Single Point Threading on a PM-1030V?

[darkzero]

Erik, what you are using there is not a threading tool, it's a turning tool. That insert is a CCMT that is a diamond shape which has an 80° included angle for the tip. Look at your fishtail pic, you can clearly see the gaps.

A triangle shape like TCMT has 60° included angle tips but they are still turning tools & the nose radius is tool large for threading. You can get away with a triangle insert for threading only if for a large diameter very coarse pitch thread.

 

[erikmannie]

Erik, what you are using there is not a threading tool, it's a turning tool. That insert is a CCMT that is a diamond shape which has an 80° included angle for the tip. Look at your fishtail pic too, you can cleay see the gaps.

A triangle shape like TCMT has 60° included angle tips but they are still turning tools & the nose radius is tool large for threading. You can get away with a triangle insert only if you are threading a large diameter coarse pitch thread.

I see. Is that an insert for both right and left hand turning? Or for chamfering, perhaps?

I have a threading kit that I ordered with the lathe. The inserts look a lot like equilateral triangles (60 degrees, now I am getting it!).

I am glad that I posted the pictures so that someone could point out this rookie mistake.

 

[darkzero]

I see. I have a threading kit that I ordered with the lathe. The inserts look a lot like equilateral triangles.

Triangle shape insert threading tools are usually found in these 2 types, the first being more common.

Lay down type

On edge/stand up type

Other than the tool you are using, keep doing what you are doing & you should produce some nice threads.

 

[darkzero]

Is that an insert for both right and left hand turning? Or for chamfering, perhaps?

A CCMT insert can be used for both RH & LH turning. That tool orientation you have can be used for turning both directions but generally not for heavy roughing. That tool orientation is more commonly used for chamfering but it's not a perfect 45° chamfer. It would give you a 40° chamfer but close enough & in most cases doesn't matter.

I use SCMT for chamfering which is a square shape insert for 45° chamfers. But that tool you have is convenient cause it saves on having to buy a different style insert & use inserts you ready have (assuming you have other tools that use CCMT).

 

[stupoty]

My chosen RPM was 263, and obviously I couldn't keep up with that. From now on, I will choose a lower RPM.

A lower rpm is much easier to work with , there is no shame in threading under 100 rpm

Stu

 

[shooter123456]

Also, it looks like you are using the high speed range. I would switch it to the low speed range instead. It is rare that anything needs to be done over 1000 RPM and you will have more torque throughout. That is especially helpful when threading because you can slow it down further and maintain the torque needed to cut.

 

[erikmannie]

Also, it looks like you are using the high speed range. I would switch it to the low speed range instead. It is rare that anything needs to be done over 1000 RPM and you will have more torque throughout. That is especially helpful when threading because you can slow it down further and maintain the torque needed to cut.

I agree. It was hard to dial in a choice between 109 and 158 RPM. I would have wanted somewhere in between for threading.

I will be changing it back to low range. The lathe is so scary at the higher RPMs!

 

[erikmannie]

So I was successful today. I won't be overdoing it on the photos after today, but I did get some good action shots. I am soliciting criticism (e.g. my parting blade is not sharpened correctly, my lathe is filthy).

 

[erikmannie]

So here's how it went. I looked up to find out that the major diameter of a 1/4-20 thread was .2500". This is mild steel turned to .2500". It looks like the forum is going to rotate some of the photos.

 

[erikmannie]

I bought a 1/2" threading kit from Precision Matthews when I bought the lathe. I had to use HSS today. In this kit, the carbide inserts only fit in the internal threading tool, and the HSS only fit in the tool shown below: