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Parting Off

 

Yesterday I had to part off some aluminum (6061), 24mm diameter, and remembered that I had had endless trouble previously with this operation - regardless of material.
?
So this time I took off the quick change toolpost and re-installed the original four-way.? The parting off process went smoothly with none of the problems I'd encountered before.? It did get jammed once - I was running the motor too slowly.? (I don't have a low gear anymore.)? Didn't matter if I used oil or not, or went fast or slow.? It was as easy as any other operation.
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Something about how the QC extends over the compound - one of the weak parts of these lathes - lessens the rigidity necessary to do this operation well.
?
-Mike
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Once I parted aluminium successfuly, like a piece of butter, since then I have had to use a hack saw for aluminium or steel.


On Thu, Apr 24, 2025, 10:56 PM Mike W via <mike.wilkens=[email protected]> wrote:
Yesterday I had to part off some aluminum (6061), 24mm diameter, and remembered that I had had endless trouble previously with this operation - regardless of material.
?
So this time I took off the quick change toolpost and re-installed the original four-way.? The parting off process went smoothly with none of the problems I'd encountered before.? It did get jammed once - I was running the motor too slowly.? (I don't have a low gear anymore.)? Didn't matter if I used oil or not, or went fast or slow.? It was as easy as any other operation.
?
Something about how the QC extends over the compound - one of the weak parts of these lathes - lessens the rigidity necessary to do this operation well.
?
-Mike
?
 

I have had great success with a parting-off tool that takes a push-in insert (all metals).
Always do it close to the chuck and never with a fixed steady or a tailstock centre.

Rgrds

MFS?

E-mail: mfslater@...



On Fri, 25 Apr 2025 at 17:13, Ralph Hulslander via <rhulslander=[email protected]> wrote:

Once I parted aluminium successfuly, like a piece of butter, since then I have had to use a hack saw for aluminium or steel.


On Thu, Apr 24, 2025, 10:56 PM Mike W via <mike.wilkens=[email protected]> wrote:
Yesterday I had to part off some aluminum (6061), 24mm diameter, and remembered that I had had endless trouble previously with this operation - regardless of material.
?
So this time I took off the quick change toolpost and re-installed the original four-way.? The parting off process went smoothly with none of the problems I'd encountered before.? It did get jammed once - I was running the motor too slowly.? (I don't have a low gear anymore.)? Didn't matter if I used oil or not, or went fast or slow.? It was as easy as any other operation.
?
Something about how the QC extends over the compound - one of the weak parts of these lathes - lessens the rigidity necessary to do this operation well.
?
-Mike
?
 

I part Al all the time with little problem...

On 4/25/2025 11:13 AM, Ralph Hulslander via groups.io wrote:
Once I parted aluminium successfuly, like a piece of butter, since then I
have had to use a hack saw for aluminium or steel.

On Thu, Apr 24, 2025, 10:56 PM Mike W via groups.io <mike.wilkens=
[email protected]> wrote:

Yesterday I had to part off some aluminum (6061), 24mm diameter, and
remembered that I had had endless trouble previously with this operation -
regardless of material.

So this time I took off the quick change toolpost and re-installed the
original four-way. The parting off process went smoothly with none of the
problems I'd encountered before. It did get jammed once - I was running
the motor too slowly. (I don't have a low gear anymore.) Didn't matter if
I used oil or not, or went fast or slow. It was as easy as any other
operation.

Something about how the QC extends over the compound - one of the weak
parts of these lathes - lessens the rigidity necessary to do this operation
well.

-Mike
 

I made a Norman style QCTP based on Ralph Patterson's drawings.? It has a large (~1.25") mounting post.? The tool holders are pretty beefy as well.? This all provides worry-free parting off, as long as the tool is sharp and at the proper height, and the compound gibs are properly adjusted.?
?
The first commercial QCTP I got for my lathe was just too lightweight.? That thing DID cause all kinds of headaches.
 

I've found parting to be much easier with a "T" shaped HSS blade, mounted with the minimum length of blade protruding out of the tool holder. It's worth the effort of modifying the tool holder to properly mount the blade.
?
Roy
?
?
 

I too use a "norman" style tool post, but mine is mounted on a 1.0 inch diameter post.
I works quite well and I have been using it for about?20?years now.
Drawings and photos are available.?
Email me at (john.mattis@...)
Regards,
John?Mattis (retired mechanical engineer)

On Fri, Apr 25, 2025 at 10:50?AM Mark Kimball via <markkimball51=[email protected]> wrote:
I made a Norman style QCTP based on Ralph Patterson's drawings.? It has a large (~1.25") mounting post.? The tool holders are pretty beefy as well.? This all provides worry-free parting off, as long as the tool is sharp and at the proper height, and the compound gibs are properly adjusted.?
?
The first commercial QCTP I got for my lathe was just too lightweight.? That thing DID cause all kinds of headaches.
 

I made a parting tool holder that holds the tool upside down on the back of the cross slide and run the motor backwards (with a clamp for the screw-on chuck). ?This works great. We had long discussions on the Boxford Users Group (io). ?I think the main difference is that the swarf drops out with gravity and does not get jammed in beside the cutting tool. There are many theories. ?Often I just use an ordinary QCTP and only bother to set up the reverse rotation if I am having trouble.
--
Evan
Lathe: 1955 Boxford Model A with screw cutting gearbox, power feed with several accessories, hand tools and a pillar drill press.
Try my Free Online Gear train Software:
You enter a thread pitch or TPI and it shows you a range of gear trains and gearbox setting to use and even a scale drawing of the gear train.
It also includes calculations for taper turning by the tailstock offset method, and cutting speeds.
It includes the specifications for many thread types eg metric, UNC, BSW, and BA.
Displays drill sizes for tapping threads at any percent thread depth (with full explanations).
My YouTube Channel and Playlist about using an engineers lathe: ?
Project to build a Greek Hero steam engine and measure its power output:?

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