Gunsmithing Lathe RPM for threading?

[Messmaker]

What RPM are you threading your barrel tennons at? I am currently using 120, but just curious what others do.

 

[7mmRM]

360

 

[Shanerbanner10]

300-400 depending on the lathe.

 

[Messmaker]

Do you use cuttin oil while cutting threads?

 

[Shanerbanner10]

Do you use cuttin oil while cutting threads?

I'm a hobbyist at best and am learning as I go. I have seen that cutting oil slightly improves finish.

 

[Messmaker]

I'm a hobbyist at best and am learning as I go. I have seen that cutting oil slightly improves finish.

Im just a hobbiest right now too and just wanted to know what the pros are doing. I've done about a dozen or so barrels now.

 

[ugsly308]

70 RPM

Casey

 

[parshal]

I've been doing around 60 with HSS bits. For those threading faster, are you using carbide?

 

[Shanerbanner10]

I've been doing around 60 with HSS bits. For those threading faster, are you using carbide?

I am. I started at 200 and worked my way up with practice.

 

[Clark]

As slow as the lathe will go.... and thankful I have a foot brake.

 

[300sniper]

I believe I'm at 900 on the tenon and 1100 on muzzle threads.

 

[BillyGoatMachine]

When threading metric I'm at a snails pace, but mostly hovering around 100-120 depending on the job. Manual machines.

 

[Mordamer]

The fastest speed on my lathe that I am comfortable with is 330 RPM. This is using carbide threading inserts. I like to let the insert get very close to the shoulder before disengaging the half nut and I can't do this when I go up to 500 RPM. The faster speeds certainly make a nicer finish on the threads and I envy those with CNC that can thread at proper speeds for carbide.

 

[hunter223]

Thread away from the chuck and you can thread as fast as you can accurately engage the half nut. Then there's no risk of crashing into the shoulder with the tool especially if you have a carriage stop.

 

[SubOptimal]

It is all going to depend on the diameter you are cutting and the material of both the barrel and the cutter.

 

[300sniper]

It is all going to depend on the diameter you are cutting and the material of both the barrel and the cutter.

For most people posting on this page, threading RPM is going to have far more to do with reaction time and comfort level than optimum SFM.

 

[skeetlee]

i use a kennametal partial profile insert and im threading at 440 to a shoulder and sometime 620 with a big relief groove like on a remington tenon. Carbide needs a little more speed as we all know. I never thread, or machine anything for that matter if im not operating at 100%. If im tired, i dont machine, if i have company in the shop, i dont machine. Lee

 

[Yondering]

For most people posting on this page, threading RPM is going to have far more to do with reaction time and comfort level than optimum SFM.

Yes, +1 to that. I normally thread at 200-300 rpm but would be up around 1,000 if my lathe had a foot brake or instant reversing capability. Someday... The limitation is the machine and my reaction time, not optimum SFM on gun work. Maybe on a 6" pipe, but not a rifle barrel.

And heck yeah, use cutting oil.

To the comment about threading away from the shoulder so you can go faster - the risk there is engaging the half nut in the wrong spot, or only partway (like if a piece of swarf gets in the nut, or the nut is worn, etc). Not a good option for some lathes, but fine on others. At higher speeds and using this method, if you engage at the wrong time, you'll destroy the threads before you can disengage. Not so much an issue going the other way.