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Pilot bushings

I've found chatter with sharp tools is usually a function of poor rigidity or odd harmonics. Typically coming up on the rpm helps. Some guys will do the wax paper trick....I have a freq drive on my lathe so rpm changes are quick and easy.
 
IMO, I would tend to be more apt to rely on a bushing if I were reaming start to finish with a finish reamer. I don't want to rely on it though.

The "modern" way of cutting a chamber using a pre-bore, and zero throat method to me, when using a bushing, would add a redundancy to the operation and may skew results depending on If you measure from the lands or grooves and where your pre-bore is in relation to that.

I've cut great chambers with/without bushings. Depends on what you are doing and how you are doing it.
 
Tucker65 said:
I chambered up a cheap fire forming barrel to fire form 300 Norma Imp. brass instead of doing that process in the actual barrel for the rifle.

The barrel was a button rifled blank and I thought this would be a good time to try and see how the outcome would be without using a bushing on the reamer.

My chambering meathod is to drill, and then set the compound to the taper of the reamer and bore the chamber close to diameter up to the body/shoulder junction. After that I just run the reamer in to cut the chamber which is basically just opening up the body diameter a little, and cutting everything from the body/shoulder junction forward.

After I finished the chamber I ran the bore scope in to take a peek at how things looked. When I spun the chuck the chamber looked great. No uneven cut lands or grooves tapering off into where the neck was cut and everything symmetrical.

So I guess from this experiment I can maybe give it another shot on an actual barrel I want to keep on the action for use other than fire forming brass. It looks just as good as one of the previous barrels I've chambered using a close fitting bushing on the reamer.
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INTJ said:
LOl! I have the same ratings.
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Pilots don’t get off the ground without a good A&P behind them :) .
 
INTJ said:
Concerning the end dialers, we know their throats are running out. Wouldn't a good floating reamer holder prevent a wallowed out throat, or is the tolerance between the bushing and reamer and between the bushing and bore allow it to wallow?
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I’d be willing to bet if you took two barrels done the two different ways with same attention to detail….the finished product you’d have a hard time telling me which one was done which way.

I know we hate hashing this topic here but to say one way produces ”wallowed out throats” just isn’t an accurate statement….based upon my experience but don’t believe me. Prove it to yourself…
 
WSnyder said:
What is an “end dialer” and why are their throats running out?
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They dial in the breech and the muzzle, usually using range rods or gauge pins. Because barrels aren't straight, dialing in this way means the throat area is running out a little.
 
INTJ said:
They dial in the breech and the muzzle, usually using range rods or gauge pins. Because barrels aren't straight, dialing in this way means the throat area is running out a little.
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I will then assume that does not include those that dial in at the location of the throat and the muzzle.
 
WSnyder said:
I will then assume that does not include those that dial in at the location of the throat and the muzzle.
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Sorry, I miss understood….^^^^ that’s what most of the “end dialers” do, I’m not aware of anyone who does breach and muzzle….because that would in itself would create a possibility for a “wallowed out“ throat. ;)

My post above was not assuming breech and muzzle but instead throat and muzzle. Sorry…ignore my post above do not test because indicating those two points, I agree with you if that bore isn’t crazy straight neither will your chamber.
 
INTJ said:
Depends on what kind of plane...... ;)
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Any certificated aircraft has the stamp of an IA and an A&P on its log books. From a J-3 to the Concord, they are all required to have their signatures (in one way or another) before they can fly.
 
INTJ said:
I recently had to cut an 11 degree crown with an 11 degree reamer that I have used many times. The reamer chattered. I fixed it with emory cloth and decided I wouldn't use a crown reamer again unless I had a snug bushing.
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No doubt. Unlike a pre-bored hole, nothing to guide the cutter; it's just wobbling around in the hole if using a floating holder. Been meaning to ask Manson if they could grind a form cutter for a recessed target crown, it'd be a big time saver...

I've also ascribed to the theory that that a properly fitted pilot prevents chatter, but I haven't had the balls yet to chamber without one and risk a $3-$400 blank. I see GM has some back in stock so one of them would be a cheaper learning experience.

I'm assuming those that ascribe to the "no pilot" school (pun intended, enrolled in ground school :)),
buy solid pilot reamers? It's rare that I've run into a groove dia more than a half thou under- so why spend the $$ for a live pilot?
 
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