For the guys that pre-bore as much of the chamber as possible....

[Jonnyofalltrades]

For the guys that "hate math".
Trigonometry is one branch of math that has many applications in the real world.
It's not like that other math that only exists in theory.

I hate math.

I LOVE trig!

 

[LVLAaron]

I know I should know some of it. It would solve a lot of problems in the shop for sure.

 

[Sniperhandle]

I know I should know some of it. It would solve a lot of problems in the shop for sure.

I wouldn't worry too much over it. You can work with your hands and figure out other ways, Same as myself, Math is not my best subject, But I do use a scientific calculator when I can.

 

[V35]

I like trig, use it often at work and in my shop, I guess put me in the nerd category .

I tried the taper bore, trig it in, verify with a indicator on a flute, and went back to just step boring.

 

[FireMedic]

Step boring for me. I don’t like moving my compound if I don’t need to. Step boring just seems to work with no downside

 

[Lucky Shooter]

I learned early on to taper bore and use a floating pusher and still
think its a very logical method-----even after spending the time
tapping on the compound to copy the reamer's body taper.

I don't chamber many barrels but this method always works very well.

When all is said and done, results are what matter---to each his own.

A. Weldy

 

[ELR LVR]

For the guys that "hate math".
Trigonometry is one branch of math that has many applications in the real world.
It's not like that other math that only exists in theory.

I hate math.

I LOVE trig!

Trig, (The study of Triangles)
If Ancient Egyptians can do it, we should be able to.

 

[X Count]

Maths is easy

Phone+google+triangle calculator= results

 

[SKWERLZ]

I know I should know some of it. It would solve a lot of problems in the shop for sure.

I know Pythagorean theorem well because i calculated the square for concrete foundations for years.
Also rudimentary diameter and circumference calculations because of my job now is basically making carbon fiber and fiberglass tubes.

 

[ShaunBrady]

Even faster is do it the other way around. Magnetic base with the indicator on the side of the compound. Roll saddle 1" . Adjust angle till it matches the body taper. Example; 308 Win has a body taper of .00524" TPI per side

The big time and sanity saver here is moving the saddle instead of cranking the compound.

The version I do is mag base on the bed, indicator on the side of the compound.
Zero the indicator at the compound pivot using the cross slide.
Roll the saddle to exactly 3" on the DRO. If my compound was longer, I'd go further.
Adjust the compound angle to give the body taper at 3".
Check zero at the pivot. Repeat as required which shouldn't be more than a couple laps.
Align the tool holder using the tailstock quill.

The larger process is drill to remove material.
Cylindrical bore using the carriage feed and cross slide to establish concentricity.
Taper bore until the pilot is 50% engaged using the reamer as a plug gage to check progress.

I'll cylindrical bore most short action stuff. Longer cartridges with low body taper are taper bored. The 33XC is my poster child for this.

I try to balance the travel and resulting wear of the throat section of the reamer against the need to clean out the body diameter. An inch is enough for higher taper cases. About 1.5" is better if the taper is below 0.010 "/" on the diameter. I'm an amateur so reamer life is meaningless. It's unlikely I'll wear one out. Maximizing the surface finish of the throat over several barrels is the priority.

 

[JFrank]

Wow, there certainly are many ways to accomplish the task.
I’ve read almost every post and took several mental notes.
Thanks guys

 

[DaveTooley]

For the guys that "hate math".
Trigonometry is one branch of math that has many applications in the real world.
It's not like that other math that only exists in theory.

I hate math.

I LOVE trig!

I have one of my Fathers college books, Handbook of Mathematical Tables and Formulas. Copyright 1940
It has 275 pages, 165 of tables. I use 9 pages in the trigonometry section and the natural trig function tables. Not as easy as a Google search but it keeps my head in the game.

 

[ricco1949]

I have one of my Fathers college books, Handbook of Mathematical Tables and Formulas. Copyright 1940
It has 275 pages, 165 of tables. I use 9 pages in the trigonometry section and the natural trig function tables. Not as easy as a Google search but it keeps my head in the game.

My Math Tables Book sits next to Machinist Handbook. I'm trying to learn to use the trig functions in phone calc app but the click sequence often eludes me and it's just easier to use use the standby MTB when needed.

 

[Sniperhandle]

My Math Tables Book sits next to Machinist Handbook. I'm trying to learn to use the trig functions in phone calc app but the click sequence often eludes me and it's just easier to use use the standby MTB when needed.

Google has trig or any other calculation or tables, It is very easy. And it is without going to another website usually.

 

[Infrequent Shooter]

This.
We had a new kid in the shop and he was flummoxed by fractions.
I remember learning fractions in the 3rd grade!

When I go the grocery store I carry extra change. If the bill is 27.76 I will give the cashier 10, 20 bill and 76 cents. It will fuck up the entire grocery line for a about two minutes.

 

[xr650rRider]

When I go the grocery store I carry extra change. If the bill is 27.76 I will give the cashier 10, 20 bill and 76 cents. It will fuck up the entire grocery line for a about two minutes.

Oh no, your that old guy with the coin purse. Licking fingers digging out a penny..........which is discontinued now.

 

[xr650rRider]

Trig or Log tables with a slide rule interpolating between values. Sure was happy when TI came out with a scientific calculator in 1974 or 1975. HP had one but never liked RPN.

 

[DaveTooley]

Trig or Log tables with a slide rule interpolating between values. Sure was happy when TI came out with a scientific calculator in 1974 or 1975. HP had one but never liked RPN.

My Dad bought me a TI out of the Wall Street Journal in about 1974. He paid $120. Big big money then. I was the first to have one, raised my grades by one letter grade. Slide rule, I still have mine and my father in laws.

 

[jackieschmidt]

You guys are WAY overthinking this.

There is one reason to pre bore a chamber before reaming. That is to establish a true bore to what ever spot in the barrel you want it to run true with. You say, “won’t a drill do that? No.
The best way to establish a true hole with a predetermined indicated spot in the barrel’s ID is to single point bore it.
I bore it on the same taper as the reamer to where the reamer live pilot sticks in just far enough to encounter the indicated ID where the throat will be.
All I am using the reamer for is to establish the final finish and dimensions of the chamber.

By the way. When I chuck a barrel and true it up, the first thing I do is establish the best chamber I can. I then work all other operations off of the chamber.

 

[Lucky Shooter]

I possibly missed the point on all this---please
correct me if I'm wrong.

Are we facing a choice of matching the body
taper per the print----or----copying the actual
taper of the reamer.

Should we trig it or tram it ?

A. Weldy