I picked up a few brass candle sticks in garage sales. I wanted to use one
for a brass sundial. It has a long stem and a cup for the candle. The stem
is irregular with some patterns on it.

I cut the stem off where I thought it would be just about right length for
the gnomon. I tried to "turn" it in my old drill press. It turned out not so
bad, I put a 10-32 thread on one end and tried to re-profile the rest of
it. It is about 5 cm long so I thought I would use the live center I have
for my sanding drums.
like this one:

http://www.leevalley.com/wood/page.a...02&cat=1,42500

This is where I run into a bit of a problem - drilling the centre hole.

The candlestick was made in India, I am not sure how. Either way not very
well so the whole thing is a bit asymmetrical. I tried to determine the
centre of the end to drill a concentric hole but found it almost impossible.
In the end when hooked up to the live centre (which is loose on the drill
press table) the live centre was running around in a small circle whatever I
did.

Now I understand (I hope!) that on a lathe the live centre on the taistock
is lined up with the centre of the chuck on the head stock and the hole will
be drilled in the centre by default. Not having a lathe the best way I found
to drill centres in a round stock is to make a paper tube around it and use
a tight fitting transfer punch to mark the centre. This works fine if the
stock is cylindrical, not on a candle stick stem which is not.

I found a thread on this group from 2004 which provided several options of
which the only one viable in my situation would have been to use a 3-jaw
chuck to center under the drill press spindle and then substitute the centre
drill. And I am indeed looking for a cheap 3-jaw chuck.

Are there any other suggestions ("Buy a lathe!" does not count)?

The other thing that puzzles me (and please note that the nearest I have
been to a lathe is in the movies and picutres in books) is how do you start
turning something that is irregular in shape? Or even how do you turn a
round piece out of a square stock? Does it not do horrible things to the
cutting tool when it contacts only at the corners? Or is there a trick to
get the shape roughly round first somehow? I want to change the shape of the
brass cup but the initial attempt was somewhat discouraging.

Thanks for all your patience,

--
Michael Koblic,
Campbell River, BC

On Wed, 27 Aug 2008 19:16:27 -0700, "Michael Koblic"
wrote:



Are there any other suggestions ("Buy a lathe!" does not count)?

The other thing that puzzles me (and please note that the nearest I have
been to a lathe is in the movies and picutres in books) is how do you start
turning something that is irregular in shape? Or even how do you turn a
round piece out of a square stock? Does it not do horrible things to the
cutting tool when it contacts only at the corners? Or is there a trick to
get the shape roughly round first somehow? I want to change the shape of the
brass cup but the initial attempt was somewhat discouraging.

Thanks for all your patience,
A file works quite well, although slowly. For even slower metal
removal, use various forms of scraper (think single tooth file). For
coarser work, use hammer and chisel. If you want power assist, use
various grinders.
Gerry :-)}
London, Canada

"Gerald Miller" wrote in message
...
A file works quite well, although slowly. For even slower metal
removal, use various forms of scraper (think single tooth file). For
coarser work, use hammer and chisel. If you want power assist, use
various grinders.

For this job symmetry was the main requirement. I find it very hard to file
irregular-shaped bars to make them into cylinders.
I tried the "reverse lathe" method using a bench sander. However, the part
is quite small and fingers are definitely an issue. I tried chucking it but
the set up was suboptimal and I nearly killed the part outright. Stopped
just in time.

I just took apart a very old Sears cordless drill and will try again
tomorrow with a better chucking arrangement.

On Aug 27, 10:16 pm, "Michael Koblic" wrote:

This is where I run into a bit of a problem - drilling the centre hole.

The candlestick was made in India, I am not sure how.

Probably cast. They had sophisticated metalworking skills when my
ancestors were still pounding rocks together. AFAIK it was all done in
small family shops with simple equipment and never grew into an
industry. Holtzapffel book IV, "Hand or Simple Turning" has the best
description I've seen of the traditional lathes of the Middle East and
Asia and the details of Western lathe development to 1880. You might
find the book very useful because the earlier versions were easier to
make than a modern lathe. "Simple" is relative; the Holtzapffels were
masters of the geometric or rose-engine lathe.

The Indian lathe pictured is made of two short stakes driven in the
ground with nails through them for centers. The tool rest is a stick
tied between them with extra supports as needed. The turner rests his
foot on the stick with the tool between his toes for coarse
positioning, and guides the end with his hand. A kid pulls the ends of
a string wrapped around the work to turn it back and forth. The Arab
lathe is only slightly fancier, a box close around the work. He has a
bow in one hand to turn the work with the string.

