It takes some experience to sort through "old iron" to find something that
still got life in it.
Unfortunately it also takes some experience with the import "kit" lathes to
tell whats wrong with them and what needs adjusting or fixing when they show
up.

If you go the new import route, I would only consider Jet and Grizzly in
that order as they have the best after sales support for the imports. Jet
will even send someone out to fix your lathe if its not running right.

Either the 12" or various 13" inch imports will do the job for you. If you
plan on making a lot of your horns I would go with the best 13" you can
afford. Stay away from the 9" imports, although in theory they could do the
job, they seem to be a large step down in quality from the larger imports.
The 12x36 imports have a lot of happy owners, and is probably the cheapest
lathe that will do the job for you pretty well.

Theres a forum on Yahoo that can be helpful in setting up and using the 12"
and 13" lathes (its called 12x).

Along with the lathe I would recommend an Aloris type quick change toolpost
set (Phase II makes a pretty good import version of this, but don't go
cheaper than that) and a set of carbide insert cutting tools. Actually, you
can get a "real" Aloris set for not that much more than the Phase II, so
check on mscindustrial.com, enco.com and the other tooling sites for the
best prices you can get on the Aloris and Phase II sets.

Don't let any oldtimers talk you into using HSS tool bits for this, that was
cool in its day but times have changed, and its a lot easier to get
repeatable results with the carbide tools, especially for learners. For this
size lathe you would need the positive relief type tools, take a look at
http://www.thegallos.com/carbide.htm for some background on this.

However, to be fully candid, to make a part to the specifications you
described takes some machining skills.
I guess you could learn this on your own, but it would be hard without
someone looking over your shoulder.

You should consider either some metalworking classes or perhaps finding a
retired machinist in your area that would be interested in helping you learn
to run a lathe, and you should be willing to pay for this. If you find the
right guy he could help you select the lathe also, and if he's familiar with
other machinists in the area might have some leads on a good used lathe.

Good luck-

Paul T.

adam smith wrote:

I want to purchase and learn to use a lathe, because I need to make
new parts for some old 1930's air horns (diaphone fog horns) that are
not otherwise available. One part I need to make is the piston, which
looks like this:

http://www.airraidsirens.com/diaphon..._front_640.jpg
http://www.airraidsirens.com/diaphon..._close_640.jpg

It's 4" in diameter at the wide end, and 2.83" diameter over the rest,
by about 5" long overall. This piece fits concentrically inside a
brass cylinder, and it reciprocates at 180Hz when in use. The original
1918 shop drawings for this device spec the precision of the diameter
of the piston as "4 inches, to gauge limits--machine all over
outside". Newer drawings have the diameter as 4.000, +0.000/-0.002

I know these are made by first casting an aluminum blank (with a core
for the hollow part), but what I do not know is what caliber of lathe
and tooling I will need to do the machine work. I am not a machinist,
but I'm going to learn with the intent of making these parts and other
pieces for various antique sirens and horns. Thus, I'm interested in
buying a lathe to learn on primarily, but I want to be sure to get one
the first time around that,when I'm skilled enough, can turn out these
parts with the specified accuracy.

I'm interested especially in which import lathes are up to the task,
and what size is required. Yes, I realize many of you are now groaning
at my use of the word "import", but please let me explain. My budget
is that of the home enthusiast and does not allow for purchasing new
made-in-the-USA equipment. I've been reading this group for many
years, and many times have I heard "get an old South Bend, Atlas or
Logan". That is undoubtedly great advice for an experienced machinist
setting up a home shop, but I'm just starting out and I do not feel
that I could safely shop for a used lathe and not end up with a
junker. I also want a tool that is ready to use and not a project unto
itself. With these criteria, is an old SB still a possibility?

Thanks,

Adam

Your first photo makes it appear that there may be a joint between the
slotted barrel and the larger portion. Is there?

I'm assuming the part is the moving section of a valve which modulates an
air flow to produce the loud 180 Hz acoustic waveform emitted by the fog
horn

Do you know how those slots were originally made? You could probably tell
from the finish of their walls whether they were cast around fins on the
core or cut with some sort of saw or milling cutter. I'll wager they were
cut though, they look pretty thin for any reasonable core material of
their original era.

Selecting a suitable lathe may well be the easiest part of your project,
and I'll leave it to the experts here to advise you on brands and sizes.
It looks like that part could be turned on most any 6 inch or larger
lathe. Anything but a real junker ought to be able to hold .002" on
diameter on a part that size.

Cutting those slots will require some kind of milling or rotary saw setup,
along with fixturing to hold and position the part in the correct location
for each slot. I suspect they have to be located axially to within maybe
ten thousandths of an inch of their design locations to keep the valving
action optimal. Again, this will probably be a trickier thing to handle
correctly than the lathe work itself.

