how can i improve the finish of my bbl threading

Many of the threading tricks (like upside down, backwards, etc.)
are ways of trying to get a little more precision out of lighter weight
(and strength) machines.
Most of the work on smaller fasteners would be done using a
screw machine cutting lathe.
They are optimized for smaller threads.

Sharp steel (HSS is better) works better than carbide especially in smaller tool sizes.

Having some carbide around can often be handy.
Make initial rough cuts using carbide, then switch over to HSS SHARP tools.
No point in making most of the cut with that carefully sharpened HSS cutter.
The wide availability of diamond tooling for sharpening HSS cutters makes things go very well.
A fine diamond paddle for the last few strokes on HSS puts Arkansas stones to shame.
 
Last edited:
2000 lbs.....
brickeyee said:
Many of the threading ticks (like upside down, backwards, etc.)
are ways of trying to get a little more precision out of lighter weight
(and strength) machines.
Most of the work on smaller fasteners would be done using a
screw machine cutting lathe.
They are optimized for smaller threads.

Sharp steel (HSS is better) works better than carbide especially in smaller tool sizes.

Having some carbide around can often be handy.
Make initial rough cuts using carbide, then switch over to HSS SHARP tools.
No point in making most of the cut with that carefully sharpened HSS cutter.
The wide availability of diamond tooling for sharpening HSS cutters makes things go very well.
A fine diamond paddle for the last few strokes on HSS puts Arkansas stones to shame.
Click to expand...
 
A friend has

a Hardinge Chucker, I think it's called, with a threading rig on it that is a cam that pulls the tool way far away from the work when it gets to where it is suppose to stop. Slickest outfit I've ever seen. Would speed up threading by at least 1/2 I'd think.

Pete
 
Joel said:
Like most things in machining lots of methods work. Some are more preferred than others but if whatever method you chose works and you are happy with it it's not my place to criticize your method. I was taught in various formal training settings that the 29 or 29 1/2 degrees had several advantages. Primarily less tool pressure and better chip flow. Normally I have the compound angled and the last light finish cuts are straight in using the cross slide. I have limited experience with CNC lathe threading so take this with a grain of salt. In the CNC usage my limited experience the most common pre-canned cycle is by alternating cutting on both sides of the v groove until the finish plunging the finish passes followed by 29/30degree tool path.. I don't remember a pre-canned CNC cycle that straight plunged the complete cycle but as stated I have only used a couple of different conversational CNC lathes for threading.

I tend to take fairly heavy cuts for rough threading and using the compound set at an angle on manual machines aids chip flow. That being said I have used zero degrees and that got the job done.

Some of the carbide tool geometry does not perform well without sufficient SFPM. My preferred insert for threading is the Kennametal NTP style inserts,. It's old school for insert technology but for manual machines I haven't found an insert that I like better.
Click to expand...

This! is pretty much everything I was taught by a retired aerospace machinist that taught a class I attended a few years back. It's the way I thread V threads usina a variety of inserts. For going slow with SS barrels I use the Arthur Warner HSS threading tool with a positive rake insert. Works good and lasts very well too.
 
I had a friend

who was an engineer at Kennametal. I asked him what he used to thread barrels with and he said Tool Steel. Said he got tired of chip balls with carbide. I had gotten a chip ball with carbide previously and what generated the question to him. I went back to my tool steel.

Pete
 
so does any make a one sided hss thread cutter /
where one can get real close to an edge look at bbl threads, a full size tool will not fit,
cut down one side and maybe
thanks'
 
rsmithsr said:
so does any make a one sided hss thread cutter /
where one can get real close to an edge look at bbl threads, a full size tool will not fit,
cut down one side and maybe
thanks'
Click to expand...
The AR Warner company makes one. Make sure that you get the one that also uses grooving inserts. I use the positive rake cutters. Only about .125" wide and will cut upto a shoulder. Use plenty of good cutting lube, bacon grease works well.
 
All:

Great thread, I have learned a lot!

This is what I do (in the interest of full disclosure, I am self taught!) - I leave the carriage locked, and cut a relief at the shoulder so I can stop the threads. I have a Clausing Colchester, I thread at 125rpm with a positive relief threading tool set at the workpiece horizontal axis. Initial cuts are .005", lessening to .003" as engagement increases - with the final cuts at .001" (straight in, no offset).

For stainless I like straight Tap Magic for thread cutting. I finish the threads externally with some 600 grit paper.

I do follow chase finish threads with an adjustable die (I must be the only person who ever got a barrel stuck in a bench rest action - that's an OMG moment! LOL), more to make sure my measurements are correct before test fitting.

Thanks again for all the great information!

kev
 
I was taking a machinist night class at the shipyard and I was told to use 29.5 for threading. They didn't have any small lathes except in the tool room, so size had nothing with what we were taught. I always used HSS for threading and ground tools for doing OD and ID work. As stated before the more you use the machine you will become comfortable with higher feeds and speeds. Maybe you could practice on some round stock that has little value.
Good luck with your threading issues....it will all come around.

Mort
 
uncle sam taught me the basics plus a little. and yes 29.5 was taught.
i have used it in the past, but not today
as i stated i turn away from the headstock which means inverted and backwards
IT WAS ALL CARBIDE due to size, but now i have warner's hss tool,,,installed for reverse away from the headstock. i expect to see a better finish.
 
After threading I touch up the top of the treads with a file and the V's as well. Leaving sharp edges on the tops can cause unnecessary problems. I damned near got a barrel locked up in the action by not doing just that. Just something you don't hear mentioned much as being an additional step. I also polish using a purple scotch bright as being my own very last step.
 
Louis.J said:
After threading I touch up the top of the treads with a file and the V's as well. Leaving sharp edges on the tops can cause unnecessary problems. I damned near got a barrel locked up in the action by not doing just that. Just something you don't hear mentioned much as being an additional step. I also polish using a purple scotch bright as being my own very last step.
Click to expand...

If you turn your starting point a few thou (0.010 - 0.020) undersized, you can skip filing the tops of the threads. I like Cratex (rubberized abrasive) for final polish - it's available in sticks (as well as bits and bobs for the Foredom/Dremel) that work great.

GsT
 
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