The lathe doesn't drive the work, it only supports it between centers.
You could turn the work directly with the motor and belt from an old
sewing machine, or a rubber caster wheel chucked in a hand drill. Be
creative, think of things as what they could do rather than what they
were meant for.

Your candlesticks may well be copied from a 2000 year old design cast
from a wooden pattern made this way. The manual skills of artisans
2000 years ago were easily equal to those today. Perhaps now those
people are surgeons rather than craftsmen.

As Watt quickly discovered, those artistic skills didn't apply to
making precision machinery.

Either way not very
well so the whole thing is a bit asymmetrical. I tried to determine the
centre of the end to drill a concentric hole but found it almost impossible.
In the end when hooked up to the live centre (which is loose on the drill
press table) the live centre was running around in a small circle whatever I
did.

Fix that. A large pointed setscrew held by nuts and washers might
work. If you make the head slide down as I suggested you can drill
another small hole in the base plate near the large one. You can align
them with a piece of wire in the chuck, bicycle spokes work well. Turn
it slowly by hand and try to make the circle the point describes small
by bending the wire. Move the head until that small circle is centered
on your center point. You can check it with a ruler.

Now I understand (I hope!) that on a lathe the live centre on the taistock
is lined up with the centre of the chuck on the head stock and the hole will
be drilled in the centre by default. Not having a lathe the best way I found
to drill centres in a round stock is to make a paper tube around it and use
a tight fitting transfer punch to mark the centre. This works fine if the
stock is cylindrical, not on a candle stick stem which is not.

Make a pair of upright Vee supports out of thin material. Rest the
candlestick on them at places you consider circular. Turn it while
holding a supported pencil against the end. The pencil will mark a
small circle around the rotational axis.

How well did you learn Euclidean geometry? It has methods for finding
the center of a circle or any other shape. One simple way is to guess
at the center, put one point of a compass there and see how far off it
is when you rotate it. Find where the compass is out furthest and
correct half the error by moving the center point, then readjust the
other point to the circle and recheck. For me this centers within
about 0.010".


I found a thread on this group from 2004 which provided several options of
which the only one viable in my situation would have been to use a 3-jaw
chuck to center under the drill press spindle and then substitute the centre
drill. And I am indeed looking for a cheap 3-jaw chuck.

Are there any other suggestions ("Buy a lathe!" does not count)?

The other thing that puzzles me (and please note that the nearest I have
been to a lathe is in the movies and picutres in books) is how do you start
turning something that is irregular in shape? Or even how do you turn a
round piece out of a square stock? Does it not do horrible things to the
cutting tool when it contacts only at the corners? Or is there a trick to
get the shape roughly round first somehow? I want to change the shape of the
brass cup but the initial attempt was somewhat discouraging.

Brass is a little tricky but it has been turned into exquisite shapes
like watch gears with hand-held tools for centuries. Heron of
Alexandria's ancient Greek gadget book used (brass?) sheet metal and
turned shafts as if they were common hardware items back then. His
book described a steam engine and also a vessel with a secret
compartment that appears to turn water into wine.

If you keep the tool's support close to the stock you avoid those
horrible things, otherwise the lathe may practice knife-throwing. I've
only done a little free-hand turning of aluminum and can't give you
much detailed help. Trying to work metal without machine tools is like
going everywhere on foot.

When I turn something from oak firewood I draw circles on the ends and
rough the blank close to them with a hatchet. On a real metal lathe
HSS bits stand up pretty well to interrupted cuts like turning a
square steel plate round, just take light cuts. This is one of the
jobs that makes a screw-on chuck hard to remove.

You can use that drill press center point to drill a centered hole
straight through a long piece.

Jim Wilkins
who -should- be out scraping paint.

"Jim Wilkins" wrote in message
...
The candlestick was made in India, I am not sure how.

Probably cast.

On close inspection I suspect you are right.

The lathe doesn't drive the work, it only supports it between centers.
You could turn the work directly with the motor and belt from an old
sewing machine, or a rubber caster wheel chucked in a hand drill. Be
creative, think of things as what they could do rather than what they
were meant for.

I do. Some "thoughts" would make your hair stand on end...:-)

I tried to determine the
centre of the end to drill a concentric hole but found it almost
impossible.
In the end when hooked up to the live centre (which is loose on the drill
press table) the live centre was running around in a small circle
whatever I
did.

Fix that. A large pointed setscrew held by nuts and washers might
work. If you make the head slide down as I suggested you can drill
another small hole in the base plate near the large one. You can align
them with a piece of wire in the chuck, bicycle spokes work well. Turn
it slowly by hand and try to make the circle the point describes small
by bending the wire. Move the head until that small circle is centered
on your center point. You can check it with a ruler.

