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Breaking carbide inserts parting off?

 

Now I know that for some folks parting off in the lathe is routine, but for some of us it's a real PITA.? Or can be.? I've tried using a nice HSS blade in a holder with lots of oil and freshly-ground tip and still got it pulling to one side, and now a 1-inch tall steel blade with carbide insert for the first time last night.? Yeah, I broke the insert.? And yes, it was a cheapo chinese insert.? As delivered, the holder body was not well made and the bottom of the slot for the tool was tapered, causing a tilt in the cutoff blade of about 3 degrees or so.? Imagine that from an ebay seller!? So I put it in the the vise and milled the slot more parallel, which corrected the vertical angle of the cutoff blade, mostly.? I tried to minimize stick-out but still got too much chatter.? Part isn't that far out from the 4-jaw, but a tailstock center might've helped on chatter.

This is on a piece of 1.5" steel rod I got left from a construction project, no idea what alloy.? Maybe I have the wrong speed going and need to crank it up for carbide cutting.? Heard people say many home lathes struggle to spin fast enough for carbide but that seems unlikely.? Haven't tested higher revs yet, wanted to get your thoughts.

I saw a youtube video this morning? where a guy made a little foot from a piece of CRS that he bolted through his tool holder that sits on the top of the cross slide to keep it from bending down which seems interesting, but not sure if I could do that or not on my lathe.??
 

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I got one of these, Nick:?

Works great! You can use it at the bench vise and just about anywhere you have enough room to bring it in.?

From: SouthBendLathe@groups.io <SouthBendLathe@groups.io> on behalf of Nick Andrews <nickjandrews@...>
Sent: Friday, April 21, 2023 2:25 PM
To: sheldonlathe@groups.io <sheldonlathe@groups.io>; SouthBendLathe@groups.io <SouthBendLathe@groups.io>
Subject: [SouthBendLathe] Breaking carbide inserts parting off?
?
Now I know that for some folks parting off in the lathe is routine, but for some of us it's a real PITA.? Or can be.? I've tried using a nice HSS blade in a holder with lots of oil and freshly-ground tip and still got it pulling to one side, and now a 1-inch tall steel blade with carbide insert for the first time last night.? Yeah, I broke the insert.? And yes, it was a cheapo chinese insert.? As delivered, the holder body was not well made and the bottom of the slot for the tool was tapered, causing a tilt in the cutoff blade of about 3 degrees or so.? Imagine that from an ebay seller!? So I put it in the the vise and milled the slot more parallel, which corrected the vertical angle of the cutoff blade, mostly.? I tried to minimize stick-out but still got too much chatter.? Part isn't that far out from the 4-jaw, but a tailstock center might've helped on chatter.

This is on a piece of 1.5" steel rod I got left from a construction project, no idea what alloy.? Maybe I have the wrong speed going and need to crank it up for carbide cutting.? Heard people say many home lathes struggle to spin fast enough for carbide but that seems unlikely.? Haven't tested higher revs yet, wanted to get your thoughts.

I saw a youtube video this morning? where a guy made a little foot from a piece of CRS that he bolted through his tool holder that sits on the top of the cross slide to keep it from bending down which seems interesting, but not sure if I could do that or not on my lathe.??
 

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??? ??? I've seen some of those parting tool supports that folks make on youtube in the past . Folks seem to like them ,? but then again its the guy that made it that says its bitchin . These folks make a longer crossslide casting that you machine to finish that allows you to put a tool post behind the work so your parting tool is mounted upside down , some folks say this is a huge improvement when parting . This is one of my projects on my list to make sometime . Are you locking the saddle & tightening the crossslide & compound gibs? when parting ?

??? ???

??? ??? animal

On 4/21/2023 11:25 AM, Nick Andrews wrote:

Now I know that for some folks parting off in the lathe is routine, but for some of us it's a real PITA.? Or can be.? I've tried using a nice HSS blade in a holder with lots of oil and freshly-ground tip and still got it pulling to one side, and now a 1-inch tall steel blade with carbide insert for the first time last night.? Yeah, I broke the insert.? And yes, it was a cheapo chinese insert.? As delivered, the holder body was not well made and the bottom of the slot for the tool was tapered, causing a tilt in the cutoff blade of about 3 degrees or so.? Imagine that from an ebay seller!? So I put it in the the vise and milled the slot more parallel, which corrected the vertical angle of the cutoff blade, mostly.? I tried to minimize stick-out but still got too much chatter.? Part isn't that far out from the 4-jaw, but a tailstock center might've helped on chatter.

This is on a piece of 1.5" steel rod I got left from a construction project, no idea what alloy.? Maybe I have the wrong speed going and need to crank it up for carbide cutting.? Heard people say many home lathes struggle to spin fast enough for carbide but that seems unlikely.? Haven't tested higher revs yet, wanted to get your thoughts.

I saw a youtube video this morning? where a guy made a little foot from a piece of CRS that he bolted through his tool holder that sits on the top of the cross slide to keep it from bending down which seems interesting, but not sure if I could do that or not on my lathe.??
 

my first lathe was a 9 inch logan ...? needed a crutch approach to do cut-offs.? now I have a 13 inch Southbend ... seldom have trouble with cutoffs.

Stiffness is the key ... also so far my best cutoff tool is a blade with carbide insert.? mine is an expensive Iscar brand .? if you go chinese, at least go Shars or someone you can complain to .. heh.

with my 9 inch Logan, I got by ok with a slower but necessary method ::? ? run cutoff blade in about 2 widths deep, the start another cutoff cut inboard to same depth.? you are making a cutoff groove wider than your tool for chip clearance ... because chips are the biggest reason for failure in cutting off.? keep " double pecking " until the parting is done.??

hope this helps ...

oh, meanwhile keep an eye out for a bandsaw that takes a metal cutting blade ...?...?
 

