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Posted: 2/21/2011 12:22:56 PM EST
Lately I discovered this site and have since built my first AR. With a couple connections I made while building I was able to get a client who wanted his stainless bull barrel threaded for a flash hider he already had on hand. This barrel is 1" in diameter and the flash hider was made for a 3/4" barrel, so the barrel had to be machined with a step accordingly. Let me know what you think of my shops work, the client was happier then a pig in ****. Also I was able to thread this barrel still assembled to its upper & forearm. My lathe allows for up to a 4" diameter spinning inside the machine, so long as there is enough barrel to grab a hold of for machining.

Pics…












Link Posted: 2/21/2011 12:23:40 PM EST
[#1]













Link Posted: 2/21/2011 12:25:15 PM EST
[#2]
Cool
Link Posted: 2/21/2011 12:25:35 PM EST
[#3]
Looks great!
Good job!
Link Posted: 2/21/2011 12:30:11 PM EST
[#4]
Link Posted: 2/21/2011 12:30:53 PM EST
[#5]
Very nice.
Link Posted: 2/21/2011 12:33:10 PM EST
[#6]
looks good
Link Posted: 2/21/2011 12:36:08 PM EST
[#7]
Looks good, man.
Link Posted: 2/21/2011 12:37:19 PM EST
[#8]
Thanks Guys

Quoted:
Did you cut the threads centered off the OD?


Yes sir, then I doubled checked it to the Id chamfer.   With turbine part machining your aren't afforded any mistakes.
Link Posted: 2/21/2011 12:39:26 PM EST
[#9]
Link Posted: 2/21/2011 12:42:09 PM EST
[#10]
Well, the problem with doing the threads of the OD is that if the bore isnt concentric, you will now get baffle strikes.

you never, ever, setup barrel threads based on the OD of the barrel, you set up the threads concentric to the bore.

I had an amateur smith ruin a barrel of mine this way.... thankfully it was only a 10/22 barrel....

Hope that works out for your customer....
Link Posted: 2/21/2011 12:47:18 PM EST
[#11]
Link Posted: 2/21/2011 12:55:12 PM EST
[#12]
Quoted:
Quoted:
Well, the problem with doing the threads of the OD is that if the bore isnt concentric, you will now get baffle strikes.

you never, ever, setup barrel threads based on the OD of the barrel, you set up the threads concentric to the bore.

I had an amateur smith ruin a barrel of mine this way.... thankfully it was only a 10/22 barrel....

Hope that works out for your customer....


What he said ^

Most all bores aren't concentric to the OD.  You should have this thread trashed quick. Pun intended


Thread trashed? How so? I just stated above that before anyting was cut the ID was checked.
Link Posted: 2/21/2011 12:56:20 PM EST
[#13]
Just curious - Was all that cutting down without oil? I imagine dry cutting would generate a lot of heat ... would that adversely affect the barrel temper or harmonics?

.
.
Link Posted: 2/21/2011 12:58:09 PM EST
[#14]
Quoted:
Quoted:
Well, the problem with doing the threads of the OD is that if the bore isnt concentric, you will now get baffle strikes.

you never, ever, setup barrel threads based on the OD of the barrel, you set up the threads concentric to the bore.

I had an amateur smith ruin a barrel of mine this way.... thankfully it was only a 10/22 barrel....

Hope that works out for your customer....


What he said ^

Most all bores aren't concentric to the OD.  You should have this thread trashed quick. Pun intended



Again, what he said.  We do alot of barrels (esp. for supressor attachment), and we NEVER go off the o.d..  We also like to remove the barrel form the upper, just a thought.
Link Posted: 2/21/2011 1:01:21 PM EST
[#15]
Some cans and mounts require a relief cut at the base of the threads.  Without this, it will not seat on the shoulder, causing skewed mounting and baffle/endcap strikes.  I have had this happen to me twice, from a manufacturer that should know better.
Link Posted: 2/21/2011 1:02:20 PM EST
[#16]
looks great, well done
Link Posted: 2/21/2011 1:07:17 PM EST
[#17]
We did one last week too!

Link Posted: 2/21/2011 1:09:35 PM EST
[#18]
Quoted:
Just curious - Was all that cutting down without oil? I imagine dry cutting would generate a lot of heat ... would that adversely affect the barrel temper or harmonics?

.
.


