How much rotation ability is required or useful in a toolholder on a
lathe?

Here are my thoughts so far; please let me know what I have gotten
wrong or have neglected.

Small rotation can be used to line up a thread tool or other form tool
accurately.

Small rotation can be used to adjust side cutting angle.

There are a few exotic screw-cutting bits that require a 30 degree
(counter-clockwise from above) rotation.

Fairly large rotation might be needed to get some kinds of bit into
the corner of a shoulder cut.

There should be no need for rotation much beyond 45 degrees since the
same thing can be accomplished with less than 45 degree rotation from
the other side of the holder.

Large rotation counter-clockwise from above will bring a corner of the
holder toward the work, and will bring the cutting bit further from
the work, so a large bit extension might be required. A special holder
with an angled mount for the tool might be better.

Large rotation clockwise from above will bring a back corner of the
holder toward the chuck, where it might get hit.

Bob

Bob S fired this volley in
:

How much rotation ability is required or useful in a toolholder on a
lathe?

No limit, Bob. An Aloris-style toolholder rotates freely. It allows quick
and easy alignment of the tool anywhere you need it.

Since full rotation is actually easier to provide than some sort of
"stopped' rotation, why would you want anything less than that?

LLoyd

"Bob S" wrote in message
...
How much rotation ability is required or useful in a toolholder on a
lathe?

Here are my thoughts so far; please let me know what I have gotten
wrong or have neglected.

Small rotation can be used to line up a thread tool or other form
tool
accurately.

Small rotation can be used to adjust side cutting angle.

There are a few exotic screw-cutting bits that require a 30 degree
(counter-clockwise from above) rotation.

Fairly large rotation might be needed to get some kinds of bit into
the corner of a shoulder cut.

There should be no need for rotation much beyond 45 degrees since
the
same thing can be accomplished with less than 45 degree rotation
from
the other side of the holder.

Large rotation counter-clockwise from above will bring a corner of
the
holder toward the work, and will bring the cutting bit further from
the work, so a large bit extension might be required. A special
holder
with an angled mount for the tool might be better.

Large rotation clockwise from above will bring a back corner of the
holder toward the chuck, where it might get hit.

Bob

I have a Multifix tool post which rotates 360 degrees in 40 steps of 9
degrees.
http://www.anglo-swiss-tools.co.uk/tool-posts.html

Rotating the holder is useful with hand-ground HSS bits when cutting
both a diameter and a shoulder, but I've placed it only square to the
work with carbide, or boring bars.

Chinese toolholders fit the Swiss center post fine.
jsw

I'm not sure why you ask, but-----

I use an "aloris style" quick change toolpost/holder. It has dovetails for
the actual tool holders that are 90° apart. I am constantly swinging it a
lot. I have several tool holders for it that have a bit sticking out both
ends, so I have to swing the toolpost around a lot.
I guess I need at least 180° of rotation.

Pete Stanaitis
-----------------

On 2014-03-29, Bob S wrote:
How much rotation ability is required or useful in a toolholder on a
lathe?

Here are my thoughts so far; please let me know what I have gotten
wrong or have neglected.

Small rotation can be used to line up a thread tool or other form tool
accurately.

Small rotation can be used to adjust side cutting angle.

There are a few exotic screw-cutting bits that require a 30 degree
(counter-clockwise from above) rotation.

The tools which I use benefit from having one face of a
quick-change toolpost (e.g. Aloris) parallel to the face of the chuck,
and the other parallel to the axis of the workpiece.

This assures that the insert tooling for threading is in the
proper position, and that turning and facing tools (e.g. the Aloris
BXA-16N) have their working edge almost at right angles to the direction
of travel during the cut. For turning, the tip very slightly leads the
rest of the side, so when you halt at a given location and switch to
cross-feed from lateral feed, you get a nice finish cut on the face left
by the previous cuts.

Also, the knurling tool is sensitive to angle, and is best used
with the faces of the knurls parallel to the axis of the workpiece.

This also means that a boring bar holder will have the boring
bar parallel to the axis, so if the tool tip is touching to cut, the
rest of the boring bar will clear the workpiece -- assuming that it is
not too large for the hole in question.

I have, in addition to this, two holders which hold the inserts
at about 60 degrees, so they look like an oversized threading tool.
These are useful for breaking (beveling) corners after the main work is
done -- without ever needing to shift the toolpost itself.

The only time I need to shift the toolpost (other than when it
has been removed to replace it with a toolpost grinder or something
else) is when I shift the compound angle from 29.5 degrees (normally
60-degree V threads) to something else, such as 14 degrees for Acme
threading, or other angles for weird threads, e.g. the 55 degree
Whitworth threads.) So -- when I shift the compound angle, I reset the
toolpost to again be parallel to the chuck face and the workpiece axis.

Fairly large rotation might be needed to get some kinds of bit into
the corner of a shoulder cut.

Selected by the bit and the holder, not by rotating the
toolpost. Aloris has some insert holders in which the insert part can
be set in 15 degree increments to produce a reasonable tool angle for
whatever you want to do. Again -- without having to move the toolpost.

There should be no need for rotation much beyond 45 degrees since the
same thing can be accomplished with less than 45 degree rotation from
the other side of the holder.

Agreed -- assuming that you need the rotation at all. I find
that I prefer the tool holder to stay in the same position. If it were
not for the occasional adjustment for the weird threads, I would drill
the compound and the toolpost for a dowel pin, so it would always go
back on at the same angle.

Large rotation counter-clockwise from above will bring a corner of the
holder toward the work, and will bring the cutting bit further from
the work, so a large bit extension might be required. A special holder
with an angled mount for the tool might be better.

Large rotation clockwise from above will bring a back corner of the
holder toward the chuck, where it might get hit.

So -- look at the Aloris holders which have the adjustable
insert holders -- and (almost) never touch the toolpost itself.

Just my own preference here.

I think that the habit of rotating the toolpost comes from the
old days of the Lantern style toolposts -- where every time you changed
a tool, you had to re-adjust all the angles prior to clamping it down
again.

Enjoy,
DoN.

--
Remove oil spill source from e-mail
Email: | (KV4PH) 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 2014-03-29, Pete S wrote:
I'm not sure why you ask, but-----

I use an "aloris style" quick change toolpost/holder. It has dovetails for
the actual tool holders that are 90° apart. I am constantly swinging it a
lot. I have several tool holders for it that have a bit sticking out both
ends, so I have to swing the toolpost around a lot.
I guess I need at least 180° of rotation.

