Indicating Barrels to chamber

[SBLH10]

Here is one and have seen plenty of other.

 

[B Nettesheim]

Before chasing the tenth indicator while setting up a barrel it would be wise to see what you are working with first by checking out your spindle bearings.

 

[tobnpr]

You're working off of two (and only two) points.
Pick 'em.
Some use the muzzle/throat.
I use breech/throat.

Arguments can be made for either method.

 

[Alex Wheeler]

I dial in as good as I can, less than .0001". Its time consuming sometimes, especially on the longer cases but its how I do it. Thats why I appreciate grooves without ratchet or radius error. Its really hard to dial in barrels to .0001" when the groove is all over the place. A lathe's bearings are the most important part of the machine, I wouldn't want one than had over .00005".

 

[WayneShaw]

Its really hard to dial in barrels to .0001" when the groove is all over the place

Not many talk about this, but it's there. Good for you.

 

[DaveTooley]

I've seen some crazy stuff in barrels. Concave land tops. Lands that had a .001" raised lip on one side. Land tops that were sloped. Grooves where the radius didn't match the caliber. That's probably the most common.
But they all shot well.

One thing that helps is setup the indicator ball above the centerline of the barrel. That puts a slight side load on the system as you rotate the barrel. That enough to steady the ball in one spot.

 

[WayneShaw]

I use the biggest "ball" end stem I have, less craziness when rotating.

 

[338 Mollett]

I wouldn't want one than had over .00005".

I'm curious what machine has less than one ten thou.spindle bore run out ?

 

[Alex Wheeler]

I'm curious what machine has less than one ten thou.spindle bore run out ?

Not spindle bore run out, we dial in barrels so all I care about is the bearings. Spindle bore would only matter if using collets. If I dial in a ground rod in either of my lathes neither will show more than half a tenth. I have a new M300 and an old Sheldon I replaced the bearings in. Hard to find bearings for some of the old lathes and they are not cheap.

 

[jkohler]

I’ve been eyeing one of those M300 myself.

 

[tom]

I dial in the throat and about 1" in front of it. I dial in as good as I can, less than .0001". Its time consuming sometimes, especially on the longer cases but its how I do it. Thats why I appreciate grooves without ratchet or radius error. Its really hard to dial in barrels to .0001" when the groove is all over the place. A lathe's bearings are the most important part of the machine, I wouldn't want one than had over .00005".

I order mine without ratchet, and error-free

 

[tobnpr]

I dial in the throat and about 1" in front of it.

Where did you find a stylus long enough to do this?
The Interapid 312-B15 is 2.75, and that won't even come close to an inch beyond the throat for some magnum length cartridges?

 

[Alex Wheeler]

I made one.

 

[linebaugh]

No I choke up on it as much as possible for rigidity. Aligned is aligned regardless of where to hold it.

Good point. Learned a new way to think there.

 

[SBLH10]

The Interapid 312-B15 is a .0005 reading indicator. Making a longer stylus makes the indicator read in larger tenths and the stylus is balanced to it's return spring weight which makes it read accurately. So making a longer stylus is no easy task to do. Be for you know it the indicator is now reading .001's not tenths and not always repeating accurately. This what the people at Long Island Indicator Service told me.
Chet

 

[Alex Wheeler]

That's all true. Overcoming the spring has not been an issue, the stylus is resting on the bore. The .001" reading has not either because we are not measuring. Just dialing to zero. It's not ideal but it's the best way to dial 4 or 5 inches up a barrel, and a whole hell of a lot better than not dialing there at all. I generally don't use a pilot, on the really long cases you have to have the barrel dialed in to get a concentric throat. Not dialing it in is not an option for me. Even with a bushing you wont get a perfect throat if the bores running out up there. That long stylus takes a lot longer to use and its finicky, there is a technique to getting accurate results, but I wont do it any other way. Not until they come out with some other way of indicating that deep.

 

[SBLH10]

Very good point and I totally agree. Just never looked at it that way. That's why you are the man.
Chet

 

[Alex Wheeler]

I wouldnt say that, its just the way I do things. It achieves what I want in a chamber job. Not saying its the best or only way.

 

[Hal]

Alex did make a whole new stylus or extend a stylus ? How long did you make yours ?
Any idea the thread size?
Do you dial in using the top of the rifling or the groves ?
Thanks for posting useable info.

Hal

 

[tobnpr]

I don't think it would be possible to extend a short stylus- they're tapered, and extending the taper would make it about as rigid as a piece of toilet paper IMO.

To be five inches long- and not deflect/be 100% repeatable- it would have to be much thicker at the indicator end. I'd make it as stout as possible to be sure it can't deflect or deform. "ZERO" deflection/distortion at that length ain't gonna happen with a skinny wire.

Way above my pay grade to figure out how "heavy" it could be, and still allow the indicator to function correctly- and Long Island would be a good source to discuss this with.

It's an good idea. But rather than a five-tenths Interapid, I'd use a tenths indicator. A stylus that long would be indicating nearly a full thousandth between hash marks at that length.