machine tools. Lacking them you could look up the old
manual
clockmaking and gunsmithing methods. I didn't find very much
useful
there, though

--jsw


FWIW (and this will be of little use to the OP), fixturing used
for
boring center holes in pinions sometimes uses a set of round pins
that
engage the teeth. The idea is that you want to locate off of a
consistent location on the gear flanks, rather than the tips of
the
teeth. And you want to average those locations, so you use pins on
a
lot of the teeth.

When I was at Wasino (now Amada Machine Tools), we designed such
fixtures for DeWalt, to bore the bevel gears used in their
angle-head
grinders. The final design actually used wedges -- one for each
tooth
-- rather than pins, but the idea was the same.

You get much smoother running of the finished gear set that way.

Wouldn't the original hole (3mm) in the replacement pinion be good
enough
to use as the reference? If the replacement pinion is all wonky
well, then
that sucks and the microscope runs a bit rough, vs. being broken.

If I had to do this on my sherline, this is how I'd proceed-

Fixture the new 3mm bore pinion in bored out Al scrap with a slit
like
suggested by somebody, put it in the the 4 jaw chuck, locate the
center
with an inserted 3mm shaft next to the pinion and inch or so away to
make
sure it's straight, then drill undersize and then with the #21 using
the
tailstock.

Assuming that the original center hole was accurate (and it probably
is), then drilling it out will almost certainly make it
*inaccurate*.
Whether it will be out-of-concntric or out-of-round by enough to
matter is questionable, but unknown until you do it.

Conventional drill bits do not drill straight holes, and the holes
are
always at least a little bit trilobal. The two lips fight each other
for dominance; there is nothing to guide the drill bit. The
interaction of two lips on a hole-drilling cutter produces, believe
it
or not, a trilobal hole. If you grind your drill bits by hand, you
often can measure the trilobal innacuracy with a dial indicator.

The way to do it would be with a single-lip cutter; ideally, in a
lathe or a really good mill, with a boring bar. Then the force is
equal all around the cut. A single-lip D-bit will do the same thing.

--
Ed Huntress

Here's how to make a 4mm D bit:
http://www.machineconcepts.co.uk/smallpipes/tools.htm
"..although I know of makers who use the twist drill, I have found it
very prone to wandering and the bore produced is generally less
accurate and somewhat rough.."

D bits aren't limited to constant diameter holes. I made one to
experiment with tapered convergent nozzles.

Manual methods for precision metalworking do exist, and were passed
along during long apprenticeships.

Is the original poster beginning to see why we purchase expensive
metal lathes for jobs like this?

--jsw

On Mon, 22 Feb 2016 23:24:18 +0000 (UTC), Cydrome Leader
wrote:

Ed Huntress wrote:
On Mon, 22 Feb 2016 22:01:01 +0000 (UTC), Cydrome Leader
wrote:

Ed Huntress wrote:
On Sat, 20 Feb 2016 09:27:24 -0500, "Jim Wilkins"
wrote:

"Bill Baxter" wrote in message
...
My son, who is in graduate school, uses a high quality but no longer
made microscope for his home studies. Recently, one of the small
brass
pinions broke in the focusing unit and he asked me if I could repair
it.
I was able to disassemble to access the pinion which is on a rod.
Unfortunately, since the scope is no longer made, the exact part is
no
longer available, but I have determined that a 64p 16T 0.4 modulus
would
fit it almost exactly except that the bore is too small (it is 3mm
and I
need it to be 4mm... actually a bit wider at #21 drill bit sized).
Unfortunately, web searching cannot locate a pinion of the proper
bore
size (all are either 2 or 3mm bore), so I am thinking of getting
one of
the 3mm ones and drilling it out to #21 sized. The problem is that
this
needs to be very precise and if off by even a little will cause
binding
and other problems in the focus mechanism. So I pose the question:
How
would I go about drilling this out from 3 mm to #21 accurately using
ONLY hand drill, vice, etc as I have no access to lathes, presses,
etc?
Thanks!

