Do you use a parting tool to cut off your barrel?

[TRECustom]

As the title says, before crowning, when cutting to length, do you use a parting tool?

--Jerry

Yes, I just like the precision and clean cut.
Tom

 

[hogpatrol]

Just an observation. I have chambered thousands of barrels with a thread relief groove at the shoulder. All work done on my Haas. I turn the tenon length short and then plunge in with a grooving insert to get the tenon length correct and cut the thread relief groove. I usually take a cut of .020-.025" off the face of the shoulder when doing this. On every barrel I can see a change in the grain structure at the location of the last pass when I turned the tenon to length and diameter. One day I decided see how far the change went. After taking off another .040" off the face of the shoulder the ring was still there on the face of the shoulder. I stopped there or I had to buy a barrel. What did this tell me. The cutting forces on the tip of a VNMG turning insert are likely much higher than a properly ground parting tool used correctly.

I do it the same, cut short and then go straight in with a HS small radius to the pitch root diameter. Not familiar with that VNMG insert tool. Is the insert held positive, negative or neutral?

 

[Will Henry]

I part-off. I always re-indicate because most barrels are not perfectly straight so the bore is likely to be a little eccentric anyway . Cut off 4 inches of barrel and it is not unusual to see two or three thou. After parting, there is like close to 1/8 inch removed during crowning. WH

 

[geo.ulrich]

Unless I missed it, nobody said that it was distorted .100. Someone asked me how much material I took off after I parted and that's what I estimated. In a 1.25" muzzle barrel I leave a lip and then put either an 11 deg or a 0 deg crown on it. In the one I was referencing I did an 11 deg crown so it took of quite a bit of material. Don't think anyone said this is the minimum.

--Jerry

reread post #30

 

[jkohler]

If your taking off .1" like was posted I dontsee that hurting you.

That's what was said by Alex. He said nothing about it distorting the bore a .100.

 

[butchlambert]

Bandsaw - horizontal or vertical?

Sorry, the Devil made me do it.

I use a Roll In saw. It is vertical. If you don't have one you should.

 

[geo.ulrich]

If your taking off .1" like was posted I dontsee that hurting you.

That's what was said by Alex. He said nothing about it distorting the bore a .100.

reread post # 8 I don't think taking .100 is going to hurt but why take more than you need to?

 

[carlsbad]

If SCE hasn't sold all of the site equipment, there were 2 Doringer cold saw's in facilities at the Mesa, and a Doringer in the big machine shop in the PA.

The mesa has been given back to the Dept of the Navy. All of the equipment was sold at auction in 2013 or 14 and employees were not allowed to bid. I understand a lot of stuff went quite cheap. --Jerry

 

[JasonT]

Anybody ever use a hacksaw while the muzzle is in the lathe? it's not a clean cut, but facing would take care of that.

 

[Someoldguy]

I use a Roll In saw. It is vertical. If you don't have one you should.

I'll continue to use my lowly Lenox hacksaw frame and blades until I find a compelling reason to do otherwise.

 

[msinc]

If you are distoring metal, pushing metal or whatever during parting...something is wrong. Mr Ulrich hit it spot on.

I agree...somebody needs to tell me the difference between parting with a properly ground tool that is correctly set up and contouring the barrel with the tool bit required. Have it x-rayed???? Magnafluxed???? You are kidding us, right???? It might affect accuracy if you simply part the barrel and take it to the range, but a barrel that has been crowned correctly afterwards???? I am wondering what kind of "parting" is going on here????

 

[sean68]

Somebody better tell Gordy to re-do the "How to chamber a match winning barrel" video he did for Grizzly.

 

[carlsbad]

Somebody better tell Gordy to re-do the "How to chamber a match winning barrel" video he did for Grizzly.

 

[carlsbad]

As usual, there is more than one right way to do things. Clearly parting can be made to work. Clearly there are those who recommend against it. I'd even say that we can conclude there have been barrels that shot poorly because of it.

Sometimes in these discussions we get focused on what the worst thing is that can happen and how can we absolutely prevent it. That doesn't mean you'll for sure screw up if you don't follow the best practice. Sometimes rules, recommendations, and good practices are designed to prevent novices from screwing up and the experienced craftsman knows the pitfalls and avoids them. In the end, there is no one set of rules.

Since you have to take it out of the lathe to flip it around, I like using the bandsaw. If my bandsaw breaks, I'll still be able to chamber barrels.

