Dialing in a barrel

Pete Wass said:
It was made to attach to my 4 jaw back plate. I tried using it for this job. I got the barrell dialed in with it BUT, there is .037" of runout @ the outboard end and it sure looked wierd under power. This spider is a perhaps 8" or 10" long aluminum tube with 2 sets of 4 set screws spaced 5 or 6" apart. There was zero runout on the face of the backer plate with the Spider off it.

IThe front Spider seems somewhat easier to use than going back and forth, chuck to tail, from what I could see.

Pete
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Pete, I don't know about everyone else but you have me totally confused!! An 8" or 10" long aluminum tube with 2 sets of 4 screws??

Try the old COLD remedy I always use-equal parts of honey, lemon juice, and a good bourbon...the honey and lemon are optional!
 
Pete there is a Youtube of Bob Pastor- VIPER chambering a barrel with something similar to what you are talking about.
 
Colds:

JerrySharrett said:
Pete, I don't know about everyone else but you have me totally confused!! An 8" or 10" long aluminum tube with 2 sets of 4 screws??

Try the old COLD remedy I always use-equal parts of honey, lemon juice, and a good bourbon...the honey and lemon are optional!
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As you probably know,Colds are viruses and there is nothing easy to get that will kill them. All any remedy does is make one feel better, which I think is your point. I'll get into the Single Malt later today. Got a great bottle of 12 YO Irish Single Malt :) .

People who go for Antibiotics only build a tolerance of the Antibiotics. When they really need it, it may not work. Don't know why Dr.'s prescribe them, or Opiates, for that matter. We have a whole culture built around both medications.

Pete
 
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It is probably the same fixture we use to hold and dial in an action for blueprinting. I use mine for short barrels all the time.
 
Pete Wass said:
I have seen a number of others in videos as well.

Pete
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That type may be widely used but it is still the dumbest setup I've ever seen to chamber a barrel. That general type design is ok for action truing but turning and threading??
Hellsbells Pete, that thing has the tenon overhung 12-15" from the headstock front bearing.....dumb, dumb, dumb!! Even in a big lathe with 10"-20" spindle bearings it still would be disastrous.


One of the most important rules of accurate machining it to keep the workpiece and tool at minimum overhang. That stupid thing goes half way to the tailstock!!
 
I know it doesn't mean much but I agree with jerry. My headstock is long to on my big grizzly. I made a tube that slipes over the end of a barrel on one end, with brass tipped set screws that makes the barrel longer. the tube threads on the other when im working on the crown of a short barrel. a simple extenson is all you need. Lee
 
JerrySharrett said:
That type may be widely used but it is still the dumbest setup I've ever seen to chamber a barrel. That general type design is ok for action truing but turning and threading??
Hellsbells Pete, that thing has the tenon overhung 12-15" from the headstock front bearing.....dumb, dumb, dumb!! Even in a big lathe with 10"-20" spindle bearings it still would be disastrous.


One of the most important rules of accurate machining it to keep the workpiece and tool at minimum overhang. That stupid thing goes half way to the tailstock!!
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Never considered that aspect Jerry but I see your point.

Pete
 
I undanderst

stool said:
he is dialing in over about 4 inches.....anyone want to guess what the muzzle end of the bbl is doing ?

i "think" using as much bbl length as possible to dial in is the best..........
if you cannot dial in on either side of the head stock, then make a tool/fixture that centers the muzzle end inside the head stock.

once again moving work away from the head stock, when it does not have to be away from the head stock, is working contrary to the design of the machine.


your mileage may, no, will vary....
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The issue becomes how much potential error is acceptable, Eh? One can indicate until the cows but once the spindle starts to turn, under power, we must accept what the results are or start over.

Pete
 
JerrySharrett said:
That type may be widely used but it is still the dumbest setup I've ever seen to chamber a barrel. That general type design is ok for action truing but turning and threading??
Hellsbells Pete, that thing has the tenon overhung 12-15" from the headstock front bearing.....dumb, dumb, dumb!! Even in a big lathe with 10"-20" spindle bearings it still would be disastrous.


One of the most important rules of accurate machining it to keep the workpiece and tool at minimum overhang. That stupid thing goes half way to the tailstock!!
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Jerry make a valid point Pete. I'd call it a cardinal rule to minimize overhang. However IF you limit your self to light cuts AND look for any deflection should be OK.

If I were in your situation I'd shorten the jig to about 5", space adjusting screws 4". I'd bore 4" diameter 6061 to about 1.5 inches leaving a wall thickness of 0.125 and bolt or weld to a proper backplate.