That's a tricky job even with a lathe, since the outer surface of the
pinion may not be "precisely" concentric with the pitch diameter which
controls smoothness of engagement.

Without a lathe you might at best achieve the accuracy of a clockmaker
from the 1700's.
http://www.ronellclock.com/Broaches_c208.htm

Our tech was little better than the Greeks' and Romans' until the
modern lathe was invented around 1800, enabling the Industrial
Revolution.
https://en.wikipedia.org/wiki/Antikythera_mechanism
"After the knowledge of this technology was lost at some point in
Antiquity, technological artifacts approaching its complexity and
workmanship did not appear again until the development of mechanical
astronomical clocks in Europe in the fourteenth century."

If precision metalworking by hand was easy we wouldn't need the
expensive machine tools. Lacking them you could look up the old manual
clockmaking and gunsmithing methods. I didn't find very much useful
there, though

--jsw


FWIW (and this will be of little use to the OP), fixturing used for
boring center holes in pinions sometimes uses a set of round pins that
engage the teeth. The idea is that you want to locate off of a
consistent location on the gear flanks, rather than the tips of the
teeth. And you want to average those locations, so you use pins on a
lot of the teeth.

When I was at Wasino (now Amada Machine Tools), we designed such
fixtures for DeWalt, to bore the bevel gears used in their angle-head
grinders. The final design actually used wedges -- one for each tooth
-- rather than pins, but the idea was the same.

You get much smoother running of the finished gear set that way.

Wouldn't the original hole (3mm) in the replacement pinion be good enough
to use as the reference? If the replacement pinion is all wonky well, then
that sucks and the microscope runs a bit rough, vs. being broken.

If I had to do this on my sherline, this is how I'd proceed-

Fixture the new 3mm bore pinion in bored out Al scrap with a slit like
suggested by somebody, put it in the the 4 jaw chuck, locate the center
with an inserted 3mm shaft next to the pinion and inch or so away to make
sure it's straight, then drill undersize and then with the #21 using the
tailstock.

Assuming that the original center hole was accurate (and it probably
is), then drilling it out will almost certainly make it *inaccurate*.
Whether it will be out-of-concntric or out-of-round by enough to
matter is questionable, but unknown until you do it.

Conventional drill bits do not drill straight holes, and the holes are
always at least a little bit trilobal. The two lips fight each other
for dominance; there is nothing to guide the drill bit. The
interaction of two lips on a hole-drilling cutter produces, believe it
or not, a trilobal hole. If you grind your drill bits by hand, you
often can measure the trilobal innacuracy with a dial indicator.

The very first hole I drilled on a lathe was a big fat triangle. Though a
1/4 inch hole in brass would be child's play. Wrong.

g You're not alone.


The way to do it would be with a single-lip cutter; ideally, in a
lathe or a really good mill, with a boring bar. Then the force is
equal all around the cut. A single-lip D-bit will do the same thing.

It sounds like the part just runs a gear rack on a microscope. How precise
does it even need to be in the first place?

The smaller the gear, the more that accuracy matters. But my son's
microscope as a spring loading the pinion into the rack, and that
probably takes care of some inaccuracy. If it's not smooth, however,
it's a real pain to use one.


I have an overbuilt (it's German) camera macro focus rail that has a
helican rack and pinion. It even has a hidden eccentric bushing to be used
for adjusting the play between the pinion and rack. Maybe the microscope
has this as well to make up for tolerances of parts and wear too.

On Mon, 22 Feb 2016 18:47:56 -0500, "Jim Wilkins"
wrote:

"Ed Huntress" wrote in message
.. .
On Mon, 22 Feb 2016 22:01:01 +0000 (UTC), Cydrome Leader
wrote:

Ed Huntress wrote:
On Sat, 20 Feb 2016 09:27:24 -0500, "Jim Wilkins"
wrote:

"Bill Baxter" wrote in message
...
My son, who is in graduate school, uses a high quality but no
longer
made microscope for his home studies. Recently, one of the
small
brass
pinions broke in the focusing unit and he asked me if I could
repair
it.
I was able to disassemble to access the pinion which is on a
rod.
Unfortunately, since the scope is no longer made, the exact part
is
no
longer available, but I have determined that a 64p 16T 0.4
modulus
would
fit it almost exactly except that the bore is too small (it is
3mm
and I
need it to be 4mm... actually a bit wider at #21 drill bit
sized).
Unfortunately, web searching cannot locate a pinion of the
proper
bore
size (all are either 2 or 3mm bore), so I am thinking of getting
one of
the 3mm ones and drilling it out to #21 sized. The problem is
that
this
needs to be very precise and if off by even a little will cause
binding
and other problems in the focus mechanism. So I pose the
question:
How
would I go about drilling this out from 3 mm to #21 accurately
using
ONLY hand drill, vice, etc as I have no access to lathes,
presses,
etc?
Thanks!

That's a tricky job even with a lathe, since the outer surface of
the
pinion may not be "precisely" concentric with the pitch diameter
which
controls smoothness of engagement.

Without a lathe you might at best achieve the accuracy of a
clockmaker
from the 1700's.
http://www.ronellclock.com/Broaches_c208.htm

Our tech was little better than the Greeks' and Romans' until the
modern lathe was invented around 1800, enabling the Industrial
Revolution.
https://en.wikipedia.org/wiki/Antikythera_mechanism
"After the knowledge of this technology was lost at some point in
Antiquity, technological artifacts approaching its complexity and
workmanship did not appear again until the development of
mechanical
astronomical clocks in Europe in the fourteenth century."

If precision metalworking by hand was easy we wouldn't need the
expensive machine tools. Lacking them you could look up the old
manual
clockmaking and gunsmithing methods. I didn't find very much
useful
there, though

--jsw


FWIW (and this will be of little use to the OP), fixturing used
for
boring center holes in pinions sometimes uses a set of round pins
that
engage the teeth. The idea is that you want to locate off of a
consistent location on the gear flanks, rather than the tips of
the
teeth. And you want to average those locations, so you use pins on
a
lot of the teeth.

When I was at Wasino (now Amada Machine Tools), we designed such
fixtures for DeWalt, to bore the bevel gears used in their
angle-head
grinders. The final design actually used wedges -- one for each
tooth
-- rather than pins, but the idea was the same.

You get much smoother running of the finished gear set that way.

Wouldn't the original hole (3mm) in the replacement pinion be good
enough
to use as the reference? If the replacement pinion is all wonky
well, then
that sucks and the microscope runs a bit rough, vs. being broken.

If I had to do this on my sherline, this is how I'd proceed-

Fixture the new 3mm bore pinion in bored out Al scrap with a slit
like
suggested by somebody, put it in the the 4 jaw chuck, locate the
center
with an inserted 3mm shaft next to the pinion and inch or so away to
make
sure it's straight, then drill undersize and then with the #21 using
the
tailstock.

Assuming that the original center hole was accurate (and it probably
is), then drilling it out will almost certainly make it
*inaccurate*.
Whether it will be out-of-concntric or out-of-round by enough to
matter is questionable, but unknown until you do it.

Conventional drill bits do not drill straight holes, and the holes
are
always at least a little bit trilobal. The two lips fight each other
for dominance; there is nothing to guide the drill bit. The
interaction of two lips on a hole-drilling cutter produces, believe
it
or not, a trilobal hole. If you grind your drill bits by hand, you
often can measure the trilobal innacuracy with a dial indicator.

The way to do it would be with a single-lip cutter; ideally, in a
lathe or a really good mill, with a boring bar. Then the force is
equal all around the cut. A single-lip D-bit will do the same thing.

--
Ed Huntress

Here's how to make a 4mm D bit:
http://www.machineconcepts.co.uk/smallpipes/tools.htm
"..although I know of makers who use the twist drill, I have found it
very prone to wandering and the bore produced is generally less
accurate and somewhat rough.."

D bits aren't limited to constant diameter holes. I made one to
experiment with tapered convergent nozzles.

Manual methods for precision metalworking do exist, and were passed
along during long apprenticeships.