While I also use an Aloris style, and I keep it locked down with
one dovetail parallel to the chuck face, and the other parallel to the
workpiece axis.

If you are putting two tools in a single holder (I don't, as
this usually requires re-adjusting the tool height when you swap between
ends), put one turning tool and one facing tool in the holder, so when
you switch from the side dovetail to the front dovetail the tool is
already at the proper angle -- no need to shift the toolpost. And
shifting it defeats the indexable tools idea, where you always have the
tool at the same projection from the post. If you use one tool to do
something, and zero the dial with that tool, then shift to another which
does not require you to re-zero the dial (e.g. facing the workpiece),
if you have not shifted the toolpost, when you go back to the first
holder the dial is still correct for the next part to be turned to the
same diameter. If you have shifted the toolpost, you will have to
re-establish the zero for that tool when you come back to it.


As I mentioned in an earlier (slightly earlier) followup in this
thread, the only time I loosen the toolpost is when I'm resetting the
compound for threading at other than 60 degree threads -- or when
putting the toolpost back on after using something like a toolpost
grinder.

Different ways for different people. :-)

Enjoy,
DoN.

--
Remove oil spill source from e-mail
Email: | (KV4PH) 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 in message
...
On 2014-03-29, Bob S wrote:
How much rotation ability is required or useful in a toolholder on a
lathe?

Here are my thoughts so far; please let me know what I have gotten
wrong or have neglected.

Small rotation can be used to line up a thread tool or other form tool
accurately.

Small rotation can be used to adjust side cutting angle.

There are a few exotic screw-cutting bits that require a 30 degree
(counter-clockwise from above) rotation.

The tools which I use benefit from having one face of a
quick-change toolpost (e.g. Aloris) parallel to the face of the chuck,
and the other parallel to the axis of the workpiece.

This assures that the insert tooling for threading is in the
proper position, and that turning and facing tools (e.g. the Aloris
BXA-16N) have their working edge almost at right angles to the direction
of travel during the cut. For turning, the tip very slightly leads the
rest of the side, so when you halt at a given location and switch to
cross-feed from lateral feed, you get a nice finish cut on the face left
by the previous cuts.

Also, the knurling tool is sensitive to angle, and is best used
with the faces of the knurls parallel to the axis of the workpiece.

Interesting. I always thought that a knurling tool was used at a very
slight angle to the work piece so that the teeth gradually cut in as you
advanced the Z axis feed.

On 3/29/2014 21:32, Bob S wrote:
How much rotation ability is required or useful in a toolholder on a
lathe?

The problem in all machines, whether it is a mill or a lathe,
is that if you have adjustable angle part, it can be off from
90 degrees (or whatever the normal setting). Perhaps it went
off last time you took a rough cut? You have to always check it.

In my early days with machinetools I though it is nice to have
adjustable things for doing those odd jobs, but I have changed
my mind regarding that. A two axis tiltable vice is just never
90 degrees, unless you spend a lot of time adjusting and measuring
it. Sure, it is nice when you need to machine the odd angled surface,
but all the other time it is a compromise compared to normal vice.
Same for bridgeport J head - it could have moved - while a sturdy mill
head with fixed angle is always at correct angle (or it is broken).
If at all possible, I nowadays have several vices etc. with different
degrees of rotation freedom - and use the one with minimum freedom
that does the job. Keeps me sane at reasonable cost.

My opinion: rotation is nice, but install some mechanism that keeps
the holder definitely at 90 degrees, when you don't want to rotate it.
(With reasonable accuracy for the job, nothing is precisily 90 degrees).

My quick-change holder has a long pin for that. After rotation (for
threading or whatever) install pin back to index it, and then
tighten the big-ass M20 nut that holds the quick-change holder body.
The pin prevents it from rotating when not wanted. The pin and its hole
have good enough fit that it really is quite close to correct angle.

Kristian Ukkonen.

On 30 Mar 2014 02:19:17 GMT, DoN. Nichols wrote:

On 2014-03-29, Bob S wrote:
How much rotation ability is required or useful in a toolholder on a
lathe?

Here are my thoughts so far; please let me know what I have gotten
wrong or have neglected.

Small rotation can be used to line up a thread tool or other form tool
accurately.

Small rotation can be used to adjust side cutting angle.

There are a few exotic screw-cutting bits that require a 30 degree
(counter-clockwise from above) rotation.

The tools which I use benefit from having one face of a
quick-change toolpost (e.g. Aloris) parallel to the face of the chuck,
and the other parallel to the axis of the workpiece.

This assures that the insert tooling for threading is in the
proper position, and that turning and facing tools (e.g. the Aloris
BXA-16N) have their working edge almost at right angles to the direction
of travel during the cut. For turning, the tip very slightly leads the
rest of the side, so when you halt at a given location and switch to
cross-feed from lateral feed, you get a nice finish cut on the face left
by the previous cuts.

Also, the knurling tool is sensitive to angle, and is best used
with the faces of the knurls parallel to the axis of the workpiece.

This also means that a boring bar holder will have the boring
bar parallel to the axis, so if the tool tip is touching to cut, the
rest of the boring bar will clear the workpiece -- assuming that it is
not too large for the hole in question.

I have, in addition to this, two holders which hold the inserts
at about 60 degrees, so they look like an oversized threading tool.
These are useful for breaking (beveling) corners after the main work is
done -- without ever needing to shift the toolpost itself.

The only time I need to shift the toolpost (other than when it
has been removed to replace it with a toolpost grinder or something
else) is when I shift the compound angle from 29.5 degrees (normally
60-degree V threads) to something else, such as 14 degrees for Acme
threading, or other angles for weird threads, e.g. the 55 degree
Whitworth threads.) So -- when I shift the compound angle, I reset the
toolpost to again be parallel to the chuck face and the workpiece axis.

Fairly large rotation might be needed to get some kinds of bit into
the corner of a shoulder cut.

Selected by the bit and the holder, not by rotating the
toolpost. Aloris has some insert holders in which the insert part can
be set in 15 degree increments to produce a reasonable tool angle for
whatever you want to do. Again -- without having to move the toolpost.

There should be no need for rotation much beyond 45 degrees since the
same thing can be accomplished with less than 45 degree rotation from
the other side of the holder.

Agreed -- assuming that you need the rotation at all. I find
that I prefer the tool holder to stay in the same position. If it were
not for the occasional adjustment for the weird threads, I would drill
the compound and the toolpost for a dowel pin, so it would always go
back on at the same angle.

Large rotation counter-clockwise from above will bring a corner of the
holder toward the work, and will bring the cutting bit further from
the work, so a large bit extension might be required. A special holder
with an angled mount for the tool might be better.