Make sure your tool is exactly perpendicular to the part/perfectly parallel to the cross-slide travel.? I have been at an angle but "the cross slide was pushing the tool perpendicular to the part" and kept binding, pushing off to side and breaking.

Ensure you are at spinning center of the part, not above and not below.

On Fri, Apr 21, 2023 at 2:49?PM ken campbell <deltainc@...> wrote:
my first lathe was a 9 inch logan ...? needed a crutch approach to do cut-offs.? now I have a 13 inch Southbend ... seldom have trouble with cutoffs.

Stiffness is the key ... also so far my best cutoff tool is a blade with carbide insert.? mine is an expensive Iscar brand .? if you go chinese, at least go Shars or someone you can complain to .. heh.

with my 9 inch Logan, I got by ok with a slower but necessary method ::? ? run cutoff blade in about 2 widths deep, the start another cutoff cut inboard to same depth.? you are making a cutoff groove wider than your tool for chip clearance ... because chips are the biggest reason for failure in cutting off.? keep " double pecking " until the parting is done.??

hope this helps ...

oh, meanwhile keep an eye out for a bandsaw that takes a metal cutting blade ...?...?
 

I have the el cheapo Bauer one and yes it works well but the idea on the lathe is for a nice clean square cut and to be able to easily make thick washers, etc.

On Fri, Apr 21, 2023 at 1:28?PM Andrei <calciu1@...> wrote:
I got one of these, Nick:?

Works great! You can use it at the bench vise and just about anywhere you have enough room to bring it in.?
From: SouthBendLathe@groups.io <SouthBendLathe@groups.io> on behalf of Nick Andrews <nickjandrews@...>
Sent: Friday, April 21, 2023 2:25 PM
To: sheldonlathe@groups.io <sheldonlathe@groups.io>; SouthBendLathe@groups.io <SouthBendLathe@groups.io>
Subject: [SouthBendLathe] Breaking carbide inserts parting off?
?
Now I know that for some folks parting off in the lathe is routine, but for some of us it's a real PITA.? Or can be.? I've tried using a nice HSS blade in a holder with lots of oil and freshly-ground tip and still got it pulling to one side, and now a 1-inch tall steel blade with carbide insert for the first time last night.? Yeah, I broke the insert.? And yes, it was a cheapo chinese insert.? As delivered, the holder body was not well made and the bottom of the slot for the tool was tapered, causing a tilt in the cutoff blade of about 3 degrees or so.? Imagine that from an ebay seller!? So I put it in the the vise and milled the slot more parallel, which corrected the vertical angle of the cutoff blade, mostly.? I tried to minimize stick-out but still got too much chatter.? Part isn't that far out from the 4-jaw, but a tailstock center might've helped on chatter.

This is on a piece of 1.5" steel rod I got left from a construction project, no idea what alloy.? Maybe I have the wrong speed going and need to crank it up for carbide cutting.? Heard people say many home lathes struggle to spin fast enough for carbide but that seems unlikely.? Haven't tested higher revs yet, wanted to get your thoughts.

I saw a youtube video this morning? where a guy made a little foot from a piece of CRS that he bolted through his tool holder that sits on the top of the cross slide to keep it from bending down which seems interesting, but not sure if I could do that or not on my lathe.??
David R8
 

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For some truly amazing parting tool action check out Robin Renzetti:


On Apr 21, 2023, at 12:11 PM, Nick Andrews <nickjandrews@...> wrote:

I have the el cheapo Bauer one and yes it works well but the idea on the lathe is for a nice clean square cut and to be able to easily make thick washers, etc.

On Fri, Apr 21, 2023 at 1:28?PM Andrei <calciu1@...> wrote:
I got one of these, Nick:?

Works great! You can use it at the bench vise and just about anywhere you have enough room to bring it in.?
From: SouthBendLathe@groups.io <SouthBendLathe@groups.io> on behalf of Nick Andrews <nickjandrews@...>
Sent: Friday, April 21, 2023 2:25 PM
To: sheldonlathe@groups.io <sheldonlathe@groups.io>; SouthBendLathe@groups.io <SouthBendLathe@groups.io>
Subject: [SouthBendLathe] Breaking carbide inserts parting off?
?
Now I know that for some folks parting off in the lathe is routine, but for some of us it's a real PITA.? Or can be.? I've tried using a nice HSS blade in a holder with lots of oil and freshly-ground tip and still got it pulling to one side, and now a 1-inch tall steel blade with carbide insert for the first time last night.? Yeah, I broke the insert.? And yes, it was a cheapo chinese insert.? As delivered, the holder body was not well made and the bottom of the slot for the tool was tapered, causing a tilt in the cutoff blade of about 3 degrees or so.? Imagine that from an ebay seller!? So I put it in the the vise and milled the slot more parallel, which corrected the vertical angle of the cutoff blade, mostly.? I tried to minimize stick-out but still got too much chatter.? Part isn't that far out from the 4-jaw, but a tailstock center might've helped on chatter.

This is on a piece of 1.5" steel rod I got left from a construction project, no idea what alloy.? Maybe I have the wrong speed going and need to crank it up for carbide cutting.? Heard people say many home lathes struggle to spin fast enough for carbide but that seems unlikely.? Haven't tested higher revs yet, wanted to get your thoughts.

I saw a youtube video this morning? where a guy made a little foot from a piece of CRS that he bolted through his tool holder that sits on the top of the cross slide to keep it from bending down which seems interesting, but not sure if I could do that or not on my lathe.??



 

This is on my 11" Sheldon lathe.? No, haven't tried snugging the gibs but did lock the saddle.? I guess if I am taking the time to make something, tweaking the gibs shouldn't seem like such a chore...

Interesting casting.? Do you then just bolt your tool post on directly somehow?


On Fri, Apr 21, 2023 at 1:49?PM mike allen <animal@...> wrote:

??? ??? I've seen some of those parting tool supports that folks make on youtube in the past . Folks seem to like them ,? but then again its the guy that made it that says its bitchin . These folks make a longer crossslide casting that you machine to finish that allows you to put a tool post behind the work so your parting tool is mounted upside down , some folks say this is a huge improvement when parting . This is one of my projects on my list to make sometime . Are you locking the saddle & tightening the crossslide & compound gibs? when parting ?

??? ???

??? ??? animal

On 4/21/2023 11:25 AM, Nick Andrews wrote:
Now I know that for some folks parting off in the lathe is routine, but for some of us it's a real PITA.? Or can be.? I've tried using a nice HSS blade in a holder with lots of oil and freshly-ground tip and still got it pulling to one side, and now a 1-inch tall steel blade with carbide insert for the first time last night.? Yeah, I broke the insert.? And yes, it was a cheapo chinese insert.? As delivered, the holder body was not well made and the bottom of the slot for the tool was tapered, causing a tilt in the cutoff blade of about 3 degrees or so.? Imagine that from an ebay seller!? So I put it in the the vise and milled the slot more parallel, which corrected the vertical angle of the cutoff blade, mostly.? I tried to minimize stick-out but still got too much chatter.? Part isn't that far out from the 4-jaw, but a tailstock center might've helped on chatter.

This is on a piece of 1.5" steel rod I got left from a construction project, no idea what alloy.? Maybe I have the wrong speed going and need to crank it up for carbide cutting.? Heard people say many home lathes struggle to spin fast enough for carbide but that seems unlikely.? Haven't tested higher revs yet, wanted to get your thoughts.

I saw a youtube video this morning? where a guy made a little foot from a piece of CRS that he bolted through his tool holder that sits on the top of the cross slide to keep it from bending down which seems interesting, but not sure if I could do that or not on my lathe.??

 

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??? ??? They have a rear mounted parting tool tool post they also sell .? I should buy the crossslide & just have it here for when I'm ready to make one . I need to learn dovetails first .

??? ??? Rear Tool Post

??? ??? animal

On 4/21/2023 12:20 PM, Nick Andrews wrote:

This is on my 11" Sheldon lathe.? No, haven't tried snugging the gibs but did lock the saddle.? I guess if I am taking the time to make something, tweaking the gibs shouldn't seem like such a chore...

Interesting casting.? Do you then just bolt your tool post on directly somehow?

On Fri, Apr 21, 2023 at 1:49?PM mike allen <animal@...> wrote:

??? ??? I've seen some of those parting tool supports that folks make on youtube in the past . Folks seem to like them ,? but then again its the guy that made it that says its bitchin . These folks make a longer crossslide casting that you machine to finish that allows you to put a tool post behind the work so your parting tool is mounted upside down , some folks say this is a huge improvement when parting . This is one of my projects on my list to make sometime . Are you locking the saddle & tightening the crossslide & compound gibs? when parting ?

??? ???

??? ??? animal

On 4/21/2023 11:25 AM, Nick Andrews wrote:
Now I know that for some folks parting off in the lathe is routine, but for some of us it's a real PITA.? Or can be.? I've tried using a nice HSS blade in a holder with lots of oil and freshly-ground tip and still got it pulling to one side, and now a 1-inch tall steel blade with carbide insert for the first time last night.? Yeah, I broke the insert.? And yes, it was a cheapo chinese insert.? As delivered, the holder body was not well made and the bottom of the slot for the tool was tapered, causing a tilt in the cutoff blade of about 3 degrees or so.? Imagine that from an ebay seller!? So I put it in the the vise and milled the slot more parallel, which corrected the vertical angle of the cutoff blade, mostly.? I tried to minimize stick-out but still got too much chatter.? Part isn't that far out from the 4-jaw, but a tailstock center might've helped on chatter.

This is on a piece of 1.5" steel rod I got left from a construction project, no idea what alloy.? Maybe I have the wrong speed going and need to crank it up for carbide cutting.? Heard people say many home lathes struggle to spin fast enough for carbide but that seems unlikely.? Haven't tested higher revs yet, wanted to get your thoughts.

I saw a youtube video this morning? where a guy made a little foot from a piece of CRS that he bolted through his tool holder that sits on the top of the cross slide to keep it from bending down which seems interesting, but not sure if I could do that or not on my lathe.??

 

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Looks like that rear parting tool is designed for 12 inch and bigger lathes. You can probably shave down the casting and alter the dovetails to make it work on your Sheldon.?

Andrei

From: SouthBendLathe@groups.io <SouthBendLathe@groups.io> on behalf of mike allen <animal@...>
Sent: Friday, April 21, 2023 3:31 PM
To: SouthBendLathe@groups.io <SouthBendLathe@groups.io>
Cc: sheldonlathe@groups.io <sheldonlathe@groups.io>
Subject: Re: [SouthBendLathe] Breaking carbide inserts parting off?
?

??? ??? They have a rear mounted parting tool tool post they also sell .? I should buy the crossslide & just have it here for when I'm ready to make one . I need to learn dovetails first .

??? ??? Rear Tool Post

??? ??? animal

On 4/21/2023 12:20 PM, Nick Andrews wrote:
This is on my 11" Sheldon lathe.? No, haven't tried snugging the gibs but did lock the saddle.? I guess if I am taking the time to make something, tweaking the gibs shouldn't seem like such a chore...

Interesting casting.? Do you then just bolt your tool post on directly somehow?

On Fri, Apr 21, 2023 at 1:49?PM mike allen <animal@...> wrote:

??? ??? I've seen some of those parting tool supports that folks make on youtube in the past . Folks seem to like them ,? but then again its the guy that made it that says its bitchin . These folks make a longer crossslide casting that you machine to finish that allows you to put a tool post behind the work so your parting tool is mounted upside down , some folks say this is a huge improvement when parting . This is one of my projects on my list to make sometime . Are you locking the saddle & tightening the crossslide & compound gibs? when parting ?

??? ???

??? ??? animal

On 4/21/2023 11:25 AM, Nick Andrews wrote:
Now I know that for some folks parting off in the lathe is routine, but for some of us it's a real PITA.? Or can be.? I've tried using a nice HSS blade in a holder with lots of oil and freshly-ground tip and still got it pulling to one side, and now a 1-inch tall steel blade with carbide insert for the first time last night.? Yeah, I broke the insert.? And yes, it was a cheapo chinese insert.? As delivered, the holder body was not well made and the bottom of the slot for the tool was tapered, causing a tilt in the cutoff blade of about 3 degrees or so.? Imagine that from an ebay seller!? So I put it in the the vise and milled the slot more parallel, which corrected the vertical angle of the cutoff blade, mostly.? I tried to minimize stick-out but still got too much chatter.? Part isn't that far out from the 4-jaw, but a tailstock center might've helped on chatter.

This is on a piece of 1.5" steel rod I got left from a construction project, no idea what alloy.? Maybe I have the wrong speed going and need to crank it up for carbide cutting.? Heard people say many home lathes struggle to spin fast enough for carbide but that seems unlikely.? Haven't tested higher revs yet, wanted to get your thoughts.

I saw a youtube video this morning? where a guy made a little foot from a piece of CRS that he bolted through his tool holder that sits on the top of the cross slide to keep it from bending down which seems interesting, but not sure if I could do that or not on my lathe.??

 

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??? ??? Yea , looks like it can be cut down some . These folks sell the drawings separate so a guy/gal can make their own with what they have . I don't see why it really has to be made from CI? but maybe someone else here can school me/us on that matter . the plans are only $ 6.00 for the tool post or the cross slide . I thought I had read somewhere at one time that if you bought the plans & then bought the casting later they would credit you on the plans when purchasing the casting ?

??? ??? IIRC OKC Bill bought a crossslide kit from a guy that bought it & never made it .

??? ??? animal

On 4/21/2023 1:29 PM, Andrei wrote:

Looks like that rear parting tool is designed for 12 inch and bigger lathes. You can probably shave down the casting and alter the dovetails to make it work on your Sheldon.?

Andrei
From: SouthBendLathe@groups.io <SouthBendLathe@groups.io> on behalf of mike allen <animal@...>
Sent: Friday, April 21, 2023 3:31 PM
To: SouthBendLathe@groups.io <SouthBendLathe@groups.io>
Cc: sheldonlathe@groups.io <sheldonlathe@groups.io>
Subject: Re: [SouthBendLathe] Breaking carbide inserts parting off?
?

??? ??? They have a rear mounted parting tool tool post they also sell .? I should buy the crossslide & just have it here for when I'm ready to make one . I need to learn dovetails first .

??? ??? Rear Tool Post

??? ??? animal

On 4/21/2023 12:20 PM, Nick Andrews wrote:
This is on my 11" Sheldon lathe.? No, haven't tried snugging the gibs but did lock the saddle.? I guess if I am taking the time to make something, tweaking the gibs shouldn't seem like such a chore...

Interesting casting.? Do you then just bolt your tool post on directly somehow?

On Fri, Apr 21, 2023 at 1:49?PM mike allen <animal@...> wrote:

??? ??? I've seen some of those parting tool supports that folks make on youtube in the past . Folks seem to like them ,? but then again its the guy that made it that says its bitchin . These folks make a longer crossslide casting that you machine to finish that allows you to put a tool post behind the work so your parting tool is mounted upside down , some folks say this is a huge improvement when parting . This is one of my projects on my list to make sometime . Are you locking the saddle & tightening the crossslide & compound gibs? when parting ?

??? ???

??? ??? animal

On 4/21/2023 11:25 AM, Nick Andrews wrote:
Now I know that for some folks parting off in the lathe is routine, but for some of us it's a real PITA.? Or can be.? I've tried using a nice HSS blade in a holder with lots of oil and freshly-ground tip and still got it pulling to one side, and now a 1-inch tall steel blade with carbide insert for the first time last night.? Yeah, I broke the insert.? And yes, it was a cheapo chinese insert.? As delivered, the holder body was not well made and the bottom of the slot for the tool was tapered, causing a tilt in the cutoff blade of about 3 degrees or so.? Imagine that from an ebay seller!? So I put it in the the vise and milled the slot more parallel, which corrected the vertical angle of the cutoff blade, mostly.? I tried to minimize stick-out but still got too much chatter.? Part isn't that far out from the 4-jaw, but a tailstock center might've helped on chatter.

This is on a piece of 1.5" steel rod I got left from a construction project, no idea what alloy.? Maybe I have the wrong speed going and need to crank it up for carbide cutting.? Heard people say many home lathes struggle to spin fast enough for carbide but that seems unlikely.? Haven't tested higher revs yet, wanted to get your thoughts.

