Hey John, nice threading job!
Your results are exactly why I use the lay-down threading inserts. I made a 5/8-10 LH ACME thread like that in making a new cross slide screw for a friend's Harrison M300 lathe that he was rebuilding. I used the same type of insert.
Be aware that there are four basic styles of pitch-specific full-form (cresting) inserts available. You can get:
RH external
LH external
RH internal
LH internal
They are available in multiple sizes, though not all pitches are available in all sizes. Obviously you wouldn't be able to find a 4TPI insert in a 8ER size, just as you can't get a 72TPI insert in a 22ER. We are very lucky here in the US, as we can buy singles of the inserts (though I always buy two of each.) I usually choose to buy the inserts from KBC Tools because they offer Vardex brand, though Carmex is also good. Ebay is another great source. Also good are inserts from the major makers such as Seco, Kennametal, Iscar, Valenite, Walter and others, but avoid any from Sandvik Coromant as they're not the standard thickness.
One of the worst/best features of using the lay-down threading insert systems is the fact that the better holders use a interchangeable carbide insert anvil (or, seat) to compensate for unusually high or low lead angles. Typical threads are OK for the standard -1.5º (external tools) or +1.5º (internal tools) that the toolholders have built into them, and they are supplied with a neutral 0º anvil. There are = & - anvils of 0.5. 1.5, 2.5, 3.5 and 4.5 degrees, both for internal and external threading. Some very small shank external or small diameter internal threading tools do not have anvils because of the size of the tool, so you're limited to the standard 1.5º. That covers the overwhelming majority of common threads.
This interchanging of anvils allows you to make left hand threads with what would normally be right hand inserts by tipping the insert in the opposite cant. A common (a good to use) application of this ability is to use a left hand tools to make right hand threads or vise-versa. That allows the people uncomfortable with threading to a shoulder to thread from the shoulder out. There's a great illustration of the various configurations on Page E46 of the 2007 Valenite Turning catalog. If I turn that page into a PDF file, where's the best place to post it here?
BTW, a friend of mine recently bought a complete set of the Vardex anvils for $78. He'll never want for the right one again! I built my complete set one or two at a time, costing me a lot more than that.
Your results are exactly why I use the lay-down threading inserts. I made a 5/8-10 LH ACME thread like that in making a new cross slide screw for a friend's Harrison M300 lathe that he was rebuilding. I used the same type of insert.
Be aware that there are four basic styles of pitch-specific full-form (cresting) inserts available. You can get:
RH external
LH external
RH internal
LH internal
They are available in multiple sizes, though not all pitches are available in all sizes. Obviously you wouldn't be able to find a 4TPI insert in a 8ER size, just as you can't get a 72TPI insert in a 22ER. We are very lucky here in the US, as we can buy singles of the inserts (though I always buy two of each.) I usually choose to buy the inserts from KBC Tools because they offer Vardex brand, though Carmex is also good. Ebay is another great source. Also good are inserts from the major makers such as Seco, Kennametal, Iscar, Valenite, Walter and others, but avoid any from Sandvik Coromant as they're not the standard thickness.
One of the worst/best features of using the lay-down threading insert systems is the fact that the better holders use a interchangeable carbide insert anvil (or, seat) to compensate for unusually high or low lead angles. Typical threads are OK for the standard -1.5º (external tools) or +1.5º (internal tools) that the toolholders have built into them, and they are supplied with a neutral 0º anvil. There are = & - anvils of 0.5. 1.5, 2.5, 3.5 and 4.5 degrees, both for internal and external threading. Some very small shank external or small diameter internal threading tools do not have anvils because of the size of the tool, so you're limited to the standard 1.5º. That covers the overwhelming majority of common threads.
This interchanging of anvils allows you to make left hand threads with what would normally be right hand inserts by tipping the insert in the opposite cant. A common (a good to use) application of this ability is to use a left hand tools to make right hand threads or vise-versa. That allows the people uncomfortable with threading to a shoulder to thread from the shoulder out. There's a great illustration of the various configurations on Page E46 of the 2007 Valenite Turning catalog. If I turn that page into a PDF file, where's the best place to post it here?
BTW, a friend of mine recently bought a complete set of the Vardex anvils for $78. He'll never want for the right one again! I built my complete set one or two at a time, costing me a lot more than that.