I have sort of worked out the headstock which should spin things as low as
60 rpm.
I am kind of stuck with the tooling side: the carriage, crosslide etc.
One of the questions I am struggling with is the size of the tooling
appropriate for this job (turning disks up to 9" in diameter). Instinctively
I feel that a 3/16 tool is not going to cut it (sorry about the pun). But am
I right?

I have a boxful of 3/16 and 1/4" tools, toolholders with carbide inserts,
toolposts and something which I take to be a crosslide of some sort into
which all these things fit. They all look rather puny. Would they do a job
of truing up the edge of a 9"x 1/4" disk? Would they face it? Or should I
design around something more beefy? If so, how much more beefy?

--
Michael Koblic,
Campbell River, BC

Michael Koblic wrote:
I have sort of worked out the headstock which should spin things as
low as 60 rpm.
I am kind of stuck with the tooling side: the carriage, crosslide etc.
One of the questions I am struggling with is the size of the tooling
appropriate for this job (turning disks up to 9" in diameter).
Instinctively I feel that a 3/16 tool is not going to cut it (sorry
about the pun). But am I right?

I have a boxful of 3/16 and 1/4" tools, toolholders with carbide
inserts, toolposts and something which I take to be a crosslide of
some sort into which all these things fit. They all look rather puny.
Would they do a job of truing up the edge of a 9"x 1/4" disk? Would
they face it? Or should I design around something more beefy? If so,
how much more beefy?

I'm using 1/4" cutters with a lantern toolpost , they should cut anything
your lathe has the power to machine . You might want to check what the tool
bits are made of , HSS is OK , but cobalt steel is better . I'm using 5% and
8% cobalt ( M35 and M42 ?) cutters , they'll do just about everything I need
.. What they won't cut , the brazed carbides will . Start out light , low ,
and slow ... light cuts at a low feed rate and slow spindle speeds .
--
Snag
every answer
leads to another
question

"Michael Koblic" wrote in message
...
I have sort of worked out the headstock which should spin things as low as
60 rpm.
I am kind of stuck with the tooling side: the carriage, crosslide etc.
One of the questions I am struggling with is the size of the tooling
appropriate for this job (turning disks up to 9" in diameter).
Instinctively I feel that a 3/16 tool is not going to cut it (sorry about
the pun). But am I right?

One of the things of concern is a tool's ability to handle heat. Small
tools dissipate less heat, thus are prone to overheating, and failure.
Same goes for the grind of the tool. Too slender of a cutting edge can also
lead to premature tool failure (assuming HSS).

If you were to machine steel at recommended speeds and feeds, using brazed
carbide, it's possible you could actually soften the silver solder to the
point of tip failure when running small shank tools. Use the largest you
can accommodate, especially if you can move up to 1/2" sizes. They are far
more robust, and should serve better than small tools. Their greater
thickness of carbide, and larger size, are a good offset for the higher
price you will pay. The added rigidity is a bonus.

Harold

I have a boxful of 3/16 and 1/4" tools, toolholders with carbide inserts,
toolposts and something which I take to be a crosslide of some sort into
which all these things fit. They all look rather puny. Would they do a job
of truing up the edge of a 9"x 1/4" disk? Would they face it? Or should I
design around something more beefy? If so, how much more beefy?

--
Michael Koblic,
Campbell River, BC

If you were to machine steel at recommended speeds and feeds, using brazed
carbide, it's possible you could actually soften the silver solder to the
point of tip failure when running small shank tools. *

Been there done that. It can cause an interesting experience if the
carbide gets trapped between the stock and the remaining shank.

JW

On Feb 9, 8:51*pm, "Michael Koblic" wrote:
I have sort of worked out the headstock which should spin things as low as
60 rpm.
I am kind of stuck with the tooling side: the carriage, crosslide etc.
One of the questions I am struggling with is the size of the tooling
appropriate for this job (turning disks up to 9" in diameter). Instinctively
I feel that a 3/16 tool is not going to cut it (sorry about the pun). But am
I right?

I have a boxful of 3/16 and 1/4" tools, toolholders with carbide inserts,
toolposts and something which I take to be a crosslide of some sort into
which all these things fit. They all look rather puny. Would they do a job
of truing up the edge of a 9"x 1/4" disk? Would they face it? Or should I
design around something more beefy? If so, how much more beefy?