I have re-read this about six times and I am not altogether sure that I
understood: I have no difficulty aligning the centre point of the live
centre with the centre of the spindle. However, when I chuck the gnomon and
put the opposite end on the live centre (using the supposedly centre hole I
drilled), the gnomon, being slightly out of alignment, moves the live centre
around.


Now I understand (I hope!) that on a lathe the live centre on the
taistock
is lined up with the centre of the chuck on the head stock and the hole
will
be drilled in the centre by default. Not having a lathe the best way I
found
to drill centres in a round stock is to make a paper tube around it and
use
a tight fitting transfer punch to mark the centre. This works fine if the
stock is cylindrical, not on a candle stick stem which is not.

Make a pair of upright Vee supports out of thin material. Rest the
candlestick on them at places you consider circular. Turn it while
holding a supported pencil against the end. The pencil will mark a
small circle around the rotational axis.

How well did you learn Euclidean geometry? It has methods for finding
the center of a circle or any other shape. One simple way is to guess
at the center, put one point of a compass there and see how far off it
is when you rotate it. Find where the compass is out furthest and
correct half the error by moving the center point, then readjust the
other point to the circle and recheck. For me this centers within
about 0.010".

The euclid works if the cross-section is truly circular. In the case of this
piece it is not. Furthermore, the smaller the diameter (in ,my case about
1/4") the more difficult the method, even if the cross-section is truly
circular. I have used this:

http://www.leevalley.com/wood/page.a...65&cat=1,42936
(the centre-finding head)

but the transfer punch/paper roll method beats it every time particularly
for small parts. There is this:

http://www.victornet.com/cgi-bin/vic...uares% 3A1242

but I have never used it and wonder if it improves accuracy over the other
one. The other issue with very small parts is to actually hit the right spot
with a centre punch: I have been using a lamp with a magnifying lens and
even that is not particularly great. I am thinking of getting this:

http://www.leevalley.com/wood/page.a...=1,42936,50298

Maybe with a centre drill you do not need to punch? Am I right in that?



I found a thread on this group from 2004 which provided several options
of
which the only one viable in my situation would have been to use a 3-jaw
chuck to center under the drill press spindle and then substitute the
centre
drill. And I am indeed looking for a cheap 3-jaw chuck.

Are there any other suggestions ("Buy a lathe!" does not count)?

The other thing that puzzles me (and please note that the nearest I have
been to a lathe is in the movies and picutres in books) is how do you
start
turning something that is irregular in shape? Or even how do you turn a
round piece out of a square stock? Does it not do horrible things to the
cutting tool when it contacts only at the corners? Or is there a trick to
get the shape roughly round first somehow? I want to change the shape of
the
brass cup but the initial attempt was somewhat discouraging.

Brass is a little tricky but it has been turned into exquisite shapes
like watch gears with hand-held tools for centuries. Heron of
Alexandria's ancient Greek gadget book used (brass?) sheet metal and
turned shafts as if they were common hardware items back then. His
book described a steam engine and also a vessel with a secret
compartment that appears to turn water into wine.

If you keep the tool's support close to the stock you avoid those
horrible things, otherwise the lathe may practice knife-throwing. I've
only done a little free-hand turning of aluminum and can't give you
much detailed help. Trying to work metal without machine tools is like
going everywhere on foot.

I was basically using files supported by a wooden block as close as possible
to the piece. I am not brave enough yet to try a proper cutting tool.

I gotta get more space on Flickr - it is so much easier to show pictures.
Anyway, thanks for the advice.

--
Michael Koblic,
Campbell River, BC

On Aug 28, 11:51 pm, "Michael Koblic" wrote:
"Jim Wilkins" wrote in message

Some "thoughts" would make your hair stand on end...:-)

What little hair is left... :-( (that's a beard, I grow it wherever
I still can)
I've run the model shop in electronics companies and thus dealt with
the creative misadventures of clever engineers with no practical
experience.

In the end when hooked up to the live centre (which is loose on the drill
press table) the live centre was running around in a small circle
whatever I did.

A large pointed setscrew held by nuts and washers might work.

Setscrew pointed upward for the center, nuts and washers to hold it
tight in the hole.

...You can align them with a piece of wire in the chuck,...

I have re-read this about six times and I am not altogether sure that I
understood: I have no difficulty aligning the centre point of the live
centre with the centre of the spindle. However, when I chuck the gnomon and
put the opposite end on the live centre (using the supposedly centre hole I
drilled), the gnomon, being slightly out of alignment, moves the live centre
around.

http://www.lindsaybks.com/bks/advmach/index.html

Don't be put off by its age. Production techniques may have improved
dramatically since then but manual lathe operations are still the
same.