That's my biggest interest in machining -- toolmaker's buttons,
D-bits, lapping, self-checking gages; the works.

Some of the most fascinating stuff I learned when I was at _American
Machinist_, back in the '70s when it was published by McGraw-Hill, was
the methods that were used to produce clock-plate master gages to 50
millionths or better accuracy -- in 1900.

And it didn't hurt that I got to have lunch with Dick Moore. He was an
inspiration.


Is the original poster beginning to see why we purchase expensive
metal lathes for jobs like this?

--jsw

"Ed Huntress" wrote in message
...
On Mon, 22 Feb 2016 18:47:56 -0500, "Jim Wilkins"
wrote:


That's my biggest interest in machining -- toolmaker's buttons,
D-bits, lapping, self-checking gages; the works.

Some of the most fascinating stuff I learned when I was at _American
Machinist_, back in the '70s when it was published by McGraw-Hill,
was
the methods that were used to produce clock-plate master gages to 50
millionths or better accuracy -- in 1900.

And it didn't hurt that I got to have lunch with Dick Moore. He was
an
inspiration.

https://archive.org/details/accuratetoolwor00stangoog

On Mon, 22 Feb 2016 20:44:32 -0500, "Jim Wilkins"
wrote:

"Ed Huntress" wrote in message
.. .
On Mon, 22 Feb 2016 18:47:56 -0500, "Jim Wilkins"
wrote:


That's my biggest interest in machining -- toolmaker's buttons,
D-bits, lapping, self-checking gages; the works.

Some of the most fascinating stuff I learned when I was at _American
Machinist_, back in the '70s when it was published by McGraw-Hill,
was
the methods that were used to produce clock-plate master gages to 50
millionths or better accuracy -- in 1900.

And it didn't hurt that I got to have lunch with Dick Moore. He was
an
inspiration.

https://archive.org/details/accuratetoolwor00stangoog

Yeah, that was one of the books in our library.

Other important ones were Dick Moore's books about the jig borer and
the jig grinder, which referenced the earlier faceplate methods;
charging diamond points; and so on.

--
Ed Huntress

On Fri, 19 Feb 2016 22:08:11 -0500, Bill Baxter wrote:

Unfortunately, web searching cannot locate a pinion of the proper bore
size (all are either 2 or 3mm bore), so I am thinking of getting one of
the 3mm ones and drilling it out to #21 sized. The problem is that this
needs to be very precise and if off by even a little will cause binding
and other problems in the focus mechanism. So I pose the question: How
would I go about drilling this out from 3 mm to #21 accurately using
ONLY hand drill, vice, etc as I have no access to lathes, presses, etc?

Well, hand drill would be hard. You could go in steps; #21 is .1590" or
4.04mm; 3mm is around #31, so one way would be to use a bunch of
intermediate drills that shave very little in each step.

If you have a lathe, I'd use a 4-jaw chuck, indicate on the existing
hole, and bore it out.

BTW, are you sure it's not metric 4mm?

On Mon, 22 Feb 2016 20:44:32 -0500, "Jim Wilkins"
wrote:

"Ed Huntress" wrote in message
.. .
On Mon, 22 Feb 2016 18:47:56 -0500, "Jim Wilkins"
wrote:


That's my biggest interest in machining -- toolmaker's buttons,
D-bits, lapping, self-checking gages; the works.

Some of the most fascinating stuff I learned when I was at _American
Machinist_, back in the '70s when it was published by McGraw-Hill,
was
the methods that were used to produce clock-plate master gages to 50
millionths or better accuracy -- in 1900.

And it didn't hurt that I got to have lunch with Dick Moore. He was
an
inspiration.

https://archive.org/details/accuratetoolwor00stangoog

Cool. (DLed a copy.)

