I use a Micro100 boring bar but I’ll look into those.
For the guys that pre-bore as much of the chamber as possible....
- Thread starter LVLAaron
- Start date
Dan-Schenk
Gold $$ Contributor
The one I use is about $30 and I just touch it up between uses with a cheap 1k grit diamond knife sharpening block. I’m a hobbiest for now but I’ve done 4 barrels using it for the crown and prebore.
STS
Silver $$ Contributor
You can put the reamer in the bore if it's already dialed in. A center in the tailstock quill and you are all set. That's the way this simple minded hillbilly does it.Using a chuck makes sense... it's gonna be hard to get the reamer between centers if a barrel is in the chuck
You guys knock off this math crap, it makes my head hurt.
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LVLAaron
Gold $$ Contributor
I spent maybe 60 or 80 dollars on a 6mm boring bar from Maritool. Good tool, but I broke it. Ended up with the bars I linked before from china/ebay. Half the price and they're my goto- especially for the larger bars.
I can do the trig, simple right triangle, but the graduations on the compound would only get close. You can set a dial indicator on the compound and run it against the TS quill for a set distance.
Sorry, somebody already posted similar.
DaveTooley
Gold $$ Contributor
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
ELR LVR
Silver $$ Contributor
"Common core math" killed it
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This.
We had a new kid in the shop and he was flummoxed by fractions.
I remember learning fractions in the 3rd grade!
I have done that as well. The reason I dial on the chuck or quill, while moving the compound, is that it gives me a true and precise measurement. Not that moving the saddle introduces a lot of error, but it is a potential variable. Since I am cutting the taper with the compound, that is all I want to measure. Also, without a digital readout, I can still easily move the compound precisely 1 inch. I know I can use a dial gauge to measure carriage travel precisely, but gauging on the quill, or the chuck, from the compound, is just easier for me. Neither way is wrong and I don't think either of us is likely wrong either. WH
Speak for yourself.
I do step bore but if I need a taper, I use the Sine bar i built for the compound on two of the latest in my shop.
Lathes --- gd auto spell.
ATAN(tpi/2) = angle per side
My 2 cents- Just cut a cylindrical pre-bore and put a little chamfer at the opening, then feed a little faster in the pre-bore section.
LVLAaron
Gold $$ Contributor
That's more or less what I do. I pre-bore just past the neck diameter, then turn a "false" shoulder that matches the shoulder angle. I find this gets the reamer started with the least drama.
I also enjoy opening a can of worms.
Do you use the same bar for crowning?
I'm currently using solid carbide no insert bars and am looking for something that I can just swap an insert.
Guess I'm a bit puzzled by all the "saves time" responses.
I just drill and pre-bore about an inch then run the reamer. Guessing you guys "saving time" are using a flush system, which means it literally takes just a few minutes to get to the depth where you need to start taking measurements.
I just don't see how with all the added time involved in the setup to taper-bore, it saves any time at all.
Probably why my wife calls me "contrary Mary"
LVLAaron
Gold $$ Contributor
Yep. Get cheap ass polished inserts in bulk from ebay as well. Even cheap polished inserts cut beautifully. Just take small bites and use a light oil.
LVLAaron
Gold $$ Contributor
Guess I'm a bit puzzled by all the "saves time" responses.
I just drill and pre-bore about an inch then run the reamer. Guessing you guys "saving time" are using a flush system, which means it literally takes just a few minutes to get to the depth where you need to start taking measurements.
I just don't see how with all the added time involved in the setup to taper-bore, it saves any time at all.
Probably why my wife calls me "contrary Mary"
I'd say most people aren't using a flush system. But if you really want to talk about saving time... look at the JGS core drills (roughing reamer)
You can bore a chamber in about 1 minute.
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