Some of the things you'll have to learn or figure out for yourself are
what kind of a chuck or other fixturing to use to hold the part and
minimize the chances for slippage or shifting while you're turning it on
the lathe, and what kind of tool bit shape and cutting fluid to use to get
the finish you need. Also, you want to avoid being bit by thermal
expansion, by making sure the part isn't much above room temperature when
you make your final sizing passes.

You didn't mention anything about where you're going to get the castings
to turn these from. If you're thinking DIY on that, you'll probably find
out that there's more skills to learn about the casting portion than what
you'll need to aquire for the simple lathe turning operations.

I suspect those six ribs inside the part were put there there to add
strength to the piece so vibration didn't cause it to crack at those
little solid sections between the ends of the slots. You might be able to
turn the part on a lathe in it's entirety from a piece of modern strong
aluminum bar stock and avoid the whole casting exercise; unless, of
course, your goal is to make exact replicas of the originals.

I'm sure others here will be able to offer helpful suggestions.

Good luck,

Jeff




--
Jeff Wisnia (W1BSV + Brass Rat '57 EE)

"If you can keep smiling when things go wrong, you've thought of someone
to place the blame on."

In article , Paul T. says...

You should consider either some metalworking classes or perhaps finding a
retired machinist in your area that would be interested in helping you learn
to run a lathe, and you should be willing to pay for this. If you find the
right guy he could help you select the lathe also, and if he's familiar with
other machinists in the area might have some leads on a good used lathe.

Good advice indeed.

Although the old timer would certainly
teach him how to offhand grind HSS tool
bits, first thing!

Jim

==================================================
please reply to:
JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com
==================================================

Adam,

Machinery prices are really in the buyer's favor right now, new and
used. Your correct about swhopping used, with no experience you could
get bit. But if someone knowledgable was able to help you could get a
real good deal on something. Looking at the pix you posted, you'll be
well off to have a patient soul helping that as well. Where are you
located? Perhaps someone in the group is near that can assist you. I
would be glad to if you are in northern California.

michael

HSS are cheaper, more forgiving, and can be easily custom ground for a job.
HSS is still the standard for lathe use, especially in a non-production
environment.

BTW what do you use for drill bits???


--
Tony

Visit TonysToolroom for info on Precision Scraping.
***Now with Powerscraping***

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..

Don't let any oldtimers talk you into using HSS tool bits for this, that
was
cool in its day but times have changed, and its a lot easier to get
repeatable results with the carbide tools, especially for learners. For
this
size lathe you would need the positive relief type tools, take a look at
http://www.thegallos.com/carbide.htm for some background on this.

In article ,
michael wrote:

Adam,

Machinery prices are really in the buyer's favor right now, new and
used. Your correct about swhopping used, with no experience you could
get bit. But if someone knowledgable was able to help you could get a
real good deal on something. Looking at the pix you posted, you'll be
well off to have a patient soul helping that as well. Where are you
located? Perhaps someone in the group is near that can assist you. I
would be glad to if you are in northern California.

Alas, I am in Boston, MA (watertown actually). I probably couldn't get
much farther from Northern CA and still be in the states :-)

-Adam

I have a turret lathe that would be great for this job, you can have it for
free


"adam smith" wrote in message
m...
I want to purchase and learn to use a lathe, because I need to make
new parts for some old 1930's air horns (diaphone fog horns) that are
not otherwise available. One part I need to make is the piston, which
looks like this:

http://www.airraidsirens.com/diaphon..._front_640.jpg
http://www.airraidsirens.com/diaphon..._close_640.jpg

It's 4" in diameter at the wide end, and 2.83" diameter over the rest,
by about 5" long overall. This piece fits concentrically inside a
brass cylinder, and it reciprocates at 180Hz when in use. The original
1918 shop drawings for this device spec the precision of the diameter
of the piston as "4 inches, to gauge limits--machine all over
outside". Newer drawings have the diameter as 4.000, +0.000/-0.002

I know these are made by first casting an aluminum blank (with a core
for the hollow part), but what I do not know is what caliber of lathe
and tooling I will need to do the machine work. I am not a machinist,
but I'm going to learn with the intent of making these parts and other
pieces for various antique sirens and horns. Thus, I'm interested in
buying a lathe to learn on primarily, but I want to be sure to get one
the first time around that,when I'm skilled enough, can turn out these
parts with the specified accuracy.

I'm interested especially in which import lathes are up to the task,
and what size is required. Yes, I realize many of you are now groaning
at my use of the word "import", but please let me explain. My budget
is that of the home enthusiast and does not allow for purchasing new
made-in-the-USA equipment. I've been reading this group for many
years, and many times have I heard "get an old South Bend, Atlas or
Logan". That is undoubtedly great advice for an experienced machinist
setting up a home shop, but I'm just starting out and I do not feel
that I could safely shop for a used lathe and not end up with a
junker. I also want a tool that is ready to use and not a project unto
itself. With these criteria, is an old SB still a possibility?