Actually after my shops 10+ years of turbine component machining and trying all sorts of lubricating options what we found was that Crisco on a brush, applying as you’re are machining works best. It melts down the piece you are machining and lubricates amazingly well and allows clear visibility of what you are machining. This barrel was very soft from what we are used to, but to reduce heat generated we shaved it down little by little.
Link Posted: 2/21/2011 1:10:30 PM EST
[#19]
Link Posted: 2/21/2011 1:12:23 PM EST
[#20]
Anytime anyone tries anything new on this board they better expect to get cut all to pieces. I think you did a good job personally. I would be more worried about the uneven weight on the barrel caused by the upper rec and handguard possibly causing some wobble if not perfectly put in the mount.  However, you look like you have done things like this before.
Link Posted: 2/21/2011 1:13:04 PM EST
[#21]
Quoted:
Quoted:
Quoted:
Well, the problem with doing the threads of the OD is that if the bore isnt concentric, you will now get baffle strikes.

you never, ever, setup barrel threads based on the OD of the barrel, you set up the threads concentric to the bore.

I had an amateur smith ruin a barrel of mine this way.... thankfully it was only a 10/22 barrel....

Hope that works out for your customer....


What he said ^

Most all bores aren't concentric to the OD.  You should have this thread trashed quick. Pun intended



Again, what he said.  We do alot of barrels (esp. for supressor attachment), and we NEVER go off the o.d..  We also like to remove the barrel form the upper, just a thought.


Damn boys, RIF (Reading is fundamental).

He checked it off the ID. You can center off OD and work the piece as long as you check it off the ID to verify accuracy.
Link Posted: 2/21/2011 1:20:40 PM EST
[#22]
Quoted:
Quoted:
Quoted:
Quoted:
Well, the problem with doing the threads of the OD is that if the bore isnt concentric, you will now get baffle strikes.

you never, ever, setup barrel threads based on the OD of the barrel, you set up the threads concentric to the bore.

I had an amateur smith ruin a barrel of mine this way.... thankfully it was only a 10/22 barrel....

Hope that works out for your customer....


What he said ^

Most all bores aren't concentric to the OD.  You should have this thread trashed quick. Pun intended


Thread trashed? How so? I just stated above that before anyting was cut the ID was checked.


If you customer has the one in a million barrel with 0 runout, good for him. If its off just a few thousandths he'll have a very noticeable POI shift, if its off 7 or more thousandths hes asking for a baffle strike.   I mean this in the nicest way, I'm suggesting you have this thread deleted because you are admitting you dont know how to thread a rifle barrel properly.


Firstly, even if my shop had made a mistake, which I know we didn't, I wouldn't run from anything or have anything deleted. I would own up to our mistake and handle it with with interest.
Secondly, 7 thousandths? In turbine machining you are playing in a world of 0-3 thousandths.

We aren't rookies by any means, it's just happens to be the first barrel we have done.

Link Posted: 2/21/2011 1:26:30 PM EST
[#23]
For anyone who is interested in checking my shop out.

We have since bought a new building and upgraded our shop but this will give you an idea.

*link deleted* (I don't want to upset the admins)
Link Posted: 2/21/2011 1:28:37 PM EST
[#24]
Looking at the pictures, I don't see any baffles in that flash suppressor,



Oh, wait, wut, OK now I remember, Flash hiders aren't supposed to have baffles.......................



Looks like a pretty good job, better than I could do.



And welcome to arfcom, the source of more info than wikipedia.

Link Posted: 2/21/2011 1:36:41 PM EST
[#25]
Nice job.
Link Posted: 2/21/2011 1:41:04 PM EST
[#26]



Quoted:


Looking at the pictures, I don't see any baffles in that flash suppressor,



Oh, wait, wut, OK now I remember, Flash hiders aren't supposed to have baffles.......................







1) Looking at the pictures, I don't see a lower either, so I guess it will never shoot bullets.



2) Obviously you cannot tell the difference between a Flash Hider and a suppressor mount that incorporates a FH.



 
Link Posted: 2/21/2011 1:41:05 PM EST
[#27]
Link Posted: 2/21/2011 1:47:18 PM EST
[#28]
In on this love fest....
Link Posted: 2/21/2011 1:48:20 PM EST
[#29]
Sounds like a range report from barrels owner will be needed on this one.
Link Posted: 2/21/2011 1:50:07 PM EST
[#30]
Quoted:

Secondly, 7 thousandths? In turbine machining you are playing in a world of 0-3 thousandths.