Large rotation clockwise from above will bring a back corner of the
holder toward the chuck, where it might get hit.

So -- look at the Aloris holders which have the adjustable
insert holders -- and (almost) never touch the toolpost itself.

Just my own preference here.

I think that the habit of rotating the toolpost comes from the
old days of the Lantern style toolposts -- where every time you changed
a tool, you had to re-adjust all the angles prior to clamping it down
again.

Enjoy,
DoN.

Thanks DoN for the clear explanation of the "no rotation" approach. It
sounds like "small rotation only for unusual threading, and everything
else handled by specialized holder". I suppose that if you did the
odd-angle threads often enough you could even make or buy a holder for
that angle, and never move the toolpost at all.

I can see that the Aloris-style holders and the carbide insert holders
seem to have undergone mutual evolution to work well together.

It looks like most of the same things could be done with HSS bits,
except for the 15 degree indexing insert holder trick.

Bob

On Sun, 30 Mar 2014 13:40:54 +0300, Kristian Ukkonen wrote:


On 3/29/2014 21:32, Bob S wrote:
How much rotation ability is required or useful in a toolholder on a
lathe?

The problem in all machines, whether it is a mill or a lathe,
is that if you have adjustable angle part, it can be off from
90 degrees (or whatever the normal setting). Perhaps it went
off last time you took a rough cut? You have to always check it.

In my early days with machinetools I though it is nice to have
adjustable things for doing those odd jobs, but I have changed
my mind regarding that. A two axis tiltable vice is just never
90 degrees, unless you spend a lot of time adjusting and measuring
it. Sure, it is nice when you need to machine the odd angled surface,
but all the other time it is a compromise compared to normal vice.
Same for bridgeport J head - it could have moved - while a sturdy mill
head with fixed angle is always at correct angle (or it is broken).
If at all possible, I nowadays have several vices etc. with different
degrees of rotation freedom - and use the one with minimum freedom
that does the job. Keeps me sane at reasonable cost.

My opinion: rotation is nice, but install some mechanism that keeps
the holder definitely at 90 degrees, when you don't want to rotate it.
(With reasonable accuracy for the job, nothing is precisily 90 degrees).

My quick-change holder has a long pin for that. After rotation (for
threading or whatever) install pin back to index it, and then
tighten the big-ass M20 nut that holds the quick-change holder body.
The pin prevents it from rotating when not wanted. The pin and its hole
have good enough fit that it really is quite close to correct angle.

Kristian Ukkonen.

Yes, I agree; an adjustable angle is likely to be a wrong angle...

A good mechanism for resetting it would be very helpful.

Bob

On Sat, 29 Mar 2014 16:45:11 -0500, Pete S wrote:

I'm not sure why you ask, but-----

Well, I was thinking about the contrast between the Aloris-style
square posts which are apparently intended to almost never rotate, and
the various round-post designs that apparently consider rotation as a
feature. I was wondering how each style worked out in practice and
whether people often wanted to rotate the non-rotating style, or never
rotated the rotating style.

I was also curious what would happen if there was an in-between style
of post that (for whatever reason) only allowed limited rotation;
would it be useable. That's why I was asking about the "requirements"
rather than the capability.

Certainly the popularity of the square-post style suggests that
rotation is not vital as long as the toolholders come in varieties
that include popular angles.



I use an "aloris style" quick change toolpost/holder. It has dovetails for
the actual tool holders that are 90° apart. I am constantly swinging it a
lot. I have several tool holders for it that have a bit sticking out both
ends, so I have to swing the toolpost around a lot.
I guess I need at least 180° of rotation.

Pete Stanaitis
-----------------




Wow, tools out both ends; that's one that I never heard of. I recall
reading about people who have tools on all four sides of a rotating
turret, and reading that they tend to acquire scars.

Bob

On Sat, 29 Mar 2014 17:23:41 -0400, Jim Wilkins wrote:


"Bob S" wrote in message
.. .
How much rotation ability is required or useful in a toolholder on a
lathe?

Here are my thoughts so far; please let me know what I have gotten
wrong or have neglected.

Small rotation can be used to line up a thread tool or other form
tool
accurately.

Small rotation can be used to adjust side cutting angle.

There are a few exotic screw-cutting bits that require a 30 degree
(counter-clockwise from above) rotation.

Fairly large rotation might be needed to get some kinds of bit into
the corner of a shoulder cut.

There should be no need for rotation much beyond 45 degrees since
the
same thing can be accomplished with less than 45 degree rotation
from
the other side of the holder.

Large rotation counter-clockwise from above will bring a corner of
the
holder toward the work, and will bring the cutting bit further from
the work, so a large bit extension might be required. A special
holder
with an angled mount for the tool might be better.

Large rotation clockwise from above will bring a back corner of the
holder toward the chuck, where it might get hit.

Bob

I have a Multifix tool post which rotates 360 degrees in 40 steps of 9
degrees.
http://www.anglo-swiss-tools.co.uk/tool-posts.html

Rotating the holder is useful with hand-ground HSS bits when cutting
both a diameter and a shoulder, but I've placed it only square to the
work with carbide, or boring bars.

Chinese toolholders fit the Swiss center post fine.
jsw


Thank you jsw

I have seen the fascinating Multifix. I assume that like most Swiss
things it works extremely smoothly and costs both arms and all legs.

So I guess that you find at least some unspecified amount of rotation
to be useful with HSS bits, and like DoN you only need it square for
carbide inserts.

Bob

On Sat, 29 Mar 2014 15:06:16 -0500, Lloyd E. Sponenburgh wrote:

Bob S fired this volley in
:

How much rotation ability is required or useful in a toolholder on a
lathe?

No limit, Bob. An Aloris-style toolholder rotates freely. It allows quick
and easy alignment of the tool anywhere you need it.

Since full rotation is actually easier to provide than some sort of
"stopped' rotation, why would you want anything less than that?

LLoyd

Well I admit that the question may seem a bit abstract.

Some types of holder systems are mostly intended to stay in one
position, like the Aloris. Yes, it can be rotated, but then you need
to re-align it if you want it square.

Some types of holder systems rotate in fixed amounts, like the
Multifix mentioned in another reply.

Some types of holder systems rotate completely freely, like any of the
DIY round-post systems.

I can certainly imagine ways to make a holder system that provides
only limited rotation, and it is possible that such a system might
offer some advantage in construction simplicity for example.

So I was curious about what is actually needed and useful, rather than
about specific systems.

