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Gunsmithing Who laps their barrel tenon threads?

chipsfan

Sergeant
Full Member
Minuteman
Jun 20, 2009
333
1
48
Northeast USA
Does anyone here lap in their barrel tenon threads? I've read about a couple guys doing it and saw it in the Gritters/Grizzly video. I never have and was wondering if it was worth a shot.
 
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What would be the benefit? If your threads are cut right and the fit is where it's supposed to be I can't see what this would benefit. I put lube on my tenon threads and run my action on a couple times. That's about it.
 
I have..... but after reading every article on the subject of thread fit...for years...done by revered builders.....I wasted my time...
 
What would be the benefit? If your threads are cut right and the fit is where it's supposed to be I can't see what this would benefit. I put lube on my tenon threads and run my action on a couple times. That's about it.

That's how I roll- I wondered if I missed something- hence the question
 
What would be the benefit? If your threads are cut right and the fit is where it's supposed to be I can't see what this would benefit. I put lube on my tenon threads and run my action on a couple times. That's about it.

There are few machines that can create "perfect threads". There are always asperities that will cause the male/female thread mating to create stresses you can't see along with variations from the actual cutting process.

When you lap the threads then every thread in the assembly, when torqued is carrying the same amount of load.

Lubing the threads and runing the tenon in and out of the action a few times IS a from of lapping. The only thing missing is a fine lapping compound that truly complete the job.

Read this---- Secrets of the Houston Warehouse
Makes for a great read. Some shooters getting together in a HUGE warehouse (controlled environment) in order to see what did and didn't work when searching for maximum accuracy.

Yes, this is a "Tactical Forum" not a "Benchrest Forum" so lapping the barrel tenon is probably going to be lost among all the other "good enough" practices.
 
One of the guys I know told me he always lapped the bbl tenon/receiver threads, but a couple of years ago, he had a real expensive experience while lapping threads on a custom 50BMG action & bbl. Got them galled so tightly that he had to cut the bbl off and send the action out to another machinist to cut the bbl stub out of the action.

The nicest looking threads I've ever seen on a bbl came out of Alan Warner's shop. I pulled & replaced a shot-out Palma bbl that he'd done, and have always wondered how on earth he manages to get that kind of finish on threads. Not that the beautiful finish on his threads does a better job than mine, but I'm still impressed by the finish he gets. Maybe he uses very sharp HSS threading tools at very slow speeds, or maybe it's due in part to the cutting lube he uses, or maybe both plus some other issue that I'm not aware of. I do know that I get a slightly better finish by using T15 inserts on a Warner Tool Co. threading tool than with carbide laydown inserts, but still nothing close to what Alan & Dan's threads look like.
 
considering alot of benchresters dont even really torque the action to the barrel, i dont know what lapping a tenon thread would gain them? a class 3a/b fit is a class 3 a/b fit. if its cut properly with a sharp tool thats been set up properly i dont think lapping is necessary or even benefical but thats just me. i agree fitting them together may be a light lap but thats as far as i go. i do however like all my components torqued.

i use arthur warner hss threading tool along with the vipers venom at 70 rpm and get great results. ymmv
 
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Dennis:

I only use lay down inserts. There is no reason in the world I can fathom to lap a thread on soft material to obtain a fit. Thread gaging is another story.
Typical speed for me on a manual lathe at 16 to 20 pitch is 160 to 200 rpm to the shoulder. If I;m in the HLVH with the auto kick out, 500 to 800 on any thread is OK with me.

HTH

Alan
 
Who laps their barrel tenon threads?

Dennis:

I only use lay down inserts. There is no reason in the world I can fathom to lap a thread on soft material to obtain a fit. Thread gaging is another story.
Typical speed for me on a manual lathe at 16 to 20 pitch is 160 to 200 rpm to the shoulder. If I;m in the HLVH with the auto kick out, 500 to 800 on any thread is OK with me.

HTH

Alan

Looking at both your threading tools on littlemachineshop.com, they both use stand-up inserts. Could you link to the tool you recommend?
 
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When you lap the threads then every thread in the assembly, when torqued is carrying the same amount of load.

Actually not true. Even with perfect threads no two threads are carrying anywhere near the same load. With a standard v-form thread the first thread carries ~36% of the load, 2nd ~23%, 3rd ~15%, 4th ~9%, etc... This is why some have tried Spiralock thread systems or way back when Stiller put a tapered thread in some of his early actions. Stiller abandoned it because they were different and too many people complained about the slight extra work fitting them.
 
Looking at both your threading tools on littlemachineshop.com, they both use stand-up inserts. Could you link to the tool you recommend?

Are you asking what a laydown inserted tool is? Alan W is talking about using a tool like this LAYDOWN THREADING TOOL

Just realized you are probably mixing up two different Warner's. See the post below.
 
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Alan,
Thanks for the reply & info. I've never attempted to cut threads to a shoulder at anything faster than 160rpm; I'd imagine that threading on a Hardinge at those speeds with carbide would probably result in a nicer finish than my typical speed of 85-115rpm. Initially, I used Kenametal N2R inserts, but found a deal on Iscar laydown inserts & holder, and most often use them. I'd be afraid to run much faster than 650rpm with a cast iron chuck, and am not sure whether my Buck Set-True chucks are steel or cast - been a few years since I machined the D1-4 backplates for them, and don't recall what the back side of the Bucks looked like.

I mistakenly stated that I also use T15 inserts from Warner Tool Co, which is your company; should've taken the time to at least look up Arthur Warner Co. to get that right. Wish I'd have asked the owner of that shot-out Palma bbl if I could keep that bbl - just to show those threads to a few of the guys I know who do their own bbl work.
 
Who laps their barrel tenon threads?

Just realized you are probably mixing up two different Warner's. See the post below.

You're right, I thought he was the same Warner.
 
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Are you asking what a laydown inserted tool is? Alan W is talking about using a tool like this LAYDOWN THREADING TOOL

Just realized you are probably mixing up two different Warner's. See the post below.


Ok, I've been still thinking about this so I'm bringing it back up. I recently started a thread asking for tooling advice, and was advised to get a threading tool with HSS inserts. The HSS inserts should give a better surface finish at the low speeds we're using while threading on a manual lathe.

As a result, I was planning to get this tool with standup HSS inserts for external threading, and the smaller one for internal.

Threading Tool, 1/2" Indexable HSS Inserts - LittleMachineShop.com

Would this be my best option, or should I look for one with lay down carbide inserts? Does anyone make a threading tool with lay down HSS inserts? For reference, I'm using a South Bend Fourteen and don't have coolant yet.
 
Most all of what I use is carbide. I use some hand ground HSS for general work or when I need something special. A lot of people are happy with the Warner HSS tooling. I own a bunch of it, rarely use it and prefer my carbide for gunsmithing. I am not aware of any HSS laydown threading inserts. They might be out there but I haven't come across any. The problem with carbide is it's expensive and there are a lot of choices. If you make the wrong choice you've got some expensive tooling that doesn't work like you expected. Best to ask what others use and go from there.