Indicating a barrel blank...

pbike said:
Jerry,

In order to reach into the chamber, neck, leade portion of the barrel to be chambered, you are using a long stylus on your indicator? Doesn't this take some of the sesitivity, or resolution out of the test indicator's reading?

Paul
Click to expand...

Yes, but, if the TIR reads zero then I figure I'm pretty close don't you?

I'm not interested in reading a certain amount of runout, I'm interested in reading no runout.

With the senstivity of an Interapid, when it shows zero travel, I start cutting.
 
Kyle,
To be honest with you I think most of this is BS or should I say overkill. I do this anyway with the copmpetition cartridges but not my hunting rifles. As Mr Jerry said the Interapid with a long stylus works good enough.
Butch
 
Matt P said:
So would you use or recommend a "range rod" or similar as sold by PTG ??
I am just getting going so forgive me if this is a silly question, but when using the range rod method if the tail stock is out of alignment does it make a difference ????
Thanks
Matt P
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The issue I have with rods are that the assumption is made the rod is perfectly round. I'm sure its so close to perfect that it really doesn't matter, but when you compound this with a spindle that may runout a little, backlash in a indicator, etc it begins to show as a tolerance stack that I personally like to try and avoid.

A well made indicator is crucial IMHO.

I indicate off the minor bore dimension as this is what the pilot of the tool is going to be inclined to follow. I single point my chambers a good length which helps promote a concentric tool engagement in the part. The floating pilot is (again IMHO) a false sense of security. The tool will take the path of least resistance, that does not mean its going to go straight down the hole. It's really easy to get it off center and have one side load heavier than the other. The result being an oversize chamber and a case web that resembles a fat girl wearing skinny girl jeans.

Tangent and concentric reamer alignment is far more critical IMO than the chosen location of where to indicate from.

Good luck and hope this helps.

C
 
pbike said:
Jerry,

In order to reach into the chamber, neck, leade portion of the barrel to be chambered, you are using a long stylus on your indicator? Doesn't this take some of the sesitivity, or resolution out of the test indicator's reading?

Paul
Click to expand...

Not if you buy the right indicator. Brown/Sharp has them with a .00005" resolution.
 
I am with Butch on the overkill thoughts... but this is the forum to discuss theories.

It would be extremely difficult to establish any difference in accuracy with a quality barrel dialed in with an indicator on the lands and grooves in the throat area or one dialed in using a piloted PT&G rod with a little weight hanging on it.

I recently bought 3 rods from PT&G and have been using them... I think they work great... only grab a 1/4 inch in the tail stock and hang 8 ounces in the middle of it...

dialinrod-0.jpg
 
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NesikaChad said:
Not if you buy the right indicator. Brown/Sharp has them with a .00005" resolution.
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I have several of these, and even with a long stylus, they are really nice. I got a few back when they came on a promo with a free set of carbide stylii. The only downside to these is the .008 total travel. But for close work, they're the dogs breakfast.

I cut a stylus in half, tig welded another section in, and away I went.
 
Dennis Sorensen said:
I am with Butch on the overkill thoughts... but this is the forum to discuss theories.

It would be extremely difficult to establish any difference in accuracy with a quality barrel dialed in with an indicator on the lands and grooves in the throat area or one dialed in using a piloted PT&G rod with a little weight hanging on it.

I recently bought 3 rods from PT&G and have been using them... I think they work great... only grab a 1/4 inch in the tail stock and hang 8 ounces in the middle of it...
Click to expand...

Why the weight ???
Thanks
Matt P
 
Matt P said:
Why the weight ???
Thanks
Matt P
Click to expand...

It preloads the rod so upwards movement is accurately detected. It takes out any 'slop' in fit between the barrel and the bushing and the bushing pilot.
 
NesikaChad said:
The issue I have with rods are that the assumption is made the rod is perfectly round. I'm sure its so close to perfect that it really doesn't matter, but when you compound this with a spindle that may runout a little, backlash in a indicator, etc it begins to show as a tolerance stack that I personally like to try and avoid.


C
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Chad, please explain....... IMO it wouldn't matter if the rod were square stock.

al
 
I am going to solder steel ball bearings to the tail stock end of the rods so they are more free to 'hang' with the weight when the chuck is lightly tightened.
 
alinwa said:
Chad, please explain....... IMO it wouldn't matter if the rod were square stock.

al
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Well, I guess I'm showing my ignorance (known to happen from time to time) I am making the assumption that a range rod is shoved inside a bore and then two indicators are put on it and the chuck is adjusted till both show zero runout. If a square rod will work just as well then obviously there's something I'm missing. I've never done it this way so I admit to knowing nothing about it.

Woops!

C
 
I think that the source of confusion is that there is more than one tool that has been called a "range rod". I believe that the one Al was referring to was the one in this video. http://www.youtube.com/watch?v=aII2tbavKnM
As the video shows, the rod does not rotate, and the only place that it is supposed to touch the barrel is at the pilot bushing, so I suppose that an indicator could be made to read off of a square rod, although I see little advantage, either in manufacture of use in making one with that shape.

Added a few minutes later: Here is a link that will further clarify. http://www.pacifictoolandgauge.com/products/gaugesnbushings/indicatorrods.htm#grizzly

In the video Gordy calls what he is using a range rod, but Dave Kiff, who makes them for sale, refers to the same tool as a Grizzly rod. Perhaps, to avoid confusion, that is the name that should be used in on line discussions.
 
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NesikaChad said:
Well, I guess I'm showing my ignorance (known to happen from time to time) I am making the assumption that a range rod is shoved inside a bore and then two indicators are put on it and the chuck is adjusted till both show zero runout. If a square rod will work just as well then obviously there's something I'm missing. I've never done it this way so I admit to knowing nothing about it.

Woops!

C
Click to expand...

Chad, the more I see (read) of you the more impressed I am. :)

al
 
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