If the chuck doesn't hold the part straight you mount it between
centers and drive it with a dog.
I think a 4-sided pyramidal point held in the drill chuck is enough to
drive brass without a dog if you take light cuts. You don't need to
make the point run perfectly true as long as you mark it so you can
remove and replace the work.

How well did you learn Euclidean geometry?
The euclid works if the cross-section is truly circular.

There are constructions for centering even a triangle.
A quick shortcut I often use is to center a thin 6" flex rule across
the work by equalizing the end readings.
For example one end is at 1-1/8", the other at 4-7/8".
Hold a scriber point against the work at the 3" mark, then turn the
rule 90 degrees and repeat.
I like the style of graduations called 3R for this.

but the transfer punch/paper roll method beats it every time particularly
for small parts.

That's a good idea I hadn't seen before. Then again I have a collet
lathe which is the perfect machine for making small round parts. Mine
would be a little more perfect if it hadn't been abused in trade
school. A small lathe with a 3-jaw chuck is close. http://www.mini-lathe.com/

Maybe with a centre drill you do not need to punch? Am I right in that?

See the center/spot/stub drill thread. With less rigid equipment like
your drill press and my 50-year-old milling machine you have to learn
what works and what doesn't. The punch mark is to align the drill bit
with your hand layout since it's very difficult to position the center
of the drill bit directly.

Jim Wilkins

"Jim Wilkins" wrote in message
...
On Aug 28, 11:51 pm, "Michael Koblic" wrote:
"Jim Wilkins" wrote in message

Some "thoughts" would make your hair stand on end...:-)

What little hair is left... :-( (that's a beard, I grow it wherever
I still can)
I've run the model shop in electronics companies and thus dealt with
the creative misadventures of clever engineers with no practical
experience.

Judging from your e-mail address you will understand how electronics were
done by amateurs before the advent of the black boxes. Except we did not
have black boxes: we had Wehrmacht surplus. And ingenuity. And fire
insurance...


In the end when hooked up to the live centre (which is loose on the
drill
press table) the live centre was running around in a small circle
whatever I did.

A large pointed setscrew held by nuts and washers might work.

Setscrew pointed upward for the center, nuts and washers to hold it
tight in the hole.

I see. I could actually clamp the "live center" in a drill press vise and
position it. I was just thinking what kind of rotation will happen to the
piece if its so bent that it moves the centre around when *not* clamped. I
guess it will find a way...

...You can align them with a piece of wire in the chuck,...

I have re-read this about six times and I am not altogether sure that I
understood: I have no difficulty aligning the centre point of the live
centre with the centre of the spindle. However, when I chuck the gnomon
and
put the opposite end on the live centre (using the supposedly centre hole
I
drilled), the gnomon, being slightly out of alignment, moves the live
centre
around.

http://www.lindsaybks.com/bks/advmach/index.html

Don't be put off by its age. Production techniques may have improved
dramatically since then but manual lathe operations are still the
same.

For that I thank you. In fact I have been actively looking for older texts
which are more in keeping with what I am doing. I think I mentioned the old
blacksmith book with wooden bearings etc. He goes into lathes a bit but not
in enough detail (where, as far as I am concerned, is where the God is).

I am waiting for my first order from Smartflix so I can see these things
actually happening. They have some extensive courses on milling and lathing.
If it works out renting from them I should move forward more quickly. In any
case, I have ordered the book you recommended.

If the chuck doesn't hold the part straight you mount it between
centers and drive it with a dog.
I think a 4-sided pyramidal point held in the drill chuck is enough to
drive brass without a dog if you take light cuts. You don't need to
make the point run perfectly true as long as you mark it so you can
remove and replace the work.

Does the dog not object? Juvenile humour aside, now I have to study how to
use a dog! I thought a dog was a sort of bent thing which held parts to a
face plate if you did not have a chuck...

How well did you learn Euclidean geometry?
The euclid works if the cross-section is truly circular.

There are constructions for centering even a triangle.
A quick shortcut I often use is to center a thin 6" flex rule across
the work by equalizing the end readings.
For example one end is at 1-1/8", the other at 4-7/8".
Hold a scriber point against the work at the 3" mark, then turn the
rule 90 degrees and repeat.
I like the style of graduations called 3R for this.

3" yes. 0.3" no...

but the transfer punch/paper roll method beats it every time particularly
for small parts.