--jerry

 

[TRA]

I do it the same, cut short and then go straight in with a HS small radius to the pitch root diameter. Not familiar with that VNMG insert tool. Is the insert held positive, negative or neutral?

VNMG is a 35 deg diamond negative 0 deg rake

Negative tooling can also be ground to have a positive cutting action in a negative insert. You loose the bottom cutting edges just like any other positive insert. That would be a VPMG insert. Not all insert manufacturers use the same nomenclature so you have to be sure what you want.

Whether a tool is negative or positive the cutter tip is still on center or a little above.

Save for a lack of communication, If you guys are talking about that real smooth, shiny surface that is about 100 thousands wide right at the OD of a round piece that's faced,, all metals including stainless chromoly and aluminum will do that. Yes it's partially due to surface speeds, but there are times where it doesn't matter how fast you spin it, that ring will still be there. And the face will have a varying surface finish.

All steel, stainless, aluminum and many other materials will exhibit this facing issue, when you use too small raw stock and don't turn that trash off the od. Most metal suppliers recommend that you remove about .06-.09 off each side. When aluminum is extruded, and steel is rolled the surface has all kinds of crap and by not removing that layer can/will cause a highly stressed part to fail. All rolled and extruded materials will have soft cores and hard tight surfaces.

 

[carlsbad]

A $400 barrel blank is not the same as hot rolled steel....just saying.

 

[msinc]

A $400 barrel blank is not the same as hot rolled steel....just saying.

I had a guy tell me once that "the best barrels are made out of re-bar"....I said, "yep, I am pretty sure that's the same stuff Ruger uses!!!"

 

[geo.ulrich]

Actually spoke with a top barrel maker today about it, he thought closer to .25" was effected by parting. Also talked about bores that opened up at the muzzle from parting, as well as curing accuracy issues by trimming the muzzle back from barrels that were parted and alot of other stories about problems traced back to it. Guys do what you want. I recommend talking to someone who deals with it on a regular basis. Keep in mind everyone's accuracy requirements are different. I deal most in BR and I do everything I can to "kid glove" things that bullets travel down.

Well o.k. here we go. "actually spoke with a top barrel maker today" sounds like listening to cnn with reliable sources statements . and " he THINKS closer to .25 was affected by parting" does or has he checked? I made some calls Tue. nite and yesterday to the ones I couldn't get ahold the previous nite to 5 barrel makers 3 cut 2 buttoned so here you go Stanley Taylor Douglas yes he parts off and yes he has / does recheck with air gage No movement , James Lederer Lederer barreals and formally of Rockcreek nothing moves and he has ,does part off, Mark b. Bartlein barrels we part off all the time here no movement, Helmut Kreiger Barrels we part off no real movement unless you turn the part blue , Wade was not in at Shilen so I can't recall name of who I spoke with but no they do not move when parting.. as for the kid glove statement its all not butterflies and unicorns when the primer ignites the powder, barrel swells and stretches powder and jacket material is laid down. I think I hit the most used at this time but don't take my word theres who I spoke with....as for everyones accuracy requirements being different B.r. is the only work I do or have done for 35 yrs. I will give credit for the rifles you have built that have won nationals and or set records but your not the only on here that's done that.....

 

[Alex Wheeler]

Well o.k. here we go. "actually spoke with a top barrel maker today" sounds like listening to cnn with reliable sources statements . and " he THINKS closer to .25 was affected by parting" does or has he checked? I made some calls Tue. nite and yesterday to the ones I couldn't get ahold the previous nite to 5 barrel makers 3 cut 2 buttoned so here you go Stanley Taylor Douglas yes he parts off and yes he has / does recheck with air gage No movement , James Lederer Lederer barreals and formally of Rockcreek nothing moves and he has ,does part off, Mark b. Bartlein barrels we part off all the time here no movement, Helmut Kreiger Barrels we part off no real movement unless you turn the part blue , Wade was not in at Shilen so I can't recall name of who I spoke with but no they do not move when parting.. as for the kid glove statement its all not butterflies and unicorns when the primer ignites the powder, barrel swells and stretches powder and jacket material is laid down. I think I hit the most used at this time but don't take my word theres who I spoke with....

I cant argue with that. I will keep bandsawing and you keep parting, no worries. If I ever get the opportunity to have some testing done so far as grain structure I'll share the results. I know a guy that can probably help with that. It may turn out to be a non-issue. Would not be the first time I was wrong, and Im ok with being wrong

 

[TRA]

A $400 barrel blank is not the same as hot rolled steel....just saying.

It had better be hot rolled. All high quality steel is hot rolled.