We aren't rookies by any means, it's just happens to be the first barrel we have done.



VrodRay

Bigbore is trying to help you.

I do not have a second thought that YOUR machine and YOUR shop is capable of keeping things to 0-3 thousandths.

What Bigbore is telling you is the people who made the BARREL probably did NOT keep the bore centered in the barrel to that degree of perfection.

If the bore is not centered and you make a PERFECTLY centered thread and crown on that barrel YOU have messed up in the job of mounting a suppressor mount on the barrel.

When working on barrels you have to base all the work off the bore, were it sits in relation to the barrel; not as you did and make the work a relation off the outside diameter of the barrel.

Trying to help ya man

Work looks nice keep it up.
Link Posted: 2/21/2011 1:55:10 PM EST
[#31]
Quoted:
Quoted:
Quoted:
Quoted:
Quoted:
Quoted:
Well, the problem with doing the threads of the OD is that if the bore isnt concentric, you will now get baffle strikes.

you never, ever, setup barrel threads based on the OD of the barrel, you set up the threads concentric to the bore.

I had an amateur smith ruin a barrel of mine this way.... thankfully it was only a 10/22 barrel....

Hope that works out for your customer....


What he said ^

Most all bores aren't concentric to the OD.  You should have this thread trashed quick. Pun intended


Thread trashed? How so? I just stated above that before anyting was cut the ID was checked.


If you customer has the one in a million barrel with 0 runout, good for him. If its off just a few thousandths he'll have a very noticeable POI shift, if its off 7 or more thousandths hes asking for a baffle strike.   I mean this in the nicest way, I'm suggesting you have this thread deleted because you are admitting you dont know how to thread a rifle barrel properly.


Firstly, even if my shop had made a mistake, which I know we didn't, I wouldn't run from anythinghave anything deleted. I would own up to our mistake and handle it with with interest.
Secondly, 7 thousandths? In turbine machining you are playing in a world of 0-3 thousandths.

We aren't rookies by any means, it's just happens to be the first barrel we have done.



I understand this is your first barrel, and I'm attempting to help you out here, but you're missing my point.  I'm sure your threads are concentric to the OD.  The problem is, its a miracle when any production barrel has a bore concentric to the OD.  3-7 thousandths off is common run out.   Barrel threads NEED to be cut centered off the BORE, not the OD, that way when the threads are cut they are concentric to the BORE.  

Rule #1 for threading a rifle barrel is center of the bore, NEVER center off the OD.

Last piece of advice - - delete your URL posted above, or the mods will trash this thread for unpaid advertising - that's site policy, not me.


I never said they both were completely concentric with one another. Ok here was my dial in procedure I did along with one of my machinists.
When starting to dial in the barrel I was obviously on the OD since it is kind of hard to dial in on a chamfer on the ID since you are no were near center. After arriving around 2-3 thousandths on the OD I placed the dial on the ID and Just happened to be on the money. I respect your opinion, you have obviously been doing this awhile, but again, we know what we are doing also.

I apologize if I sounded a little harsh back there, but when my work is immediately questioned without knowing the points which I know I've covered I snap back a little.

And I appreciate the head up about the link. Not trying to advertise, just showing we are a professional outfit.
Link Posted: 2/21/2011 2:14:53 PM EST
[#32]
Link Posted: 2/21/2011 2:18:44 PM EST
[#33]
this is fun.

I was always told if you ask 10 machinist how to do something that you will get 15 different answers. I always added that at least 8 or 9 of them will be the wrong way.

I've threaded a few barrels. I never post pics. my first one was pretty nasty compared to this one

your threads look pretty good for a first barrel. continue
Link Posted: 2/21/2011 2:21:48 PM EST
[#34]
IN for the range report.
Link Posted: 2/21/2011 2:22:20 PM EST
[#35]
Link Posted: 2/21/2011 2:24:49 PM EST
[#36]
Nice, makes me want to buy an upper like that :)

BTW, what suppressor mount is that? YHM?
Link Posted: 2/21/2011 2:32:08 PM EST
[#37]
That mount would be for an AAC. However it looks like its the FH that comes with the Sig rifles, which (if my memory serves me correct) AAC has said NOT to use with their suppressors.