That's a good idea I hadn't seen before. Then again I have a collet
lathe which is the perfect machine for making small round parts. Mine
would be a little more perfect if it hadn't been abused in trade
school. A small lathe with a 3-jaw chuck is close.
http://www.mini-lathe.com/

Ha! You heard it here first! I have never seen it myself elsewhere, it just
came to me when I was trying to drill centre hole in the end of a 3/16"
copper rivet to stick on the end of my gnomon. I had to make another jig to
hold the rivet in the drill press vise but it works just fine.


Maybe with a centre drill you do not need to punch? Am I right in that?

See the center/spot/stub drill thread. With less rigid equipment like
your drill press and my 50-year-old milling machine you have to learn
what works and what doesn't. The punch mark is to align the drill bit
with your hand layout since it's very difficult to position the center
of the drill bit directly.

I have been following that thread - and I was not sure. I bought a centre
drill and promptly broke one end. The other end worked well, but I used a
punch. I believe you have to run them quite fast.

As an update: I bought a $17 Jacobs 1/2" chuck today and was able to chuck
one of the brass cups in it safely and tidied it up by the "reverse lathe"
method of holding it and rotating it by hand against a 220-grit belt sander.
I even found 3 1/2"-20 bolts of different lengths and am thinking of making
a jig to drill concentric holes along the lines recommended in the 2004
thread (there they used a wooden block on its side to drill a centre hole in
a long rod - rather ingenious I thought).

--
Michael Koblic,
Campbell River, BC
-ex OL1AGS
-ex G4GIU
-ex GW4GIU
-VE7EQG (QRT 7 years)

On 2008-08-30, Michael Koblic wrote:

"Jim Wilkins" wrote in message
...
On Aug 28, 11:51 pm, "Michael Koblic" wrote:
"Jim Wilkins" wrote in message

[ ... ]

A large pointed setscrew held by nuts and washers might work.

Setscrew pointed upward for the center, nuts and washers to hold it
tight in the hole.

I see. I could actually clamp the "live center" in a drill press vise and
position it.

If you add a V block to the vise to keep things from shifting.
upright round objects are difficult to clamp reliably in a vise, but add
a V-block and you can do a better job with a cylindrical item. However
a live center typicaly has a Morse taper shank, so you'll need some
extra tricks to make up for the taper itself.

I was just thinking what kind of rotation will happen to the
piece if its so bent that it moves the centre around when *not* clamped. I
guess it will find a way...

:-)

[ ... ]

http://www.lindsaybks.com/bks/advmach/index.html

Don't be put off by its age. Production techniques may have improved
dramatically since then but manual lathe operations are still the
same.

For that I thank you. In fact I have been actively looking for older texts
which are more in keeping with what I am doing. I think I mentioned the old
blacksmith book with wooden bearings etc. He goes into lathes a bit but not
in enough detail (where, as far as I am concerned, is where the God is).

I am waiting for my first order from Smartflix so I can see these things
actually happening. They have some extensive courses on milling and lathing.

Hopefully, they will also tell you that while you are using a
lahte, you are *not* "lathing", but rather "turning". :-)

If it works out renting from them I should move forward more quickly. In any
case, I have ordered the book you recommended.

If the chuck doesn't hold the part straight you mount it between
centers and drive it with a dog.
I think a 4-sided pyramidal point held in the drill chuck is enough to
drive brass without a dog if you take light cuts. You don't need to
make the point run perfectly true as long as you mark it so you can
remove and replace the work.

Does the dog not object? Juvenile humour aside, now I have to study how to
use a dog! I thought a dog was a sort of bent thing which held parts to a
face plate if you did not have a chuck...

It is used with a face plate, to impart rotation to a workpiece
suspended between centers. The one in the headstock spindle rotates,
but it does not have enough contact area to really drive the workpiece,
so the dog is clamped onto a part of the workpiece which you are not
(currently) changing, and its tail is driven by a slot in the faceplate
(if a bent-tail dog), or by a bolt through the faceplate (if a
straight tail dog). These do not wag. :-)

If you are trying to drive something with a drill chuck which
has a poor enough finish on the end so you can't clamp it and prevent it
from wobbling, then you clamp the drill chuck onto some steel rod, take
a file to it while it is rotating to form it to a point (60 degree
angle), and use this to hold the upper end of your workpiece. You will
then need to clamp a bent-tail dog onto the upper end of the workpiece,
and a collar of some sort around the drill chuck to drive the dog's
tail.

Another thing to worry about is that most drill presses don't go
slow enough, and if the workpiece, collar, and dog are not fairly well
balanced, the drill press will try to walk around the floor (or the
workbench, if it is a benchtop drill press).