--
Michael Koblic,
Campbell River, BC

Context? Are you building the redneck lathe?

The 3/4 HP available on my lathe hasn't burned or broken 1/4" HSS bits
yet, possibly because I keep the belts somewhat loose.

Jim Wilkins

Jim Wilkins wrote:

Context? Are you building the redneck lathe?

The 3/4 HP available on my lathe hasn't burned or broken 1/4" HSS bits
yet, possibly because I keep the belts somewhat loose.

You know me far too well!

I just had a go with a jury-rigged system just to see how things behave. I
have had good results with doing the edges by an improvised grinding post
(read: Dremel) but facing is still an issue.

Not needing a tailstock makes things considerably easier. I have an idea of
a crosslide based on $9 drill press vise but before I design it completely I
wanted to make sure that all that little tooling I have in the drawer is
useable in this application.

--
Michael Koblic,
Campbell River, BC

On Feb 10, 9:03*pm, "Michael Koblic" wrote:
Jim Wilkins wrote:
Context? Are you building the redneck lathe?

The 3/4 HP available on my lathe hasn't burned or broken 1/4" HSS bits
yet, possibly because I keep the belts somewhat loose.

You know me far too well!

I just had a go with a jury-rigged system just to see how things behave. I
have had good results with doing the edges by an improvised grinding post
(read: Dremel) but facing is still an issue.

Not needing a tailstock makes things considerably easier. I have an idea of
a crosslide based on $9 drill press vise but before I design it completely I
wanted to make sure that all that little tooling I have in the drawer is
useable in this application.

--
Michael Koblic,
Campbell River, BC

I started off by milling on the drill press with a cheap X-Y vise. It
worked as poorly as others have said on metal but was OK for making
plastic electrical connector housings. The vise as bought was a flock
of crudely machined parts flying in loose formation. The cast iron was
soft enough to file and stone smooth and carefully adjust to a better
fit without tight or loose spots. I "lapped" the slides with fine SiC
sandpaper.

One of the reasons I suggested Holtzapffel was to show you how
serviceable lathes were made without accurate machined ways in the
early 1800's. The cross slide was a bolt-on accessory that was aligned
to the spindle axis with a simple jig or test bar. For instance if you
want the vise jaw opening perpendicular to the spindle to hold a tool
bit, clamp a long straight bar and tap it parallel to the face plate,
or tram it like a mill. This should align the X and Y axis with the
spindle. You could make a sheet-metal gage that rests on the ways with
a shelf at center height to set tool bits easily.

When I design a machine or a circuit or a program I break it up into
modules first and try to clearly define and minimize their
interaction, without too much concern for the internal details except
for any difficult ones, i.e. the critical path. For a machine I build
the frame and provide a nice flat solid mounting surface wherever I'll
need to add something later. Each module can be assembled and tested
in order of importance and any changes added to the spec list for the
next assembly.

Sometimes a wooden model helps. I made one for my front end loader's
frame to determine clearance for the front wheels and steering
linkage, and assembled the sawmill wheels on 2X4s first before welding
the steel frame.

Jim Wilkins

Jim Wilkins wrote:
... The vise as bought was a flock
of crudely machined parts flying in loose formation. ...

I love it! What wonderful imagery.

Bob

Jim Wilkins wrote:
I started off by milling on the drill press with a cheap X-Y vise. It
worked as poorly as others have said on metal but was OK for making
plastic electrical connector housings. The vise as bought was a flock
of crudely machined parts flying in loose formation. The cast iron was
soft enough to file and stone smooth and carefully adjust to a better
fit without tight or loose spots. I "lapped" the slides with fine SiC
sandpaper.

For $9 I am expecting something very similar. As usual, it has to come from
Calgary...

One of the reasons I suggested Holtzapffel was to show you how
serviceable lathes were made without accurate machined ways in the
early 1800's. The cross slide was a bolt-on accessory that was aligned
to the spindle axis with a simple jig or test bar. For instance if you
want the vise jaw opening perpendicular to the spindle to hold a tool
bit, clamp a long straight bar and tap it parallel to the face plate,
or tram it like a mill. This should align the X and Y axis with the
spindle. You could make a sheet-metal gage that rests on the ways with
a shelf at center height to set tool bits easily.