I saw a youtube video this morning? where a guy made a little foot from a piece of CRS that he bolted through his tool holder that sits on the top of the cross slide to keep it from bending down which seems interesting, but not sure if I could do that or not on my lathe.??

 

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Parting in the front tool post on relatively small or light lathes can be a pain. I have a Myford ML7 at home. It's in nice nick, and I have NEVER succeeded in parting at the front. The tool digs in and snaps pretty well as soon as it touches. Fortunately, I have a rear toolpost that works a treat. If you look at a manual capstan lathe, parting is ALWAYS done from the back. I have recently acquired a rear toolpost for the railway's Colchester Triumph 2000 (AKA Clausing 15") and that will happily run a 4mm HSS blade. Internal screwcutting has now been promoted to my most feared operation in place of parting (I have to make 3 off 1 1/8 BSP nuts for steam pipe unions as soon as the 1 7/8 A/F Hex leaded gunmetal turns up).


The tool needs to be absolutely sharp. If you need to apply an increasing force to drive it in, that is a recipe for disaster.


If a hand ground blade, polish with a diamond file.


The tool must be narrow, and the smaller the lathe, the narrower the tool. I front part successfully with carbide on our 14.5" SB with taper turning attachment because that won't conveniently take a rear toolpost, but wouldn't use anything wider than a 3mm cutter. It is, nonetheless, nerve wracking.


If you look at (e.g.) the Iscar catalogue you will see dozens of different chip geometries on the same size of tip. Pick one with the correct geometry for the material you are cutting.


Work support is vital. Cut at no more than 1/4 diameter distance from the chuck or collet, and ensure they are TIGHT. Ensure there is at least 1.5 x diameter still in the chuck. If not, add a centre at the outer end whether you think it needs it or not. Neglect of any of this could result in the job deflecting badly in the chuck (etc.).


Trace and rectify any source of toolpost deflection under load. Have the compound slide set so that the sliding part is not overhanging the fixed part, and ensure that the leading corner of the toolpost is over solid metal. With the job moving downwards as in front cutting, any deflection results in the tool moving into the job, increasing the cutting force, which increases the deflection etc. With the job moving upwards as in rear cutting, the tool tends to deflect away from the job (phew!) This is why folk construct tool props for front parting.


On small lathes, part off at a relatively low speed, regardless of tool type.


Not sure about small quantities of cutting oil, but if parting something that normally takes coolant, even if optional, I would use coolant flow during parting, if available. Obviously not for cast iron or cheap brass.


Parting in stages that create a swarf anti jamming gap as described by someone else works well, especially if using the sort of carbide tip that is moulded to curl the edges of the swarf inwards and you are cutting material that produces springy swarf in spiral coils. That stuff can spring out towards flat as soon as it leaves the tip, and jam in the groove. Intermittent cutting helps by breaking that sort of swarf into shorter coils.


The cross feed during parting generally needs to be done manually, and slower than the slowest available powered feed.


I think that's all for the moment.


Eddie





------ Original Message ------
From: "mike allen" <animal@...>
To: SouthBendLathe@groups.io
Cc: sheldonlathe@groups.io
Sent: Friday, 21 Apr, 23 At 20:31
Subject: Re: [SouthBendLathe] Breaking carbide inserts parting off?

They have a rear mounted parting tool tool post they also sell . I should buy the crossslide & just have it here for when I'm ready to make one . I need to learn dovetails first .

Rear Tool Post

animal

On 4/21/2023 12:20 PM, Nick Andrews wrote:
This is on my 11" Sheldon lathe. No, haven't tried snugging the gibs but did lock the saddle. I guess if I am taking the time to make something, tweaking the gibs shouldn't seem like such a chore...

Interesting casting. Do you then just bolt your tool post on directly somehow?

On Fri, Apr 21, 2023 at 1:49?PM mike allen <animal@...> wrote:

I've seen some of those parting tool supports that folks make on youtube in the past . Folks seem to like them , but then again its the guy that made it that says its bitchin . These folks make a longer crossslide casting that you machine to finish that allows you to put a tool post behind the work so your parting tool is mounted upside down , some folks say this is a huge improvement when parting . This is one of my projects on my list to make sometime . Are you locking the saddle & tightening the crossslide & compound gibs when parting ?

animal

On 4/21/2023 11:25 AM, Nick Andrews wrote:
Now I know that for some folks parting off in the lathe is routine, but for some of us it's a real PITA. Or can be. I've tried using a nice HSS blade in a holder with lots of oil and freshly-ground tip and still got it pulling to one side, and now a 1-inch tall steel blade with carbide insert for the first time last night. Yeah, I broke the insert. And yes, it was a cheapo chinese insert. As delivered, the holder body was not well made and the bottom of the slot for the tool was tapered, causing a tilt in the cutoff blade of about 3 degrees or so. Imagine that from an ebay seller! So I put it in the the vise and milled the slot more parallel, which corrected the vertical angle of the cutoff blade, mostly. I tried to minimize stick-out but still got too much chatter. Part isn't that far out from the 4-jaw, but a tailstock center might've helped on chatter.

This is on a piece of 1.5" steel rod I got left from a construction project, no idea what alloy. Maybe I have the wrong speed going and need to crank it up for carbide cutting. Heard people say many home lathes struggle to spin fast enough for carbide but that seems unlikely. Haven't tested higher revs yet, wanted to get your thoughts.

I saw a youtube video this morning where a guy made a little foot from a piece of CRS that he bolted through his tool holder that sits on the top of the cross slide to keep it from bending down which seems interesting, but not sure if I could do that or not on my lathe.

