Why dial a rifle bore within .0001"

[Canadian Bushman]

JE

I think you might be a place off on some of your decimals. Ive never seen a 5 millionths indicator (.000005).

One micron is the finest resolution typically used in the machining industry and that is .000046.

.1 = 1 tenth
.01 = 1 hundreth
.001 = 1 thousandth
.0001 = 1 ten thousandth - finest resolution mesurable on most simple geometry
.00001 = 1 hundred thousandth / 10 millionths - beyond most grinders tolerances
.000001 = 1 millionth - impossible resolution of measurement with anything but lights and lasers in vacuums.

Very high end grinding and honing will generally assure uniformity within .00002 and dimensional tolerancing to +\-.00005. Even this is very expensive and time consuming. Most grinders will run +\-.0002 pretty regularly with a uniformity inside .0002.
Check out gauge pin certifications for more info - http://www.deltronic.com/literature/Deltronic-Gage-Guide-2014.pdf

Tailstock alignment is something i pay a lot of attention to because it will negate the hard work that was used to align the barrel when the reamer is traveling on a vector that is not in line with the headstock ( even with floating reamer holders ).

It is also extremely easy to change. If your foundation moves in your shop it can flex the ways and throw alignment out. If you take a heavy cut and it chatters, the machine can walk and alignment will change. If you tighten the lock more or less you can toss alignment. Over time the ways wear and alignment is different for every position across bed length. Hell sometimes the taper is ground crooked.

This is part of what urged me to start this thread. I heard guys drone on and on about how well they can idicate a crooked rod inside a barrel and then cram a reamer in a tailstock an shove it in a barrel. You will loose more tolerance on a chamber with a tailstock than you could ever gain by indicating that last .0001 out of a rifle barrel.

How many guys have checked the concentricity of the 30 deg grind in the back of a reamer? Lock that sucker onto a perfectly aligned tailstock and guess what happens.

Some things matter, some things dont. I want to spend my allowance of attention to every detail that matters and squander none on details that dont.

 

[Doublezranch]

After reading this whole thread....this is all I can come up with

 

[Edd]

It's a measuring contest.

 

[J E Custom]

JE

I think you might be a place off on some of your decimals. Ive never seen a 5 millionths indicator (.000005).

One micron is the finest resolution typically used in the machining industry and that is .000046.

.1 = 1 tenth
.01 = 1 hundreth
.001 = 1 thousandth
.0001 = 1 ten thousandth - finest resolution mesurable on most simple geometry
.00001 = 1 hundred thousandth / 10 millionths - beyond most grinders tolerances
.000001 = 1 millionth - impossible resolution of measurement with anything but lights and lasers in vacuums.


Once again CB you are correct about the decimal place I have a habit of placing the decimal in the wrong place because I always use a zero before the decimal.

It should be 0.00005 instead of 0.000005.

Here is the indicator that I used

0.5" Digimatic Indicator - Dial Indicators - Measuring - Products

PS ; It is not a measuring contest, I just wanted to share what could be done to a mid priced machine If you worked on it and did not settle for less because it took some time.

I guess I am the only one that cares how accurate the set up is because everyone that can/does
remains silent. I am glad that I don't depend on gunsmith to work on my rifles and do what I think is best. I still learned from this post and hope that Others have also.

I was also going to post the results of the bore straightness test, But will decline because no one seems to care. Sad.

J E CUSTOM

 

[Edd]

I care. I Like seeing and knowing about quality parts and workmanship.

 

[Pdvdh]

PS ; It is not a measuring contest, I just wanted to share what could be done to a mid priced machine If you worked on it and did not settle for less because it took some time.

I guess I am the only one that cares how accurate the set up is because everyone that can/does
remains silent. I am glad that I don't depend on gunsmith to work on my rifles and do what I think is best. I still learned from this post and hope that Others have also.

I was also going to post the results of the bore straightness test, But will decline because no one seems to care. Sad.

J E CUSTOM

Yeah, I thought some of the posts were needlessly negative. But I'm interested in your test data also. And for what it's worth, the smaller the number the better - as far as I'm concerned. Nobody has ever posted that smaller runout numbers hurt rifle accuracy, or that straighter bores will degrade accuracy. I'd be doing the same thing you do if I had the equipment and did my own work. I admit I'm a little obsessive/compulsive, and I enjoy being that way.

 

[IdahoCTD]

JE,

I'm curious how your measuring the ID of a bore using a OD indicator? Most things like range rods have inherent inaccuracies built in and I didn't think you were using grizzly rods so I'm wondering what your technique is.

 

[J E Custom]

JE,

I'm curious how your measuring the ID of a bore using a OD indicator? Most things like range rods have inherent inaccuracies built in and I didn't think you were using grizzly rods so I'm wondering what your technique is.

Sorry, I don't use the dial indicator in the bore Because of the rifling. I use 2 indicator rods (One in each end. They have bushings so I can fit the bore perfectly. and with the dial Indicator I have, I Should get good readings.

The problem is interpretation of the data. I just want to be sure that the results are accurate and if not I will try to improve or change the way I have been doing it.

Thanks for asking, and I do know that some do care about the accuracy of setting up but are probably hesitant about posting because of the flack I have gotten.

J E CUSTOM

 

[shortgrass]

, and I do know that some do care about the accuracy of setting up but are probably hesitant about posting because of the flack I have gotten.

J E CUSTOM

Why would anyone want to participate in a thread that becomes nothing more than a 'game' of words and 'one-ups-manship'? 40+ yrs. of precision machining allows me to understand what IS possible and what is NOT. The end result is what is truely important....

 

[Canadian Bushman]

JE

I think you might be a place off on some of your decimals. Ive never seen a 5 millionths indicator (.000005).

One micron is the finest resolution typically used in the machining industry and that is .000046.

.1 = 1 tenth
.01 = 1 hundreth
.001 = 1 thousandth
.0001 = 1 ten thousandth - finest resolution mesurable on most simple geometry
.00001 = 1 hundred thousandth / 10 millionths - beyond most grinders tolerances
.000001 = 1 millionth - impossible resolution of measurement with anything but lights and lasers in vacuums.


Once again CB you are correct about the decimal place I have a habit of placing the decimal in the wrong place because I always use a zero before the decimal.

It should be 0.00005 instead of 0.000005.

Here is the indicator that I used

0.5" Digimatic Indicator - Dial Indicators - Measuring - Products

PS ; It is not a measuring contest, I just wanted to share what could be done to a mid priced machine If you worked on it and did not settle for less because it took some time.

I guess I am the only one that cares how accurate the set up is because everyone that can/does
remains silent. I am glad that I don't depend on gunsmith to work on my rifles and do what I think is best. I still learned from this post and hope that Others have also.

I was also going to post the results of the bore straightness test, But will decline because no one seems to care. Sad.

J E CUSTOM

I care intimately about the results of your test, your results, and why you conducted the test in that manner.

I have and do spend a lot of time checking and testing my equipment, but it often becomes an overload of info when i cant undeestand what its representing, or the result is in the end product.

If you guys dont feel like commenting thats fine, its your right, but please dont dissuade other from sharing their views an opinions. No one ever gained understanding from restricting discussion.