Great minds (and mine, sometimes) think alike! That is the sort of thing I
am planning. The additional advantages I have over proper machinists are the
absence of necessity to do things to tight tolerances (BTW what are all
those zeros after the decimal point on my calipers for?) and sufficient time
to work on a piece.

BTW Holztapffel is a source of constant inspiration.

When I design a machine or a circuit or a program I break it up into
modules first and try to clearly define and minimize their
interaction, without too much concern for the internal details except
for any difficult ones, i.e. the critical path. For a machine I build
the frame and provide a nice flat solid mounting surface wherever I'll
need to add something later. Each module can be assembled and tested
in order of importance and any changes added to the spec list for the
next assembly.

I am trying to follow a similar path: However, one needs to keep in mind the
project as a whole, all aspects of it, physical, social and economical
included. As I mentioned I think the headstock concept is sorted *but* I do
not want to spend a lot of time and money on it if the concept of tool
application is vague. To exaggerate somewhat, it would make no sense to go
ahead and build the headstock for $100 only to realize that the crosslide
etc. will require additional $500 to complete. I might as well save me some
time and buy the whole thing ready made. Interestingly, I saw some economic
analysis of home-built machine tooling and the sums were more or less
identical to the cost of lower end commercially available machinery. I am
hoping to avoid that pitfall through my incredible ingenuity and foresight.
Failing that, denial.

Sometimes a wooden model helps. I made one for my front end loader's
frame to determine clearance for the front wheels and steering
linkage, and assembled the sawmill wheels on 2X4s first before welding
the steel frame.

The wooden version 1.01 is in operation, version 1.02 should be in progress
tomorrow depending on supplies delivery. BTW has anyone noticed lack of
scrap at local scrap yards? Ours was nearly empty today.

When your wife begins to scream at you: "For God's sake buy the bloody lathe
already!" you know you have become a bit of a bore on the subject (of course
the threat of being asked to turn various handles and her need for a new
iPod go some way to explain this laxity of fiscal policy). Still, I propose
to give it the last shot before I cave in.

--
Michael Koblic,
Campbell River, BC

On Feb 11, 8:42*pm, "Michael Koblic" wrote:
...Interestingly, I saw some economic
analysis of home-built machine tooling and the sums were more or less
identical to the cost of lower end commercially available machinery. I am
hoping to avoid that pitfall through my incredible ingenuity and foresight.

In article ,
"Michael Koblic" wrote:

Jim Wilkins wrote:
I started off by milling on the drill press with a cheap X-Y vise. It
worked as poorly as others have said on metal but was OK for making
plastic electrical connector housings. The vise as bought was a flock
of crudely machined parts flying in loose formation. The cast iron was
soft enough to file and stone smooth and carefully adjust to a better
fit without tight or loose spots. I "lapped" the slides with fine SiC
sandpaper.

For $9 I am expecting something very similar. As usual, it has to come from
Calgary...

One of the reasons I suggested Holtzapffel was to show you how
serviceable lathes were made without accurate machined ways in the
early 1800's. The cross slide was a bolt-on accessory that was aligned
to the spindle axis with a simple jig or test bar. For instance if you
want the vise jaw opening perpendicular to the spindle to hold a tool
bit, clamp a long straight bar and tap it parallel to the face plate,
or tram it like a mill. This should align the X and Y axis with the
spindle. You could make a sheet-metal gage that rests on the ways with
a shelf at center height to set tool bits easily.

Great minds (and mine, sometimes) think alike! That is the sort of thing I
am planning. The additional advantages I have over proper machinists are the
absence of necessity to do things to tight tolerances (BTW what are all
those zeros after the decimal point on my calipers for?) and sufficient time
to work on a piece.

BTW Holztapffel is a source of constant inspiration.

When I design a machine or a circuit or a program I break it up into
modules first and try to clearly define and minimize their
interaction, without too much concern for the internal details except
for any difficult ones, i.e. the critical path. For a machine I build
the frame and provide a nice flat solid mounting surface wherever I'll
need to add something later. Each module can be assembled and tested
in order of importance and any changes added to the spec list for the
next assembly.