--
No greater wrong can ever be done than to put a good man at the mercy
of a bad, while telling him not to defend himself or his fellows;
in no way can the success of evil be made quicker or surer.
--Theodore Roosevelt

Thanks to all, but what I ended up doing was borrowing a neighbour's
drill press. I took two pieces of oak scrap, but them together tightly
in a drill press vice, and then drilled a hole at the seam just slightly
smaller than the pinion diameter. I then unclamped, inserted the pinion,
tightened, checked alignment with a bit of the same size as the bore
first, then carefully oiled the pinion area and proceeded drilling out
to #21 drill bit size at highest drill speed setting. The result ended
up great and the pinion works like a charm. My biggest concern was the
pinion itself; upon arrival, it wasn't as thick as I anticipated and I
had concerns about drilling the bore out to a larger size. With perfect
alignment of the press, it turned out to be a non-issue, but there's no
way I could have done this by hand I don't think.

All this experience has me thinking that I need to get a drill press.
Problem is that I don't have a lot of money (I'm retired on fixed
income), and I don't have the space for a regular sized press. I've
tried the hand drill to press half plastic jigs in the past, but they
could never do something like I did with the neighbour's press. Is there
a small, accurate and less costly press available anywhere at US
retailers? I was eyeballing a currently for sale $69 Harbor Freight unit
that could even be acquired for around $55 or so with an online coupon,
but it had bad reviews so decided not to. My neighbour says his press
was around $200. Unfortunately, too costly for me and too large. I would
appreciate any suggestions.

thanks again, Bill

"Bill Baxter" wrote in message
...
Thanks to all, but what I ended up doing was borrowing a neighbour's
drill press. I took two pieces of oak scrap, but them together
tightly in a drill press vice, and then drilled a hole at the seam
just slightly smaller than the pinion diameter. I then unclamped,
inserted the pinion, tightened, checked alignment with a bit of the
same size as the bore first, then carefully oiled the pinion area
and proceeded drilling out to #21 drill bit size at highest drill
speed setting. The result ended up great and the pinion works like a
charm. My biggest concern was the pinion itself; upon arrival, it
wasn't as thick as I anticipated and I had concerns about drilling
the bore out to a larger size. With perfect alignment of the press,
it turned out to be a non-issue, but there's no way I could have
done this by hand I don't think.

All this experience has me thinking that I need to get a drill
press. Problem is that I don't have a lot of money (I'm retired on
fixed income), and I don't have the space for a regular sized press.
I've tried the hand drill to press half plastic jigs in the past,
but they could never do something like I did with the neighbour's
press. Is there a small, accurate and less costly press available
anywhere at US retailers? I was eyeballing a currently for sale $69
Harbor Freight unit that could even be acquired for around $55 or so
with an online coupon, but it had bad reviews so decided not to. My
neighbour says his press was around $200. Unfortunately, too costly
for me and too large. I would appreciate any suggestions.

thanks again, Bill

You could look for a hobby milling machine that its owner outgrew.
This gives an idea of what's available new at the lowest cost end:
http://tinyurl.com/jjpmxp7

Without trying it my guess is that a machine that lightweight might be
adequate to mill or drill (slowly) plastic, aluminum and perhaps
brass, but probably not steel. I wouldn't expect good accuracy from it
without careful testing, and filing or shimming the joints.

Personally I like to see and try before I buy, which is why I don't
own a Sherline lathe or mill. I need to cut threads in up to 1" steel
rod.

You can get a pretty good idea of how square the spindle is to the
table by chucking a paper clip bent to an L shape, finding the high
spot where the outer tip grazes the table or barely drags a small
piece of paper, turning the spindle half way around and gauging the
clearance with sheet(s) of paper. Stiffer wire and feeler gauges would
be better, but I tend to stumble onto good deals unexpectedly and have
to make do with office supplies. I keep a 4" dial caliper in the car
just in case.

--jsw

Larry Jaques wrote:
On Mon, 22 Feb 2016 20:44:32 -0500, "Jim Wilkins"
wrote:

"Ed Huntress" wrote in message
...
On Mon, 22 Feb 2016 18:47:56 -0500, "Jim Wilkins"
wrote:


That's my biggest interest in machining -- toolmaker's buttons,
D-bits, lapping, self-checking gages; the works.