Thanks,

Adam

Adam Smith

Believe me, I do wish I knew some machinists! Unfortunately, most of my
contemporaries here in the Boston area are in the computer business.
I'll ask around though, maybe somebody I know knows somebody...

The New England Model Engineering Society meets first Thursday nights (7:00) of
each month, at the Charles River Museum of Industry, Moody Street (named for a
truly great early machinist, btw), center of Waltham, MA.

http://www.newenglandmodelengineeringsociety.org/

(sorry for the bad wrap)

Try both carbide and HSS.
(wouldn't want HSS to get a bad rap without empirical evidence)
Frank Morrison

(adam smith)

I want to purchase and learn to use a lathe, because I need to make
new parts for some old 1930's air horns (diaphone fog horns) that are
not otherwise available. One part I need to make is the piston, which
looks like this:

http://www.airraidsirens.com/diaphon..._front_640.jpg
http://www.airraidsirens.com/diaphon..._close_640.jpg

It's 4" in diameter at the wide end, and 2.83" diameter over the rest,
by about 5" long overall. This piece fits concentrically inside a
brass cylinder, and it reciprocates at 180Hz when in use. The original
1918 shop drawings for this device spec the precision of the diameter
of the piston as "4 inches, to gauge limits--machine all over
outside". Newer drawings have the diameter as 4.000, +0.000/-0.002

It's interesting that this would have been cast aluminum back in 1918.

The cylinder is lathe finished, but the slots are probably made on a mill (a
horizontal mill, back then would have been more in use).

You really need to find some place where you can use the machinery, rather than
buying the tooling for making one/a few part(s).
Frank Morrison

I pretty much agree with Paul T. except on the HSS tool bits. For
turning aluminum, the HSS bits will work well as you can grind them to
have more relief than the carbide tools intended for steel ( there
must be carbide bits for aluminum, but I don't have any ).

Dan




"Paul T." wrote in message news:w1v3b.16260

Don't let any oldtimers talk you into using HSS tool bits for this, that was
cool in its day but times have changed, and its a lot easier to get
repeatable results with the carbide tools, especially for learners. For this
size lathe you would need the positive relief type tools, take a look at
http://www.thegallos.com/carbide.htm for some background on this.



Good luck-

Paul T.

In article please_look-CEA2EA.21280228082003
@news.easynews.com, says...

Alas, I am in Boston, MA (watertown actually). I probably couldn't get
much farther from Northern CA and still be in the states :-)


Not real close to Watertown, but what about this:

http://continuinged.uml.edu/CSCE/Cur...msearch_detail.
cfm?coursenum=23.301&secnum=-001

Perhaps check Wentworth as well.

Ned Simmons

On 29 Aug 2003 03:09:49 GMT, (Fdmorrison)
pixelated:

(adam smith)

I want to purchase and learn to use a lathe, because I need to make
new parts for some old 1930's air horns (diaphone fog horns) that are
not otherwise available. One part I need to make is the piston, which
looks like this:

http://www.airraidsirens.com/diaphon..._front_640.jpg
http://www.airraidsirens.com/diaphon..._close_640.jpg

It's 4" in diameter at the wide end, and 2.83" diameter over the rest,
by about 5" long overall. This piece fits concentrically inside a
brass cylinder, and it reciprocates at 180Hz when in use. The original
1918 shop drawings for this device spec the precision of the diameter
of the piston as "4 inches, to gauge limits--machine all over
outside". Newer drawings have the diameter as 4.000, +0.000/-0.002

It's interesting that this would have been cast aluminum back in 1918.

I was amazed to hear that the pyramid cap of the Washington
Monument, made in 1884, was all aluminum. I heard the reference
to it on the History channel program on metals the other evening.

http://www.tms.org/pubs/journals/JOM...wski-9511.html
It's an interesting read on old metal casting.

- - -
Brain cells come and brain cells go, but fat cells live forever.
---
http://diversify.com Website Application Programming for YOU!

Paul T. scribed in
:

Don't let any oldtimers talk you into using HSS tool bits for
this, that was cool in its day but times have changed, and its a
lot easier to get repeatable results with the carbide tools,
especially for learners. For this size lathe you would need the
positive relief type tools, take a look at
http://www.thegallos.com/carbide.htm for some background on this.

well, I'm 36 and purchased my lathe in 2000, so I'm not an oldtimer,
and I'll tell you straight that you speak nonsense above.
carbide is not the answer to the HSM question. carbide is designed
for high speed production rates and does that very well, doing deep
cuts to final dimension (which is often oversize and final size is
achieved on a grinder because it is cheaper that way)

what is DOESN'T do well at all is sneak up on a dimension which is
what the home machinist does a lot of becasue we do ONE part so it is
not set up for production runs to tolerance. sharp HSS can take off
curls of steel that just about float in the air and can be the
difference between a fit and a scrap part. can carbide do that? no
it cannot, because its edge is not *sharp*. Also, HSS is much easier
to grind to shape or sharpen with nothing more than an ordinary bench
grinder with the wheels it came rom China with on it.

yes, carbide has a place in every shop, but not the *only* place. it
cannot do everything, just as HSS cannot do everything, and don't
forget a place for a few old files that can heated and bent, then
hardened and ground, for those special jobs.