Bob

"Bob S" wrote in message
...
On Sat, 29 Mar 2014 17:23:41 -0400, Jim Wilkins wrote:


Thank you jsw

I have seen the fascinating Multifix. I assume that like most Swiss
things it works extremely smoothly and costs both arms and all legs.

So I guess that you find at least some unspecified amount of
rotation
to be useful with HSS bits, and like DoN you only need it square for
carbide inserts.

Bob

The toolholder has to be square for parting, knurling, boring and
threading too.

If you grind your HSS bit point symmetrically, like a threading bit
but at an angle closer to 90, it both turns and faces when set to 45
degrees on the toolpost. Bent Armstrong-style bit holders accomplish
the same thing in a standard toolpost.

I paid $50 for the Multifix post plus a cutoff, boring, and two
turning toolholders, and special-ordered some import clone
toolholders. I had gone looking for an Aloris clone and from my
experience using a Dorian on a CNC lathe would have been happy with
that style too.

The compound also rotates, steplessly to any angle, and on the
Multifix the toolholder can be mounted on the right side of the post
and reset square by pressing the toolholder against the tailstock
spindle. On my lathe it's more accurate to remove the collet and press
the cutoff holder against the face of its adapter
jsw

On Sat, 29 Mar 2014 15:32:32 -0400, Bob S
wrote:

How much rotation ability is required or useful in a toolholder on a
lathe?

Here are my thoughts so far; please let me know what I have gotten
wrong or have neglected.

Small rotation can be used to line up a thread tool or other form tool
accurately.

Small rotation can be used to adjust side cutting angle.

There are a few exotic screw-cutting bits that require a 30 degree
(counter-clockwise from above) rotation.

Fairly large rotation might be needed to get some kinds of bit into
the corner of a shoulder cut.

There should be no need for rotation much beyond 45 degrees since the
same thing can be accomplished with less than 45 degree rotation from
the other side of the holder.

Large rotation counter-clockwise from above will bring a corner of the
holder toward the work, and will bring the cutting bit further from
the work, so a large bit extension might be required. A special holder
with an angled mount for the tool might be better.

Large rotation clockwise from above will bring a back corner of the
holder toward the chuck, where it might get hit.

Bob
Greetings Bob,
I've read the other responses and thought I'd contribute, since it is
metalworking afterall. I own a machine shop and make my living with
it. I have an Aloris tool post on one lathe. It mostly sits square
with the X and Z axes. Sometimes I rotate it a bit for one job or
another. But even though it is mostly normal to the axes it is almost
never square with the compound. The compound gets slewed over to
different positions on a regular basis. For example, I might need to
use the compound to machine a taper or a large chamfer. It might be
set at 29.5 degrees for threading 60 degree threads. And then it will
need to be rotated again to cut some Acme threads. And then maybe the
next day rotated again for clearance. But no matter what angle the
copmound is set at the tool post will still probably be square. So
having 360 degree rotation of the tool post is really nice.
Eric

On Sun, 30 Mar 2014 17:36:59 -0400, Jim Wilkins wrote:

"Bob S" wrote in message
.. .
On Sat, 29 Mar 2014 17:23:41 -0400, Jim Wilkins wrote:


Thank you jsw

I have seen the fascinating Multifix. I assume that like most Swiss
things it works extremely smoothly and costs both arms and all legs.

So I guess that you find at least some unspecified amount of
rotation
to be useful with HSS bits, and like DoN you only need it square for
carbide inserts.

Bob

The toolholder has to be square for parting, knurling, boring and
threading too.

If you grind your HSS bit point symmetrically, like a threading bit
but at an angle closer to 90, it both turns and faces when set to 45
degrees on the toolpost. Bent Armstrong-style bit holders accomplish
the same thing in a standard toolpost.

I paid $50 for the Multifix post plus a cutoff, boring, and two
turning toolholders, and special-ordered some import clone
toolholders. I had gone looking for an Aloris clone and from my
experience using a Dorian on a CNC lathe would have been happy with
that style too.

The compound also rotates, steplessly to any angle, and on the
Multifix the toolholder can be mounted on the right side of the post
and reset square by pressing the toolholder against the tailstock
spindle. On my lathe it's more accurate to remove the collet and press
the cutoff holder against the face of its adapter
jsw



$50!!! Where did you get a deal like that? I thought it was several
times that much!

It looks like a nice gadget.

I am not sure that it matters anyway; it looks like the smallest size
might just barely fit on the cross slide, but not the top slide, on a
Proxxon.

Bob

On Sun, 30 Mar 2014 17:22:55 -0700, wrote:

On Sat, 29 Mar 2014 15:32:32 -0400, Bob S
wrote:

How much rotation ability is required or useful in a toolholder on a
lathe?

Here are my thoughts so far; please let me know what I have gotten
wrong or have neglected.

Small rotation can be used to line up a thread tool or other form tool
accurately.

Small rotation can be used to adjust side cutting angle.

There are a few exotic screw-cutting bits that require a 30 degree
(counter-clockwise from above) rotation.

Fairly large rotation might be needed to get some kinds of bit into
the corner of a shoulder cut.

There should be no need for rotation much beyond 45 degrees since the
same thing can be accomplished with less than 45 degree rotation from
the other side of the holder.

Large rotation counter-clockwise from above will bring a corner of the
holder toward the work, and will bring the cutting bit further from
the work, so a large bit extension might be required. A special holder
with an angled mount for the tool might be better.

Large rotation clockwise from above will bring a back corner of the
holder toward the chuck, where it might get hit.

Bob
Greetings Bob,
I've read the other responses and thought I'd contribute, since it is
metalworking afterall. I own a machine shop and make my living with
it. I have an Aloris tool post on one lathe. It mostly sits square
with the X and Z axes. Sometimes I rotate it a bit for one job or
another. But even though it is mostly normal to the axes it is almost
never square with the compound. The compound gets slewed over to
different positions on a regular basis. For example, I might need to
use the compound to machine a taper or a large chamfer. It might be
set at 29.5 degrees for threading 60 degree threads. And then it will
need to be rotated again to cut some Acme threads. And then maybe the
next day rotated again for clearance. But no matter what angle the
copmound is set at the tool post will still probably be square. So
having 360 degree rotation of the tool post is really nice.
Eric

Thank you Eric for pointing out so clearly what I had completely
overlooked. Its not just the tool angle. The post system has to be
able to rotate enough to compensate for whatever angle the compound
slide is at. It might not matter much for turning a slight taper but
it would matter a lot for half-angle threading.