Semper Fi,

WallyW
 
Pete Wass said:
The issue becomes how much potential error is acceptable, Eh? One can indicate until the cows but once the spindle starts to turn, under power, we must accept what the results are or start over.

Pete
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Pete there is no acceptable amount of error if that amount can be removed!!
 
I think I have gleaned - -

stool said:
he is dialing in over about 4 inches.....anyone want to guess what the muzzle end of the bbl is doing ?

i "think" using as much bbl length as possible to dial in is the best..........
if you cannot dial in on either side of the head stock, then make a tool/fixture that centers the muzzle end inside the head stock.

once again moving work away from the head stock, when it does not have to be away from the head stock, is working contrary to the design of the machine.


your mileage may, no, will vary....
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there are a couple of theories on indicating barrels. Some believe the only important area is the area of the chamber and just ahead of the throat when chambering and some believe in having the muzzle and breech reading the same. I tend to think like the former folks. Considering many barrels are banana shaped, What is the point of having the muzzle indicating the same as the breech? One has no relationship to the other if there is a bend in the barrel, in my view. It would be pretty tough to convince me otherwise.

Pete
 
Pete Wass said:
there are a couple of theories on indicating barrels.

One has no relationship to the other if there is a bend in the barrel, in my view. It would be pretty tough to convince me otherwise.

Pete
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Pete, the path of the exited bullet does not follow the curvature within the barrel. It is important that all the forces of ignition and recoil be as near along the same axis as possible, unless, of course, you want to shoot around corners!!
 
JerrySharrett said:
Pete, the path of the exited bullet does not follow the curvature within the barrel. It is important that all the forces of ignition and recoil be as near along the same axis as possible, unless, of course, you want to shoot around corners!!
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A very important point Jerry. IMO that axis must be the bore. What else are we to use? Where are all these "bent" barrels coming from. Modern barrels are made to such close tolerances. When was the last barrel anyone received that the O.D. varied significantly from the I.D.? Wouldn't suggest anyone use that as a reference but does illustrate the care used in making modern barrels.

Carefully aligning muzzle and breach using the bore as a reference is, IMO, all important. If you have a bent or crooked barrel I'd ship it back and get a straight one. BTW what method does the non-barrel maker use in discovering a unstraight barrel?

Semper Fi,

WallyW
 
wallyw said:
A. BTW what method does the non-barrel maker use in discovering a unstraight barrel?

Semper Fi,

WallyW
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If you have both ends aligned, turn the spindle on and look through the bore. What we are calling "badly" bent barrels are generally, at the extreme, about 0.015". That s not much really unless you miss the matchup of the chamber and the bore by that much. One thing for sure I don't want a "straightened" barrel!!
 
wallyw said:
A very important point Jerry. IMO that axis must be the bore. What else are we to use? Where are all these "bent" barrels coming from. Modern barrels are made to such close tolerances. When was the last barrel anyone received that the O.D. varied significantly from the I.D.? Wouldn't suggest anyone use that as a reference but does illustrate the care used in making modern barrels.

Carefully aligning muzzle and breach using the bore as a reference is, IMO, all important. If you have a bent or crooked barrel I'd ship it back and get a straight one. BTW what method does the non-barrel maker use in discovering a unstraight barrel?

Semper Fi,

WallyW
Click to expand...

No Wally, barrels are not straight. This is not a problem. I would never send back a "bent" barrel. In fact, I believe that it's harder to get the straight(er) ones to shoot well, I rejoice in the curve.

99.9% of all "machinists" set up on the premise that the line of the bore from chamber to muzzle is a straight line. Most others, your new friend Jerry included, believe that "straight or crooked, it's best to TREAT IT AS A STRAIGHT LINE..." And to align the two points as much as possible to the proscribed "centerline of the rifle."

I don't believe this and in fact build the entire rifle around the throat, attempting to install a stress-free chamber coaxial to and aligned with that small section of bore in which the throat occurs.

I can predict within an inch or two where my first bullet will hit at 100yds. Many times that poi is many inches from the centerline of the rifle, as much as 16" or even 20" IMLE

This is a big bone of contention, a big disagreement between accuracy-minded gun machiners :)

BTW, Jerry "won't read this" because I'm "on his ignore list"

It might get cornfusing, our replies may be unrelated, redundant or contradictory but not directly related.....

facebook drama ALA BRC, LOL!!!

al
 
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