So, Adam Smith, get a 12x or 13x lathe (I agree with Paul on that at
least), and get some HSS toolbits. Trawl the web for how to grind
it, and cut metal/plastic/Barbie dolls till you figure you can make
one of those horn parts. Then do it. I'd say you can be making
successful parts within 3 months of purchase. And don't be afraid of
books... there are a LOT of good books to help you start that will
still be useful in 20 years time, buy them, it's the cheapest
education available in the world.

swarf, steam and wind

--
David Forsyth -:- the email address is real /"\
http://terrapin.ru.ac.za/~iwdf/welcome.html \ /
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If you receive email saying "Send this to everyone you know," / \
PLEASE pretend you don't know me.

jim rozen scribed in
:

Although the old timer would certainly
teach him how to offhand grind HSS tool
bits, first thing!

and so would teenut have, no?

swarf, steam and wind

--
David Forsyth -:- the email address is real /"\
http://terrapin.ru.ac.za/~iwdf/welcome.html \ /
ASCII Ribbon campaign against HTML E-Mail - - - - - - - X
If you receive email saying "Send this to everyone you know," / \
PLEASE pretend you don't know me.

"Paul T." wrote in message
...

Don't let any oldtimers talk you into using HSS tool bits for this, that
was
cool in its day but times have changed, and its a lot easier to get
repeatable results with the carbide tools, especially for learners. For
this
size lathe you would need the positive relief type tools, take a look at
http://www.thegallos.com/carbide.htm for some background on this.

There's a lot of good advice in your post, Paul, but I strongly disagree
with you about this one. I used mostly carbide when I worked in a commercial
shop but I would never recommend it for a hobby shop. I have both right now,
which I use on my SB, and I don't have to pay for my carbide. Still, I
consider it to be my last choice when doing one-at-a-time work. I use it for
abrasive materials and for those rare occassions when I'm cutting very hard
steel.

And I'm not a Luddite about it. I'm the Tooling editor for Machining
magazine, and I spend a lot of my days researching and extolling the virtues
of new cutter designs and materials. They are amazing. If I could inventory
enough of them and if I could affort all the holders, I might even be able
to do as much with them as I can do with a few pieces of 3/8" HSS. But it
would never quite match it.

adam smith is cutting aluminum; unless he's making his castings from
hypereutectics, there's no reason in the world to use carbide for
aluminum -- unless you're doing batch lots of 1,000 pieces or so. My HSS
cutters ground for aluminum get sharpened once every year or two. g

I realize the arguments about this can go on forever, but, FWIW, I'm well
aware of the latest in positive-rake, cobalt-enriched, multi-coated inserts,
and I find no use at all for them in my shop. Not even for a zero-rake piece
of C2. That is, until I have to cut some filled plastic or to face off some
piece of really hard steel.

Ed Huntress

Fdmorrison wrote:

Adam Smith

Believe me, I do wish I knew some machinists! Unfortunately, most of my
contemporaries here in the Boston area are in the computer business.
I'll ask around though, maybe somebody I know knows somebody...

The New England Model Engineering Society meets first Thursday nights (7:00) of
each month, at the Charles River Museum of Industry, Moody Street (named for a
truly great early machinist, btw), center of Waltham, MA.

http://www.newenglandmodelengineeringsociety.org/

(sorry for the bad wrap)

Try both carbide and HSS.
(wouldn't want HSS to get a bad rap without empirical evidence)
Frank Morrison

I wuz just about to make the same suggestion Adam. Get thee over to the next town
from you next Thursday night and buddy with the guys there. I'm not a member, but
I've been to a couple of meetings. I found the membership an eclectic mixture of
old farts like me and some younger guys who are into computers, robots and CAM.

BTW, If you don't know where the entrance to the museum is, you might want to scout
it out in the daytime. The first time I went there (after dark) I had a heck of a
time figuring out where to stash my car, and almost fell in the Charles River!

Jeff , In Winchester, MA. Whose son Adam's company near you in Watertown makes all
kinds of stuff from metal. (http:// www.pbasics.com)

--
Jeff Wisnia (W1BSV + Brass Rat '57 EE)

"If you can keep smiling when things go wrong, you've thought of someone to place
the blame on."