Bob

On Sun, 30 Mar 2014 15:01:13 -0400, Bob S
wrote:

On Sat, 29 Mar 2014 15:06:16 -0500, Lloyd E. Sponenburgh wrote:

Bob S fired this volley in
m:

How much rotation ability is required or useful in a toolholder on a
lathe?

No limit, Bob. An Aloris-style toolholder rotates freely. It allows quick
and easy alignment of the tool anywhere you need it.

Since full rotation is actually easier to provide than some sort of
"stopped' rotation, why would you want anything less than that?

LLoyd

Well I admit that the question may seem a bit abstract.

Some types of holder systems are mostly intended to stay in one
position, like the Aloris. Yes, it can be rotated, but then you need
to re-align it if you want it square.

Some types of holder systems rotate in fixed amounts, like the
Multifix mentioned in another reply.

Some types of holder systems rotate completely freely, like any of the
DIY round-post systems.

I can certainly imagine ways to make a holder system that provides
only limited rotation, and it is possible that such a system might
offer some advantage in construction simplicity for example.

So I was curious about what is actually needed and useful, rather than
about specific systems.

Bob


If you use the old "Standard Tool Post", to use one term, you could
rotate it to any position while, if I am not mistaken, the original
"Quick Change" tool posts rotated in 90 degree steps. This meant that,
using the standard tool post, the angle you ground on your tool bit
were far less critical as the tool holder could be rocked, to raise or
lower, the cutting edge and rotated for any cutting angle.
The 90 degree "quick change" tool posts required the tool bit to be
ground much more accurately as the tool post lacked the degree of
movement that was inherent to the standard tool post.

While it seems common for small lathes to now use Quick Change tool
posts some years ago the Standard tool post was the most common. I
remember as an apprentice turning a piece of 12 inch line shafting
from an old woolen mill into a 4 inch cutting head for a planer (we
did it because there had a lot of that line shaft donated to the
school) on a 24 inch lathe and making 5/8" cuts using a standard tool
post. Granted it was slow - we spent about 4 hour a day in the shop
and you could never start and finish a cut in that period - but it did
the job :-)

So, to answer your question, if you can grind your tool bits very
accurately you can get away with the 90 degree quick change but some
movement will give you more flexibility in tool setting.
--
Cheers,

John B.

On 2014-03-30, Bob La Londe wrote:


"DoN. Nichols" wrote in message
...

[ ... ]

Also, the knurling tool is sensitive to angle, and is best used
with the faces of the knurls parallel to the axis of the workpiece.

Interesting. I always thought that a knurling tool was used at a very
slight angle to the work piece so that the teeth gradually cut in as you
advanced the Z axis feed.

O.K. My knurler (an Aloris scissors style knurler with arms on
dovetail slides and a single leadscrew adjusting both symmetrically
around the set height), happens to be fitted with knurling rollers with
a slight rounded bevel, which handles that part.

And it is often used in the middle of a workpiece (where the
knurl happens to be needed) just by positioning it there and either
clamping it down at that point, or (if already set for the depth of
knurl desired) by using the cross-feed to remove it from the first
workpiece and then advance it into the second.

I certainly agree that a bump style knurler would benefit from
the slight angle, but I think that a scissors style does not need it.

Enjoy,
DoN.

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On 2014-03-30, Kristian Ukkonen wrote:

On 3/29/2014 21:32, Bob S wrote:
How much rotation ability is required or useful in a toolholder on a
lathe?

The problem in all machines, whether it is a mill or a lathe,
is that if you have adjustable angle part, it can be off from
90 degrees (or whatever the normal setting). Perhaps it went
off last time you took a rough cut? You have to always check it.

Agreed.

[ ... ]

Same for bridgeport J head - it could have moved - while a sturdy mill
head with fixed angle is always at correct angle (or it is broken).

Not all J-heads are adjustable. The Bridgeport used in their
early CNC machines had a choice -- rigid ram, or adjustable one. The
rigid ram is normally set up *once*, and taper pins used to lock it once
you have it right. (Before pinning there is a very small freedom of
adjustment if the bolts are lose.) And yes, that machine *did* have a
J-head.

Enjoy,
DoN.

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On 2014-03-30, Bob S wrote:
On 30 Mar 2014 02:19:17 GMT, DoN. Nichols wrote:

On 2014-03-29, Bob S wrote:
How much rotation ability is required or useful in a toolholder on a
lathe?

[ ... ]

The tools which I use benefit from having one face of a
quick-change toolpost (e.g. Aloris) parallel to the face of the chuck,
and the other parallel to the axis of the workpiece.

[ ... ]

The only time I need to shift the toolpost (other than when it
has been removed to replace it with a toolpost grinder or something
else) is when I shift the compound angle from 29.5 degrees (normally
60-degree V threads) to something else, such as 14 degrees for Acme
threading, or other angles for weird threads, e.g. the 55 degree
Whitworth threads.) So -- when I shift the compound angle, I reset the
toolpost to again be parallel to the chuck face and the workpiece axis.

[ ... ]

Thanks DoN for the clear explanation of the "no rotation" approach. It
sounds like "small rotation only for unusual threading, and everything
else handled by specialized holder". I suppose that if you did the
odd-angle threads often enough you could even make or buy a holder for
that angle, and never move the toolpost at all.

Well ... not really -- because the adjustment for the odd-angle
threading involves shifting the angle of the *compound* for the correct
infeed angle (typically a half degree less than one-half the thread
included angle). When you shift the compound, since the toolpost is
mounted on it (unless you have a lathe like a Myford where the compound
itself is an option), you will change the angle of the tool mounted in
the toolpost (along with the toolpost itself). So, when I shift the
compound, I have to shift the toolpost in the opposite direction so the
dovetails are again parallel to the chuck face and the workpiece
centerline. This assumes a proper ground HSS tool bit for the thread
angle being cut. (Last time I did this was for an Acme thread when
helping a friend make a new nut for his log-splitter.) I actually had
to make two -- one for external threads, and one for internal, since I
did not have the leadscrew available for test fitting. :-)

This also applies if I am using the compound to cut an angle,
though usually when I want to cut an angle I use the angle attachment on
the lathe bed, so I don't have to adjust the compound. The adjustment
of the compound only happens if I am cutting an angle beyond the range
of the angle-turning attachment (+/- 10 degrees or so, IIRC).

I can see that the Aloris-style holders and the carbide insert holders
seem to have undergone mutual evolution to work well together.

Yes. In particular, Aloris makes tool holders which directly
hold the inserts (I like the BXA-16N -- there are other sizes of
course), which holds two inserts on the two ends -- one for turning and
one for facing.