I am trying to follow a similar path: However, one needs to keep in mind the
project as a whole, all aspects of it, physical, social and economical
included. As I mentioned I think the headstock concept is sorted *but* I do
not want to spend a lot of time and money on it if the concept of tool
application is vague. To exaggerate somewhat, it would make no sense to go
ahead and build the headstock for $100 only to realize that the crosslide
etc. will require additional $500 to complete. I might as well save me some
time and buy the whole thing ready made. Interestingly, I saw some economic
analysis of home-built machine tooling and the sums were more or less
identical to the cost of lower end commercially available machinery. I am
hoping to avoid that pitfall through my incredible ingenuity and foresight.
Failing that, denial.

Sometimes a wooden model helps. I made one for my front end loader's
frame to determine clearance for the front wheels and steering
linkage, and assembled the sawmill wheels on 2X4s first before welding
the steel frame.

The wooden version 1.01 is in operation, version 1.02 should be in progress
tomorrow depending on supplies delivery. BTW has anyone noticed lack of
scrap at local scrap yards? Ours was nearly empty today.

When your wife begins to scream at you: "For God's sake buy the bloody lathe
already!" you know you have become a bit of a bore on the subject (of course
the threat of being asked to turn various handles and her need for a new
iPod go some way to explain this laxity of fiscal policy). Still, I propose
to give it the last shot before I cave in.

The truth emerges at last - it's all a scheme to convince the CDFO to
allow the purchase.

Joe Gwinn

"Michael Koblic" wrote in message
...
I have sort of worked out the headstock which should spin things as low as
60 rpm.
I am kind of stuck with the tooling side: the carriage, crosslide etc.
One of the questions I am struggling with is the size of the tooling
appropriate for this job (turning disks up to 9" in diameter).
Instinctively I feel that a 3/16 tool is not going to cut it (sorry about
the pun). But am I right?

I have a boxful of 3/16 and 1/4" tools, toolholders with carbide inserts,
toolposts and something which I take to be a crosslide of some sort into
which all these things fit. They all look rather puny. Would they do a job
of truing up the edge of a 9"x 1/4" disk? Would they face it? Or should I
design around something more beefy? If so, how much more beefy?

--
Michael Koblic,
Campbell River, BC

It's probably related more to HP than swing, and how much of your lathes HP
are you really using. You can do a LOT of very useful work with 3/16 and
especially 1/4 tools.

On 2009-02-10, Michael Koblic wrote:
I have sort of worked out the headstock which should spin things as low as
60 rpm.
I am kind of stuck with the tooling side: the carriage, crosslide etc.
One of the questions I am struggling with is the size of the tooling
appropriate for this job (turning disks up to 9" in diameter). Instinctively
I feel that a 3/16 tool is not going to cut it (sorry about the pun). But am
I right?

What *material* do you expect to cut? A 3/16" tool would be
fine for aluminum or brass. A bit marginal with bronze, and quite
questionable for steel -- especially tough steel. (This is assuming
that you are talking about the shank of tools mounted in a quick-change
toolpost. In the old style lantern tool post and the forged holders,
1/4 HSS bits would probably be within reason, as the toolpost and holder
offer more give than the tool itself does.

I have a boxful of 3/16 and 1/4" tools, toolholders with carbide inserts,
toolposts and something which I take to be a crosslide of some sort into
which all these things fit. They all look rather puny. Would they do a job
of truing up the edge of a 9"x 1/4" disk? Would they face it? Or should I
design around something more beefy? If so, how much more beefy?

I would judge based on the standard tool holders for a
quick-change toolpost sized to fit the machine. A 9" lathe by South
Bend for example would use an AXA sized quick change toolpost, and the
standard holders for that accept up to 1/2" shanks. I'm using a 12"
swing Clausing, and I use the BXA toolpost which accepts 5/16" shanks in
the standard holders. Larger machines (say 15" swing) would use CXA
which will accept 3/4" shanks. These are pretty much scaled for the
load which the machine will put on them.

FWIW -- my 12" Clausing will go down to 35 RPM in back gear, and
to 210 RPM in direct drive. Most of the time, for what I do with steel,
when I'm in back gear I typically am at the middle speed -- 100 RPM,
though I am likely to go all the way down to 35 RPM when knurling steel.

But all of this assumes that the bed, the cross-slide, and the
compound are made proportional to the swing. Since you appear to be
considering making your own, you need to know how stiff these parts are
made first.