[ ... ]

That's a good idea I hadn't seen before. Then again I have a collet
lathe which is the perfect machine for making small round parts. Mine
would be a little more perfect if it hadn't been abused in trade
school. A small lathe with a 3-jaw chuck is close.
http://www.mini-lathe.com/

Ha! You heard it here first! I have never seen it myself elsewhere, it just
came to me when I was trying to drill centre hole in the end of a 3/16"
copper rivet to stick on the end of my gnomon. I had to make another jig to
hold the rivet in the drill press vise but it works just fine.

The ability to make fixtures is an important one in any kind of
metalwork, and some woodwork as well.


Maybe with a centre drill you do not need to punch? Am I right in that?

See the center/spot/stub drill thread. With less rigid equipment like
your drill press and my 50-year-old milling machine you have to learn
what works and what doesn't. The punch mark is to align the drill bit
with your hand layout since it's very difficult to position the center
of the drill bit directly.

I have been following that thread - and I was not sure. I bought a centre
drill and promptly broke one end. The other end worked well, but I used a
punch. I believe you have to run them quite fast.

How large a diameter of center drill? The proper speed for one
is a function of its maximum diameter -- and the metal into which you
are drilling.

To avoid snapping off the point, you need a way to prevent the
workpiece from tilting in the drill press. Also, a proper
coolant/cutting fluid would help them to survive. But center drills
(like all drills) are "consumables" so keep spares on hand.

Good Luck,
DoN.

--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

On Aug 29, 10:06 pm, "Michael Koblic" wrote:
"Jim Wilkins" wrote in message
On Aug 28, 11:51 pm, "Michael Koblic" wrote:
"Jim Wilkins" wrote in message

Judging from your e-mail address you will understand how electronics were
done by amateurs before the advent of the black boxes. Except we did not
have black boxes: we had Wehrmacht surplus. And ingenuity. And fire
insurance...

We had plenty of US mil-surp gear to play with too. The aircraft stuff
often ran on 400 Hz AC and operated on 225-400 MHz which is military-
only here.

I used to have a working copy of a German aircraft-detection radar
transmitter from 1931(?) sitting on my Mac's monitor. It consisted of
a high-voltage transformer and a spark gap. The two spark gap
electrodes formed a dipole about 100mm long. There was enough lead
wire connected to it that I wouldn't predict the frequency and I
expect it was broadly tuned, but it could have been over 1 GHz. When I
rescued it from a lab I was closing down it was in an aquarium tank
because it was so dangerous. I removed the power cord. Spark gap
transmitters are illegal to operate now anyway.

As I understand it, the receiver was shielded from the transmitter and
only received the CW signal when it reflected off an airplane.
Detecting the audio-frequency Doppler shift in the return seems
unlikely for biplane speeds and spark-gap bandwidth and it goes away
as the plane approaches.

In "The Wizard War" Dr Jones wrote that early '40's German field radar
transmitters were as stable in frequency as the best British lab
standards, apparently because they could grind quartz crystals better.
He certainly had a lot of respect for German equipment. Then again,
the British chose to use American aircraft radios rather than their
own. As with Russia and Japan their theoretical and lab work was
excellent but they had trouble mass producing it.

but the transfer punch/paper roll method beats it every time particularly
for small parts.

That's a good idea I hadn't seen before.

Ha! You heard it here first!

The traditional center punching tool looks like a funnel with the
center punch sliding in the spout.

These are a gold mine of information;
http://www.amazon.com/Hand-Simple-Tu...s-Practice/dp/
0486264289/ref=sr_1_3?ie=UTF8&s=books&qid=1220099472&sr=1-3
If the link is broken, Google for "Holtzapffel"

The yellow one concentrates on turning and should answer your
questions very well, the red one is about hand tools and the history
of screw threads. I don't have the other books yet. They describe
Victorian-era technology in exquisite detail from a master toolmaker's
perspective and often give the inventor of our common tools, for
example Mr. Hale registered the centering square in 1862, Holtzapffel
and Deyerlein began making 3-jaw self-centering lathe chucks in 1811.

Like anything German they are ignored in most English-language history
books although they worked in London since 1787 and helped train
Whitworth. "English and American Tool Builders" gives them only a
paragraph. The Holtzappfel books complement that biographical one by
showing their work.

Jim Wilkins

On Aug 27, 10:16*pm, "Michael Koblic" wrote:
...And I am indeed looking for a cheap 3-jaw chuck....
Michael Koblic,

http://www.harborfreight.com/cpi/cta...temnumber=4486

The chuck mount is M12 x 1.0. It isn't too bad for the price.