I've looked at the clone maker's offerings, but they tend to
provide angled tools only (triangle point towards the workpiece), not
with the triangle oriented so one edge is almost square in the direction
of cut). The 'N' in the part number says that the pockets are angled
for negative rake inserts (thus giving three working points on the top,
and three more on the bottom), and with a proper chipbreaking groove,
you have the effect of a positive rake anyway.

And Aloris also has the swivel insert holders, both in
single-ended and double-ended versions. I may eventually get that, but
my straight shank holders give the angles I commonly need, so that
purchase is not particularly urgent. :-)

It looks like most of the same things could be done with HSS bits,
except for the 15 degree indexing insert holder trick.

I understand that you *can* find HSS inserts to fit the holders
for carbide inserts. (No, I don't know where.)

Normally, a good HSS can get a sharper edge than the typical
carbide -- especially the carbide inserts which have been TiN coated,
which tends to round the edges a little. I have some small
diamond-shaped carbide inserts which are ground quite sharp, without a
TiN coating, which I prefer when I want a really smooth finish, and feel
too lazy to grind a HSS bit to size. (Besides, I have a large bag of
these inserts, and not that many remaining HSS bits. :-)

Enjoy,
DoN.

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Bob S fired this volley in
:

Some types of holder systems are mostly intended to stay in one
position, like the Aloris. Yes, it can be rotated, but then you need
to re-align it if you want it square.


With an Aloris-style toolpost, re-aligning it is as easy as "kissing" the
front face of your chuck with the empty toolpost, and tightening the
capture nut. Quick, easy.

LLoyd

On 31 Mar 2014 04:24:43 GMT, "DoN. Nichols"
wrote:

On 2014-03-30, Bob S wrote:
On 30 Mar 2014 02:19:17 GMT, DoN. Nichols wrote:

On 2014-03-29, Bob S wrote:
How much rotation ability is required or useful in a toolholder on a
lathe?
big snip
I understand that you *can* find HSS inserts to fit the holders
for carbide inserts. (No, I don't know where.)

I use Arthur R. Warner Co http://www.arwarnerco.com/ . They are
expensive, but work well.

snip
Enjoy,
DoN.

Pete Keillor

"Bob S" wrote in message
...
On Sun, 30 Mar 2014 17:36:59 -0400, Jim Wilkins wrote:
...
I paid $50 for the Multifix post plus a cutoff, boring, and two
turning toolholders, and special-ordered some import clone
toolholders. I had gone looking for an Aloris clone and from my
experience using a Dorian on a CNC lathe would have been happy with
that style too....
jsw

$50!!! Where did you get a deal like that? I thought it was several
times that much!

http://www.brentwoodmachine.com/
I had to saw off and replace the bent and mushroomed M7 clamping
screws.

It looks like a nice gadget.

I am not sure that it matters anyway; it looks like the smallest
size
might just barely fit on the cross slide, but not the top slide, on
a
Proxxon.
Bob

It's nice, but I didn't claim it's any better than the Aloris / Dorian
style, especially if you use carbide bits which already have the
correct cutting edge angles.

I can tolerate a lantern or turret toolpost by planning the job
carefully and milling custom-height shim blocks, some of which I still
use to position small bits under the screws on the Multifix.

I started with a lantern toolpost I made from a bolt, partly by hand,
and partly by clamping a tool bit to the top of the compound with a
strap and two carriage bolts with heads ground down to fit the slot.
jsw

SNIP
Bob
Greetings Bob,
I've read the other responses and thought I'd contribute, since it is
metalworking afterall. I own a machine shop and make my living with
it. I have an Aloris tool post on one lathe. It mostly sits square
with the X and Z axes. Sometimes I rotate it a bit for one job or
another. But even though it is mostly normal to the axes it is almost
never square with the compound. The compound gets slewed over to
different positions on a regular basis. For example, I might need to
use the compound to machine a taper or a large chamfer. It might be
set at 29.5 degrees for threading 60 degree threads. And then it will
need to be rotated again to cut some Acme threads. And then maybe the
next day rotated again for clearance. But no matter what angle the
copmound is set at the tool post will still probably be square. So
having 360 degree rotation of the tool post is really nice.
Eric

Thank you Eric for pointing out so clearly what I had completely
overlooked. Its not just the tool angle. The post system has to be
able to rotate enough to compensate for whatever angle the compound
slide is at. It might not matter much for turning a slight taper but
it would matter a lot for half-angle threading.

Bob
You're welcome Bob. That's part of what this group is supposed to be
all about.
Eric

On Mon, 31 Mar 2014 05:36:21 -0500, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com wrote:

Bob S fired this volley in
:

Some types of holder systems are mostly intended to stay in one
position, like the Aloris. Yes, it can be rotated, but then you need
to re-align it if you want it square.


With an Aloris-style toolpost, re-aligning it is as easy as "kissing" the
front face of your chuck with the empty toolpost, and tightening the
capture nut. Quick, easy.

LLoyd

Im rather partial to KDK tool holders.

I have a 100 Series on the HLV-H and a 150 on the 1500 Clausing.

And I regularly swap all the various tool holders between lathes..with
a mix of 100 and 150 tool holders of all sorts.

Gunner


--

"
I was once told by a “gun safety” advocate back in the Nineties
that he favored total civilian firearms confiscation.
Only the military and police should have weapons he averred and what did I think about that?

I began to give him a reasoned answer and he
cut me off with an abrupt, “Give me the short answer.”

I thought for a moment and said, “If you try to take our firearms we will kill you.”"

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On 31 Mar 2014 04:24:43 GMT, DoN. Nichols wrote:

On 2014-03-30, Bob S wrote:
On 30 Mar 2014 02:19:17 GMT, DoN. Nichols wrote:

On 2014-03-29, Bob S wrote:
How much rotation ability is required or useful in a toolholder on a
lathe?

[ ... ]

The tools which I use benefit from having one face of a
quick-change toolpost (e.g. Aloris) parallel to the face of the chuck,
and the other parallel to the axis of the workpiece.

[ ... ]

The only time I need to shift the toolpost (other than when it
has been removed to replace it with a toolpost grinder or something
else) is when I shift the compound angle from 29.5 degrees (normally
60-degree V threads) to something else, such as 14 degrees for Acme
threading, or other angles for weird threads, e.g. the 55 degree
Whitworth threads.) So -- when I shift the compound angle, I reset the
toolpost to again be parallel to the chuck face and the workpiece axis.