 

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The GTN2 inserts seem to be the smallest you can find easily. I saw Shars selling them for their parting tools. I never used one, but I have been tempted a few times to purchase.?

From: SouthBendLathe@groups.io <SouthBendLathe@groups.io> on behalf of eddie.draper@... via groups.io <eddie.draper@...>
Sent: Friday, April 21, 2023 4:47 PM
To: SouthBendLathe@groups.io <SouthBendLathe@groups.io>
Subject: Re: [SouthBendLathe] Breaking carbide inserts parting off?
?
Parting in the front tool post on relatively small or light lathes can be a pain. I have a Myford ML7 at home. It's in nice nick, and I have NEVER succeeded in parting at the front. The tool digs in and snaps pretty well as soon as it touches. Fortunately, I have a rear toolpost that works a treat. If you look at a manual capstan lathe, parting is ALWAYS done from the back. I have recently acquired a rear toolpost for the railway's Colchester Triumph 2000 (AKA Clausing 15") and that will happily run a 4mm HSS blade. Internal screwcutting has now been promoted to my most feared operation in place of parting (I have to make 3 off 1 1/8 BSP nuts for steam pipe unions as soon as the 1 7/8 A/F Hex leaded gunmetal turns up).


The tool needs to be absolutely sharp. If you need to apply an increasing force to drive it in, that is a recipe for disaster.


If a hand ground blade, polish with a diamond file.


The tool must be narrow, and the smaller the lathe, the narrower the tool. I front part successfully with carbide on our 14.5" SB with taper turning attachment because that won't conveniently take a rear toolpost, but wouldn't use anything wider than a 3mm cutter. It is, nonetheless, nerve wracking.


If you look at (e.g.) the Iscar catalogue you will see dozens of different chip geometries on the same size of tip. Pick one with the correct geometry for the material you are cutting.


Work support is vital. Cut at no more than 1/4 diameter distance from the chuck or collet, and ensure they are TIGHT. Ensure there is at least 1.5 x diameter still in the chuck. If not, add a centre at the outer end whether you think it needs it or not. Neglect of any of this could result in the job deflecting badly in the chuck (etc.).


Trace and rectify any source of toolpost deflection under load. Have the compound slide set so that the sliding part is not overhanging the fixed part, and ensure that the leading corner of the toolpost is over solid metal. With the job moving downwards as in front cutting, any deflection results in the tool moving into the job, increasing the cutting force, which increases the deflection etc. With the job moving upwards as in rear cutting, the tool tends to deflect away from the job (phew!) This is why folk construct tool props for front parting.


On small lathes, part off at a relatively low speed, regardless of tool type.


Not sure about small quantities of cutting oil, but if parting something that normally takes coolant, even if optional, I would use coolant flow during parting, if available. Obviously not for cast iron or cheap brass.


Parting in stages that create a swarf anti jamming gap as described by someone else works well, especially if using the sort of carbide tip that is moulded to curl the edges of the swarf inwards and you are cutting material that produces springy swarf in spiral coils. That stuff can spring out towards flat as soon as it leaves the tip, and jam in the groove. Intermittent cutting helps by breaking that sort of swarf into shorter coils.


The cross feed during parting generally needs to be done manually, and slower than the slowest available powered feed.


I think that's all for the moment.


Eddie





------ Original Message ------
From: "mike allen" <animal@...>
To: SouthBendLathe@groups.io
Cc: sheldonlathe@groups.io
Sent: Friday, 21 Apr, 23 At 20:31
Subject: Re: [SouthBendLathe] Breaking carbide inserts parting off?

They have a rear mounted parting tool tool post they also sell . I should buy the crossslide & just have it here for when I'm ready to make one . I need to learn dovetails first .

Rear Tool Post

animal

On 4/21/2023 12:20 PM, Nick Andrews wrote:
This is on my 11" Sheldon lathe. No, haven't tried snugging the gibs but did lock the saddle. I guess if I am taking the time to make something, tweaking the gibs shouldn't seem like such a chore...

Interesting casting. Do you then just bolt your tool post on directly somehow?

On Fri, Apr 21, 2023 at 1:49?PM mike allen <animal@...> wrote:

I've seen some of those parting tool supports that folks make on youtube in the past . Folks seem to like them , but then again its the guy that made it that says its bitchin . These folks make a longer crossslide casting that you machine to finish that allows you to put a tool post behind the work so your parting tool is mounted upside down , some folks say this is a huge improvement when parting . This is one of my projects on my list to make sometime . Are you locking the saddle & tightening the crossslide & compound gibs when parting ?

animal

On 4/21/2023 11:25 AM, Nick Andrews wrote:
Now I know that for some folks parting off in the lathe is routine, but for some of us it's a real PITA. Or can be. I've tried using a nice HSS blade in a holder with lots of oil and freshly-ground tip and still got it pulling to one side, and now a 1-inch tall steel blade with carbide insert for the first time last night. Yeah, I broke the insert. And yes, it was a cheapo chinese insert. As delivered, the holder body was not well made and the bottom of the slot for the tool was tapered, causing a tilt in the cutoff blade of about 3 degrees or so. Imagine that from an ebay seller! So I put it in the the vise and milled the slot more parallel, which corrected the vertical angle of the cutoff blade, mostly. I tried to minimize stick-out but still got too much chatter. Part isn't that far out from the 4-jaw, but a tailstock center might've helped on chatter.

This is on a piece of 1.5" steel rod I got left from a construction project, no idea what alloy. Maybe I have the wrong speed going and need to crank it up for carbide cutting. Heard people say many home lathes struggle to spin fast enough for carbide but that seems unlikely. Haven't tested higher revs yet, wanted to get your thoughts.