"Jim Wilkins" wrote in message
...
On Aug 27, 10:16 pm, "Michael Koblic" wrote:
...And I am indeed looking for a cheap 3-jaw chuck....
Michael Koblic,

http://www.harborfreight.com/cpi/cta...temnumber=4486

The chuck mount is M12 x 1.0. It isn't too bad for the price.

****Thanks, but AFAIK they do not ship to Canada. I have a few under
surveillance on EBay.

On Wed, 27 Aug 2008 19:16:27 -0700, "Michael Koblic"
wrote:

The other thing that puzzles me (and please note that the nearest I have
been to a lathe is in the movies and picutres in books) is how do you start
turning something that is irregular in shape? Or even how do you turn a
round piece out of a square stock? Does it not do horrible things to the
cutting tool when it contacts only at the corners?

No, there is no trick, just that lathes are usually very heavy and
stiff (and have a lot of inertia) compared to the few thou of material
that will be removed on each hit..

What you're talking about is called an "interrupted cut" and it causes
vibration (and a sound that might be alarming the first time you hear
it) but it's not really a problem. You can turn a hex or square piece
of stock into round without problems, just don't feed too fast, and,
obviously, get the cutter outside for certain before starting or
you'll have a "crash" rather than an "interrupted cut").

Or is there a trick to
get the shape roughly round first somehow? I want to change the shape of the
brass cup but the initial attempt was somewhat discouraging.

Thanks for all your patience,
Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

"Michael Koblic" wrote in message
...
I picked up a few brass candle sticks in garage sales. I wanted to use one
for a brass sundial. It has a long stem and a cup for the candle. The stem
is irregular with some patterns on it.

I cut the stem off where I thought it would be just about right length for
the gnomon. I tried to "turn" it in my old drill press. It turned out not
so bad, I put a 10-32 thread on one end and tried to re-profile the rest
of it. It is about 5 cm long so I thought I would use the live center I
have for my sanding drums.
like this one:

http://www.leevalley.com/wood/page.a...02&cat=1,42500

This is where I run into a bit of a problem - drilling the centre hole.

The candlestick was made in India, I am not sure how. Either way not very
well so the whole thing is a bit asymmetrical. I tried to determine the
centre of the end to drill a concentric hole but found it almost
impossible. In the end when hooked up to the live centre (which is loose
on the drill press table) the live centre was running around in a small
circle whatever I did.

Now I understand (I hope!) that on a lathe the live centre on the taistock
is lined up with the centre of the chuck on the head stock and the hole
will be drilled in the centre by default. Not having a lathe the best way
I found to drill centres in a round stock is to make a paper tube around
it and use a tight fitting transfer punch to mark the centre. This works
fine if the stock is cylindrical, not on a candle stick stem which is not.

I found a thread on this group from 2004 which provided several options of
which the only one viable in my situation would have been to use a 3-jaw
chuck to center under the drill press spindle and then substitute the
centre drill. And I am indeed looking for a cheap 3-jaw chuck.

Are there any other suggestions ("Buy a lathe!" does not count)?

The other thing that puzzles me (and please note that the nearest I have
been to a lathe is in the movies and picutres in books) is how do you
start turning something that is irregular in shape? Or even how do you
turn a round piece out of a square stock? Does it not do horrible things
to the cutting tool when it contacts only at the corners? Or is there a
trick to get the shape roughly round first somehow? I want to change the
shape of the brass cup but the initial attempt was somewhat discouraging.

Thanks for all your patience,

--
Michael Koblic,
Campbell River, BC



An option to buyalathe is cobble together a facsimilie from surplus.

The surplus houses I've been to have mechanical components, or specif
purpose machines that have been retired.
We've bought lots of little machines for the components.

Sometimes you can get a huge pile of stuff for around $100us

also, scrounge your local scrap dealer for compnents.

For example, a front-wheel-drive auto spindle/bearing assembly is not far
removed from a lathe spindle.

Early metal turning was done on what were essentially wood lathes, with
similar turning tools.

Wood lathes are cheep, and/or easy to build.

"Jon" wrote in message
news:u4ztk.949$p72.578@trnddc05...
An option to buyalathe is cobble together a facsimilie from surplus.

The surplus houses I've been to have mechanical components, or specif
purpose machines that have been retired.
We've bought lots of little machines for the components.

Sometimes you can get a huge pile of stuff for around $100us

also, scrounge your local scrap dealer for compnents.

For example, a front-wheel-drive auto spindle/bearing assembly is not far
removed from a lathe spindle.