[ ... ]

Thanks DoN for the clear explanation of the "no rotation" approach. It
sounds like "small rotation only for unusual threading, and everything
else handled by specialized holder". I suppose that if you did the
odd-angle threads often enough you could even make or buy a holder for
that angle, and never move the toolpost at all.

Well ... not really -- because the adjustment for the odd-angle
threading involves shifting the angle of the *compound* for the correct
infeed angle (typically a half degree less than one-half the thread
included angle). When you shift the compound, since the toolpost is
mounted on it (unless you have a lathe like a Myford where the compound
itself is an option), you will change the angle of the tool mounted in
the toolpost (along with the toolpost itself). So, when I shift the
compound, I have to shift the toolpost in the opposite direction so the
dovetails are again parallel to the chuck face and the workpiece
centerline. This assumes a proper ground HSS tool bit for the thread
angle being cut. (Last time I did this was for an Acme thread when
helping a friend make a new nut for his log-splitter.) I actually had
to make two -- one for external threads, and one for internal, since I
did not have the leadscrew available for test fitting. :-)

This also applies if I am using the compound to cut an angle,
though usually when I want to cut an angle I use the angle attachment on
the lathe bed, so I don't have to adjust the compound. The adjustment
of the compound only happens if I am cutting an angle beyond the range
of the angle-turning attachment (+/- 10 degrees or so, IIRC).

I can see that the Aloris-style holders and the carbide insert holders
seem to have undergone mutual evolution to work well together.

Yes. In particular, Aloris makes tool holders which directly
hold the inserts (I like the BXA-16N -- there are other sizes of
course), which holds two inserts on the two ends -- one for turning and
one for facing.

I've looked at the clone maker's offerings, but they tend to
provide angled tools only (triangle point towards the workpiece), not
with the triangle oriented so one edge is almost square in the direction
of cut). The 'N' in the part number says that the pockets are angled
for negative rake inserts (thus giving three working points on the top,
and three more on the bottom), and with a proper chipbreaking groove,
you have the effect of a positive rake anyway.

And Aloris also has the swivel insert holders, both in
single-ended and double-ended versions. I may eventually get that, but
my straight shank holders give the angles I commonly need, so that
purchase is not particularly urgent. :-)

It looks like most of the same things could be done with HSS bits,
except for the 15 degree indexing insert holder trick.

I understand that you *can* find HSS inserts to fit the holders
for carbide inserts. (No, I don't know where.)

Normally, a good HSS can get a sharper edge than the typical
carbide -- especially the carbide inserts which have been TiN coated,
which tends to round the edges a little. I have some small
diamond-shaped carbide inserts which are ground quite sharp, without a
TiN coating, which I prefer when I want a really smooth finish, and feel
too lazy to grind a HSS bit to size. (Besides, I have a large bag of
these inserts, and not that many remaining HSS bits. :-)

Enjoy,
DoN.


Thanks again, yes I had forgotten about rotating the compound
requiring rotating the tool holder.

I gather that you seldom use the compound rotation for anything but
threads and the rare fast taper, is that correct?

Bob

"Bob S" wrote in message
...
On 31 Mar 2014 04:24:43 GMT, DoN. Nichols wrote:

Thanks again, yes I had forgotten about rotating the compound
requiring rotating the tool holder.

I gather that you seldom use the compound rotation for anything but
threads and the rare fast taper, is that correct?

Bob

You can set the compound to 5 or 6 degrees off parallel to the ways
and gain a decimal place of control over the cutting depth, that is,
0.001 of compound travel moves the bit 0.0001" toward or away from
(boring) the centerline axis. I haven't found this precise enough to
try to set the compound to the angle whose sine is 0.1000, 5.739
degrees. 5 degrees cuts slightly less than indicated, which is safer,
and it's easy to remember.

With the compound parallel to the ways you can control the feed into a
recess in a face, such as an o-ring groove in a pipe flange, or the
width of a shoulder if you don't have an indicator displaying carriage
travel or a micrometer carriage stop.

The proper groove angle for a vee belt pulley varies with its
diameter, since the belt grabs by expanding sideways against the
groove walls when it wraps around the pulley.
http://shopswarf.orconhosting.net.nz/vee.html
I made a vee belt drive for a heavily loaded hydraulic pump on my
tractor that needed everything done by the book to survive.
jsw

On 2014-03-31, Bob S wrote:
On 31 Mar 2014 04:24:43 GMT, DoN. Nichols wrote:

On 2014-03-30, Bob S wrote:

[ ... ]

It looks like most of the same things could be done with HSS bits,
except for the 15 degree indexing insert holder trick.

I understand that you *can* find HSS inserts to fit the holders
for carbide inserts. (No, I don't know where.)

Normally, a good HSS can get a sharper edge than the typical
carbide -- especially the carbide inserts which have been TiN coated,
which tends to round the edges a little. I have some small
diamond-shaped carbide inserts which are ground quite sharp, without a
TiN coating, which I prefer when I want a really smooth finish, and feel
too lazy to grind a HSS bit to size. (Besides, I have a large bag of
these inserts, and not that many remaining HSS bits. :-)

[ ... ]

Thanks again, yes I had forgotten about rotating the compound
requiring rotating the tool holder.

Start using your machine more -- it will remind you of these
things. :-)

I gather that you seldom use the compound rotation for anything but
threads and the rare fast taper, is that correct?

That is correct. One other possible use of the rotation is when
you are using a toolpost grinder on the lathe (in which case the
toolpost is off anyway), and you want to get extra-fine diametric
infeed. In that case, you want the compound rotated as close as you can
get it to either 84.28 degrees or 5.71 degrees -- whichever gets your
compound closer to the axis of the workpiece. This trick gives you
0.0001" infeed for each 0.001" on the compound's dial. You're not
likely to get much benefit from that trick with normal turning, except
with a *very* rigid lathe, and a *very* sharp tool edge, but the forces
involved in toolpost grinding are quite low, and the possibility of
removing in "tenths" is there, while usually with normal turning tools,
the spring in both the lathe and the workpiece means that a very fine
infeed will probably just spring things until you build up to a certain
level, at which it will cut it all at once -- and likely overshoot your
target dimension.

Enjoy,
Don.

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On 2014-03-31, Gunner Asch wrote:
On Mon, 31 Mar 2014 05:36:21 -0500, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com wrote:

[ ... ]

With an Aloris-style toolpost, re-aligning it is as easy as "kissing" the
front face of your chuck with the empty toolpost, and tightening the
capture nut. Quick, easy.

Agreed. As long as the chuck is not occupied by something too
large.

Im rather partial to KDK tool holders.