Some of the most fascinating stuff I learned when I was at _American
Machinist_, back in the '70s when it was published by McGraw-Hill,
was
the methods that were used to produce clock-plate master gages to 50
millionths or better accuracy -- in 1900.

And it didn't hurt that I got to have lunch with Dick Moore. He was
an
inspiration.

https://archive.org/details/accuratetoolwor00stangoog

Cool. (DLed a copy.)

Me too .

--
Snag

"Terry Coombs" wrote in message
...
Larry Jaques wrote:
On Mon, 22 Feb 2016 20:44:32 -0500, "Jim Wilkins"
wrote:

"Ed Huntress" wrote in message
...
On Mon, 22 Feb 2016 18:47:56 -0500, "Jim Wilkins"
wrote:


That's my biggest interest in machining -- toolmaker's buttons,
D-bits, lapping, self-checking gages; the works.

Some of the most fascinating stuff I learned when I was at
_American
Machinist_, back in the '70s when it was published by
McGraw-Hill,
was
the methods that were used to produce clock-plate master gages to
50
millionths or better accuracy -- in 1900.

And it didn't hurt that I got to have lunch with Dick Moore. He
was
an
inspiration.

https://archive.org/details/accuratetoolwor00stangoog

Cool. (DLed a copy.)

Me too .

--
Snag

I've used the button jig method to transfer hole spacings to within a
few ten-thousandths. I put one dowel pin in the first hole and chucked
a second in the mill collet, then moved the buttons on them into light
contact.
--jsw

"Terry Coombs" wrote in message
...
Larry Jaques wrote:
On Mon, 22 Feb 2016 20:44:32 -0500, "Jim Wilkins"
wrote:

"Ed Huntress" wrote in message
...
On Mon, 22 Feb 2016 18:47:56 -0500, "Jim Wilkins"
wrote:


That's my biggest interest in machining -- toolmaker's buttons,
D-bits, lapping, self-checking gages; the works.

Some of the most fascinating stuff I learned when I was at
_American
Machinist_, back in the '70s when it was published by
McGraw-Hill,
was
the methods that were used to produce clock-plate master gages to
50
millionths or better accuracy -- in 1900.

And it didn't hurt that I got to have lunch with Dick Moore. He
was
an
inspiration.

https://archive.org/details/accuratetoolwor00stangoog

Cool. (DLed a copy.)

Me too .

--
Snag

Here's the hard copy:
http://www.amazon.com/Accurate-Tool-.../dp/0917914821

I snapped up nearly all of Lindsay's technology offerings.
--jsw

On Tue, 23 Feb 2016 07:56:29 -0600, "Terry Coombs"
wrote:

Larry Jaques wrote:
On Mon, 22 Feb 2016 20:44:32 -0500, "Jim Wilkins"
wrote:

"Ed Huntress" wrote in message
...
On Mon, 22 Feb 2016 18:47:56 -0500, "Jim Wilkins"
wrote:


That's my biggest interest in machining -- toolmaker's buttons,
D-bits, lapping, self-checking gages; the works.

Some of the most fascinating stuff I learned when I was at _American
Machinist_, back in the '70s when it was published by McGraw-Hill,
was
the methods that were used to produce clock-plate master gages to 50
millionths or better accuracy -- in 1900.

And it didn't hurt that I got to have lunch with Dick Moore. He was
an
inspiration.

https://archive.org/details/accuratetoolwor00stangoog

Cool. (DLed a copy.)

Me too .

My buddy, Glenn, keeps reminding me that "Metal isn't wood, and you
can't get away with a 1/16" tolerance." for some reason.

--
No greater wrong can ever be done than to put a good man at the mercy
of a bad, while telling him not to defend himself or his fellows;
in no way can the success of evil be made quicker or surer.
--Theodore Roosevelt

"Larry Jaques" wrote in message
...

My buddy, Glenn, keeps reminding me that "Metal isn't wood, and you
can't get away with a 1/16" tolerance." for some reason.

Well you can, if you don't mind living in the 1700's.