Early metal turning was done on what were essentially wood lathes, with
similar turning tools.

Wood lathes are cheep, and/or easy to build.

I am slowly acquiring a pile of stuff. Right now the closest I am getting is
the old drill press. I am wondering if simply mounting it on its side and
improvising some sort of tailstock in the place of the base might be a good
idea...

On Aug 27, 8:16*pm, "Michael Koblic" wrote:
I picked up a few brass candle sticks in garage sales. I wanted to use one
for a brass sundial. It has a long stem and a cup for the candle. The stem
is irregular with some patterns on it.

I cut the stem off where I thought it would be just about right length for
the gnomon. I tried to "turn" it in my old drill press. It turned out not so
bad, I put a *10-32 thread on one end and tried to re-profile the rest of
it. It is about 5 cm long so I thought I would use the live center I have
for my sanding drums.
*like this one:

http://www.leevalley.com/wood/page.a...02&cat=1,42500

*This is where I run into a bit of a problem - drilling the centre hole..

The candlestick was made in India, I am not sure how. Either way not very
well so the whole thing is a bit asymmetrical. I tried to determine the
centre of the end to drill a concentric hole but found it almost impossible.
In the end when hooked up to the live centre (which is loose on the drill
press table) the live centre was running around in a small circle whatever I
did.

Now I understand (I hope!) that on a lathe the live centre on the taistock
is lined up with the centre of the chuck on the head stock and the hole will
be drilled in the centre by default. Not having a lathe the best way I found
to drill centres in a round stock is to make a paper tube around it and use
a tight fitting transfer punch to mark the centre. This works fine if the
stock is cylindrical, not on a candle stick stem which is not.

I found a thread on this group from 2004 which provided several options of
which the only one viable in my situation would have been to use a 3-jaw
chuck to center under the drill press spindle and then substitute the centre
drill. And I am indeed looking for a cheap 3-jaw chuck.

Are there any other suggestions ("Buy a lathe!" does not count)?

The other thing that puzzles me (and please note that the nearest I have
been to a lathe is in the movies and picutres in books) is how do you start
turning something that is irregular in shape? Or even how do you turn a
round piece out of a square stock? Does it not do horrible things to the
cutting tool when it contacts only at the corners? Or is there a trick to
get the shape roughly round first somehow? I want to change the shape of the
brass cup but the initial attempt was somewhat discouraging.

Thanks for all your patience,

--
Michael Koblic,
Campbell River, BC

Marking rough castings for centerdrilling used to be a must-have
skill. My 1905 Audel's shows one way. You use an oddleg caliper, one
leg is curved like normal outside calipers, the other is straight(and
sharp). Set the thing a little more than half-way to the other side
and draw an arc off the edge. Rotate about 90 degrees and repeat,
repeat 2 more times and and you'll have a rough box shape marked out.
Use a machinist's rule across the diagonal and scribe a line.
Repeat. Centerpunch the intersection and it should be close enough to
center. Drill using a center drill. Repeat on the other end.

As far as interrupted cuts, castings were snagged off using chisels
and grinders so they weren't really too far out. With iron castings,
you have to make sure you get under the hard skin on the first cut,
otherwise the tool edge disappears. With brass, you just have to make
sure you aren't cutting sponge with embedded sand. Slow speeds and
feeds help if the lathe isn't a 2 ton heavyweight. Once the
interrupted cut disappears, speed can be increased.

Stan

wrote in message
...
Marking rough castings for centerdrilling used to be a must-have
skill. My 1905 Audel's shows one way. You use an oddleg caliper, one
leg is curved like normal outside calipers, the other is straight(and
sharp). Set the thing a little more than half-way to the other side
and draw an arc off the edge. Rotate about 90 degrees and repeat,
repeat 2 more times and and you'll have a rough box shape marked out.
Use a machinist's rule across the diagonal and scribe a line.
Repeat. Centerpunch the intersection and it should be close enough to
center. Drill using a center drill. Repeat on the other end.

***I believe it is called a hermaphrodite caliper. I have one of those but
on small parts it is quite useless. I have gone into this in my reply to Jim
Wilkins. I did like his idea of spinning the part and letting a pencil draw
a circle about the rotational axis the other end. I have not tried it yet.

As far as interrupted cuts, castings were snagged off using chisels
and grinders so they weren't really too far out. With iron castings,
you have to make sure you get under the hard skin on the first cut,
otherwise the tool edge disappears. With brass, you just have to make
sure you aren't cutting sponge with embedded sand.

***That would be the residue of casting?

Thanks

--
Michael Koblic,
Campbell River, BC