Setting up the bore?

C

Curious

New member
Dave Tooley said:
Everyone is looking at the various ways to hold a reamer. Important yes and no, but not the only thing to be considered.

For your consideration and to get further into the weeds. Has there been any discussion as to the best way to setup and align the bore for reaming? Across multiple barrel makers, both cut and buttoned what works? Does it take more than one technique/setup to get consistant results, whatever that means to you? Arguably more important than how you hold the reamer. YMMV
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Great question Dave and one which deserves a thread of its own I feel.
 
This subject has been discussed countless times on this Forum.

From a Machinist standpoint, when you are attempting to true a piece up that is not truly straight with it's own self, (ie, the ID of a barrel), all you can hope for is to true two places up.

The big questions have always been, what two places do you true up, and what places do you want any subsequent machine operations to run truly straight with.

Much of this is predicated on the machinery on hand, and the craftsmans choice of set-up based on his own experience.
 
Much of this is predicated on the machinery on hand, and the craftsmans choice of set-up based on his own experience.

Exactly Jackie. We all have different experience levels. Each of us that do this more than casually have developed skills/techniques based on experience that we can't teach someone. I like to say it's 80% craftsman and 20% artist. That 20% artistry allows us to achieve repeatable results regardless of other factors. We make adjustments on the fly without knowing we do them.
 
Dave Tooley said:
Much of this is predicated on the machinery on hand, and the craftsmans choice of set-up based on his own experience.

Exactly Jackie. We all have different experience levels. Each of us that do this more than casually have developed skills/techniques based on experience that we can't teach someone. I like to say it's 80% craftsman and 20% artist. That 20% artistry allows us to achieve repeatable results regardless of other factors. We make adjustments on the fly without knowing we do them.
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Those of us that don't have much experience sure THANK YOU guys that take the time and effort to try and pass on your skills, techniques and years of experience. It's nice to have someone explain to us and answer questions. Thanks again.

Hal
 
Curious said:
Great question Dave and one which deserves a thread of its own I feel.
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Here is a thread that Gary Walters helped me set up on chambering a barrel when you have a Lathe that is perfectly suitable for the task except with a very long headstock


http://benchrest.com/showthread.php...)&highlight=Jackie+Schmidt+chambering+a+barre

If you are in this predicament, I guarantee that if you follow these steps to the letter, you will come out with a chamber, threads, shoulder, and cone that is truly straight with that very first part of the lands that the bullet "see's" when it exists the case neck.

Granted, it helps that the center hole in the Lathe spindle does run within a couple of thousands true. On our Pratt & Whitney, I reached in with a long bar and trued it up where it needed.

Be aware, you can't cut corners. But then, that's a general rule in all good machine shop practice.
 
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I saw Alex posted on the other thread about the curve in a barrel. I could see a helix, but how in the World could a barrel have a curve?
 
Butch Lambert said:
I saw Alex posted on the other thread about the curve in a barrel. I could see a helix, but how in the World could a barrel have a curve?
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Butch, curve could be the wrong term, I just use it to get the point across. I have no way to map the entire length of the bore so I really dont know exactly what the bore is up to in the middle. One thing I know is its not a consistent curve. If I indicate in the breech and have say .030" runout at the muzzle, when I flip it and indicate the muzzle there is usually a different amount of runout at the breech. Usually more. Tells me theres more curve in the bore in the muzzle end, most of the time.
 
zfastmalibu said:
Butch, curve could be the wrong term, I just use it to get the point across. I have no way to map the entire length of the bore so I really dont know exactly what the bore is up to in the middle. One thing I know is its not a consistent curve. If I indicate in the breech and have say .030" runout at the muzzle, when I flip it and indicate the muzzle there is usually a different amount of runout at the breech. Usually more. Tells me theres more curve in the bore in the muzzle end, most of the time.
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Kinda figured that was what you meant. The bore can wander differently through the length of the barrel. I think a lot of people think the bore travels in a curve.
 
Probably 70% of the barrels I have observed while spinning in a lathe, after being dialed in on both ends, look like the bore has a curve somewhere along their path. It may not be a radial Bend of constant radius but they darned sure ain't straight!

Have I seen any detriment to accuracy? None that I could detect. I had one that looked like a 2girl jump rope. Next season after it performed greatly I cut it apart at where I could best determine to be the most off axis and it MEASURED to be only 0.013" off axis.


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Alignment ring:

Jackie,

Would you please explain your alignment ring, how it is configured, etc.?

Thanks,

Pete
 
Pete Wass said:
Jackie,

Would you please explain your alignment ring, how it is configured, etc.?

Thanks,

Pete
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There is a small fit machined on the end of the barrel that the ring is a light tap on, we will call it a "metal to Metal" fit. The fit on the barrel is machined true with the lands.

This ring has no more than .001 slip fit into the spindle bore. That is what locates the muzzle end while I am performing all of the operations on the chamber end.
 
jackie schmidt said:
There is a small fit machined on the end of the barrel that the ring is a light tap on, we will call it a "metal to Metal" fit. The fit on the barrel is machined true with the lands.

This ring has no more than .001 slip fit into the spindle bore. That is what locates the muzzle end while I am performing all of the operations on the chamber end.
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Did you get my PM?
 
Thanks Jackie,

jackie schmidt said:
There is a small fit machined on the end of the barrel that the ring is a light tap on, we will call it a "metal to Metal" fit. The fit on the barrel is machined true with the lands.

This ring has no more than .001 slip fit into the spindle bore. That is what locates the muzzle end while I am performing all of the operations on the chamber end.
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I wondered if it was machined like an inverted doughnut so the barrel could shed the curve or what ever crooked word one wishes to use. I once saw a Smith use a tapered sleeve when he chambered a barrel in a long spindle. Anyway, thanks for your response.

Pete
 
jackie schmidt said:
There is a small fit machined on the end of the barrel that the ring is a light tap on, we will call it a "metal to Metal" fit. The fit on the barrel is machined true with the lands.

This ring has no more than .001 slip fit into the spindle bore. That is what locates the muzzle end while I am performing all of the operations on the chamber end.
Click to expand...

If, as Jackie mentions, the muzzle bore is dialed in closely before turning the fit for the support bushing, this will align the bullet exit on the same axis as the chamber and tenon shoulder. In doing this correctly, when a previously zeroed barrel is removed, the newly finished barrel first bullet will impact within a couple of inches of where the last bullet of the old barrel impacted. Ever notice some shooters trying to hit a 36" x 36" target to "get on paper"?

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