On Fri, 29 Aug 2003 12:50:59 +0000 (UTC), DejaVU wrote:
what is DOESN'T do well at all is sneak up on a dimension which is
what the home machinist does a lot of becasue we do ONE part so it is
not set up for production runs to tolerance. sharp HSS can take off
curls of steel that just about float in the air and can be the
difference between a fit and a scrap part. can carbide do that? no
it cannot, because its edge is not *sharp*. Also, HSS is much easier
to grind to shape or sharpen with nothing more than an ordinary bench
grinder with the wheels it came rom China with on it.

Actually, carbide *can* do that. You want *uncoated* carbide. The
coated stuff has a rounded edge, but uncoated carbide can be
scary sharp (and you can make it even more so with a diamond
hone). It'll stay that way a lot longer than HSS too. When it
does dull, just rotate the insert to bring a fresh edge to the work.
You don't have to reset the tool, your geometry is still perfect.

HSS has a place in the shop. It is still the most economical thing
for form cutters, and it stands up well to interrupted cuts. But carbide
insert tooling is the way to go for most shop tasks. Just remember
that for small lathes you want positive rake tooling and *uncoated*
carbide inserts.

The coated negative rake carbide is for the big boys with high
horsepower rigid machinery. It'll handle feeds and speeds you
wouldn't dream of attempting on small machinery, but it won't do fine
shaving cuts. Positive rake uncoated carbide will.

Gary

In article
, Stans4
@americanisp.net says...

It's interesting that this would have been cast aluminum back in 1918.

Why? Aluminum castings have been around a lot longer than that. Ever
see a Liberty engine crankcase casting? It was a WW-1 vintage
aircraft engine, a very elaborate casting. There was just no real
standardization of alloys like we have today.


Not a whole lot longer, at least not in commercial
quantities.

http://www.world-aluminium.org/history/index.html#

Ned Simmons

On Fri, 29 Aug 2003 13:27:07 -0400, the renowned Ned Simmons
wrote:

In article
, Stans4
says...

It's interesting that this would have been cast aluminum back in 1918.

Why? Aluminum castings have been around a lot longer than that. Ever
see a Liberty engine crankcase casting? It was a WW-1 vintage
aircraft engine, a very elaborate casting. There was just no real
standardization of alloys like we have today.


Not a whole lot longer, at least not in commercial
quantities.

http://www.world-aluminium.org/history/index.html#

So Eros of Picadilly Circus is aluminum? Cool! Cast ca. 1893 (supposed
to be the first statue cast of aluminum, or perhaps we should say
"aluminium").

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

"Tony" wrote in message
news
HSS are cheaper, more forgiving, and can be easily custom ground for a
job.
HSS is still the standard for lathe use, especially in a non-production
environment.

If I had lots of free time on my hands I'd probably use HSS cutting tools
more often, but now I only use them for special purposes, like a special
formed tool. It just takes too long to form and resharpen HSS tools compared
to swapping in an insert.
Also, when you swap an insert your setup is still correct, but when you have
to resharpen an HSS tool now you need to change your setup to compensate for
the different tool length.

We do prototyping and small runs here and I have a guy who helps me and
basically acts as a machine operator, but he doesn't really have any
machinist skills or training.
With the insert tools I can have him swap inserts when one gets dull, but
there's no way he could handle reshapening the tool and then doing the setup
again.


BTW what do you use for drill bits???


Big difference here, I can buy a HSS drill bit for less than a buck ready to
go, and when its dull, we chuck it in the recycle bin and put in a new one.
At less than a buck cost, its not worth the time to stop work and resharpen
them.
If you could buy a HSS lathe tool preformed and presharped at a reasonable
price we'd probably use them a lot more.

By the way, when I first learned to run machine tools, I had a great
instructor who taught us how to grind an HSS lathe tool from scratch, and
for a few years all I used was HSS. It has its place, but for the work we do
here that place has gotten smaller and smaller.

Also, I find almost any lathe can be used with insert tooling as long as its
positive relief. You can't take monster cuts on an older smaller lathe with
the inserts, but you can't do that with HSS tools either on those lathes.

We're still using a 1933 11" SouthBend lathe here with an AXA toolpost and
cutting tools that almost all use TPG222 type insert tooling.
APT makes a boring tool that takes this insert and works well with the AXA
tool post.
This way we don't have to stock as many different insert types.
We've got a Clausing 5914 thats being prepped up to replace the SB, so soon
we'll move from a 70 year old lathe to a 30 year old lathe.

Paul T.

On 29 Aug 2003 03:09:49 GMT, (Fdmorrison) wrote:

You really need to find some place where you can use the machinery, rather than
buying the tooling for making one/a few part(s).
Frank Morrison

I agree. Maybe you should look into having these made.
If you want to cast them, I suggest reading
http://groups.yahoo.com/group/castinghobby/

BTW, do you have the drawings in electronic form? I'd love to see
them.