I have a 100 Series on the HLV-H and a 150 on the 1500 Clausing.

And I regularly swap all the various tool holders between lathes..with
a mix of 100 and 150 tool holders of all sorts.

My lathes are a bit too far apart in size to do that, and while
the 12x24" Clausing has an Aloris style system (really a Dorian for the
toolpost, and a mix of new and used Aloris and some Phase-II holders,
the Compact-5/CNC has a toolpost patterned after the Dickson ones, but
smaller than any I have seen. That is a little 5" swing machine. So,
there is little point to trying to keep the same style of toolpost on
both machines, since swapping between them is pretty useless anyway.
The Aloris knurling head on the Clausing is bigger than the cross-slide
on the Compact-5. :-)

Enjoy,
DoN.

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"DoN. Nichols" wrote in message
...

My lathes are a bit too far apart in size to do that, and while
the 12x24" Clausing has an Aloris style system (really a Dorian for
the
toolpost, and a mix of new and used Aloris and some Phase-II
holders,
the Compact-5/CNC has a toolpost patterned after the Dickson ones,
but
smaller than any I have seen. That is a little 5" swing machine.
So,
there is little point to trying to keep the same style of toolpost
on
both machines, since swapping between them is pretty useless anyway.
The Aloris knurling head on the Clausing is bigger than the
cross-slide
on the Compact-5. :-)

Enjoy,
DoN.

I've used a Compact-5 on only aluminum, to learn G code. Is it
actually capable of good accuracy on hard metals like drill rod or
stainless?
jsw

"Jim Wilkins" fired this volley in news:lhe8d1$i3t$1
@dont-email.me:

hard metals like drill rod or
stainless?


Which is it, Jim? Hard, or stainless? G

Lloyd

"Lloyd E. Sponenburgh" lloydspinsidemindspring.com wrote in message
. 3.70...
"Jim Wilkins" fired this volley in
news:lhe8d1$i3t$1
@dont-email.me:

hard metals like drill rod or
stainless?


Which is it, Jim? Hard, or stainless? G

Lloyd

All of them are easy for you, right?

"Jim Wilkins" fired this volley in news:lhehcq$tli$1
@dont-email.me:

All of them are easy for you, right?


No, but stainless is what I'd call "tough", not "hard", unless you
mistakenly work-harden it.

Lloyd

"Lloyd E. Sponenburgh" lloydspinsidemindspring.com wrote in message
. 3.70...
"Jim Wilkins" fired this volley in
news:lhehcq$tli$1
@dont-email.me:

All of them are easy for you, right?


No, but stainless is what I'd call "tough", not "hard", unless you
mistakenly work-harden it.

Lloyd

Compared to aluminum??

"Jim Wilkins" fired this volley in news:lhepvm$7om$1
@dont-email.me:

Compared to aluminum??

"Hard" carries certain connotations not associated with aluminum or
stainless steel. Aluminum is SOFT, SS not so, but 'hardly hard'.

(unless you make it so)

Lloyd

On 2014-04-01, Jim Wilkins wrote:
"DoN. Nichols" wrote in message
...

My lathes are a bit too far apart in size to do that, and while

[ ... ]

the Compact-5/CNC has a toolpost patterned after the Dickson ones,
but
smaller than any I have seen. That is a little 5" swing machine.

[ ... ]

I've used a Compact-5 on only aluminum, to learn G code. Is it
actually capable of good accuracy on hard metals like drill rod or
stainless?

"Good accuracy" is asking a lot of a machine whose diameter
turning varies in steps of either 0.02mm or 0.002" -- and both are
approximations based on what the ballscrew can deliver with the step
size of the stepper motors. Try to turn a Morse taper with it, and it
will be *visibly* stepped.

Coarse threads are sort of a stairstep wrapped around the shank,
too. Limited by the step size, and the number of indicated points
for a full rotation of the spindle. I think that it is either 100 or
128 points. And the CPU is an ancient 6502 (the thing which ran old
Commodore PETs and Apple-][s among other things. It is seriously
strained, and limits the spindle speed to something like 200 RPM or
less for coarser threads.)

And even repeatability is a problem. Especially in inch mode,
it tends to gain or lose a step every run or so -- either diameter or
Z-axis (along the bed). If you are doing a long series of runs, set up
indicators to allow you to verify position at the start of each run, and
adjust it before you hit the "start" button.

But -- it is the easiest way to cut metric threads that I have.
I've got a change gear set for the Clausing, but metric threads on an
inch leadscrew are a real pain.

And certain complex things are easier to do on it than on a
manual machine.

Now -- I recently saw one which had been modified by another
member of the local metalworking club, with finer and faster stepper
motors (with microstepping), and a LinuxCNC controller. That would make
it a much nicer machine.

Some of these days, I plan to retrofit mine with servo motors
and encoders instead of the coarse steppers. A *lot* faster, and
smoother -- even if the resolution is only 0.001" on radius (and it can
be made a lot better during the conversion) the servo operation would
make the Morse taper a proper smooth taper instead of a stepped cone.

Oh yes -- the original has filled plastic wear strips on the
underside of the bed, held down by two cap screws, and they tend to wear
rather quickly under the heads, and give a lot more play to the
carriage. Take some 1/8" aluminum, cut it to the size of the wear
strips, counterbore the holes for the screws, and it spreads the force
of the screws over a much larger percentage of the wear strips, and
causes a lot more operating time between needs to adjust the strips.
(Like years instead of months).

Enjoy,
DoN.

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"DoN. Nichols" wrote in message
...
On 2014-04-01, Jim Wilkins wrote:

I've used a Compact-5 on only aluminum, to learn G code. Is it
actually capable of good accuracy on hard metals like drill rod or
stainless?

"Good accuracy" is asking a lot of a machine whose diameter
turning varies in steps of either 0.02mm or 0.002" -- and both are
approximations based on what the ballscrew can deliver with the step
size of the stepper motors. Try to turn a Morse taper with it, and
it
will be *visibly* stepped.

Coarse threads are sort of a stairstep wrapped around the shank,
too. Limited by the step size, and the number of indicated points
for a full rotation of the spindle. I think that it is either 100
or
128 points. And the CPU is an ancient 6502 (the thing which ran old
Commodore PETs and Apple-][s among other things. It is seriously
strained, and limits the spindle speed to something like 200 RPM or
less for coarser threads.)

Thanks.
They show up second-hand sometimes but it sounds like they aren't that
useful as-is, or worth the time and expense to upgrade, if you have
larger machines that also need attention. I suspected that the
training exercises concealed their limitations.
jsw