How to measure runout
- Thread starter tjensen
- Start date
4
4Mesh
Guest
Here's how I'd check a remington if it were me.
Take a round of aluminum 1.250 or bigger. Drill and tap the end of it with a 1/4" pipe tap. Go to your bandsaw or hacksaw and split the part on the end about 2' by cutting an X. It is very important that you cut evenly and on center. If you have a 1/16" cutter for in your mill that will go that deep, do it that way. Clean the threads, and go back to the lathe.
Turn a very close fitting thread for your action but turn the major diameter smaller than nominal by quite a bit. Go 20 under on the OD to be threaded and be sure to turn back around 1.250-1.500 length. OD is now 1.040-1.045. Thread a very nice thread high on the tolerance so the action just barely screws on. With a long allen wrench perhaps on the end of a quarter inch drive extension insert your pipe plug until it is tight and the action frozen on the expanding thread.
Now that your action is tight, you may go check alignment to your hearts delight. This method is certainly not perfect by inspection standards, but it's about as close as you can get to measuring without influencing the part. This also does not sit on the receiver face on a cut surface which would render all your measurements useless. The extra clearance you added behind the thread will allow you to check how close the face is to the thread axis. Be certain when screwing the action on not to bottom the thread. Go to where the action stops screwing on and back off at least one full revolution or the exit of the threading tool will influence the actions position on your fixture.
With as flimsy as a Remington is in the mid section, I think checking much at the rear of the action is really a waste. If the receiver end is bad, fix all at one time.
As a rule, I don't think people really check actions before truing. First, it's a pain, second, it is almost as much work to check as it is to fix, so just getting it over with is the usual process. When you're done, you know what you have in your hand and that's really about all that matters.
Take a round of aluminum 1.250 or bigger. Drill and tap the end of it with a 1/4" pipe tap. Go to your bandsaw or hacksaw and split the part on the end about 2' by cutting an X. It is very important that you cut evenly and on center. If you have a 1/16" cutter for in your mill that will go that deep, do it that way. Clean the threads, and go back to the lathe.
Turn a very close fitting thread for your action but turn the major diameter smaller than nominal by quite a bit. Go 20 under on the OD to be threaded and be sure to turn back around 1.250-1.500 length. OD is now 1.040-1.045. Thread a very nice thread high on the tolerance so the action just barely screws on. With a long allen wrench perhaps on the end of a quarter inch drive extension insert your pipe plug until it is tight and the action frozen on the expanding thread.
Now that your action is tight, you may go check alignment to your hearts delight. This method is certainly not perfect by inspection standards, but it's about as close as you can get to measuring without influencing the part. This also does not sit on the receiver face on a cut surface which would render all your measurements useless. The extra clearance you added behind the thread will allow you to check how close the face is to the thread axis. Be certain when screwing the action on not to bottom the thread. Go to where the action stops screwing on and back off at least one full revolution or the exit of the threading tool will influence the actions position on your fixture.
With as flimsy as a Remington is in the mid section, I think checking much at the rear of the action is really a waste. If the receiver end is bad, fix all at one time.
As a rule, I don't think people really check actions before truing. First, it's a pain, second, it is almost as much work to check as it is to fix, so just getting it over with is the usual process. When you're done, you know what you have in your hand and that's really about all that matters.
jackie schmidt
New member
Here is how to check one.
You will need to turn a rod about 9 inches long that is approx .700, or just a slight slip fit into the action raceway. Actually, alight interferrencepush wouldbe perfect.
Next, chuck up a piece of steel that is at least 1.200 diameter. An old barrel drop works great. Machine and thread a 1.062 16 tpi with a shoulder exactly like the barrel tenon. Being carefull not to disturb the piece in the chuck, screw the action upon this "dummy" tenon and seat it against the shoulder.
Insert your .700 rod, and place an indicator on the part sticking out.
Now, all this will tell you is how true the threads and shoulder is with the action boltway. It will not tell you where the problem is if the rod does not run true, whether it be the action threads out of whack, (pretty common), or the face of the action not machined square.........jackie
You will need to turn a rod about 9 inches long that is approx .700, or just a slight slip fit into the action raceway. Actually, alight interferrencepush wouldbe perfect.