Enjoy,
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 ---

DoN. Nichols wrote:
What *material* do you expect to cut?

Mild steel and brass.

A 3/16" tool would be
fine for aluminum or brass. A bit marginal with bronze, and quite
questionable for steel -- especially tough steel. (This is assuming
that you are talking about the shank of tools mounted in a
quick-change toolpost. In the old style lantern tool post and the
forged holders, 1/4 HSS bits would probably be within reason, as the
toolpost and holder offer more give than the tool itself does.

This has not been finalized by any means. This is the sort of concept I have
in mind:

http://www.majosoft.com/metalworking..._toolpost.html

Not quite sure where the "quick change" comes into it.

I have a boxful of 3/16 and 1/4" tools, toolholders with carbide
inserts, toolposts and something which I take to be a crosslide of
some sort into which all these things fit. They all look rather
puny. Would they do a job of truing up the edge of a 9"x 1/4" disk?
Would they face it? Or should I design around something more beefy?
If so, how much more beefy?

I would judge based on the standard tool holders for a
quick-change toolpost sized to fit the machine. A 9" lathe by South
Bend for example would use an AXA sized quick change toolpost, and the
standard holders for that accept up to 1/2" shanks. I'm using a 12"
swing Clausing, and I use the BXA toolpost which accepts 5/16" shanks
in the standard holders. Larger machines (say 15" swing) would use
CXA which will accept 3/4" shanks. These are pretty much scaled for
the load which the machine will put on them.

FWIW -- my 12" Clausing will go down to 35 RPM in back gear, and
to 210 RPM in direct drive. Most of the time, for what I do with
steel, when I'm in back gear I typically am at the middle speed --
100 RPM, though I am likely to go all the way down to 35 RPM when
knurling steel.

At this point my wife can crank the handle at 120 rpm but will slow down if
asked nicely.

But all of this assumes that the bed, the cross-slide, and the
compound are made proportional to the swing. Since you appear to be
considering making your own, you need to know how stiff these parts
are made first.

This is being currently determined by experiments. The small version - not
very. Produced an interesting pattern of chatter marks on the face. Perhaps
useful in future but not what I was looking for immediately.

--
Michael Koblic,
Campbell River, BC

On 2009-02-11, Michael Koblic wrote:
DoN. Nichols wrote:
What *material* do you expect to cut?

Mild steel and brass.

A 3/16" tool would be
fine for aluminum or brass. A bit marginal with bronze, and quite
questionable for steel -- especially tough steel. (This is assuming
that you are talking about the shank of tools mounted in a
quick-change toolpost. In the old style lantern tool post and the
forged holders, 1/4 HSS bits would probably be within reason, as the
toolpost and holder offer more give than the tool itself does.

This has not been finalized by any means. This is the sort of concept I have
in mind:

http://www.majosoft.com/metalworking..._toolpost.html

Not quite sure where the "quick change" comes into it.

O.K. The "Quick change" here comes from the fact that you have
multiple blocks each with a specific tool mounted in it. The upright
screw near the gold colored post in the drawing at the top sets how high
the tip of the tool is from the surface of the compound. The
counterbore mounted screw at the lower right-hand corner clamps the
block at the split to grip the gold colored cylinder post. So -- you
can loosen the crew a quarter turn, lift the tool off the post, and put
another one on there which is already preset for its height and clamp
the screw in it.

What is missing here is provisions for making sure that each
tool holder slid onto the post is in the same position -- especially so
when you replace a tool holder which you removed earlier in the project
it will have its tip in the same position.

There seem to be provisions to prevent the post itself from
turning, but nothing to assure that the holders always go on in the same
position. So -- for my purposes, it is only part of a quick-change
toolpost.

It does avoid having to put a stack of shim stock under each
tool to raise it to the right height, so that is a major benefit from it
(also present in the Aloris style quick change toolposts which also
assure the position of the tool is always the same.)

Anyway -- if the tools can be used with very little extension,
as shown in the drawing you can get away with bits with smaller shanks,
other than the question of heat transfer which another mentioned.

Note that he frequently says "bold" when he means "bolt", but
that English is not his native language, so it takes a bit of knowledge
to interpret what he says in places.

It looks as though he has the information in several languages,
which makes it an even more impressive task.