Bill Baxter wrote:
Thanks to all, but what I ended up doing was borrowing a neighbour's
drill press. I took two pieces of oak scrap, but them together tightly
in a drill press vice, and then drilled a hole at the seam just slightly
smaller than the pinion diameter. I then unclamped, inserted the pinion,
tightened, checked alignment with a bit of the same size as the bore
first, then carefully oiled the pinion area and proceeded drilling out
to #21 drill bit size at highest drill speed setting. The result ended
up great and the pinion works like a charm. My biggest concern was the
pinion itself; upon arrival, it wasn't as thick as I anticipated and I
had concerns about drilling the bore out to a larger size. With perfect
alignment of the press, it turned out to be a non-issue, but there's no
way I could have done this by hand I don't think.

Yay! See folks, he didn't need excessive precision for this job.

All this experience has me thinking that I need to get a drill press.
Problem is that I don't have a lot of money (I'm retired on fixed
income), and I don't have the space for a regular sized press. I've
tried the hand drill to press half plastic jigs in the past, but they
could never do something like I did with the neighbour's press. Is there
a small, accurate and less costly press available anywhere at US
retailers? I was eyeballing a currently for sale $69 Harbor Freight unit
that could even be acquired for around $55 or so with an online coupon,
but it had bad reviews so decided not to. My neighbour says his press
was around $200. Unfortunately, too costly for me and too large. I would
appreciate any suggestions.

Not sure about new. I'd shop used for two reasons if possible. Old stuff
is better, and no doubt an old taiwanese drill press is made better than a
new chinese one. Used is cheaper too. Just try before you buy. I've seen
real bad play on some stuff at the pawn shop.

"Cydrome Leader" wrote in message
...
..
Not sure about new. I'd shop used for two reasons if possible. Old
stuff
is better, and no doubt an old taiwanese drill press is made better
than a
new chinese one. Used is cheaper too. Just try before you buy. I've
seen
real bad play on some stuff at the pawn shop.


I bought some dogs before I knew what to look for.

So I took a night school machining class and used it to fix them, and
gain experience on a good lathe, mill, bandsaw and surface grinder.

--jsw

Jim Wilkins wrote:
"Cydrome Leader" wrote in message
...
..
Not sure about new. I'd shop used for two reasons if possible. Old
stuff
is better, and no doubt an old taiwanese drill press is made better
than a
new chinese one. Used is cheaper too. Just try before you buy. I've
seen
real bad play on some stuff at the pawn shop.


I bought some dogs before I knew what to look for.

So I took a night school machining class and used it to fix them, and
gain experience on a good lathe, mill, bandsaw and surface grinder.

The 15" clausing drill press project was sort along those lines. It cost
about as much to fix up as it cost in the first place, but the defect it
had was peculiar and I learned quite a bit in the process. I still need to
tear the rest apart to check the variable speed sheaves and overaul the
motor. It's completely usable now though. I filed and stoned the table so
the vise floats around nicely now.

Larry Jaques wrote:

My buddy, Glenn, keeps reminding me that "Metal isn't wood, and you
can't get away with a 1/16" tolerance." for some reason.

He apparently never had to work with Bongossi or some such...

--

"I'm a doctor, not a mechanic." Dr Leonard McCoy
"I'm a mechanic, not a doctor." Volker Borchert

Wouldn't the original hole (3mm) in the replacement pinion be good enough
to use as the reference? If the replacement pinion is all wonky well, then
that sucks and the microscope runs a bit rough, vs. being broken.

If I had to do this on my sherline, this is how I'd proceed-

Fixture the new 3mm bore pinion in bored out Al scrap with a slit like
suggested by somebody, put it in the the 4 jaw chuck, locate the center
with an inserted 3mm shaft next to the pinion and inch or so away to make
sure it's straight, then drill undersize and then with the #21 using the
tailstock.




I would set it up about the same way, then drill with a #22 and use
http://www.hobbyking.com/hobbyking/s...rm_Reamer.html
to finish ream to 4mm.

Might have 10 bucks in the entire job.

--
Steve W.