Ron Thompson
On the Beautiful Mississippi Gulf Coast
USA

http://www.plansandprojects.com

Where did everyone go? Oh, yeah.
http://groups.yahoo.com/group/castinghobby/
Y'all come, ya hear?
*******

On Fri, 29 Aug 2003 13:27:07 -0400, Ned Simmons wrote
In article
, Stans4
says...
It's interesting that this would have been cast aluminum back in 1918.

Why? Aluminum castings have been around a lot longer than that. Ever
see a Liberty engine crankcase casting? It was a WW-1 vintage
aircraft engine, a very elaborate casting. There was just no real
standardization of alloys like we have today.

Not a whole lot longer, at least not in commercial quanities

The reason of course is that before widespread availability of electric
power, and the Hall process, aluminum was a very rare and expensive
metal. At the French court, the very highest ranked guests got to eat using
aluminum utensils, the lower ranked guests had to make do with gold.

Gary

On Fri, 29 Aug 2003 13:52:49 GMT, "Ed Huntress"
wrote:

"Paul T." wrote in message
.. .

Don't let any oldtimers talk you into using HSS tool bits for this, that
was
cool in its day but times have changed, and its a lot easier to get
repeatable results with the carbide tools, especially for learners. For
this
size lathe you would need the positive relief type tools, take a look at
http://www.thegallos.com/carbide.htm for some background on this.

There's a lot of good advice in your post, Paul, but I strongly disagree
with you about this one. I used mostly carbide when I worked in a commercial
shop but I would never recommend it for a hobby shop. I have both right now,
which I use on my SB, and I don't have to pay for my carbide. Still, I
consider it to be my last choice when doing one-at-a-time work. I use it for
abrasive materials and for those rare occassions when I'm cutting very hard
steel.

And I'm not a Luddite about it. I'm the Tooling editor for Machining
magazine, and I spend a lot of my days researching and extolling the virtues
of new cutter designs and materials. They are amazing. If I could inventory
enough of them and if I could affort all the holders, I might even be able
to do as much with them as I can do with a few pieces of 3/8" HSS. But it
would never quite match it.

adam smith is cutting aluminum; unless he's making his castings from
hypereutectics, there's no reason in the world to use carbide for
aluminum -- unless you're doing batch lots of 1,000 pieces or so. My HSS
cutters ground for aluminum get sharpened once every year or two. g

I realize the arguments about this can go on forever, but, FWIW, I'm well
aware of the latest in positive-rake, cobalt-enriched, multi-coated inserts,
and I find no use at all for them in my shop. Not even for a zero-rake piece
of C2. That is, until I have to cut some filled plastic or to face off some
piece of really hard steel.

Ed Huntress

Once again I agree with Ed.

Damn..this is getting scary........


Gunner

"The people who believe that, as a result of industrial development, life is about to become a hell,
or may be one already, are guilty, at least, of sloppy pronouncements.
On page 8 of Earth in the Balance, Al Gore claims that his study of the arms race gave him
"a deeper appreciation for the most horrifying fact in all our lives:
civilization is now capable of destroying itself."

In the first place, the most horrifying fact in many of our lives is that
our ex-spouse has gotten ahold of our ATM card.
And civilization has always been able to destroy itself. The Greeks of ancient Athens,
who had a civilization remarkable for lack of technological progress
during its period of greatest knowledge and power, managed to destroy themselves just fine."
-- P.J. O'Rourke, All the trouble in the world. The lighter side of famine, pestilence, destruction and death.

"jim rozen" wrote in message
...

Some of the postive rake, uncoated carbide inserts (with
formed-in chipbreakers) were *too* sharp when I was
turning nylon parts for a second job. It was common
practice to go and deliberately break the edge, with an
arkansas stone to prevent the material from chipping out
at high speeds and feed rates.

An Arkansas stone? On carbide? I'd think it would gouge the stone, no?

As for the positive rake, positive rake for what? Steel? Aluminum? And do
you keep a separate set of zero-rake tools for brass? Or is one supposed to
just cross his fingers that he doesn't have a crash?

I'm not arguing with you. I'm arguing with the idea of using carbide as your
basic tool material for hobby machining. I've used a lot of carbide over 30
years, and I wouldn't do it. Not on my South Bend, and not on a Chinese
lathe.

Ed Huntress

In article , Ed Huntress says...

"jim rozen" wrote in message
...

Some of the postive rake, uncoated carbide inserts (with
formed-in chipbreakers) were *too* sharp when I was
turning nylon parts for a second job. It was common
practice to go and deliberately break the edge, with an
arkansas stone to prevent the material from chipping out
at high speeds and feed rates.

An Arkansas stone? On carbide? I'd think it would gouge the stone, no?