[ ... ]

FWIW -- my 12" Clausing will go down to 35 RPM in back gear, and
to 210 RPM in direct drive. Most of the time, for what I do with
steel, when I'm in back gear I typically am at the middle speed --
100 RPM, though I am likely to go all the way down to 35 RPM when
knurling steel.

At this point my wife can crank the handle at 120 rpm but will slow down if
asked nicely.

But -- can she keep up that 120 RPM if you are taking a deep cut
at an 8" radius? :-)

But all of this assumes that the bed, the cross-slide, and the
compound are made proportional to the swing. Since you appear to be
considering making your own, you need to know how stiff these parts
are made first.

This is being currently determined by experiments. The small version - not
very. Produced an interesting pattern of chatter marks on the face. Perhaps
useful in future but not what I was looking for immediately.

O.K.

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 ---

DoN. Nichols wrote:

Not quite sure where the "quick change" comes into it.

O.K. The "Quick change" here comes from the fact that you have
multiple blocks each with a specific tool mounted in it.

big snip

So -- for my purposes, it is only part of a
quick-change toolpost.

I thought I only saw position for one tool hence my doubt about the changes
being all that quick. I can understand when you have four of them.

It does avoid having to put a stack of shim stock under each
tool to raise it to the right height, so that is a major benefit from
it (also present in the Aloris style quick change toolposts which also
assure the position of the tool is always the same.)

The speed of change is not a priority for me, so I can take my time
shimming. It should simplify the design considerably.

Anyway -- if the tools can be used with very little extension,
as shown in the drawing you can get away with bits with smaller
shanks, other than the question of heat transfer which another
mentioned.

I think I can get quite close. The one problem is workholding: The steel
doughnuts are easy to work on the inside edge (boring bar, I think), outside
edge (several methods including my very own red Neck lathe gave good
results) but holding to be able to get to the whole face is a bit tricky. At
this point I have the doughnut on a sort of wooden face plate and it is held
to it by a wooden plug which is ever so slightly conical. Thus it holds the
doughnut through the central hole but does not overhang enough to stop the
tool getting to the whole area of the face. However, with toolposts,
toolholders and crosslide it may be less easy. I am thinking going back to
the double-sided sticky tape with a thin boss sticking out of the centre of
the faceplate to allow indexing and centering. My other thought is magnets
and a similar central boss - it works with the angle grinder...

Of course this will mean making a different faceplate for different
doughnuts but so be it. Another option is to look at central holding by a
3-jaw chuck but I suspect it wil not be a free lunch either.

At this point my wife can crank the handle at 120 rpm but will slow
down if asked nicely.

But -- can she keep up that 120 RPM if you are taking a deep cut
at an 8" radius? :-)

Training is everything. An a new iPod...

--
Michael Koblic,
Campbell River, BC

On 2009-02-13, Michael Koblic wrote:
DoN. Nichols wrote:

Not quite sure where the "quick change" comes into it.

O.K. The "Quick change" here comes from the fact that you have
multiple blocks each with a specific tool mounted in it.

big snip

So -- for my purposes, it is only part of a
quick-change toolpost.

I thought I only saw position for one tool hence my doubt about the changes
being all that quick. I can understand when you have four of them.

It one tool per block -- and multiple blocks which slide onto
the cylindrical post which mounts on the lathe's compound.

The screw which adjusts the height of the tool would be right
only for one tool even if you had slots four four tools like a turret
toolpost. So -- each holder has its own height adjusting screw, and
when you change tools, each one lands at the proper height -- assuming
that you set it properly when the tool was first put in the holder. (I
do not remember seeing a lock nut for the height screw, but one really
should be there.

It does avoid having to put a stack of shim stock under each
tool to raise it to the right height, so that is a major benefit from
it (also present in the Aloris style quick change toolposts which also
assure the position of the tool is always the same.)

The speed of change is not a priority for me, so I can take my time
shimming. It should simplify the design considerably.

Hmm ... maybe you should look at a turret toolpost. It has four
slots, and can hold four tools (if all the same orientation, or three
tools if one is set to bore or face because they would otherwise
interfere with each other.

A turret style toolpost is fairly easy to make. Square up a
block of steel, mill four slots at the right height so the cutting edge
of the tool can be raised to the right height with only a few shims.
Drill three holes from the top for screws to lock the tools into the
slots, and drill a larger central hole about which the post pivots when
the locking nut is loosened.

