Aloris Parting Tools - I don't understand...

[jakes_66]

There must be something I'm missing here, but I don't get what the difference is between the Aloris #7 parting tool and the #7R? What is the 'rear cut-off use' under the #7R description?



This snapshot is taken from the Aloris tool catalog. I've been considering purchase of a parting tool holder for my Atlas/Craftsman 12" lathe. I think either style would work fine for me, I just want to understand the difference.

Thanks,

-Jake

 

[T Bredehoft]

A rear cut parting tool is mounted on the cross feed, behind (and upside down) the work on a lathe. It seems that the cutting action is less prone to shock, more smooth cutting than when the tool in in front (and right side up) of the work.

 

[David S]

Rather than approach the work piece from the front (normal). The R is used by parting from the rear of the work piece with blade upside down. I am not sure all the reasons, but I have seen Keith Fenner part from behind when he is cutting cast iron and doesn't want to spray the chips all over the place.

David

 

[higgite]

The #7R is made to use on a rear tool post with the blade mounted upside down. The clamping mechanisms on the tool holders are near the “business” ends of the blade on both models for better rigidity.

Tom

Edit: Looks like I finished 3rd in the race to answer this question. I hate it when that happens.

 

[jakes_66]

I see.... but I don't understand the benefit of any operation that tends to lift the crossfeed carriage up off the ways. On a machine with 'V' ways, you would tend to loose the self-centering nature of the shape of the 'V'. Also it would allow chips to pass beneath the wipers and destroy the surfaces...

Thanks for the replies. That certainly helps me make my decision!

 

[Uglydog]

Great question.
If you have a lathe which has a rear tool post in addition to a front toolpost, then you have an option of mounting tooling on the backside of the crossfeed. This allows for faster production work due to fewer set-ups. I built one for my Gisholt Ram Turret lathe. A turret on the compound or in place of the compound in addition to a turret where the tailstock normally resides really expedites production.

The attached pic shows a rear tool post and is from: http://www.homemadetools.net/uploads/107461/rear-tool-post-2.jpeg
The 7R above assumes that you have not changed rotation direction.

I've also attached a pic of a turret lathe without the posts. Perhaps you can see the T slots on the cross-feed and the turret in which multiple options of cutting tools might fit.

Daryl
MN

 

[Uglydog]

If you want more pics or explanation please advise.
This ends up being a very rigid set up,

Daryl
MN

 

[mikey]

I see.... but I don't understand the benefit of any operation that tends to lift the crossfeed carriage up off the ways. On a machine with 'V' ways, you would tend to loose the self-centering nature of the shape of the 'V'. Also it would allow chips to pass beneath the wipers and destroy the surfaces...

Thanks for the replies. That certainly helps me make my decision!

Actually, a rear mounted parting tool pushes down on the cross slide/ways and increases rigidity. It is a vastly superior way to part on a lathe.

 

[4ssss]

You can also use it if you have a lever sliding compound like on a secondary machine. Here's an example.


http://www.lathes.co.uk/derbyshire/page2.html

 

[Silverbullet]

Actually, a rear mounted parting tool pushes down on the cross slide/ways and increases rigidity. It is a vastly superior way to part on a lathe.

I think that's if you run in reverse. The tool he's showing cuts from the back upside down material turning towards front tool post.