Yes. We kept one stone just for doing this, in the toolbox.
I know it sounds crazy but at the speeds and feeds we were
turning annealed nylon 6,6 it would tend to form tiny
pits on the surface when brand new tooling was installed
and you could either a) reduce the speeds and feeds for about
20 parts, or you could knock the brand new edge off the
insert. After 20 parts the insert was broken in and would
not show the problem.

As for the positive rake, positive rake for what? Steel? Aluminum? And do
you keep a separate set of zero-rake tools for brass? Or is one supposed to
just cross his fingers that he doesn't have a crash?

In this case it was a production environment - and nothing but
nylon 6,6 was in the machines. When they did profile aluminum
jaws the chip bins had to be cleaned out because all the chips
were sent out for recycling, they were used for injection molding
feedstock.

I'm not arguing with you. I'm arguing with the idea of using carbide as your
basic tool material for hobby machining. I've used a lot of carbide over 30
years, and I wouldn't do it. Not on my South Bend, and not on a Chinese
lathe.

As per my other posts, I agree with this. I do have some lathe
holders that run TPG221 inserts, only for turning hard parts
that HSS won't touch. They get used on occasion, at home.
But mostly I run with three tools in the toolpost, a positive
rake turning tool, a grooving tool, and a 60 degree threading
tool. All made from 3/8 HSS blanks. The QC station of the
toolpost typically either gets a HSS cuttoff tool, or a HSS
bokum type boring bar.

I've been meaning to try to find some tpg221 HSS inserts, and
also some uncoated carbide ones as well, but the need hasn't
been very pressing.

Jim

==================================================
please reply to:
JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com
==================================================

In article , Gary Coffman says...

.... At the French court, the very highest ranked guests got to eat using
aluminum utensils, the lower ranked guests had to make do with gold.

The very top of the Washington Monument has a pyramid
of pure aluminum, so it is said. Precious metal and all
that.

Jim

==================================================
please reply to:
JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com
==================================================

DejaVU

Jim
Although the old timer would certainly
teach him how to offhand grind HSS tool
bits, first thing!

DF
and so would teenut have, no?

And even offhand carbide grinding.
FM

In article , Fdmorrison says...

And even offhand carbide grinding.
FM

And there is the sticking point.

First you have to break the news to the
new lathe owner, that the lathe is basically
no good unless he has a pedestal grinder.

"What, I gotta buy something *else*?"

Now you, sir, are elected to tell the poor
neophyte that really, he has to buy TWO
grinders!



Jim

==================================================
please reply to:
JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com
==================================================

Your first photo makes it appear that there may be a joint between the
slotted barrel and the larger portion. Is there?

Nope, it's a single cast piece, no joints.

I'm assuming the part is the moving section of a valve which modulates an
air flow to produce the loud 180 Hz acoustic waveform emitted by the fog
horn

That is correct.

Do you know how those slots were originally made? You could probably tell
from the finish of their walls whether they were cast around fins on the
core or cut with some sort of saw or milling cutter. I'll wager they were
cut though, they look pretty thin for any reasonable core material of
their original era.

On the very oldest samples of these horns, the piston's slots are
lathed, and only the 6 inner ribs hold the rest together. On the newer
style pistons (1930's on) as seen in my photos, the slots do not go all
the way around and they are cut on a mill with a circular cutter.

Cutting those slots will require some kind of milling or rotary saw setup,
along with fixturing to hold and position the part in the correct location
for each slot. I suspect they have to be located axially to within maybe
ten thousandths of an inch of their design locations to keep the valving
action optimal.

Actually, the diaphone gets its rich-in-harmonics tone from the piston's
slots aligning with the outer cylinder's slots for only a small fraction
of the piston's stroke, producing more of a pulse waveform than the
sinusoid you would get with just enough excursion for the slots to go
completely in and out of alignment. The slots have to be spaced fairly
precisely, but slop in their width will not significantly affect the
tone and will not affect operation at all. The wide rear section of the
piston is the "motor section" that produces the back and forth movement.

I suspect those six ribs inside the part were put there there to add
strength to the piece so vibration didn't cause it to crack at those
little solid sections between the ends of the slots.

As noted earlier, the ribs were originally there so that the slots could
be cut fully around on a lathe. The shop drawings for all diaphone
pistons show this was how it is supposed to be done. For some reason,
they switched to milling the slots later in the production of these
horns, but did not change the castings (probably for cost reasons).

-Adam

On Sun, 31 Aug 2003 01:02:04 -0700, mikee wrote:

Amen to the HSS route. Try facing 0.001 inch off a rifle barrel shoulder with a
carbide tool bit. Piece of cake with a sharp HSS bit, not so easy with one of
those through away carbide bits.

Mike Eberlein

Amen to that!