Anyway -- if the tools can be used with very little extension,
as shown in the drawing you can get away with bits with smaller
shanks, other than the question of heat transfer which another
mentioned.

I think I can get quite close. The one problem is workholding: The steel
doughnuts are easy to work on the inside edge (boring bar, I think), outside
edge (several methods including my very own red Neck lathe gave good
results) but holding to be able to get to the whole face is a bit tricky. At
this point I have the doughnut on a sort of wooden face plate and it is held
to it by a wooden plug which is ever so slightly conical. Thus it holds the
doughnut through the central hole but does not overhang enough to stop the
tool getting to the whole area of the face. However, with toolposts,
toolholders and crosslide it may be less easy. I am thinking going back to
the double-sided sticky tape with a thin boss sticking out of the centre of
the faceplate to allow indexing and centering. My other thought is magnets
and a similar central boss - it works with the angle grinder...

Hmm ... what I would suggest is that you get a three-jaw chuck
with two-piece jaws, then pick up a set of soft jaws to fit in place of
the hardened top jaws.

Tighten it onto perhaps a 1/2" diameter bar, and turn the jaws
leaving a projection a little thinner than the workpiece is to be near
the outside end for the smallest plate which you wish to face. Then you
can accommodate several larger sizes with the same set of top jaws just
by opening the chuck more. (Needless to say, the 1/2" diameter bar does
not remain in the chuck while you are using it -- it is only to set the
position of the jaws while you bore and face them.

Of course this will mean making a different faceplate for different
doughnuts but so be it. Another option is to look at central holding by a
3-jaw chuck but I suspect it wil not be a free lunch either.

Central holding will be better (once you have the center hole
bored), but it will be difficult to face right up to the chuck jaws.
Maybe a second set of soft jaws, turned to have a step to hold from the
inside instead. This way, the rest of the jaw's surface supports the
workpiece, so it is less likely to ring like a bell while you are
turning.

Magnets are used to hold workpieces which are being ground, but
don't have enough grip to handle workpieces which are being turned. The
forces are a lot higher.

At this point my wife can crank the handle at 120 rpm but will slow
down if asked nicely.

But -- can she keep up that 120 RPM if you are taking a deep cut
at an 8" radius? :-)

Training is everything. An a new iPod...

:-)

Enjoy,
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 Feb 11, 1:43*am, "Michael Koblic" wrote:

http://www.majosoft.com/metalworking..._toolpost.html

Interesting link. I don't know how the author came up with that
design, but you might want to look at the KRF Omnipost, http://www.krfcompany.com/

On Feb 12, 10:10*am, woodworker88 wrote:
On Feb 11, 1:43*am, "Michael Koblic" wrote:

http://www.majosoft.com/metalworking..._toolpost.html

Interesting link. *I don't know how the author came up with that
design, but you might want to look at the KRF Omnipost,http://www.krfcompany.com/

The old lantern / rocker / American style tool post is easy to make
out of a large bolt and much less fussy to use if you mill riser
blocks that locate tool bits or Armstrong-type holders at the correct
height. Don't grind any top rake on the tool bits so the cutting edge
stays at the same level. They won't cut as freely but they will be
less likely to dig in, which is valuable on a flexible home-made
machine.

Jim wilkins

Jim Wilkins wrote:

The old lantern / rocker / American style tool post is easy to make
out of a large bolt and much less fussy to use if you mill riser
blocks that locate tool bits or Armstrong-type holders at the correct
height. Don't grind any top rake on the tool bits so the cutting edge
stays at the same level. They won't cut as freely but they will be
less likely to dig in, which is valuable on a flexible home-made
machine.

After scurrying to Google to see what these things look like I am not
entirely clear on the advantages of the lantern type holder: Is it because
they can accommodate different styles of tools at different heights (needing
the risers as you mentioned)? Are the tools held at a different angle from
the quick change toolpost? I thought they were both essentially horizontal.

Also, the way the toolbits ar held in the respective toolposts suggests that
the QC holds the bits more rigidly. In the lantern type there is a sort of
fulcrum where the holding screw comes down on the bit. Are you saying this
is actually an advantage in a floppy machine?

--
Michael Koblic,
Campbell River, BC