I saw a youtube video this morning where a guy made a little foot from a piece of CRS that he bolted through his tool holder that sits on the top of the cross slide to keep it from bending down which seems interesting, but not sure if I could do that or not on my lathe.

 

开云体育

Speaking as someone that struggled with parting, it is something that requires knowing the lathe you are using. Square, center, and lock the tool tight. Lock the carriage and compound. It would not hurt to snug the cross lock just enough that you can still move it with effort. Do not extend your tool further than necessary. Watch for tool movement that would indicate something is not tight. Use back gear and go slow. Recently, I have been using .004" on the automatic cross feed of my SB9A at around 100 rpm with excellent results. The auto cross feed prevents feeding too fast and frees my hand to drip oil and catch the part. The flat belt will slip in the event of a problem.

A couple of days ago, I tried parting some mystery metal. Turns out after several attempts that it had been surface hardened. I had to cut through the first few thou with a carbide turning tool before switching to my HSS parting tool.

On 4/21/2023 4:50 PM, Andrei wrote:

The GTN2 inserts seem to be the smallest you can find easily. I saw Shars selling them for their parting tools. I never used one, but I have been tempted a few times to purchase.?
From: SouthBendLathe@groups.io <SouthBendLathe@groups.io> on behalf of eddie.draper@... via groups.io <eddie.draper@...>
Sent: Friday, April 21, 2023 4:47 PM
To: SouthBendLathe@groups.io <SouthBendLathe@groups.io>
Subject: Re: [SouthBendLathe] Breaking carbide inserts parting off?
?
Parting in the front tool post on relatively small or light lathes can be a pain. I have a Myford ML7 at home. It's in nice nick, and I have NEVER succeeded in parting at the front. The tool digs in and snaps pretty well as soon as it touches. Fortunately, I have a rear toolpost that works a treat. If you look at a manual capstan lathe, parting is ALWAYS done from the back. I have recently acquired a rear toolpost for the railway's Colchester Triumph 2000 (AKA Clausing 15") and that will happily run a 4mm HSS blade. Internal screwcutting has now been promoted to my most feared operation in place of parting (I have to make 3 off 1 1/8 BSP nuts for steam pipe unions as soon as the 1 7/8 A/F Hex leaded gunmetal turns up).


The tool needs to be absolutely sharp. If you need to apply an increasing force to drive it in, that is a recipe for disaster.


If a hand ground blade, polish with a diamond file.


The tool must be narrow, and the smaller the lathe, the narrower the tool. I front part successfully with carbide on our 14.5" SB with taper turning attachment because that won't conveniently take a rear toolpost, but wouldn't use anything wider than a 3mm cutter. It is, nonetheless, nerve wracking.


If you look at (e.g.) the Iscar catalogue you will see dozens of different chip geometries on the same size of tip. Pick one with the correct geometry for the material you are cutting.


Work support is vital. Cut at no more than 1/4 diameter distance from the chuck or collet, and ensure they are TIGHT. Ensure there is at least 1.5 x diameter still in the chuck. If not, add a centre at the outer end whether you think it needs it or not. Neglect of any of this could result in the job deflecting badly in the chuck (etc.).


Trace and rectify any source of toolpost deflection under load. Have the compound slide set so that the sliding part is not overhanging the fixed part, and ensure that the leading corner of the toolpost is over solid metal. With the job moving downwards as in front cutting, any deflection results in the tool moving into the job, increasing the cutting force, which increases the deflection etc. With the job moving upwards as in rear cutting, the tool tends to deflect away from the job (phew!) This is why folk construct tool props for front parting.


On small lathes, part off at a relatively low speed, regardless of tool type.


Not sure about small quantities of cutting oil, but if parting something that normally takes coolant, even if optional, I would use coolant flow during parting, if available. Obviously not for cast iron or cheap brass.


Parting in stages that create a swarf anti jamming gap as described by someone else works well, especially if using the sort of carbide tip that is moulded to curl the edges of the swarf inwards and you are cutting material that produces springy swarf in spiral coils. That stuff can spring out towards flat as soon as it leaves the tip, and jam in the groove. Intermittent cutting helps by breaking that sort of swarf into shorter coils.


The cross feed during parting generally needs to be done manually, and slower than the slowest available powered feed.


I think that's all for the moment.


Eddie



------ Original Message ------ From: "mike allen" <animal@...> To: SouthBendLathe@groups.io Cc: sheldonlathe@groups.io Sent: Friday, 21 Apr, 23 At 20:31 Subject: Re: [SouthBendLathe] Breaking carbide inserts parting off?

They have a rear mounted parting tool tool post they also sell . I should buy the crossslide & just have it here for when I'm ready to make one . I need to learn dovetails first .

Rear Tool Post

animal

On 4/21/2023 12:20 PM, Nick Andrews wrote:
This is on my 11" Sheldon lathe. No, haven't tried snugging the gibs but did lock the saddle. I guess if I am taking the time to make something, tweaking the gibs shouldn't seem like such a chore...
Interesting casting. Do you then just bolt your tool post on directly somehow?
On Fri, Apr 21, 2023 at 1:49?PM mike allen <animal@...> wrote:

I've seen some of those parting tool supports that folks make on youtube in the past . Folks seem to like them , but then again its the guy that made it that says its bitchin . These folks make a longer crossslide casting that you machine to finish that allows you to put a tool post behind the work so your parting tool is mounted upside down , some folks say this is a huge improvement when parting . This is one of my projects on my list to make sometime . Are you locking the saddle & tightening the crossslide & compound gibs when parting ?