Unless its a really old AAC mount.
Link Posted: 2/21/2011 2:35:16 PM EST
[#38]
Looks like it turned out well. I am no machinist, I work with wood and +/- 1/32 to 1/64  is all I need to hold to. But I am surprised that you were able to have the entire upper chucked up in that lathe. One would think it would be all over the place as the weight certainly isn't  the same on all sides of the barrel. But what do I know,lol!!!
A range report would be great.
Link Posted: 2/21/2011 2:52:35 PM EST
[#39]
Quoted:
Looks like it turned out well. I am no machinist, I work with wood and +/- 1/32 to 1/64  is all I need to hold to. But I am surprised that you were able to have the entire upper chucked up in that lathe. One would think it would be all over the place as the weight certainly isn't  the same on all sides of the barrel. But what do I know,lol!!!
A range report would be great.


Thanks!
Of course ideally the barrel would be separated from the upper. But the guy didn't want to disassemble it, and the machine has the capability, so we went for it. When first mounting it I had a very close eye on it inside the tube (The tube rotates with the chuck). So I was prepared to brace it with towel/rags/expanding foam if necessary, but she spun like a top with no vibration, perfectly centered in the tube.
Link Posted: 2/21/2011 2:56:40 PM EST
[#40]
Hey OP, NICE JOB! Screw all the nay-sayer's. If they actually would read the posts, they would know you checked everything for center and alignment after the job was done. I've never seen a bull barrel with that done, looks great, it looks like you guys do quality work
Link Posted: 2/21/2011 3:05:09 PM EST
[#41]
Looks good .  Keep up the good work .


Link Posted: 2/21/2011 3:43:22 PM EST
[#42]
I'd love to learn how to machine parts - hence me being a tad bit jealous of your capabilites!

Link Posted: 2/21/2011 5:53:28 PM EST
[#43]
Quoted:
Did you cut the threads centered off the OD?


Monkey see monkey do...
Link Posted: 2/22/2011 4:16:38 AM EST
[#44]
Link Posted: 2/22/2011 8:39:04 AM EST
[#45]
Listen to ADCO they know there shit.
Link Posted: 2/22/2011 8:42:51 AM EST
[#46]
Looks good.

Since I've no idea how to do anything like this, I have no say in the process.

I'd like to see a pic of the complete setup with can attached.
Link Posted: 2/22/2011 9:28:23 AM EST
[#47]
No one is arguing process here, we are both in absolute agreement that the ID is what should be used as reference for cutting the thread. It's just that bigbore had jumped to conclusions as if I had said both the OD and the ID were completely concentric. All I had said was that I began on the OD and got close and then checked the ID and happened to be right on the money. Some of you guys are like a sewing circle having read two posts and you've got the whole story down.
I'm of the school of thought where if I saw work of this caliber, I might start the sentence off with, nice work, or clean job etc, and not ask "how'd you do it" right off the bat and then proceed to tell you you don't know what you are doing......but that's just me, I must be crazy.
By the way, 2 hour turn around time.
Link Posted: 2/22/2011 9:39:23 AM EST
[#48]
Nice job. The main thing I like about the thread is the disclosure that apparently most regular production barrels have a bore that is a little 'off' from being perfectly concentric. This is interesting because when it was discovered that some CMMG barrels were like that a few years ago, you would have thought that they were the only company selling such barrels judging by the indignant comments posted here.
Link Posted: 2/22/2011 9:40:14 AM EST
[#49]
Quoted:
Nice job. The main thing I like about the thread is the disclosure that apparently most regular production barrels have a bore that is a little 'off' from being perfectly concentric. This is interesting because when it was discovered that some CMMG barrels were like that a few years ago, you would have thought that they were the only company selling such barrels judging by the indignant comments posted here.


Makes me want to throw a few barrels in my lathe and see what happens.
Link Posted: 2/22/2011 10:25:28 AM EST
[#50]
Gotta love the ar15.com attitude...  one way to do it right or its wrong and useless.

That said, nice work.  Im just getting started in machining, looking to buy my own lathe soon, can't imagine a 4" spindle bore. Lathe must be pretty big.  A lot of people don't realize that you can turn things off center to the OD, even things that aren't round at all.  I don't claim to know it all but I see no problem with what you did.  If the bore is spinning centered, its centered.


Out of curiosity, what in the production process causes the 3-7 thou. Runout?
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