DoN. Nichols wrote:

On 2010-02-02, danmitch wrote:

Mostly, I use the Aloris BX style quick-change post for probably 98% of
my work. I sure would NOT want to go back to the lanturn post for most work.

However, I sometimes find myself having to work into odd corners or
recesses that cannot be easily reached with standard quick change
tooling. I've made special quick-change tool-holders for some of these
situations, but even then, the problem arises. It's often quicker to
switch to the lantern toolpost than make a new toolholder, or custom
grind a special tool bit for some oddball one-off application.


There are some Aloris holders which might make a difference, if
you are willing to work with insert tooling.

First -- consider the following toolpost:

http://www.aloris.com/index.php/pages/Qualified%20Super%20Precision.html

which has *three* dovetails instead of two allowing work closer to a fat
live center in the tailstock.

Then look at:

http://www.aloris.com/index.php/pages/Shank%20Type.html

and scroll down to the description for the #13 and #13L which allows a
longer reach without sacrificing as much rigidity as a extended tool
shank would sacrifice.

For general use, I like the #16N:

http://www.aloris.com/index.php/pages/Aloris%20Catalog.html
click on the: "Combination Carbide Insert Cutting Tools with Adjustibale
chipbreaker"

Add in the ones on this page:

http://www.aloris.com/index.php/pages/Mini%20Swivel.html

or

Go back to the:
http://www.aloris.com/index.php/pages/Aloris%20Catalog.html
and clock on the "Universal Tool Holders, Quick Change #20, #22, #30" to
see ones where the tip can be adjusted to many angles at 15 degree
intervals.



Note that I already have a HUGE collection of odd custom toolbits and
"Armstrong" style tool holders with various angles to choose from. Thus
some one of these is probably very close to what I need for any application.


The existing collection of Armstrong style tool holders makes a
difference. The only ones which I have are for the little
Atlas/Craftsman 6x18" lathe.


And, sure, you can set a quick-change post at odd angles, but then
you've lost one of the advantages of even having a quick-chage post ...
repeatability after changing tools. After such a change you have to
reset the post, which wastes time.


While with the #20, #22, or #30 insert holding tools, you can
maintain the indexing, thus saving time.


You create the same problem when switching to the lantern post. So, it
becomes a question of whether it takes more time to realign the
toolpost, or custom grind some really odd toolbit.


And with HSS tools, and the proper Armstrong type holders, you
can use this collection more easily.


I realize that there are some other more elaborate quick-change posts
that allow intermediate settings, and might solve some of this problem,
but that's not what I have.


Also -- some more elaborate tool holders for the simple Aloris
style quick-change toolpost -- as shown above.

Enjoy,
DoN.

I'll agree with most of what Don states above, with the following
observations ...

My toolpost is a Phase-II "BXA" sized dovetail post. It is completely
satisfactory on the Rockwell 14" lathe I have at the university. I have
a similar "AXA" size post on my Logan 10" at home.

Yes, I have lantern toolposts and extensive sets of Armstrong-style tool
holders and bits for both lathes at both locations. This *IS* important
for my original argument. For most of my odd jobs I will already have
some tool/holder combination that is close to what I need. Perhaps only
some minor regrind is necessary, if that.

Without the above collection of tooling, in most cases the work could be
done by setting the quick-change toolpost to some odd angle and
custom-grinding some weird toolbit (this can take considerable time, and
may require a non-common toolbit (extra long, etc.). Switching to the
lantern post and existing tooling is often much quicker.

Basically, there's not much if anything that CAN'T be done with either
style post. The advantages of the quick change a 1) rapid changing of
tools without having to set angles and heights. 2) Repeatability of
settings when changing tools. HOWEVER, when the work won't allow these
things (easily), then the more versatile (if troublesome) lantern post
may be the answer.

Some of the specialized Aloris toolholders Don mentions would certainly
assist in solving some problems. Sadly, the Aloris items are fairly
expensive, and our department budget usually requires a cheap, of time
consuming, solution. We're often "long on time and short on money".
Phase-II doesn't offer nearly the variety in low-cost toolholders. I've
made a few special holders for the Phase-II post (that hold tool bits at
odd angles) that are useful.

Some of the work I need to do involves machining (often INSIDE) complex
shaped existing vacuum fittings and chambers and such. Cutting
additional O-ring grooves or adding/altering ports are such
applications. These structures are fabrications, customized for various
research applications, and often have odd protrusions either inside or
outside. Often these things are not well planned, but just 'grow' as the
project develops. New ports are added, or fittings silver-soldered on.
Old ports get plugged (not always neatly). THEN somebody wants further
modifications. Just getting into the thing, or around the obstructions,
is usualy the problem.

Tooling to do this often requires a long reach and strange angles.
Sometimes a boring bar, sometimes used as an EXTERNAL toolholder, is the
answer. Sometimes a lantern post is the solution. In either case, a long
reach is often needed, with corresponding lack of rigidity. Light cuts
with sharp tools are a necessity. As is often the case, one spends 95%
of the time on the setup, and 5% making the cut.

Such problems rarely arise when making new items.

Dan Mitchell
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