Next, chuck up a piece of steel that is at least 1.200 diameter. An old barrel drop works great. Machine and thread a 1.062 16 tpi with a shoulder exactly like the barrel tenon. Being carefull not to disturb the piece in the chuck, screw the action upon this "dummy" tenon and seat it against the shoulder.
Insert your .700 rod, and place an indicator on the part sticking out.
Now, all this will tell you is how true the threads and shoulder is with the action boltway. It will not tell you where the problem is if the rod does not run true, whether it be the action threads out of whack, (pretty common), or the face of the action not machined square.........jackie
D
Dennis Sorensen
Guest
I insert a tight mandrel through the action.. this mandrel has 60 degree centering holes in each end...
I then place it on centers in the lathe (live center in tail stock)... spinning at about 500 rpm I remove about 1 or 2 thou from the face of the action... just enough that I can see it has made a clean cut.... the action face is now square to the bore of the action...
Then I check it on a stub in the lathe the way Jackie described... if the run out is 10 thou or less don't bother rethreading on varmint/hunting rigs... it really isn't required.
Setting up off this mandrel and machining the lock lug recesses square is more important I think... so many lug recesses are off. The bolt lugs require machining as well.
I then place it on centers in the lathe (live center in tail stock)... spinning at about 500 rpm I remove about 1 or 2 thou from the face of the action... just enough that I can see it has made a clean cut.... the action face is now square to the bore of the action...
Then I check it on a stub in the lathe the way Jackie described... if the run out is 10 thou or less don't bother rethreading on varmint/hunting rigs... it really isn't required.
Setting up off this mandrel and machining the lock lug recesses square is more important I think... so many lug recesses are off. The bolt lugs require machining as well.
P
PPP MMM
Guest
Find where the problem is
Take a piece of steel (4140) turn it to 30mm in diameter and 75mm long, drill 15-16mm diameter hole through it, turn down 25mm of the shoulder to be just 2mm larger then the threaded tenon, turn the tenon, cut the (tight fit) thread, turn (ream) the bored hole to the desired size of the action inner diameter.All under one set up.
Make an indicator holder to fit around the mandrel, install the indicator.
Screw the receiver on the jig, tight it firm, but just by hand.
Don't disturb the jig in the chuck.
Use the tightly fitted mandrel from the rear end to indicate the receiver hole runout.( just a normal indicator stand)
Take the jig out from the lathe and measure the thread/face runout.
Use the mandrel from the front with the indicator/holder mounted on it,( fit the mandrel into the hole of the jig all the way) turn around the mandrel to indicate the runout of the receiver thread/face front.
If the hole through the receive is out, the indicator dial will show it at the rear end of the receiver on the mandrel.
If the receiver is straight, the mandrel will go through both, the jig and the receiver and the face will indicate zero.
If the face of the thread is out it will show on the indicator dial, while the mandrel is fitted into the jig and rotated, while the stem of the indicator that's fitted to the holder clamping the mandrel is running on the face of the receiver.
Shoot well
Peter
Take a piece of steel (4140) turn it to 30mm in diameter and 75mm long, drill 15-16mm diameter hole through it, turn down 25mm of the shoulder to be just 2mm larger then the threaded tenon, turn the tenon, cut the (tight fit) thread, turn (ream) the bored hole to the desired size of the action inner diameter.All under one set up.
Make an indicator holder to fit around the mandrel, install the indicator.
Screw the receiver on the jig, tight it firm, but just by hand.
Don't disturb the jig in the chuck.
Use the tightly fitted mandrel from the rear end to indicate the receiver hole runout.( just a normal indicator stand)
Take the jig out from the lathe and measure the thread/face runout.
Use the mandrel from the front with the indicator/holder mounted on it,( fit the mandrel into the hole of the jig all the way) turn around the mandrel to indicate the runout of the receiver thread/face front.
If the hole through the receive is out, the indicator dial will show it at the rear end of the receiver on the mandrel.
If the receiver is straight, the mandrel will go through both, the jig and the receiver and the face will indicate zero.