animal

On 4/21/2023 11:25 AM, Nick Andrews wrote:
Now I know that for some folks parting off in the lathe is routine, but for some of us it's a real PITA. Or can be. I've tried using a nice HSS blade in a holder with lots of oil and freshly-ground tip and still got it pulling to one side, and now a 1-inch tall steel blade with carbide insert for the first time last night. Yeah, I broke the insert. And yes, it was a cheapo chinese insert. As delivered, the holder body was not well made and the bottom of the slot for the tool was tapered, causing a tilt in the cutoff blade of about 3 degrees or so. Imagine that from an ebay seller! So I put it in the the vise and milled the slot more parallel, which corrected the vertical angle of the cutoff blade, mostly. I tried to minimize stick-out but still got too much chatter. Part isn't that far out from the 4-jaw, but a tailstock center might've helped on chatter.
This is on a piece of 1.5" steel rod I got left from a construction project, no idea what alloy. Maybe I have the wrong speed going and need to crank it up for carbide cutting. Heard people say many home lathes struggle to spin fast enough for carbide but that seems unlikely. Haven't tested higher revs yet, wanted to get your thoughts.
I saw a youtube video this morning where a guy made a little foot from a piece of CRS that he bolted through his tool holder that sits on the top of the cross slide to keep it from bending down which seems interesting, but not sure if I could do that or not on my lathe.

 

I did, but didn't get the drawing. Was just the casting, but was also cheap... Like me. :)

Bill in OKC?

William R. Meyers, MSgt, USAF(Ret.)

Aphorisms to live by:
Good judgement comes from experience. Experience comes from bad judgement.?
SEMPER GUMBY!
Improvise, Adapt, and Overcome.
Physics doesn't care about your schedule.
The only reason I know anything is because I've done it wrong enough times to START to know better.
Expect in one hand, expectorate in the other. See which one gets full first.



On Friday, April 21, 2023 at 03:46:55 PM CDT, mike allen <animal@...> wrote:


??? ??? Yea , looks like it can be cut down some . These folks sell the drawings separate so a guy/gal can make their own with what they have . I don't see why it really has to be made from CI? but maybe someone else here can school me/us on that matter . the plans are only $ 6.00 for the tool post or the cross slide . I thought I had read somewhere at one time that if you bought the plans & then bought the casting later they would credit you on the plans when purchasing the casting ?

??? ??? IIRC OKC Bill bought a crossslide kit from a guy that bought it & never made it .

??? ??? animal

On 4/21/2023 1:29 PM, Andrei wrote:
Looks like that rear parting tool is designed for 12 inch and bigger lathes. You can probably shave down the casting and alter the dovetails to make it work on your Sheldon.?

Andrei

Sent: Friday, April 21, 2023 3:31 PM
To: SouthBendLathe@groups.io <SouthBendLathe@groups.io>
Cc: sheldonlathe@groups.io <sheldonlathe@groups.io>
Subject: Re: [SouthBendLathe] Breaking carbide inserts parting off?
?

??? ??? They have a rear mounted parting tool tool post they also sell .? I should buy the crossslide & just have it here for when I'm ready to make one . I need to learn dovetails first .

??? ??? Rear Tool Post

??? ??? animal

On 4/21/2023 12:20 PM, Nick Andrews wrote:
This is on my 11" Sheldon lathe.? No, haven't tried snugging the gibs but did lock the saddle.? I guess if I am taking the time to make something, tweaking the gibs shouldn't seem like such a chore...

Interesting casting.? Do you then just bolt your tool post on directly somehow?

On Fri, Apr 21, 2023 at 1:49?PM mike allen <animal@...> wrote:

??? ??? I've seen some of those parting tool supports that folks make on youtube in the past . Folks seem to like them ,? but then again its the guy that made it that says its bitchin . These folks make a longer crossslide casting that you machine to finish that allows you to put a tool post behind the work so your parting tool is mounted upside down , some folks say this is a huge improvement when parting . This is one of my projects on my list to make sometime . Are you locking the saddle & tightening the crossslide & compound gibs? when parting ?

??? ???

??? ??? animal

On 4/21/2023 11:25 AM, Nick Andrews wrote:
Now I know that for some folks parting off in the lathe is routine, but for some of us it's a real PITA.? Or can be.? I've tried using a nice HSS blade in a holder with lots of oil and freshly-ground tip and still got it pulling to one side, and now a 1-inch tall steel blade with carbide insert for the first time last night.? Yeah, I broke the insert.? And yes, it was a cheapo chinese insert.? As delivered, the holder body was not well made and the bottom of the slot for the tool was tapered, causing a tilt in the cutoff blade of about 3 degrees or so.? Imagine that from an ebay seller!? So I put it in the the vise and milled the slot more parallel, which corrected the vertical angle of the cutoff blade, mostly.? I tried to minimize stick-out but still got too much chatter.? Part isn't that far out from the 4-jaw, but a tailstock center might've helped on chatter.

This is on a piece of 1.5" steel rod I got left from a construction project, no idea what alloy.? Maybe I have the wrong speed going and need to crank it up for carbide cutting.? Heard people say many home lathes struggle to spin fast enough for carbide but that seems unlikely.? Haven't tested higher revs yet, wanted to get your thoughts.

I saw a youtube video this morning? where a guy made a little foot from a piece of CRS that he bolted through his tool holder that sits on the top of the cross slide to keep it from bending down which seems interesting, but not sure if I could do that or not on my lathe.??

 

You said there is an issue with chatter. ? Are the gibs adjusted properly on the compound and cross slide? ? Do you lock the carage firmly? ?Dont let the tool protrude any further than needed.

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