And I used to take off a couple of tenths sometimes too. It was
harder to measure the cut than it was to make it. I did the cut with
a specially ground 3/8" Mo-Max HSS cutting bit that I had that was
used for nothing else.



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Very interesting link. Thanks for posting. I did not realize that the cap
on the Washington Monument was aluminum, much less cast aluminum.

Mike Eberlein

Larry Jaques wrote:

http://www.tms.org/pubs/journals/JOM...wski-9511.html
It's an interesting read on old metal casting.

jim rozen scribed in
:

In article , DejaVU says...

sharp HSS can take off
curls of steel that just about float in the air and can be the
difference between a fit and a scrap part. can carbide do that?
no it cannot, because its edge is not *sharp*.

Uncoated carbide can. Most hsm types purchase coated
carbide, and the coatings don't stick to a dead sharp
edge. The manufacturer gives those edges a 'hone'
or turned-over edge.

Uncoated carbide inserts can be purchased that are
razor-blade sharp.

thanks Jim, noted

But the hss does seem to be the best overall for
home shop use, in general. The versatility of

being able to profile unique shapes with a simple
pedestal grinder is real handy.

yup...

swarf, steam and wind

--
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Paul T. scribed in
:

We do prototyping and small runs here and I have a guy who helps
me and basically acts as a machine operator, but he doesn't really
have any machinist skills or training.
With the insert tools I can have him swap inserts when one gets
dull, but there's no way he could handle reshapening the tool and
then doing the setup again.

and for the rest of his life he'll be standing there operating and
will never learn a thing that will help him along in life, like WHY
is that cutting edge THAT shape.....and what happens when you get it
wrong (-:

swarf, steam and wind

--
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Adam Smith scribed in please_look
:

On the very oldest samples of these horns, the piston's slots are
lathed, and only the 6 inner ribs hold the rest together. On the
^^^^^^^
crumbs, I thought only my 6 year old son said that!
the term is 'turned' in a lathe. lathe is a noun....

swarf, steam and wind

--
David Forsyth -:- the email address is real /"\
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"DejaVU" wrote in message
...
Adam Smith scribed in please_look
:

On the very oldest samples of these horns, the piston's slots are
lathed, and only the 6 inner ribs hold the rest together. On the
^^^^^^^
crumbs, I thought only my 6 year old son said that!
the term is 'turned' in a lathe. lathe is a noun....

It's also a transitive verb, although we very rarely hear it used that way
in metalworking. It was used more often in the early part of the last
century to refer to decorative turned woodwork.

Ed Huntress

Ed Huntress scribed in
:

"DejaVU" wrote in message
are lathed, and only the 6 inner ribs hold the rest together.
On the
^^^^^^^
crumbs, I thought only my 6 year old son said that!
the term is 'turned' in a lathe. lathe is a noun....

It's also a transitive verb, although we very rarely hear it used
that way in metalworking. It was used more often in the early part
of the last century to refer to decorative turned woodwork.

Thanks Ed. I grew up speaking English every day, and still do, and
'lathed' just sounds wrong, and I have never seen it used anywhere
except by my 6 year old son who invented it because he didn't know
the correct term (but I told him straight away...)

swarf, steam and wind

--
David Forsyth -:- the email address is real /"\
http://terrapin.ru.ac.za/~iwdf/welcome.html \ /
ASCII Ribbon campaign against HTML E-Mail - - - - - - - X
If you receive email saying "Send this to everyone you know," / \
PLEASE pretend you don't know me.

"DejaVU" wrote in message
...
Ed Huntress scribed in
:

"DejaVU" wrote in message
are lathed, and only the 6 inner ribs hold the rest together.
On the
^^^^^^^
crumbs, I thought only my 6 year old son said that!
the term is 'turned' in a lathe. lathe is a noun....

It's also a transitive verb, although we very rarely hear it used
that way in metalworking. It was used more often in the early part
of the last century to refer to decorative turned woodwork.

Thanks Ed. I grew up speaking English every day, and still do, and
'lathed' just sounds wrong, and I have never seen it used anywhere
except by my 6 year old son who invented it because he didn't know
the correct term (but I told him straight away...)

You hear it occassionally from crafts people who don't have any industrial
background. It does sound wrong to our ears, but I guess it enjoyed a short
period of common usage.

--
Ed Huntress
(remove "3" from email address for email reply)

In article ,
Larry Jaques wrote:
On Wed, 3 Sep 2003 08:21:19 +0000 (UTC), DejaVU
pixelated:

[ ... ]

I just can't bear to watch people reverse-gerundize things like that.
I really can't.

P.S: Zaire's internet is still asleep. I can't get through to any
of your listed sites today. Wake her up, will ya?

I think that is South Africa, not Zaire. (Zud Africa, I think.)

Enjoy,
DoN.
--
Email: | Voice (all times): (703) 938-4564
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