If the face of the thread is out it will show on the indicator dial, while the mandrel is fitted into the jig and rotated, while the stem of the indicator that's fitted to the holder clamping the mandrel is running on the face of the receiver.
Shoot well
Peter
Last edited by a moderator:
Bill Leeper
New member
If you are going to go through all that trouble, you might just as well set the darn thing up and recut it!
The easy way is to simply turn and thread a piece in the chuck and don't remove it, screw the receiver on to it, and dial a mandrel slipped into the action. The mandrel should be a close fit over a very short distance in the receiver bridge ( It's likely best if the contact surface is spherical in cross section) and at the receiver ring right behind the lug abutments. I don't like for the piece to contact the face of the receiver, only the threads. I think it is as good a system as any. Except for the receiver face contact, this is the same as described by Jackie and Dennis.
If one has a short (12" or so) and straight piece of barrel fitted to the Remington action and a hollow mandrel truned on centers, he can install the short barrel and slip the mandrel into the receiver. Just looking through it will allow one to see a surprisingly small amount of error. It's even better if the barrel stub has no rifling. Regards, Bill
The easy way is to simply turn and thread a piece in the chuck and don't remove it, screw the receiver on to it, and dial a mandrel slipped into the action. The mandrel should be a close fit over a very short distance in the receiver bridge ( It's likely best if the contact surface is spherical in cross section) and at the receiver ring right behind the lug abutments. I don't like for the piece to contact the face of the receiver, only the threads. I think it is as good a system as any. Except for the receiver face contact, this is the same as described by Jackie and Dennis.
If one has a short (12" or so) and straight piece of barrel fitted to the Remington action and a hollow mandrel truned on centers, he can install the short barrel and slip the mandrel into the receiver. Just looking through it will allow one to see a surprisingly small amount of error. It's even better if the barrel stub has no rifling. Regards, Bill
jackie schmidt
New member
Bill
Geeze, talk about over complicating a simple situation. In Peters post, that little phrase, "make an indicator holder to fit around the mandrel" probably lost 95 percent of the hobbiest Gunsmith right there.
In all honesty, I have checked multitudes of Remington actions and have NEVER found one that did not need trueing, or at least brought to the truness that the shooters who frequent Benchrest.com expect.
So, the best thing to do is just true the thing and be done with it.
As a machinist, I do not think much of the "kits" that allow you to "true" an action without a lathe. The simple fact is, the tried, and true, method of single point tooling is the only way to accomplish this......jackie
Geeze, talk about over complicating a simple situation. In Peters post, that little phrase, "make an indicator holder to fit around the mandrel" probably lost 95 percent of the hobbiest Gunsmith right there.
In all honesty, I have checked multitudes of Remington actions and have NEVER found one that did not need trueing, or at least brought to the truness that the shooters who frequent Benchrest.com expect.
So, the best thing to do is just true the thing and be done with it.
As a machinist, I do not think much of the "kits" that allow you to "true" an action without a lathe. The simple fact is, the tried, and true, method of single point tooling is the only way to accomplish this......jackie
W
wnroscoe
Guest
The Manson tooling is the same / similar to the PTG Tooling. It relies on tight fitting bushings in the bolt raceway to align the mandrel portion of the tool. Both the receiver facing and threading tool are fitted with the same ground diameter mandrel. The key is to have two of several different size receiver bushings to assure a proper fit. No matter which technique is used for truing a receiver, it starts with a tight fitting mandrel that is held in the bolt raceway.
After owning numerous Remington’s I can tell you, the receiver face needs to be recut along with the locking lug recess. The threads, more than likely, are also out of square. After all, the receiver is mass produced and not held to the same standard or tolerances as a custom CNC job like the Stolle, Bat, and Viper etc. If your starting from scratch and don’t have any tooling, buy a custom receiver, you'll be $$$$ ahead.
William
P
PPP MMM
Guest
Jackie
Jackie, I couldn't agree more with everything that you've said in this post.
Shoot well
Peter
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Jackie, I couldn't agree more with everything that you've said in this post.
Shoot well
Peter
D
Dennis Sorensen
Guest
Do the locking lug recesses and the action face in the same set up...
check this site out... http://www.bryantcustom.com/articles/true.htm